[V8] Testing Fuel Injectors, stumble, miss

[Ed Kellock]

I have done this too.  I've been chasing a surge for quite a while.  My car runs great w/o the oxs connected, but I've left it connected so I don't quit trying to fix the surge.

The last thing I did which seemed to change the behavior dramatically was when I change the connection point of the ground wire of the 4-wire oxs.  I attached it to a bolt on the back of the driver's side of the engine block, up just under the head-block mating point.  It's kind of behind the cruise control and throttle linkages.  I almost couldn't find it.  

When I loosened this bolt (I did not remove it all the way for fear of dropping it), I sprayed some carb cleaner and then some brake cleaner liberally back there to clean the mating surfaces.  The engine and rpm sensors are mounted in the area below this and I strongly suspect that the solvent washed those in some way.

I think that may be more responsible for the change in the way the car ran than the regrounding of the sensor because they symptoms, the surging and the cutting out at 1k rpm when opening the throttle, have partially returned.  My distributor gaskets are leaky and I feel that the leak has had time to foul the sensors again.  

I'm going to go back in at some point and pull the distributors to put in new gaskets and pull and clean the sensors and see what happens.

Ed 
Colorado Springs

============================================================
From: <dsaad at icehouse.net>
Date: 2004/03/08 Mon AM 08:52:04 MST
To: <v8 at audifans.com>
Subject: Re: [V8] Testing Fuel Injectors, stumble, miss

One trick I have used is to unplug the O2 sensor. This should force the ECU 
into a failsafe openloop mode. If your surge goes away, you can assume you have 
some sort of mixture problem. If it does not, maybe ignition problem or erratic 
fuel pressure or ???

Mine seems to run pretty good with the O2 sensor unplugged. Mileage and power 
are probably reduced but it runs smooth.
Do you have access to something like VAG-COM? That may give you some clues too.


Dave


Quoting "Korn, Bob" <Bob.Korn at Fike.com>:

> Anyone know an easy way to test fuel injectors or is this a job for
> someone
> who has the proper test equipment?
> 
> I've done the test using the ECU and they all buzz or click accordingly.
> Pulled them all and replaced the seals and caps, used the NAPA kit that
> crosses to a ford previously mentioned on the list. The caps are
> slightly
> different, had to modify slightly before installation. 
> 
> Still have a miss or stumble under steady acceleration.  Could a bad
> fuel
> pressure regulator cause this?  I do not have a pressure gauge
> set......yet.
> May have to bite the bullet and go buy.   Getting frustrated, been
> chasing
> this one for awhile.
> 
> New plugs, caps, wires, rotors, and Fuel pressure reg 25K ago.
> Since miss started:
> Techron through two tanks fuel, always AMOCO Premium.
> New O2 sensor
> New fuel filter
> New breather hoses
> New seals on injectors
> 
> Any ideas???
> 
> I keep thinking fuel with all the new ignition components. Guess you
> never
> know, better go back and check spark in all the holes.
> 
> 
> Thanks,
> 
> 
> Bob
> 90 V8Q 135K Pearl  
> 
> 
> 
> 
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