[V8] Major Issue today w/V8

[Professor GT gmail]

Chris,

Sounds like the injector is being electrically held wide open constantly, either because of a shorted driver circuit in the ECU, or more likely the harness is shorted to ground on that injector circuit. The injectors are given power constantly and the ECU switches them on and off at a particular duty cycle based upon engine load. It's time to break out a noid light ($10 a set at Harbor Freight) and check to see if the light is flashing with the engine running at idle or is on steady. In fact, if the circuit is shorted you will probably get a steady light with just KOEO (key on engine off), at which point the light should be off, and then start flashing when you crank the engine. Once you confirm this, it's simply a matter of running down the short. Easiest is a visual inspection first, then disconnect the circuit from the ECU by backing out the injector driver pin from the ECU connector. If by doing that the noid light goes out, the driver in the ECU is internally shorted, and it's time for a replacement ECU. If not the wire is shorted to ground between the injector and the ECU - prolly pinched somewhere.

If none of this makes any sense to you then you need to get the car to a truly qualified tech, and not a wanna-be, as you are already experiencing the result of what happens when you have unqualified individuals, sometimes very well-imtentioned, messing with your stuff.

I once went on a tech-assist to help a dealer tech figure out why a car was running so poorly. The thing was dumping so much fuel that not only was it smoking terribly, but raw fuel was dripping out of the tailpipe! Shame on him! But it was a small dealer in the middle of nowhere, and the tech had no training.
We went back to basics, and in a matter of minutes found an injector driver in the ECU had shorted closed, holding the injector wide open, just like what you are experiencing.
After replacing the ECU, it took 15 miles of driving to clear out the exhaust, and I suggested that he replace the cat and the O2 sensor, and do an oil change for good measure. Lord knows how much damage that particular cylinder suffered from the washdown of it's oil, but compression measured good so we left well enough alone.

Hope this helps.

Thanks,
Gerard

ProfessorGT
(Sent from my iPhone4)

From: chris brown <sacheldog at hotmail.com>
To: v8 club <v8 at audifans.com>
Subject: [V8] major issue today with new v8
Message-ID: <SNT133-W6EB7CCD6ECEF485D35DF4B33B0 at phx.gbl>
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Today i went to get my car at my mechanic. I different guy who i trust a lot more than who did the initial swap. He found that one of my cylinders had no fuel getting to it due to a injector connection that was not hooked up properly. They cylinder had good compression like 200 lbs. when he hooked up the connection for the injector the motor began to fire on all 8 and sounded smooth and seemed like i was in business. As far as i know he didnt do anything else. I left the shop with the car and i didnt get about a half mile when the car lost all power and it began to run horrible. I couldnt get it up to even 40 miles per hour. The CAT light came on and the CAT itself got red hot and began dripping a liquid that appears to be oil. It was actually so hot that as the liquid dripped from the CAT it was on fire. Little balls of fire dripping. It smoked really bad for a while.  I just found it odd that the CAT went bad almost at the exact same time he found the cylinder problem, alth
ough i know its possible. 
What would cause oil to get into my cat and for it to get so hot that is smoked and caught fire?   I was very lucky not to lose the car if i had not turned around and took it back to the shop immediately it would have caught fire for sure.   I really need advice on this one. 
 Ive been driving the car for about 2 weeks now occasionaly and i never had a CAT issue at all. It actually ran pretty good on the 7 good cylinders.  Basically we hooked up cylinder 8 and it smoothed out the motor, then almost immediately the cat clogged  and almost caught fire. 
thanks chris                             

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