*video* 92 Sub... Idle surging intermittantly, poor spray pattern, etc

[shibbershabber]

SO I have been battling this thing for a while and have shotgunned parts at it to no avail.

I normally dont just start replacing , but I intend to keep this thing so I dont see it as a waste of time or money.


Anyhow, This all started when I tried to diagnose a small issue of it randomly dying. No big deal but I thought I may as well nip it in the bud before it becomes worse...

Put a light on it and saw that the timing mark fluctuated ever so slightly, wobbling even.
So I replaced the dizzy with a new one. Ran like crap... retimed everything, even had three mechanics mess with it to verify timing.
Still ran like crap, timing mark still wobbled, so I replaced the timing gears and chain. Still nothing.

Then I did the ECM, IAC, CTS, MAP, EST Module, Knock Sensor... And nothing.

The problem seems to be more intermittent now, I will start it and it will idle fine for several minutes before starting to act up... other times it does it right away.

I can watch the RPMs drop nearly to a stall, and then shoot back up. And then back down again...
With the timing light I can watch the timing retard 10* when the idle drops and come back up.
With the hood open I can hear the engine sucking air to save itself...

Until now I have been thinking it was a timing issue or an electronic issue relating to the timing.

I had mostly overlooked the fuel system as the entire thing was replaced 4k miles ago.
Rebuilt the TB (incl. FPR), new injectors, injector wire harness/clips, fuel filter and new fuel pump assembly (incl. strainer, sending unit, etc.) I also did a new TPS and EGR at that time.

Paying attention to it again I can see that the spray pattern is crap.

http://youtu.be/HMyP6hu7nOM <--- VIDEO of injector spray, also you can hear the suck/surge going on towards the end

So my question is...

Could something be failing in the fuel system, or is it that I have another component sending bad signals to the injectors causing this? And would that account for the timing surge?

OR do I still have a timing issue that is causing mixed signals to the EFI system? If so, where do I look to now?

 

[great white]

Did you adjust/verify the pintle length when you replaced the IAC solenoid?

Did you disconnect the EST timing wire when you set/adjusted the timing?

Are there any active or history obd trouble codes?

 

[shibbershabber]

I got a 43 or 42 code months ago, dont recall which. But it never came back again.

I did disconnect when setting base timing (0*)

I did not do anything to the IAC before installing it. Though it didnt run any better or worse than it did before.
what should I have looked for?

 

[CrustyJunker]

I'm not sure if you're having the same problem with your spray pattern, but some years ago, my friend's remanufactured injector dropped the little screen off the bottom that gave it the nice fan mist. It was just spitting in the motor and ran like crap. Just throwing an idea out there.

 

[CrustyJunker]

Oh, if you haven't tried an O2 sensor yet, you may want to consider that. If it's fine for several minutes then turns bad, it might be doing weird stuff when it enters closed loop.

Good luck!

 

[94Sierra4x4]

Check your fuel pressure for sure, definitely looks like an ugly spray pattern

 

[great white]

Just looked at video. Driver side injector spray no es bueno.

Filter, regulator, pressure injector o rings, etc need to be checked....

 

[shibbershabber]

Well I took the injectors out and had a look at them, they looked fine... Just as nice as the day they were new. Both looked the same.

The diaphragm in the regulator looked fine too as it only has a few thousand miles on it too.

I will test for pressure this afternoon. Though I suspect that it will be fine. I feel that some other part is making them shoot like that.

here is another video I shot, its a little longer and you can see/hear it having trouble a few times.

http://www.youtube.com/watch?v=1jZhDH1HqMw

 

[shibbershabber]

Ive ordered an adapter so I can check the fuel pressure.

I also disconnected the O2 sensor before starting it... this has zero effect on the truck. Is this an indicator that the Oxygen Sensor is bad/good/?

 

[shibbershabber]

Okay, checked the pressure this afternoon and...


1. When I turn the key on, the pump runs and I show about 11psi... then it drops down to 0 again unless I start the truck

2. when running the engine the pressure holds at about the same pressure even while the engine is acting up.


Should the pressure hold once the pump primes, or does this all seem okay?