I finally registered to the greatest forum ever because I truly need help. I have used this for the last year to solve every issue I have come across, so thanks for all the info. I have a 99' A4 Quattro 1.8L Turbo
Here is the problem:
Went to start my car after stopping at the store and it had trouble turning over but eventually started. It ran very rough after it finally started so I limped it home. Seems like a dead cylinder. Replaced my plugs with no change. Replaced all of my Coils, still running rough. If I disconnect the MAS it will not turn over at all. Timing belt is new. I am loosing it!!!!

I hate the idea of watching my beautiful car on the back of a flatbed tow truck.

Any help would be great.....

Thanks again,
Poper

 

After working with the best Bosch certified mechanic Bruce, we have trouble shot exactly what the issue is. The ECU is shot..... Now I am having a lot of trouble finding this anywhere online... I need help...

Thanks again...
Poper

 

If anyone wants to know how I resolved this problem please PM me.... My mechanic showed me how to test all of the possibilities (vacuum leak, bad coil, Plug dead, misc) with a simple pc of wire and a $5.00 low voltage test light. I have read hundreds of articles but no one explained it like I have been shown. I have also found a way to save a lot of time searching for hard to find parts.... www.car-parts.com I found my ECU with a 1 yr warranty, shipped next day for $250.00 to my door.... Thanks chris@PES in Denver for the hookup.... You da man...

 

I learned a lot in the last week dealing with my car issues. The first item I forgot to mention is that I also replaced my Ignition Control Module... I spent hours researching all the articles on this forum but I tried everything with no result. After a very expensive week, I asked my mechanic why this happened? He broke it down in a very simple way for me to understand and I want to share it to anyone else who might be dealing with this same issue so you do not end up spending as much as I did!

With this process my mechanic used the computer only to Identify what we already knew which that the number 2 cylinder was misfiring. We came to that conclusion before by unhooking each coil at a time while the car was running until it did not make a difference... Obviously number 2...

1st: My worn coils caused all of this damage! The resistance of a worn coil will can cause the entire system to heat up creating major damage. As a coil begins to degrade, it will miss fire under high use and chances are you will not notice it when you are driving the car under power! That is why we love Audi...

2nd: As this misfire continues to occur it will begin to heat up the Ignition Control Module. The ICM can take the heat for a good amount of time because it is air cooled with a heat sink through the air box. This will pass the resistance into the ECU which is not a good thing. The ECU in the early years of AUDI are not built to take a lot of heat and they will fail with this extra resistance!

3rd: When the ECU has taken to much the system fails! This will cost you a lot of time and a bit of money in the end.... The hardest time I had was locating a ECU without spending 3 hours of phone calls or sending it out for repair! I ended up removing the shrink wrap off of every wire in the entire ignition system to locate the path of wires. I noticed on the number 2 cylinder (in regard to the excess resistance) had fried the number 1 pin port wire all the way to the ICM... (pulse fire wire) Obviously the resistance was very serious and caused a lot of damage to the single wire connecting the number 2 cylinder to the ICM. Now that all the wires were open I replaced the single wire but it required a ton of work to do so! About 3 hours of work for a single wire!

4th: After all the work was completed, I hooked up the battery, cleared the codes and she runs 100% better than she ever has since I first got her. Her name is Ruby and I am damn glad I did not see her towed on the back of a flat bed!!!!!

Conclusion: Now that I have spent the time and money to solve this issue, change those coils more often than you would think! It will save you a lot of time, patients, and money in the end. My A4 runs smoother than I have ever driven her. Blown away at the increase in quality and I have owned this car for a very long time.....

Hope this helps.....
Poper

 

Good info.

 

I need a good mechanic...

 

hi everybody i have a 98 b5 a4 1.8t. yesterday on christmas i was driving around wen suddenly my engine started bogging out and getting ready to stal but if i kept my foot on the pedal lt will slowly rev up . i noticed i got toabout 3k rpm in 2nd gear it would run ok. but if it went lower then the engine lossed alot of power and almost stalled. if i let it idle it runs but really rough. i just replaced waterpump also because right before this i had coolant problems. it ran great for a week and then out of nowhere now that just happined. im not sure wat it could be maybe my belt slipped? now timing is off? or maybe plugs? please reply back if you have any ansers. thank you.

 

b5a41.8t,
I don't think it has to do with your new water pump. The best thing to do is get your car coded and see what is failing. If it comes back as a dead cylinder or you can't get it coded, here is what to do. Your situation sounds a lot like mine. First, I would (with the car running) remove each coil at a time and see if it the car runs the same or if it gets worst. If you pull a coil and there is no change then you know the cylinder that is causing trouble. Once you locate the dead cylinder you can pull the plug, insert it into the exposed coil, ground coil and check for firing. Good idea to have 1 new plug at this time. Insert the new plug into the exposed coil and repeat to see if it fires. If the plug fires you had a bad plug, if not then you have a bigger issue. Second thing to change is the coil. You can buy them individually but I would recommend replacing the entire set. Repeat the step with a new coil and plug before you put it all back together. If it fires then you are all set. if not the last wear and tear electrical item on the car is the ICM... If none of the other parts lead you to success then it most likely is the ICM... I hope this helps out a bit....

Poper

 

I vote boost leak/disconnection. Fix whatever piece of intake plumbing you knocked off when you did the pump.

 

I just had this happen to my 99 A4 1.8T Quattro. My problem was the ignition coil needed to be replaced. Cost me somewhere around 250 at an independent mechanic.