Hey everyone here on the messageboard. I'm a long time reader first time poster. I normally am able to find everything I need to know about my car (1995 A4 Z28) by just perusing through the forums, but this time I'm really stuck. First a small intro to previous problems I've had with my car, which may or may not be related to the current problem. Sorry for being so long, but I figure the more details the better.

Back in November, I had the low RPM stumble at higher temperatures that some seem to be experiencing on the board. I can't really explain what happened, but it just went away one day.

In February, I installed Mac Midlength headers on my car, and cracked open the Y-pipe connectors on manifolds to begin work. I had to go somewhere real quick, so I decided to take the car out, everything was still connected (O2's), but the car refused to start. It would crank until the battery died, but it would not turn over. Sometimes it would start to ignite, but then quickly die. I decided to go ahead and do the header install and worry about my starting woes later, and after I finished the install (5-6 days later, working 4 hours a day give or take) the car started up perfectly fine, and ran great up until a week ago.

The low RPM stumble came back, and seemed to get even worse, as now I would lose power and it would miss up to approximately 3,000 RPMs, although not anywhere near as bad as between 1,000 - 2,000 RPMs. I took the car over to a local shop, just to see what his take on it was. Long story short, after testing a few things, my car would no longer start. It would crank fine, but would not turn over. Like when I did my headers, the engine would almost start up every once in a while, but then die out. The mechanic decided to clean the MAF sensor. After spraying it throughly and blowing it clean with some compressed air, I went back to try and start up my car. Turns out a few drops of the cleaning solution fell into the engine bay, on top of/around the air pump, causing a small fire when I started the car. Unable to blow it out, a fire extinguisher was used. The damage: a few melted plastic wire looms and a melted vacuum hose (immediately replaced).

Fast foward to last night. I had changed my plugs/wires out in January, and the one of the plugs we pulled was not receiving a spark. Myself and the mechanic went through the tiresome task of replacing the optispark (optispark kit; rotor/cap). After everything was back in place (water pump is still disconnected, although power is plugged in), we went to go start the car. Still not starting, but we did receive a bonus: Now instead of the engine almost turning over, we were gifted with a blue puff of smoke shooting out the MAF sensor (intake bellow/air filter disconnected).

As of today, I just finished removing all the spark plugs, cleaning them all out (fouled pretty bad), cleaning out the spark plug holes with fuel injection cleaner/compressed air, and replacing all the plugs. I found one sort of burnt (cracked plastic) wire, which was resting slightly on a header. I used electrically tape to temporarily mend over the small cracks. After I finished up all the spark plugs, I once again went to go start the car. Same effect as after the opti-swap, crank and blueish smoke coming out. I'm fresh out of ideas, and don't know how/what to check next. Possibly fuel problem? Not even sure how to check that. Anyway to pinpoint where and if spark is failing? Thanks to all of you for any help you can give me.

 

could be a few things:
your fuel pump..
water temp sensor disconnected....about 8-10 inches below throttle body (this one kicked my butt for a while after changing the blower belt, I accedently broke the sensor off and the car would not start!
ignition coil
bad ground
Alternator


My car was acting similar except every once in a while I could get it to start. Alternator fixed it. Had old one tested before replacing. It tested okay becuase they could not load it down.

Friends sunfire symptoms more like yours, problem was the fuel pump.

I am changing mine as soon as it comes in the mail because everyonce in a while the car stumbles, or idles low and I have replaced everything else so I figure why not.

Good luck!

 

Blue puff of smoke out the intake means your car is probably backfiring through the intake. You didn't mention it popping though - backfires are loud as hell and you would know. This brings me to the next point - are you sure the plug wires were hooked back up in the correct order? Incorrect firing order is the #1 cause of intake backfires in my experience.

Now for the stumble you are experiencing, let me share my story with you. Up to day I replaced my plugs and wires a couple of days ago, my car had an annoying stumble which became worse with heat. The car used to fall flat on its face like the engine died if I tried accelerating in too high a gear. New plugs and wires solved the problem, specifically PROPERLY GAPPED NEW PLUGS. I originally gapped the new plugs at .052" then went to .060". The stumble came right back with the .060" gap and it's even worse now. Tomorrow I will go down to a more conventional .045" gap.

I had always been told the cause of the stumble could be anything from dying Opti to weak coil. Simply turned out to be improperly gapped plugs. I know your problem may not be the specifically the same as mine but you might want to check these simple things out first. Good luck