455 bin using a Holley TB

[Eric Schmidt]

Hello all!

    I am having a heckuva time with my "tune". The engine runs great after warm up, but until then it is VERY lean. I am running a separate WB O2 gauge to monitor things. 

   Specifics: I have a Holley TB, fuel pressure is at 20 psi (lower pressure didn't run well at power speeds, hills, etc), rebuilt 455 with headers. 

   When I bought the system from one of our vendors, I waited months because they didn't have a TB for the kit, and the 1st ECU was an old, outdated one, so they replaced it. The Holley TB had a couple broken screws in it, and looked to be tampered with, but because it took so long to get I fixed it myself. 

   BVV helped me sort out a few tuning issues, but there continue to be some things that just do not seem right. Again, most of that isn't my current concern. The lean cold start is. It stays very lean until about 120 degress, and improves after that.

   Is anyone else running a Holley that wouldn't mind sharing their bin? I understand that there were 2 different sized injectors, and the "fix" is to raise the pressure if you had the smaller ones, which I have not yet proven, but it acts as though it does.

   I have been tinkering with the Open Loop AFR Multiplier vs CTS, and the Park idle speed (which did nothing), but either I am not being aggressive enough, or am not on the right path!

   Ideas, suggestions? Thanks in advance!

[Bill Van Vlack]

I think the easiest thing would be to replace the TB with a GM one at this point, unless someone here knows what your Holley TB really is and can advise. Most of the folks on this Board are familiar with the GM TB and it performs just fine. You should be able to load the 455 BIN, do some Learns, and go.

Bill

--
You received this message because you are subscribed to the Google Groups "GMCMH EFI" group.
To unsubscribe from this group and stop receiving emails from it, send an email to gmcmh-efi+...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/2a5f506a-1eaf-4b6d-a00c-a4e111021756n%40googlegroups.com.

[BruceHislop]

Eric,
I suspect your intake manifold has the exhaust crossover blocked off and the intake air pre-heater is long gone.  This leaves you with a "cold intake manifold".  Mine is the same way and even with the EBL and GM Rochester TB, it doesn't idle real nice from stone cold startup.  I had a Holley TB with small injectors then went to the Rochester TB which works considerably better. Mine starts fine, a bit rich though, because it soon goes lean and the idle speed ramps up and down a bit.  After a couple of minutes, I rev up the engine to about 2,000 rpm and it belches a bit of black smoke, then runs fine for the rest of the day.

I'm thinking what happens is with the stone cold intake, the evaporating fuel cools the intake down and fuel starts to condensate on the cold intake runners leaving a leaner mixture.  When I rev up the engine, the increased air speed in the runners picks up the condensed fuel causing a rich mixture for a few seconds or so, then clears.  After that there is enough heat in the intake manifold to prevent the fuel condensation in the runners.

My advice is to keep your cold idle RPMs up around 1100-1200 rpm till the coolant temp gets above 100F or so to keep the air velocity in the runners up.  I set the Park and Drive idle RPMs the same in both tables.

For Holley TB's, the desired 80pph injectors have a rounded top cap, whereas the smaller injectors have a flat top cap.  I suspect you have the smaller injectors since I was one of the first to be cursed by the smaller injectors back in 2009.

Bruce Hislop

[Eric S.]

Thanks Bill! I have been hoping to make this Holley work better, even though I have since acquired a Rochester. This puts me steps closer to doing the swap!

You received this message because you are subscribed to a topic in the Google Groups "GMCMH EFI" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/gmcmh-efi/Ty32E9HQNlY/unsubscribe.
To unsubscribe from this group and all its topics, send an email to gmcmh-efi+...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CA%2BX-fMcx1SWYMbNXebDjnspMPX5nF6G1_EyRh79mXqQB8tr0Bg%40mail.gmail.com.

[BruceHislop]

Eric,
There is an input available on the EBL system that connects to the Neutral Safety Switch which tells the EBL whether the transmission is in gear or not.  Most people (including myself) do not connect this input so I believe the default is then "Park/Neutral.

I just populate both Park and Drive RPM vs Coolant temperature idle RPM charts with the same settings.

Bruce Hislop

On 15/05/2024 11:25 p.m., Eric S. wrote:

Thanks Bruce. Everything you said makes sense, and I was hoping that I was just missing something in the tune. Helpful tips though. You are correct in that I have an aluminum intake with no crossover.

   I had only changed 1 idle table, and was trying figure out how the ECU would know what gear I might be in, other than "guessing" because of the load, rpm, tps, etc.

   I will make the changes and report back in a few days. I probably will not swap out the tb just yet. 1 or 2 trackable changes at a time!

[James Hupy]

Geez, times have changed since the"good old days" Had a "check engine light" come on on my Chev trailblazer Vortec in line 6 cylinder. Turned out to be "just a thermostat" But, the catch is, you no longer can just remove a couple of bolts and a gasket and a low cost thermostat. Seems it is now a housing and thermostat combined. Only? a $540.00 repair now. Praise the simpler days of 455 Oldsmobiles, boys. 

Jim Hupy

Salem, Oregon

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/e76c57fb-6bc4-4534-a867-f8b0e62ec865%40gmail.com.

[Johnny Bridges]

My VW (nee mopar) van has both with housing and alone. Good one from VW was32 bucks.  The aftermarket ones are famous for not holding temp which lights the light.  Housing adds$20if you want, but it's easily replaceable from the old housing.  Two bolts, one hose and it's swapped.  And you can see >all< of it by simply opening the hood.  Some designer's heads will roll for making it accessible.

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CALxoeytXjECTT0rpkUvSHDfMYj0ZLc5o4ZyMiebxBmuv_Y40Hw%40mail.gmail.com.

[Eric Schmidt]

OK, so Bruce verified that I have the small injectors. Fuel pressure is 20 psi. I made both of the idle tables the same and not much change. It definitely is not keeping the programmed rpm. It hunts A LOT until it gets warm, and even then it is not very smooth until it is completely warm. IAC counts are high even though the rpms are low when cold, WB O2 gauge reads LEAN, but in reality it is rich, per this clip from thirdgen.org:

"Now, keep in mind that there is an oxygen sensor that measures the amount of oxygen present in the exhaust stream. When it detects the unburned intake charge from the high-overlap cam, it tells the ECM that there is a lean condition (assuming closed loop is enabled). The Integrator, INT, then changes to compensate for this "phantom lean condition." As the INT moves, it updates the BLM, essentially dumping extra, unneeded fuel into the engine because the ECM thinks it's needed. Run like this for a little while, let the learn feature kick in, and pretty soon your car will smell like a gas station AND it'll cause all sorts of unusual characteristics at idle."

I don't think I have a high overlap cam, and closed loop is enabled, but not yet active. It reads that Learn will not cure the problem, but make it worse. I need to get some rest and stare at this more tomorrow because this is looking like hieroglyphics!

[BruceHislop]

Eric,
One thing you might want to check is
IdLSA - (option word 4 bit 1)  This determines if while idling,does the engine use the SA table or a fixed SA (Idle State SA)
Idle State SA - This is the fixed SA while idling if IdLSA (above) is set to 1.

You might want to set the IdLSA to 1 and Idle State SA to a fixed spark advance when idling (mine is set to 20 degrees).  It smoothed my idle.
  

Bruce Hislop

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/ce47d942-2468-41c4-bb17-688e333a808cn%40googlegroups.com.

[Jon Roche]

How is the exhaust??   I had a very small manifold leak that put the o2 sensor reading wrong. 

On May 16, 2024, at 9:58 PM, BruceHislop <bhis...@gmail.com> wrote:

 Eric,

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/61176406-61ed-4375-95fe-268f3a939fe4%40gmail.com.

[Eric Schmidt]

I am running headers with Remflex gaskets. I know, leaky headers are common. I have a set of manifolds ready to go on, but I have to take it to a shop for install because I would be driving without the O2 sensor if I did the job at home. Another issue with my setup!

[Bill Van Vlack]

The ECM uses the IAC  to control idle speed and IAC steps should be relatively low. The attached  file discusses the operation of the IAC, and why the throttle blades should be set so that at idle most of the air goes past the throttle blades rather than bypassing through the IAC.

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/ce47d942-2468-41c4-bb17-688e333a808cn%40googlegroups.com.

[Keith V]

So the WB02 says it's lean, what does the holly controller say?

If the Holly thinks it's lean and the injector duty cycle is not 100% your tables are messed up.

If the injector duty cycle IS 100% your fuel pressure is too low.

How did you pick the 20PSI? that seems low

What is the flow rate of your injectors?

Keith

---

From: gmcm...@googlegroups.com <gmcm...@googlegroups.com> on behalf of Bill Van Vlack <bill.va...@gmail.com>
Sent: Thursday, May 16, 2024 11:13 PM
To: gmcm...@googlegroups.com <gmcm...@googlegroups.com>
Subject: Re: [GMCMH-EFI] 455 bin using a Holley TB

 

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CA%2BX-fMf8Lp6L-nwS4vycvJ0xM94kMtJ3xyciV42%2B7uneuJ8APA%40mail.gmail.com.

[BruceHislop]

Keith, I believe his Holly TB is running 60( or is it 63)pph @ 13PSI injectors.  Running them at 20PSI brings them closer to 80pph that the engine needs at wide open throttle.

Eric,  Don't forget your WB sensor needs a minute or so to heat up to operating temperature. Mine seems closer to 2 minutes before it gives stable readings.


Bill, Thanks for the document on the IAC.

Bruce Hislop

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/DS0PR19MB7742E39DF9E48D74D54E970EA4EE2%40DS0PR19MB7742.namprd19.prod.outlook.com.

[Bill Van Vlack]

Bruce,

 Here's a few more from Bob R:

  It's too bad the 'Files' section is gone; that's where these belong.

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/c3e38f34-84f6-4079-a0e0-6163a271c200%40gmail.com.

[BruceHislop]

Maybe we can have Christo add an EFI category in resources at gmcmotorhome.org to save this stuff and more.

Bruce Hislop

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CA%2BX-fMeHWxha%2BOLMMTg%3DPkDE5sYgzmqq%3DfJEKPBgp%2B9dks1-yA%40mail.gmail.com.

[gbec...@graestone.org]

I’m not sure the Holly pressure controller can handle much more than 18 PSI. If you got to 20 and its not twitchy, then good. 

My rig runs at 18 psi, with one of the Howell early Holly TBIs. I can keep duty cycle under 80%. Wideband gets as low as 11.8 on a long hard pull. The Holly can squirt enough gas to run a 455 unless you are turning 5000 RPM. I rarely run mine over 3400. I try to keep it under 3K.

I can find no reason why fuel pressure would cause irratic warmup. (Unless the 20 psi is making the fuel pressure twitchy.) At fast idle, there is no way the TBI is running out of fuel, even at 13 PSI, which is what Howell spected before EBL.

Speaking of fast idle, if you look at cars in the 2000-2010, they warm up at 1200-1500 rpms for the first 30 seconds or so. You might fiddle with RPMs at startup, tapering it quickly as the engine begins even the first signs of warming. 

At warm up, extra gas is being squirted on the throttle plates. I am convinced that the TBI has the plates so far closed to allow the ECM to control idle that gas is pooling  on the plates and then suddenly sucked down. (Watch it.) I further believe that the gas tends to remain liquid in cold start, and gathers in the intake runners. Higher idle helps keep it moving until things get warm.

Bob R, (EBL) leaves the exhaust tube that warms intake air on his Corvette for cold weather starts. We GMCers are so sure we know better than GM engineers that we plug the crossover, and remove the intake heater and then wonder when we have trouble at startup idle.

On May 18, 2024, at 9:46 AM, BruceHislop <bhis...@gmail.com> wrote:

So the WB02 says it's lean, what does the holly controller say?

If the Holly thinks it's lean and the injector duty cycle is not 100% your tables are messed up.

If the injector duty cycle IS 100% your fuel pressure is too low.

How did you pick the 20PSI? that seems low

What is the flow rate of your injectors?

---------

Best Wishes,

George
gbec...@graestone.org

[James Hupy]

Back to simpler fixes, "Is your coolant completely filled"? If the sensor that the EBL uses for it's reference signal in not completely covered with coolant, warm up issues like you are having will rear their ugly heads and no amount of bin file changes or other tweaks will be effective. 

      Please don't ask me how I know this.😁

Jim Hupy

Salem, Oregon

--
You received this message because you are subscribed to the Google Groups "GMCMH EFI" group.
To unsubscribe from this group and stop receiving emails from it, send an email to gmcmh-efi+...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/3A45FE81-DD51-42DC-B354-3E54ABC46A40%40graestone.org.