I have a 230/232 Futral Motorsports FM13 cam on a 112LSA with 4 degrees of advance ground in, and patriot performance "special" LS6 heads. I've had this setup for 4 years+ and the power is nice. With the first tune I received the car behaved well around 1000-1200RPM for a few months and then the bucking started with anything below 1500.
I dealt with it for a couple of years then upgraded to a Z06 MAF, 30lb injectors, and received another tune from the same shop but different tuning tech. (They gave me a discount for a "retune".) The car drove even better than with the first tune, but again 4-6 months later the bucking problem came back. I have to ride through parking lots with the clutch half engaged, otherwise the car bucks violently.
I didn't think my cam was big enough that anything below 1500RPM would drastically buck. It seems like the tunes would last for a hot/cold season and then are crap for driveability. Wouldn't the MAF compensate for the different weather conditions? Is this typical of a head/cammed car to have to get a retune constantly? Or is there something else going on?
__________________ Click the image to visit my vette's info 1999 Navy Blue Coupe: HUD and MN6 Best Dyno: 435/400 rwhp/tq Best 1/4: 11.72 @ 122mph
Are you using an oiled air filter...if so maybe a bit too much and your MAF is getting oiled. Get a good electronics part cleaner and just spray the elements...don't brush or touch them, they are fragile.
OH MY GOD, THIS IS EXACTLY WHAT MY CAR DOES!!!!!!!!!!!!!!!! I never knew how to really explain it, Ive tried over in tech and people were saying I had an intake leak. Im highly doubting that. I am still a stock cam, used to be charged before I bought it and still have large injectors. I even have problems on the highway with the cruise on if it gets to be going too slow and the rpms drop into the 12-1500 range. If you find a cure for this please let me know, it too is annoying to drive into work, people probably think I cant drive or something!
Both of you should find a member of your local Corvette Clubs that have HPTuner or EFIlive and scan for the problem. Much easier than quessing. If you buy them a drink, they will come
Someone in wisconsin, please have a need for alcohol!!!!
PM or reach out to Tom (Y2KVert4me). He is in Pewaukee and pretty good at EFI Live. I have it also, but am in Belgium, WI and not as skilled as Tom. Let me know if you still need a hand sometime!
Are you using an oiled air filter...if so maybe a bit too much and your MAF is getting oiled. Get a good electronics part cleaner and just spray the elements...don't brush or touch them, they are fragile.
How many miles a month do you drive the car?
Ed M
Good call; the MAF was oiled from my K&N filter. I cleaned it and went for a test drive, but unfortunately it didn't fix the problem or improve anything.
Good call; the MAF was oiled from my K&N filter. I cleaned it and went for a test drive, but unfortunately it didn't fix the problem or improve anything.
It may take 50-100 miles for the trims to re-learn
Like Bill Curlee said - check your LTFT's. Sounds like your O2 sensors are gradually moving your tune away. Easy enough to check... if that is the problem you may consider turning them off completely and running with the STFT's only. Good luck,
Gabe
BTW - where is Green Cove Springs? I am in Cape Canaveral.
OH MY GOD, THIS IS EXACTLY WHAT MY CAR DOES!!!!!!!!!!!!!!!! I never knew how to really explain it, Ive tried over in tech and people were saying I had an intake leak. Im highly doubting that. I am still a stock cam, used to be charged before I bought it and still have large injectors. I even have problems on the highway with the cruise on if it gets to be going too slow and the rpms drop into the 12-1500 range. If you find a cure for this please let me know, it too is annoying to drive into work, people probably think I cant drive or something!
I have seen it happen with injectors that are too large.
My stock '02 Z06 did it when I first got it 3 years ago. It started bucking right away, took it to the Chevy stealer, and it took them a week to find the issue. It turns out the wiring going to the MAF was either causing electrical noise or was receiving electrical noise. They wrapped the wiring with aluminum wiring shield and it solved the issue.
OH MY GOD, THIS IS EXACTLY WHAT MY CAR DOES!!!!!!!!!!!!!!!! I never knew how to really explain it, Ive tried over in tech and people were saying I had an intake leak. Im highly doubting that. I am still a stock cam, used to be charged before I bought it and still have large injectors. I even have problems on the highway with the cruise on if it gets to be going too slow and the rpms drop into the 12-1500 range. If you find a cure for this please let me know, it too is annoying to drive into work, people probably think I cant drive or something!
Depending on the size of injectors that is quite possibly your problem. Running huge injectors at tiny duty cycles can be hard, the spray pattern etc isn't going to be as uniform as a smaller injector. Plus, depending on the tuner, you might not have all the right injector data in the tune in the first place. If you haven't got need for the bigger injectors sell them off and put stock ones or even SVO red tops in with accurate injector data and you'd be amazed how much better the car will run.
Corvette Store
Whats the bucking problem with my car
