pls evaluate my assumptions

[Cameron]

hi,

so, this is a long story that I will attempt to summarize but also attempt to include enough info to "evaluate my assumptions".

last year I bought a harness and distributor from affordable efi and an ecm from dynamic efi.  I have been learning the old fashioned way for quite some time now, with lots of greatly appreciated input from this forum.  however, I still had an issue that has been dogging me.

I have been troubleshooting an intermittent problem where the engine would just die for apparently no reason.  seemed to be worse when the engine heated up - but would still sometimes run perfectly.

knowing that an engine just needs 3 things to run I have spent various amounts of time troubleshooting each.  culminating today with my question on the air cleaner which was disappointing since my config was virtually identical to Jon's.  so, unlikely I had found the culprit. 

the reason I suspected it, was yesterday on a test run the engine started running *horribly* (not just intermittently dying, but backfiring and missing..  those symptoms went away when I pulled the engine cover and the air cleaner (was going to try and 'watch' for a fuel issue).

I drove the coach today with out the 4' 4" hose to the air cleaner thinking that I was troubleshooting if it wasnt getting air.  and unfortunately it started running really poorly again.  I pulled over, tried a couple flashes of different bin's all with the same result.  so, I thought 'I will just pull the darn air cleaner again!'.  it worked.  the coach ran perfect.

so, after 15min of good performance, I thought 'ok, lets put the snorkel back on and see how it does (engine cover was still off).  the coach still ran perfect.

so, I started thinking 'what could be different with the engine cover on!?   my PO had put some heat shielding on the bottom of the hatch.  which, because he wasnt a big spender amounted to not much more than aluminum foil..  I pulled that off and drove another 15min - and the coach ran perfect..

well, here is where I would like the evaluation;

1. do you think that the aluminum foil would be causing electrical interference?  it seems really likely that all the backfiring and misfiring could be related to that.

2. would that explain the symptoms being worse when the engine (and that foil, i'm sure) was hot?

3. would that explain the intermittent dying? (oh, something I didnt include above, I replaced the spark plug wires while troubleshooting spark as a culprit).  so, could the new wires have exacerbated the dying to misfiring (they are spiral core - not solid - but now running at the recommended 500ohm per foot - old wires were couple thousand ohm per foot, hence changing them)?

thanks in advance for any opinions!

Cameron

[Jon Roche]

My only thought is some sort of vacuum leak….   Something with the adaptor or ??  That changes when it gets bumped or flexed? 

 I cant imagine the foil causing electrical issue unless it is shorting something.  

On Aug 19, 2024, at 5:25 PM, Cameron <cbi...@gmail.com> wrote:



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[Gerald Work]

Hi Cameron,  I have not posted in a long time but your issue sure sounds like an air intake issue that is somehow caused by the cover being on.  Years ago a bunch of GMCs were evaluated at the Dyno Shop in Santee, CA.  They found that all the GMCs running any kind of after market air cleaner caused restriction of air making  a tight turn going down into the carb (the Jeep hat style things) caused the coaches to run poorly and stop making power at rather low RPMS.  You say yours runs well with the cover off and poorly with the cover on so I think you should look closely at how air is introduced into your EFI.  Take the cleaner clear off and run with the hatch off.  If it runs well, then put the hatch back on and run it again.  If it runs poorly then look at your intake manifold/EFI housing to see if the air intake is too close to the bottom of the cover resulting in a sharp air turn into the EFI air intake.  If it runs ok with the air cleaner off and the housing on, then suspect the air cleaner restricting air flow.

Jerry

Jerry Work

The Dovetail Joint

Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR

 

glw...@mac.com

http://jerrywork.com

[Keith V]

First, backfiring and misfiring is certainly not an air supply issue, gotta be electrical, otherwise it wouldn't come and go.

Air restriction would have to be pretty severe to cause the engine to die, and backfiring? I doubt it

Is something shorting to the aluminum foil? A connector being crunched and opening?

Look at the injector harness where it goes into the TB, maybe the hat is causing problems? (but backfireing? Doubt it)

---

From: gmcm...@googlegroups.com <gmcm...@googlegroups.com> on behalf of Cameron <cbi...@gmail.com>
Sent: Monday, August 19, 2024 5:25 PM
To: gmcm...@googlegroups.com <gmcm...@googlegroups.com>
Subject: [GMCMH-EFI] pls evaluate my assumptions

 

[James Hupy]

Well, it most ceetainly could be a vacuum leak under the throttle body. You absolutely need to check for the correct gasket. This kind of stuff frequently rears it ugly head when adaptimg a 2 barrel valve body on to a 4 barrel manifold. Easy check, spray wd-40 around the base of the valve body when engine is running. If there is any change, investigate.
Jim Hupy

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/LV8P223MB11472183F867820A07110412A48D2%40LV8P223MB1147.NAMP223.PROD.OUTLOOK.COM.

[Johnny Bridges]

Begins to sound like dying coil, module, rotor, or cap.

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/LV8P223MB11472183F867820A07110412A48D2%40LV8P223MB1147.NAMP223.PROD.OUTLOOK.COM.

[Jon Roche]

I think his ignition stuff is new and been swapped out trying ti figure this out????

A lean condition will cause backfiring and misfiring.  I know that from experience.     

Are you logging while you are test running?

I cant remember if you habe the wide band o2 working or not?  Or if you ever got the fuel

Pressure display figured out. 

On Aug 20, 2024, at 9:41 AM, 'Johnny Bridges' via GMCMH EFI <gmcm...@googlegroups.com> wrote:



To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/433787871.5295137.1724164885535%40mail.yahoo.com.

[Cameron]

keith,

totally agree that the misfiring and backfiring do not sound like intake issues.  when I pulled the engine cover (the first time) wasnt looking for an air problem. was looking for a fuel problem.  it just so happened, that pulling the snorkel seemed to have solved the problem when it was actually pulling the engine cover that solved it and I conflated that solution with the air intake.

I dont think anything is/was shorting to the foil.  was really hoping this group would say the foil too close to the distributor was the culprit.  anybody else using that sort of heat shield under the engine cover?

I will drive it home (in a few days) and see if it runs properly.  if it does, I will look for something that could need grounding...

Gerald - what are you using for an air intake?  something different than the snorkel setup?

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/LV8P223MB11472183F867820A07110412A48D2%40LV8P223MB1147.NAMP223.PROD.OUTLOOK.COM.

[Cameron]

well, unfortunately it is not the heat shielding.  it does appear to be the heat, tho.  I drove it home today, and about 45min into the trip it started running really rough.  backfiring, missing, etc.  I pulled over, pulled the engine cover and let it cool down.  after about 5 min, leaving the cover off, drove it home and it ran fine.  

I would like to say it is the ignition module, but I *just* replaced it before this trip.  I also bought 'special' heat sync paste (instead of the presumably cheap stuff that comes with the module).  I am also running with out the fender wells in, since I have been doing various work.  so, it is as cool under there as it could be (today was only 70's driving home, so not even that hot outside, really).

the coil is 'pretty new' but not *brand new* like the ignition module.

any ideas??

thanks!

Cameron

[Dolph Santorine]

How is your fuel pressure when it misbehaves?

It’s easy to measure. 

Dolph Santorine

Do...@DolphSantorine.com

Excuse me for not being my usual wordy and sporadically verbose self. This message is sent from my iPhone.   

No trees were killed in the sending of this message and few long dead dinosaurs were involved. A large number of electrons were terribly inconvenienced.

On Aug 25, 2024, at 3:54 PM, Cameron <cbi...@gmail.com> wrote:



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[Cameron]

unfortunately, the answer is 'hard to tell'.  when it starts to misbehave, everything is across the board,  everything just bounces around until it evens out (after cooling off).

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/879375CB-8D3B-4B7B-891E-AB5ACC12233B%40dolphsantorine.com.

[MICHAEL ORLANDI]

What brand parts are you running. In the past I have had trouble with Chinese parts.

Sent from my iPhone

On Aug 25, 2024, at 1:29 PM, Cameron <cbi...@gmail.com> wrote:



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[Cameron]

the only parts that I know of that are chinese is the fuel pressure sensor.

I bought the ebl from dynamic

I bought the harness from 'affordable efi'

I am definitely not 'intentionally buying cheap chit'.

Cameron

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/9856F889-FD3B-4468-BBF3-EAB14A2132CB%40sbcglobal.net.

[Bill Van Vlack]

When it's hot and the engine not running (but ignition on) is the WUD still 'bouncing around'?

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CAMM5UnjPWK_VOuj65y7K4EMKKCKrS6rqW11DekiG9mZCGuRCSQ%40mail.gmail.com.

[Cameron]

I, unfortunately, dont know.  I am trying to parse the log file now to see if I can find where this was taking place. 

my current thought is to put a stock distributor back on it and separate fuel from spark issues.  in my obviously not expert opinion, this is an ignition issue.  I dont know why the ignition is going crazy, but it sure seems to be.

Cameron

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CA%2BX-fMd7RS6JuDXXZMcxWrhDZ5q1jvaL1AqHiG686wAN4ea5iw%40mail.gmail.com.

[gbec...@graestone.org]

You are doing all the right stuff. I agree this is ignition and that means coil or module. Bad coils tear up modules.

I was helping with one this spring with the same problems and we eneded up swapping the distributor with another coach. Fixed it, so it must have been the pickup or something.

Take the rotor off and look at the underside very carefully. Tiny cracks have been known to form. This lets it short down to the advancement weights.

I would think a 5 minute cool down wouldn’t be much help to the module or coil, but would lean toward the coil—creating/shorting internally.

We have had bad modules out of the box. “Good ones" made in the USA.

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CAMM5UniXk4-xd6uRvp4-_bUOkFPRVoh7-aiDF1K4yzJqVZwpng%40mail.gmail.com.

---------

Best Wishes,

George
gbec...@graestone.org

[gbec...@graestone.org]

Oh, if you have an analog tach, try unplugging it when it is acting up.

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CA%2BX-fMd7RS6JuDXXZMcxWrhDZ5q1jvaL1AqHiG686wAN4ea5iw%40mail.gmail.com.

[MICHAEL ORLANDI]

On all ignition stuff I would use only known good, new dose not mean good. If suspect use Delco or standard if made in the US. If I was suspect I would change the pickup coil module and coil all as a matched set. Keep the old ones as spares. 

Have you ever done a voltage drop on the ground s and positive cables?

Sent from my iPhone

On Aug 25, 2024, at 1:55 PM, Cameron <cbi...@gmail.com> wrote:



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[BruceHislop]

Several months ago I helped a friend change his wiring harness. At the same time we also added ESC spark control. Normally I don't like to change two things at once, but keeping the OEM HEI meant moving the little buffer circuit board to the new wiring harness, then removing it after a test drive to upgrade to ESC so we did ESC at the same time.

The engine ran great, until it warmed up, in his case that only took about 10 -15 mins on the road.  It would then bog and sputter.  We found a few issues and it seemed to run fine, so they set off for the 4 hour drive home.  They only got about 30 minutes before it we acting up again.  So I drove down  to help him.  We reinstalled the HEI distributor including moving the buffer circuit over.  It did the same thing.  Long story short (including having the governor gear fail and he has headers!) We pulled the snorkel off so I could watch the injector spray.  I could only get a good vision on one injector and its pattern went south when the engine started to act up.

He had an old Holley with 80pph injectors which are no longer available.  He decided to obtain a Rochester TB.  He got the Rochester installed, but then the IAC didn't work.  New IAC and reverse 2 of the wires on it and now it runs like a top.  Reinstalled the ESC, a few VE learns and it works great.

Only thing I can think of is the old wiring harness had so many splices that the injectors were not getting full voltage.  They wore in like that and now they are getting full voltage from the new wiring harness.  The injectors now get "stuck" in an unworn area when the engine and Tb heats up.  Anyway, ESC is now back in and his coach runs great, been on several trips included a 2 week one.

Just my recent experience.

Bruce Hislop

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CAMM5UniXk4-xd6uRvp4-_bUOkFPRVoh7-aiDF1K4yzJqVZwpng%40mail.gmail.com.

[Larry Davick]

it may not be related, however I saw an episode of Bus Grease Monkey where he couldn’t figure out why his VW Thing would stumble on the freeway.

He’d tried everything.

These are old machines and it seems that at some point a second fuel pump and filter was installed but unseen. Bypassing them was the trick.

Could there be something a PO installed that’s unseen?

Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca.

[Cameron]

I am seriously considering putting a stock distributor in and removing ESC to see if that has an impact.  I really dont want to do that, since I really wanted the ESC component of the computer.  but, at this point (literally a year after starting this 'journey') it is $120 and a few hours of work to remove a variable from this equation.  will this mess with the EBL?

fuel delivery is a question.  I have had a *hell* of a time getting a FPS to work consistently.  however, I do not currently think fuel is the problem.  tho my FPS doesnt work great (long story) it doesnt seem to have any variation at the time the engine is misbehaving.

Cameron

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[Dick Paterson]

Just my 2 cents worth ---on module installation & heat sink paste………………

 

From: gmcm...@googlegroups.com <gmcm...@googlegroups.com> On Behalf Of Cameron
Sent: August 26, 2024 1:56 PM
To: gmcm...@googlegroups.com
Subject: Re: [GMCMH-EFI] pls evaluate my assumptions

 

I am seriously considering putting a stock distributor in and removing ESC to see if that has an impact.  I really dont want to do that, since I really wanted the ESC component of the computer.  but, at this point (literally a year after starting this 'journey') it is $120 and a few hours of work to remove a variable from this equation.  will this mess with the EBL?

fuel delivery is a question.  I have had a *hell* of a time getting a FPS to work consistently.  however, I do not currently think fuel is the problem.  tho my FPS doesnt work great (long story) it doesnt seem to have any variation at the time the engine is misbehaving.

Cameron

 

On Sun, Aug 25, 2024 at 6:49 PM 'Larry Davick' via GMCMH EFI <gmcm...@googlegroups.com> wrote:

it may not be related, however I saw an episode of Bus Grease Monkey where he couldn’t figure out why his VW Thing would stumble on the freeway.

He’d tried everything. 

These are old machines and it seems that at some point a second fuel pump and filter was installed but unseen.   Bypassing them was the trick.

Could there be something a PO installed that’s unseen?

Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca.

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[Dick Paterson]

 

From: Dick Paterson <di...@paterson-gmc.com>

Sent: August 26, 2024 2:06 PM
To: 'gmcm...@googlegroups.com' <gmcm...@googlegroups.com>

Subject: RE: [GMCMH-EFI] pls evaluate my assumptions

 

Just my 2 cents worth ---on module installation & heat sink paste………………

 

From: gmcm...@googlegroups.com <gmcm...@googlegroups.com> On Behalf Of Cameron

Sent: August 26, 2024 1:56 PM
To: gmcm...@googlegroups.com

Subject: Re: [GMCMH-EFI] pls evaluate my assumptions

I am seriously considering putting a stock distributor in and removing ESC to see if that has an impact.  I really dont want to do that, since I really wanted the ESC component of the computer.  but, at this point (literally a year after starting this 'journey') it is $120 and a few hours of work to remove a variable from this equation.  will this mess with the EBL?

fuel delivery is a question.  I have had a *hell* of a time getting a FPS to work consistently.  however, I do not currently think fuel is the problem.  tho my FPS doesnt work great (long story) it doesnt seem to have any variation at the time the engine is misbehaving.

Cameron

 

On Sun, Aug 25, 2024 at 6:49 PM 'Larry Davick' via GMCMH EFI <gmcm...@googlegroups.com> wrote:

it may not be related, however I saw an episode of Bus Grease Monkey where he couldn’t figure out why his VW Thing would stumble on the freeway.

He’d tried everything. 

These are old machines and it seems that at some point a second fuel pump and filter was installed but unseen.   Bypassing them was the trick.

Could there be something a PO installed that’s unseen?

Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca.

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[Jon Roche]

I forget where you are located?

What did you do with your old distributor?

On Aug 26, 2024, at 12:56 PM, Cameron <cbi...@gmail.com> wrote:



To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CAMM5UnjcpSjUgjinGWcMwyV70zg-jYh6j8V6MEmasNun9ss0wg%40mail.gmail.com.

[Dick Paterson]

 

 

From: Dick Paterson <di...@paterson-gmc.com>

Sent: August 26, 2024 2:09 PM
To: 'gmcm...@googlegroups.com' <gmcm...@googlegroups.com>

Subject: RE: [GMCMH-EFI] pls evaluate my assumptions

 

 

From: Dick Paterson <di...@paterson-gmc.com>
Sent: August 26, 2024 2:06 PM
To: 'gmcm...@googlegroups.com' <
Subject: RE: [GMCMH-EFI] pls evaluate my assumptions

 

Just my 2 cents worth ---on module installation & heat sink paste………………

 

From: gmcm...@googlegroups.com <gmcm...@googlegroups.com> On Behalf Of Cameron

Sent: August 26, 2024 1:56 PM
To: gmcm...@googlegroups.com

Subject: Re: [GMCMH-EFI] pls evaluate my assumptions

I am seriously considering putting a stock distributor in and removing ESC to see if that has an impact.  I really dont want to do that, since I really wanted the ESC component of the computer.  but, at this point (literally a year after starting this 'journey') it is $120 and a few hours of work to remove a variable from this equation.  will this mess with the EBL?

fuel delivery is a question.  I have had a *hell* of a time getting a FPS to work consistently.  however, I do not currently think fuel is the problem.  tho my FPS doesnt work great (long story) it doesnt seem to have any variation at the time the engine is misbehaving.

Cameron

 

On Sun, Aug 25, 2024 at 6:49 PM 'Larry Davick' via GMCMH EFI <gmcm...@googlegroups.com> wrote:

it may not be related, however I saw an episode of Bus Grease Monkey where he couldn’t figure out why his VW Thing would stumble on the freeway.

He’d tried everything. 

These are old machines and it seems that at some point a second fuel pump and filter was installed but unseen.   Bypassing them was the trick.

Could there be something a PO installed that’s unseen?

Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca.

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[BruceHislop]

You can remove the ESC distributor and install an HEI, BUT you need to add a buffer/filter to convert the noisy 12V Tach signal from the HEI distributor down to a clean 5 volt pulse.  On the Howell system there was a small circuit board that did this.  The input comes from the Tach pin of the HEI and the output goes to Pin D4 on the 7747.  Get 5 volts and ground from the 7747.

Dick Paterson's suggestion of making sure you have heat-sink compound is very important!


Here is a schematic of the circuit you need to build.  Use a 74HC14 chip instead of the 7414 part number shown.

Bruce Hislop

On 26/08/2024 1:56 p.m., Cameron wrote:

I am seriously considering putting a stock distributor in and removing ESC to see if that has an impact.  I really dont want to do that, since I really wanted the ESC component of the computer.  but, at this point (literally a year after starting this 'journey') it is $120 and a few hours of work to remove a variable from this equation.  will this mess with the EBL?

fuel delivery is a question.  I have had a *hell* of a time getting a FPS to work consistently.  however, I do not currently think fuel is the problem.  tho my FPS doesnt work great (long story) it doesnt seem to have any variation at the time the engine is misbehaving.

Cameron

[bc...@juno.com]

Having driven the same engines, transmissions, and 70s fuel
injection as the GMCs in my 70s cars, for near a million miles,
I have seen plenty of such problems. At this age blocked or
rusted fuel lines, bad wiring, collapsed hoses, etc happen and
are pretty hard to track down by part swapping. My approach
is to have lots of operational gauges, to see what is changing
if a problem occurs.

Usually the first question is, is it fuel or spark? I have resorted
to using fuel pressure gauges to check the source, and a Wide
Band OX sensor to check if it is enough. Have not figured out a
spark energy detector, any ideas?
good luck,
Bruce Roe
+++++++++++++++++++++++++++++++++++++++++++++++++++
From: Cameron <cbi...@gmail.com>
To:gmcm...@googlegroups.com
26 Aug 24

[Cameron]

ugh.  I am definitely not qualified to do this..

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/0458b377-22cb-4131-8d1b-3e0895fcc591%40gmail.com.

[Cameron]

Dick,
`
I used "ARCTIC MX-6 (4 g) - Ultimate Performance Thermal Paste for
CPU, Consoles, Graphics Cards, laptops, Very high Thermal
Conductivity, Long Durability, Non-Conductive "
https://www.amazon.com/dp/B09VDL3CW6?ref=ppx_yo2ov_dt_b_fed_asin_title

I did apply 'broadly' across the module and did not apply to the
secrews holding it down. should I 1. reapply? or 2. buy what you have
suggested and reapply?

thanks!
Cameron

On Mon, Aug 26, 2024 at 11:11 AM Dick Paterson <di...@paterson-gmc.com> wrote:
>
>
>
>
>
> From: Dick Paterson <di...@paterson-gmc.com>
> Sent: August 26, 2024 2:09 PM
> To: 'gmcm...@googlegroups.com' <gmcm...@googlegroups.com>
> Subject: RE: [GMCMH-EFI] pls evaluate my assumptions
>
>
>
>
>

> From: Dick Paterson <di...@paterson-gmc.com>
> Sent: August 26, 2024 2:06 PM
> To: 'gmcm...@googlegroups.com' <
> Subject: RE: [GMCMH-EFI] pls evaluate my assumptions
>
>
>
> Just my 2 cents worth ---on module installation & heat sink paste………………
>
>
>
> From: gmcm...@googlegroups.com <gmcm...@googlegroups.com> On Behalf Of Cameron
> Sent: August 26, 2024 1:56 PM
> To: gmcm...@googlegroups.com
> Subject: Re: [GMCMH-EFI] pls evaluate my assumptions
>
>
>
> I am seriously considering putting a stock distributor in and removing ESC to see if that has an impact. I really dont want to do that, since I really wanted the ESC component of the computer. but, at this point (literally a year after starting this 'journey') it is $120 and a few hours of work to remove a variable from this equation. will this mess with the EBL?
>

> fuel delivery is a question. I have had a *hell* of a time getting a FPS to work consistently. however, I do not currently think fuel is the problem. tho my FPS doesnt work great (long story) it doesnt seem to have any variation at the time the engine is misbehaving.
>

> Cameron
>
>
>
> On Sun, Aug 25, 2024 at 6:49 PM 'Larry Davick' via GMCMH EFI <gmcm...@googlegroups.com> wrote:
>
> it may not be related, however I saw an episode of Bus Grease Monkey where he couldn’t figure out why his VW Thing would stumble on the freeway.
>
> He’d tried everything.
>
> These are old machines and it seems that at some point a second fuel pump and filter was installed but unseen. Bypassing them was the trick.
>
> Could there be something a PO installed that’s unseen?
>
> Larry Davick
> A Mystery Machine
> 1976(ish) Palm Beach
> Fremont, Ca.
>
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[Cameron]

hey Jon,

I am in NorCal (specifically east bay).

unfortunately, I threw away the old distributor. I did not expect to need it...

Cameron

> To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/28C558C1-D378-4831-A434-E73D859985D7%40gmail.com.

[Jon Roche]

Cameron.

1. We know your fuel pressure reading is a little off.

2. How about wide band o2? Do you have regular readings on that??

[Jon Roche]

I just wonder if someone has a known distributor to loan you for testing. Or if there are other efi people to assist locally.

You are close to jimK. ?



> On Aug 26, 2024, at 2:06 PM, Cameron <cbi...@gmail.com> wrote:
>
> hey Jon,

> To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CAMM5UnhhLHXjVoX2QioYvE%3DsUmfHSUED0u0h5X7jFOugSWZ77A%40mail.gmail.com.

[Jon Roche]

Honestly…. Buying a a-1 cardone rebuild distributor.  And swapping the entire thing in is not a terrible idea.  

I am now in the camp as a complete distributor as a spare is a smart thing to carry.   Just to hold/store all needed ign spares(coil, rotor, cap, module).    When you need a coil you have assemble the whole cap anyway.  

Then if the coil,cap or rotor or module doesnt fix a problem.  You have a pickup coil already ready to go.  Otherwise you are pulling existing distributor and having to do lots of work to rebuild that one rather then a swap of entire distributor.   

Cardine 301873 distributor is $102 at rock auto. 

On Aug 26, 2024, at 2:02 PM, Cameron <cbi...@gmail.com> wrote:



ugh.  I am definitely not qualified to do this..

On Mon, Aug 26, 2024 at 11:15 AM BruceHislop <bhis...@gmail.com> wrote:

You can remove the ESC distributor and install an HEI, BUT you need to add a buffer/filter to convert the noisy 12V Tach signal from the HEI distributor down to a clean 5 volt pulse.  On the Howell system there was a small circuit board that did this.  The input comes from the Tach pin of the HEI and the output goes to Pin D4 on the 7747.  Get 5 volts and ground from the 7747.

Dick Paterson's suggestion of making sure you have heat-sink compound is very important!


Here is a schematic of the circuit you need to build.  Use a 74HC14 chip instead of the 7414 part number shown.

<Tach Filter Schematic - Use 74HC14.jpg>

<Tach Filter2.jpg>

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CAMM5UnjhjVZm6cqYVK1LznEbnCWjJ3DBcwNC%3D5XR9y9fWce1Wg%40mail.gmail.com.

[Larry Davick]

I’m that guy.

I have my distributor and carb sitting in a box in my garage. 1976 Palm beach. Willing to loan.

Larry Davick
Fremont, CA

> On Aug 26, 2024, at 12:11 PM, Jon Roche <lqqk...@gmail.com> wrote:
>
> I just wonder if someone has a known distributor to loan you for testing. Or if there are other efi people to assist locally.

[Dick Paterson]

Cameron I would lift the module and clean off the outboard ends ----keeping the paste on center .... about 1/4 inch away from the screw holes ---clean up the 2 mounting screw threads and GO

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CAMM5Ung%3DtgVdvehTv%2BU6aEw25dX%3DC%2BPVC3AjTAycb3t%2BTp4kfA%40mail.gmail.com.

[Dick Paterson]

Jon    “jus sayin”----the coil  should be  ylw---red wires – (  reverse wound -for the front wheel drive)      not the red / white wires

 

From: gmcm...@googlegroups.com <gmcm...@googlegroups.com> On Behalf Of Jon Roche
Sent: August 26, 2024 3:18 PM
To: gmcm...@googlegroups.com
Subject: Re: [GMCMH-EFI] pls evaluate my assumptions

 

Honestly…. Buying a a-1 cardone rebuild distributor.  And swapping the entire thing in is not a terrible idea.  

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/9C3E1B61-C7D8-408C-AE85-78BE58C0AB19%40gmail.com.

[Cameron]

Larry, you're my neighbor, practically. thanks for the offer!

current plan;
replace cap (long'ish story, but while installing the new spark plug
wires, I broke one of the plug mounts on my new cap, so put the old
one back on).
replace coil (it does have the yellow/red wires Dick mentions, but I
replaced the ignition module and not the coil, so going to do that)
replace ignition module (it is a 'standard' brand with a lifetime
warranty, so I will just error on the side of caution and doesnt cost
me anything)

Dick. when you say 'clean up the threads' do you mean 'apply the
paste to the threads'? that appears to be what is in the images you
sent, but want to make sure I am following directions.

if I have the same issues after that 'spark rebuild', I will ask to
borrow your distributor Larry.

thanks for everyone's input here. giving me a plan (which is not to
difficult and not too expensive) will at least help me to sleep at
night and not keep me tossing and turning trying to come up with a
plan.

Cameron

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[Bill Van Vlack]

Don't apply the paste to the threads: they are part of the grounding path.

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CAMM5UngSwM%3Dus_Kum77DsQPUKCh%3D%2BGnoBZDqdUcZbQjVgCo7ow%40mail.gmail.com.

[Dick Paterson]

No the threads must be "hospital " clean they are important grounds

-----Original Message-----
From: gmcm...@googlegroups.com <gmcm...@googlegroups.com> On Behalf Of Cameron

Sent: August 26, 2024 6:26 PM
To: gmcm...@googlegroups.com
Subject: Re: [GMCMH-EFI] pls evaluate my assumptions

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CAMM5UngSwM%3Dus_Kum77DsQPUKCh%3D%2BGnoBZDqdUcZbQjVgCo7ow%40mail.gmail.com.

[Dick Paterson]

Jus sayin .............. the long pos battery cable on the toro running back to the starter -- had some early SERVICE bulletins -relating to rough idle and hard starting .. due to EMI ----(Same as chev) the pick up coil was reverse wound to match the coil to combat this ( id: by the YLW terminal connector) . The gmc application lacks metal inner fenders and hood to capture the errand signals , so the FI application would be subject to these errant signals . Not sure if there is an instrument available that could read this.

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/006201daf86c%24c57a3d50%24506eb7f0%24%40paterson-gmc.com.

[Cameron]

Dick, question please.

is your advice on the coil also applicable to the ESC distributor? or
just the original manual distributor?

thanks!
Cameron

> To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/000a01daf87b%24b9d6aa10%242d83fe30%24%40paterson-gmc.com.

[Dick Paterson]

Yes ...I would stay with the red/ylw coil

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CAMM5UnieW7RrqxoHSNj-_4PdJYxFKrCvZ72o3yGitM%2BRVLURFw%40mail.gmail.com.

[Bob BRAAF]

Dick, 

I have need for new plug wires for my GMC Springfield distributor.  Can you please tell me the best supplier? 

Also, is there such a thing as a complete Howell EFI kit? 

Thanks. 

Bob Braaf 

970-531-3216

Sent from my Verizon, Samsung Galaxy Tablet
Get Outlook for Android

[Dick Paterson]

Bob   APPLIED  GMC   our wire sets  ---they are on back order for us  here….   ….I don’t  know  who  stocks   Howell……….regards    dick

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[gbec...@graestone.org]

Applied also has the complete EBL EFI kit. I would not recommend a straight Howell, as I’m not sure anyone is attempting to burn chips anymore. Painful process. Make changes to the tuning, send a blank chip to “someone” wait and hope the burn doesn’t fail, wait for them to send it back, install the chip and hope the change fixed the problem.

Or, get EBL and be able to flash changes into 8 memory banks. I keep what I have if I am adjusting. That way I can always change back to the current with a click.

Cameron, who has posted recently, bought a wiring harness and got the EBL from BobR. (The designer) That may be how Applied puts together thier kit. 

On Sep 2, 2024, at 7:27 PM, Bob BRAAF <bbr...@msn.com> wrote:

Also, is there such a thing as a complete Howell EFI kit? 

---------

Best Wishes,

George
gbec...@graestone.org

[Cameron]

hey Bob,

as George mentioned, I bought a kit through Affordable EFI which was a
harness, TBI and a 7747 ECM. however, I had to buy the EBL separately
through Dynamic EFI. if you go this route, make sure you let the guys
at Affordable know your intentions as they sell a different harness
for the ECM used by Dynamic.

you will also have to source some of the sensors yourself (the NB and
WB 02 sensors, speed and knock sensor I sourced myself with advice
from this forum).

Cameron

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[Keith V]

Buy the ECU from EBL. Let them solder the EBL on and test it.

Unless you have a known good working ECU it's not worth it

---

From: gmcm...@googlegroups.com <gmcm...@googlegroups.com> on behalf of Cameron <cbi...@gmail.com>
Sent: Tuesday, September 3, 2024 9:05 AM
To: gmcm...@googlegroups.com <gmcm...@googlegroups.com>
Subject: Re: [GMCMH-EFI] Supplier Questions

 

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CAMM5Ungxf5rbkiqfcB6eeMujkC6xocS0rr4ERJg6B02eWVE5pQ%40mail.gmail.com.

[James Hupy]

Keith, AMEN!!
Jim Hupy

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/LV8P223MB114744508077DCDB17B37106A4932%40LV8P223MB1147.NAMP223.PROD.OUTLOOK.COM.

[gbec...@graestone.org]

Agreed. I bought the EBL installed in a 7747 ECU. I keep my old 7747 without EBL under the dinette. I plugged it in a couple of years ago and the coach fired right up. Nice to have a backup. 

On Sep 3, 2024, at 7:33 AM, James Hupy <james...@gmail.com> wrote:

Buy the ECU from EBL. Let them solder the EBL on and test it.

Unless you have a known good working ECU it's not worth it

[Bob BRAAF]

Should I buy a spare ECU?

---

From: gmcm...@googlegroups.com <gmcm...@googlegroups.com> on behalf of James Hupy <james...@gmail.com>
Sent: Tuesday, September 3, 2024 10:33 AM

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CALxoeyussU1nDoKKn9brCJ7L2v1cLnZp0FWeTTP8LvVS7DrUkQ%40mail.gmail.com.

[gbec...@graestone.org]

Not necessarily. GM cars didn’t come with an extra. They are pretty bullet proof. I started EFI way back with a Howell kit, so I had one. I decided to buy the complete EBL from Dynamic EFI. I’ve done over 100K with EFI and probably 90K with EBL with no failures. If I go out to the barn, the coach will start right up. I’m getting about 9.4 mpg on flat land, but I don’t tow. I live at 2400 feet. I get great mileage going down to the valley. Coming up—not so much.

On Sep 3, 2024, at 8:03 AM, Bob BRAAF <bbr...@msn.com> wrote:

Should I buy a spare ECU?

[BruceHislop]

It appears now that you must send Dynamic EFI your own ECM (7747) for RobR to install the EBL board into.

It appears that RobR no longer will supply an ECM and install the EBL board into it.

http://dynamicefi.com/EBL_Flash.php

Bruce Hislop

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CALxoeyussU1nDoKKn9brCJ7L2v1cLnZp0FWeTTP8LvVS7DrUkQ%40mail.gmail.com.

[James Hupy]

My experience with the Howell system with the ECU has been that there is no particular problems, ( except for the owner caused ones ), with the EBL. If there are any, they usually occur in the first couple of weeks.
Jim Hupy

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/RIZP284MB1276432D79B897289FD5D795D1932%40RIZP284MB1276.BRAP284.PROD.OUTLOOK.COM.

[Bill Van Vlack]

The only problem with the EBL is that the starting BIN that is normally provided has a VE table that has some cells set to the high 90s, leaving no room for Learns that need to raise VEs in those cells,  Randy provided me with a modified version that brought the whole table down. Since the 'Files' site is no longer available, I am attaching it here.

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CALxoeys6P0Wgj6s%3Digc0chszG_Zdxdg0mbxNaGW%2B4mf8%2Bc6dQg%40mail.gmail.com.