How to test spider injectors

[stry...@yahoo.com]

Is there a way to test the spider injectors on my 1996 silverado with csfi? I am having an intermittenant radom multiple cylinder misfire code. This truck has 359,000 but other than that runs good. I am getting a higher than normal fuel trim on bank one.

I was wondering if there is a way to pulse each fuel injector to read the pressure drop to see if I could locate a bad one. I dont have a machine to pulse it but would a 9 volt batter or something similar work?

I appreciate any help!

[Steve W.]

Random misfires are 99% of the time fuel pressure related. Check the
pressure KOEO then with the engine running.
Also check the pressure drop with the engine running, you rev the engine
and watch the pressure.
You want a minimum of 60 psi KOEO, Should hold that for 10 seconds or
more when you turn off the key.

Next check for vacuum leaks. High trim on one bank only, could also be
related to a bad O2 sensor.


--
Steve W.

[stry...@yahoo.com]

On Monday, December 17, 2012 7:32:33 PM UTC-6, Steve W. wrote:
> stry...@yahoo.com wrote:
>
> > Is there a way to test the spider injectors on my 1996 silverado with
>
> > csfi? I am having an intermittenant radom multiple cylinder misfire
>
> > code. This truck has 359,000 but other than that runs good. I am
>
> > getting a higher than normal fuel trim on bank one.
>

> > I have had this problem since last year. Last year I replaced the fuel pump with a delphi unit from NAPA. It did not fix the problem. I tested the fuel pressure. I will say I am getting 58 psi when I checked it the other day but becasue it had the problem with the old fuel pump I am thinking it is not that.

I have no codes for the o2 sensor. On my scanner they both seem to be switching normally.

Actually, I am trying to make a smoke machine to check for vacuum leaks. (trying to figure out what I can use to produce smoke". I did spray brake cleaner and found one leak.

The problem is the cutting out is only under certain conditions at part throttle. I have checked pretty much every sensor and replaced the plugs and wires and cap last year.

[stry...@yahoo.com]

On Monday, December 17, 2012 7:32:33 PM UTC-6, Steve W. wrote:

> stry...@yahoo.com wrote:
>
> > Is there a way to test the spider injectors on my 1996 silverado with
>
> > csfi? I am having an intermittenant radom multiple cylinder misfire
>
> > code. This truck has 359,000 but other than that runs good. I am
>
> > getting a higher than normal fuel trim on bank one.
>

> > It does hold pressure for ten minutes by the way.

[Steve W.]

stry...@yahoo.com wrote:
> On Monday, December 17, 2012 7:32:33 PM UTC-6, Steve W. wrote:
>> stry...@yahoo.com wrote:
>>
>>> Is there a way to test the spider injectors on my 1996 silverado
>>> with csfi? I am having an intermittenant radom multiple cylinder
>>> misfire code. This truck has 359,000 but other than that runs
>>> good. I am getting a higher than normal fuel trim on bank one. I
>>> have had this problem since last year. Last year I replaced the
>>> fuel pump with a delphi unit from NAPA. It did not fix the
>>> problem. I tested the fuel pressure. I will say I am getting 58
>>> psi when I checked it the other day but becasue it had the
>>> problem with the old fuel pump I am thinking it is not that.
>
> I have no codes for the o2 sensor. On my scanner they both seem to be
> switching normally.

58 psi when?
Post -
Key on Engine off -
Engine Idle -
Engine at 2000 rpm -
How long it holds pressure when turned off.

When was the last fuel filter change?

>
> Actually, I am trying to make a smoke machine to check for vacuum
> leaks. (trying to figure out what I can use to produce smoke". I did
> spray brake cleaner and found one leak.

MUCH easier way - Take a cheap propane torch, Turn it on but don't light
it. Trace the lines and around the gaskets. When you get near a leak the
engine will rev up a bit.

Smoke works very well BUT if you put certain chemicals in there it can
really screw things up.

What are the short term and long term fuel trims?

>
> The problem is the cutting out is only under certain conditions at
> part throttle. I have checked pretty much every sensor and replaced
> the plugs and wires and cap last year.

What conditions and approx what throttle position?

You said you replaced the pump, plugs, wires and such last year.
Were the ignition parts before or after the problem?

Truck stock? Any performance stuff?

What scan tool are you using? Might be able to give you some things to
look for if I know what the tool can do.

--
Steve W.

[stry...@yahoo.com]

plugs and pump were replaced after the problem. Fuel pressure KOEO. Help pressure with keu off over 10 minutes. Truck bone stock. Scan tool most expensive one at harbor freight.

Mainly wanted to build a smoker for fun but also for this project.

Fuel trims varry. Long term on bank one goes as high as 13. Usually 6-7. Other bank usually 3 less than bank one.

[Steve W.]

LT fuel trim normally doesn't go much over +5 normally.
What are the average voltages shown by the O2 sensors?

How about compression numbers?

--
Steve W.

[stry...@yahoo.com]

One of my plans is to do a compression test this weekend. o2 sensors switch quickly from a low of .100 to a high of .800. Hard to tell but it seems like the bank I am having toruble with goes a little higher than that and stays at .800 a second longer. I believe I replaced one of the sensors last year but it did not change anything.

By the way the hesitation or miss seems to be at slight throttle over level ground. No problem when giving gas to pass or at idle.

I am curious though back to my origional question, is it possible to pulse these injectors at home without special equipment to read the fuel pressure drop?

[jim beam]

only one? ?

anyway, swap them and see if it changes the bank that's "misfiring".

>
> By the way the hesitation or miss seems to be at slight throttle over
> level ground. No problem when giving gas to pass or at idle.
>
> I am curious though back to my origional question, is it possible to
> pulse these injectors at home without special equipment to read the
> fuel pressure drop?

why do you keep coming back with this vehicle and its same old problem?
you ask for help, then ignore it, and then wonder why you don't fix
anything.


--
fact check required

[Steve W.]

stry...@yahoo.com wrote:
> One of my plans is to do a compression test this weekend. o2 sensors
> switch quickly from a low of .100 to a high of .800. Hard to tell but
> it seems like the bank I am having toruble with goes a little higher
> than that and stays at .800 a second longer. I believe I replaced one
> of the sensors last year but it did not change anything.
>
> By the way the hesitation or miss seems to be at slight throttle over
> level ground. No problem when giving gas to pass or at idle.
>
> I am curious though back to my origional question, is it possible to
> pulse these injectors at home without special equipment to read the
> fuel pressure drop?

Nope. Even with a tech 2 the only testing available is shutting off the
injectors one cylinder at a time.
This design is not the common design of an injector. A common injector
will spray fuel when opened. The SCPI unit will not spray fuel unless
there is engine vacuum at the poppet valve on the end of the tube at the
same time the injector pulses.

The thing is that you are seeing one bank lean and misfiring. The SCPI
system won't do that. It can cause an overall lean or overall rich but
not single bank problems.
Being that the FP held I don't believe you have a leaking fuel pressure
regulator in the intake (which can cause one side to run rich)
You could swap the O2s side/side and see if anything changes. It is
possible you just have a lazy sensor or one that is marginal.


--
Steve W.

[stry...@yahoo.com]

WOuld a vacuum leak cause these symptoms?

[Steve W.]

stry...@yahoo.com wrote:
>>
>> Steve W.
>
> WOuld a vacuum leak cause these symptoms?

Anything that allows air in after the MAF can cause a lean misfire.
Vacuum leak, bad intake gasket, cracked intake.


--
Steve W.

[mikesj...@gmail.com]

I have aa almost dead miss at times on a 99 suburban, 5.7 with the vortec. The genesys scanner showed over 10k misfired on 1 cylinder, I suspect injector, being that plug, and wire made no change, 2 of the other cylinders showed 60 to 70 misfires in same cycle while the other 5 cylinders show no misfires, is it possible to check this injection package before a 300 dollar visit to parts store