3.0t misfire under high rpm HELP!

[f4m0u5]

Sorry forclong post but i want to lay it all out there.


Car is on 034 stage 2+ superduper tb 91 oct file. apr coils with 10k miles and ngk oem plugs woth 5k miles gapped to .026. car had carbon cleaning, waterpump/ thermo stat and new intercooler brics as precation 6 months ago. 0 coolant loss


3 weeks ago i replaced my hpfp with a new oem unit and at same time added 034 piston upgrade. car looked great in logs . rarely hiting 70% duty 0 codes. sent logs to 034 and they said looks perfect.


2 weeks later installed 034 super duper tb and switched to the correct tune. log here https://datazap.me/u/f4m0u582090/good-run-superduper-tb?log=0&data=45

a week later went to do a draggy run and at the top of 3rd start of 4th i got a epc/ cel. pulled over instantly shut off car and checked for codes. CYL 1, CYL 3, CYL 4 misfire WTF. owned car for 3 years never 1 misfire.

cleared code and did a log of issue happening.

https://datazap.me/u/f4m0u582090/bad-run-super-tb?log=0&data=45


Evrything seems ok i belive in the log above besides lean after the misfire unless im missing something.

WHAT I HAVE TRIED:
tried gapping plugs down to .024 and the samething happens with misfire but now just cyl 4 . swapped the coil from cyl 4 to 1 and still cyl 4 misfire......


current log with plug gap at .024 (happens right around 7k rpm in log)
https://datazap.me/u/f4m0u582090/7k-rpm-misfire?log=0&data=45


what gets me is then next drive it may drive fine. such as this log this morning with 0 hicups.

https://datazap.me/u/f4m0u582090/good-run-end-4th?log=0&data=45

Then ride home back to misfire cyl 4.

[prestige.phantom]

Have you checked your cats? This sounds exactly like what happened to me before my cats failed and blew my motor.

[f4m0u5]

i have relocated cats a few feet back from engine, with rear o2 wores extended and siting behind the aftermaket cats. id thonk id get a code for the rear o2 if they clogged

[f4m0u5]

Have you checked your cats? This sounds exactly like what happened to me before my cats failed and blew my motor.


cats are rattleing when i knock on them. getting them removed in a little bit not taking chances there.

[ANMS4]

cats are rattleing when i knock on them. getting them removed in a little bit not taking chances there.

Yea man be careful clogged cats cost me my motor remember

[Patrick Matte]

Tell me you did a TB adaptation when you installed the TB ?

Fuel your car with premium fuel after a TB adaptation and i bet a cherry coke this problem will dissapear.

Fuel is low quality during winter, dont forget that. For exemple here on Canada the 93 OCT contain 10% of Ethanol all summer! During winter i rarely see higher than 4% of Ethanol.

So every winter i go back to 91 OCT file, if i dont do that, knock will occur. Also keep un mind the 034 tune is more TIMING oriented than my IE tune.


Envoyé de mon iPhone en utilisant Audizine Forum

[Valpo A7]

Possible fuel injector problems?

[f4m0u5]

Yea man be careful clogged cats cost me my motor remember

yes ofcourse! i had to gut them out but work good as heat shielded test pipes




Tell me you did a TB adaptation when you installed the TB ?

Fuel your car with premium fuel after a TB adaptation and i bet a cherry coke this problem will dissapear.

Fuel is low quality during winter, dont forget that. For exemple here on Canada the 93 OCT contain 10% of Ethanol all summer! During winter i rarely see higher than 4% of Ethanol.

So every winter i go back to 91 OCT file, if i dont do that, knock will occur. Also keep un mind the 034 tune is more TIMING oriented than my IE tune.


Envoyé de mon iPhone en utilisant Audizine Forum

Yes did tb and also running 93 oct fuel on 034 91 oct file! ty though for help


Possible fuel injector problems? tht was one of my next checks but lucked out it was the cat broken up and rolling around inside clogging it sometimes



https://i.imgur.com/dMwQyOV.jpg

[Valpo A7]

Alright so you think the broken cat was causing the misfire but why is it always cyl 4? I am saying don’t discount there is another issue. A cat shouldn’t randomly keep misfiring on the same cylinder.

[f4m0u5]

Alright so you think the broken cat was causing the misfire but why is it always cyl 4? I am saying don’t discount there is another issue. A cat shouldn’t randomly keep misfiring on the same cylinder.

not positive but if i remember the misfire detector isnt exact so it might have been just coincidence. the first time it happend it was cyl 1 3 and 4, even tho the cat was on bank 2 where cyl 4 5 6 is

im thinking the cat blew because the small 2.25 diameter i used and the fact of 3.25 PR past summer with 110 degree days. i heard a change rattle sound few months back but it went away so i thought nothing of it

We will see what happens i appreciate it and will definitely keep an eye on things. im religious with logging my car when ever i do a 1/8 run to try and beat old times ,so i have logs from various weeks and never see any issues till this happend


Have you checked your cats? This sounds exactly like what happened to me before my cats failed and blew my motor.


Also thanks for the advice to check cats, you and roof rails in other thread were spot on!
what confused me was the problem being intermittent but now looking at the cat i see why it was only sometimes and higher rpm where it could get lodged and clog the exit