Resolved : 3.4 Camaro Rough Idle, Sputtering PROBLEM SOLVED

[project95]

Purchased and flat bedded home a ‘95 Camaro, 3.4 w/178k miles for $350 with a blown head gasket. The car had not been driven for over a year. You will see later why I mentioned this. So, after draining the milkshake, I went thru the heads and had them clarified cut, cleaned all of the built up carbon from the upper/lower intake and EGR valve assembly with PurplePower degreaser (awesome stuff) and installed a GM brown o-ring for the distributor shaft, since I had the intake off, ez fix. Re-installed everything by the book, installed new spark plugs/wires, added 5 fresh gallons of fuel and fired her up. Seemed to idle a little rough, but I wrote it off to the car sitting for over a year. Took her out on the road and felt like she’s running on 5 cylinders. It would chug on every rev and really pound when acceleration was ‘attempted’. So folks, let the ‘sputtering, misfire, idles rough, plugged injector‘, diagnosis games begin.

These parts tested in order within limits; Compression test, Fuel pressure/regulator, Coils, ICM, TPS, MAP. Installed; New A/C Delco plugs/wires, used (from a good running 94) fuel injectors. Still chugs. Dangit!! I Decided to do another compression test and noticed on plug removal that #1 plug is black, all others clean. Now I have a suspect cylinder and I am still convinced it’s an injector issue. Next, I disconnected the 2 wire harness on the #1 injector and plugged in a noid light, cranked engine……DEAD. No flashy. The 5 others checked fine.

Now we’re closer... I then checked continuity on the 12 pin inj. harness connector on top of the fuel rail and for obvious wire breaks etc. for #1. Next, tested for 12v to the (pink/black) pulse drive wire with a telst light on #1 with key on, it’s good. Last check, I had to trace the #1 injector (black) inj. control wire back to the PCM to check for continuity. Upon pulling the PCM up and out to access the 32 wire connector (on the bottom), I found my #1 injector control wire broken (#14 circuit), and shredded insulation on 4 other injector control wires due to a mouse living beneath the PCM!! My 24x ref. signal wire had one strand holding it together! How this car ran, or didn’t burn down is beyond me. Thankfully, Mr. Mouse left me enough clean wire outside of the connector to splice in new jumper wires. I completed repair, runs like a champ and accelerates like it's hands are on the stove!

[86FieroSEv6]

Right on. A little known fact is that with the rise in petroleum prices the manufacturers have started using soy oil to create the wire insulation. Needless to say that rodents find this to be a rather yummy solution for supplying wire insulation to the industry.

[60dgrzbelow0]

I have to hand it to you, project95... Your post... from problem isolation through to finding the solution(s) should be made a New STICKY. Your admirable approach to discovery followed a sound and scientific methodology of "Only Change or Test One Variable at a Time!" using orders of logic that lead very soon to the fixes and repairs that worked in a very straight forward fashion. Sometimes... frantic folks come here with new issues and describe a sort of "shotgun solutions" and disorganized approaches they've tried and failed with... often spending a great deal of time and money unnecessarily and use description paragraphs that are all over the place (often reading like Schizophrenic's Rorschach Tests). Yours is the best posting I've read in here in a very long time. Congratulations on choosing your car...and for having the thinking and mechanical skills to quickly and efficiently find the means to get that machine up and running again... and then SHARING WHAT YOU DID AND HOW YOU DID IT WITH US ALL... and for a mere $350 plus the essentials to do so... Too! WOW!!! Happy Motoring, Brother!

--==Bob==--

[bszopi]

Although I probably won't make it a sticky, I will most likely create a new article, titled something along the lines of Good Troubleshooting Practices, and use this post as the example part of the article.

[60dgrzbelow0]

X2^ Brad!!! Great Idea!!!.... and just like your Main Page Admonitions for new users along the "READ THIS FIRST..." Having a "Best Practices" recommendation post would help us all out out in so many other ways, too....and pics.....lots and lots of pics...or links to sites with their own "How To Do This ...." sort of visual archive help would also be greatly appreciated.