Hi guys! I am new to this forum and i would like to thank everyone in advance for the help. Here's what happend. I have an audi A4 1.8t AEB engine with 5 speed gear box, i got the car 1 year ago and i had trouble with a missfire on cyl. number 3, I changed all 4 plugs for brk7e copper, and chipped stage 1 with intake and it ran fine for all winter.

Yesterday, I decided to test compression in all cylinders, because i had a gauge in hands and the time to spare, so i go ahead, unscrew all the plugs, put a LITTLE dip of full syntech oil in all 4 cylinders, unplug the injectors, and crank it to get 180 psi on all cylinders, good news right? Well not really, I put the plugs back in, start it and it ran good, until i get a p0303 code and flashing CEL , so i tried swapping plugs and etc, checked injectors, working, checked coils, working,so i said to myself lets put 4 new NGK plugs in there, bought new brk7e and gapped them to .030, and it still misfires on cyl, number 3!!! Its unbeleivable, i dont know what to do now my wife needs the car this week and it can't run on all 4 cylinders, it never did that before.

The only scary thing i can think of is a cracked piston maybe? or a non properly sealed valve? Because if its only intermitent ? it idles perfect, only when you push the gas pedal it starts to missfire. Guys i really need help on that one i have all i need to check and recheck i just need ideas for what to look!

 

After a couple more research i think its the icm? my buddy has a 2002 scrapped passat but those have integrated icm in the coil packs, so i cant test it, i saw on ebay they are 15$ + 10 shipping but they will take 2 weeks to get where i am, so i can't say for sure

 

After ALOT of work on the car, I still have little to no spark on cylinder 3...

Here is what I have done:

Engine rebuilt
New ICM
New plugs
Wiring from ECU to ICM then from ICM to COIL is new wires
Timing belt/All the stuff around new

Now i get 200 psi per cylinder, car starts like before, still little to no spark on the 3rd cyl.

This car needs to be sent to research in paranormals for sure, or it just needs another ECU, but would the ECU give me signal but no enough so the ICM would give weak spark? Coils are good, injectors are good , cam and crank sensors are good if the thing starts, I get flashing CEL while pushing on it then p0303, besides that everything works around it...

Last thing i'll do is try another ECU , I have to buy one from Ebay this week and get it reprogramed by a guy here, if it need reprog, then after that, its gonna rot in the yard, I can't do more then that really... I've put about 2k$ on it the last 2 months and still have the same issue.

HELP !!! I really need it!

 

I found the problem!!! but not the cause... My ECU is short to ground on the cylinder 3 pin.. That means i have constant mass going to my ICM, so the ICM just burns automaticly. I dont know what caused it, its really weird, but 12V test light,clip it to possitive side of battery and look the output of the ICM , light flashes and engine lowers in rev because you take all the juice going to the coils, my number 3 doesnt light up at all and on the input side (5 pin side) number 3 as constant light (ground) and all the others wires have signal ground.

This is a weird one and ive never saw that before, ECU shorting ICM ..

Anyway i hope this helps other people diagnosis in findind missfires on b5's after changing ICM,Coils,Wires and nothing changes.

Thanks for inputs guys!