So for over 8 months now (part because dont have the time) ive been chasing this damn misfire problem. 01 a4 1.8t. The cars been chipped, tt n75, borja exhaust, intake, and some cosmetics with 115000 on the dial. i had problems with misfires when i first bought the car 3 yrs ago, but nothing more than coils.
so now with the new misfires have been killing me. First i replaced coils (the 4th time now), and that seemd to work for awhile. Then got the high rev misfires on the freeway...arrrg.(had to let the rsx go) when i read the cel i got number 1 and number 3 misfires. swapd coils to 2 and 4. no bad coils. checked plugs..looked good but replaced them neways. worked for the ride home, and next day...DAMN IT! more misfires number 2 and 4. checked AF unpluged maf. worked for a quicked test drive and on the way back misfired again. (cleaned the maf throttle body but to no availe.) so i replaced the fuel filter...hooray rite...NOPE. so ordered new injectors from ecs tuning. installed cars fine for 2 days...(BTW easiest injector change ive ever done) so went to my dad. (mechanic for life) checked all vaccum lines replced a few...ran the cel...misfires 1 and 4...swap to 2 and 3 and test drive. number 1 coil is fd. number 4 coil is good. still have misfire on cylinder 4. HOWEVER...now the misfire on cyl 4 is very mild. no stuttering stalling while driving. At idle its a little rough...but none the less drives, but no boost pressure building...
so im at the point where ive pulled all my hair out and im giving in to ask for help. if anyone can give me some insite or suggestions id appreciate it.
Faithful af reader...Nate in SoCal.
P.S. my clutch is slipping. Just thought id throw that in there.

 

maybe the n75 is bad, i know when i had a mbc in my car it got loose once, and had air leaking and stuff, caused a misfire for me. you can also maybe check the dv to see if its not shot. thats really the only thing i can think of since its not ur coils. im assuming u checked your plugs and there fine?

 

never thought about checkn the n75. ill give it a look. thanks for the ideas.

 

Did you ever get the misfire taken care of?

 

if you gap your plugs to .028 it makes a big difference as far as misfires go when you chip the 1.8 b5's

 

Do you have a boost gauge and access to VagCom? Take a spin and log the boost data with the software, while a buddy notes the indicated boost. You should be able to tell if the car is metering boost properly. Also, you'll know how much boost you're actually seeing at the engine. If boost on the gauge is different than what you should get with your mods, you may have a turbo problem. I'm wondering if the wastegate actuator is failing, allowing you to actually boost higher than you should be...

 

What if it is a 2.8...Should I regap my plugs? I am getting codes 300,301,302 and 303. Just replaced the coils and plugs today.

 

so did it work? you may also need to change the ICM, ignition contorl module. that broke on me a couple months back.

 

ha, i just realized that this thread started about a year ago....