[BoostaVita]

Hi all, I have a slight suspicion of a possible injector failure due to misfire (no codes, very frustrating). I would like to know the ecu parameters to log with cobb in order to pinpoint the failing injectors. In addition, how to interpret that log afterwards. Please help nurse this 145k miles young n54. Thanks.

[BoostaVita]

anyone?

[Wedge1967]

what cylinder is the misfire on? did you move the coil to see if it follows? if not, how about the spark plug? I would rule out all the others prior to going after the injector.

[BoostaVita]

car's been having occasional slight acceleration stutter on WOT. pulled spark plugs and they looked ok. pretty sure not the coil since I just changed them not long ago. Therefore I wanna start logging to pinpoint the issue. Just wish to know the set of ecu parameters to log that is relevant in checking injector functionality. Thanks for the reply.

[Wedge1967]

Originally Posted by Bossimo

car's been having occasional slight acceleration stutter on WOT. pulled spark plugs and they looked ok. pretty sure not the coil since I just changed them not long ago. Therefore I wanna start logging to pinpoint the issue. Just wish to know the set of ecu parameters to log that is relevant in checking injector functionality. Thanks for the reply.

Sounds like you're getting throttle closures due to your tune being too aggressive for the fuel you're running.

Can you reset adaptations to see if it goes away? Maybe drop back to another tune that isn't as aggressive to see if it does the same thing.

Data logs will probably be the only way you'll really know. Everything else is just guessing.

[BoostaVita]

Yes, I have used BT tool to reset ecu and transmission adaptations to no avail. Gonna try reset throttle adaptation tonite. 'Throttle closure due to fueling issue' really makes sense. Thanks. If anyone can enlighten me on what data to log (eg, A/F ratio, Cyl. timing) will be greatly appreciated.
Strangely, as the weather gets colder, acceleration stutter seems to occur less. I wish the car can throw me a code so I can pinpoint.....

[BoostaVita]

Quick update: Wedge (the lone helper, thanks) is right. I followed his advice and downgrade from cobb aggressive to sport map after much resets (throttle, ecu, transmission). The accel. stutter is almost gone now. Much props to you wedge.

[BoostaVita]

2nd update: No more WOT stutter even after changing back to aggressive map. All I did was replacing coil #3 since that cylinder shows timing correction on WOT. Maybe cooler weather has something to do with it too. Hopefully this could help someone with similar problem. Happy labor day everyone.

[GreaseMonkey]

I've been havin more pronounced sympoms than you, including rough starts and idle as well as misfires and stumbling throttle. My car has not thrown any codes, which makes things difficult. How would I moniter each cylinder to pinpoint where the trouble is? I'll also pull the spark plugs tomorrow morning after the car has sat overnight to check for any fuel saturation ala leaky injector. Thanks

[BoostaVita]

What I did was I logged timing correction for each cylinder with cobb while going WOT. The optimal value for timing correction should be 0 (Someone correct me if I'm wrong because I really am not too resourceful at this). I saw cylinder 3 value changed while other cylinder values remain 0 under WOT. So i changed coil and spark plug on cylinder 3. Good luck.