Tips for reducing very light throttle buck below 2k rpm.....E40 PCM

[quik95lt1]

Hi :)

I have an 06 GTO M6 with an E40PCM that I recently installed a 226/234 .600/.600 112+3LSA cam in.......ive got the car running pretty well but it seems as though at very light throttle below 2krpm i feel slight surging and bucking from the car. Give it more throttle and it goes away......it almost feels like the pcm is trying to acutate the throttle blades at the part throttle positions and causing the buck.........any suggestions??? Also id like to delay my injector events at idle to reduce fuel smell out the exhaust but i cant seem to figure out what table to adjust they are all labeled oddly in the software.....

thanks,
Mike

[minytrker]

Log your timing, alot of timing the bucking is when it changes timing tables and they do not match so the timing is jumping up and down.

[Chalky]

Can't help you on injector changes.

I can tell you that the cam is causing your fuel smell issues. Unburnt fuel passing through the exhaust contains unburnt oxygen. Your 02's think car is lean and keeps adding fuel. I wish I could tell you how to work around this but I haven't played with a cammed car in 4 years. Maybe someone can chime in.

[turbo_bu]

Can't help you on injector changes.

I can tell you that the cam is causing your fuel smell issues. Unburnt fuel passing through the exhaust contains unburnt oxygen. Your 02's think car is lean and keeps adding fuel. I wish I could tell you how to work around this but I haven't played with a cammed car in 4 years. Maybe someone can chime in.

Is this why some guys end up trying to run open loop at idle? Then they can make sure the O2's don't overcompensate.

[Chalky]

I would think that is a good reason. My cammed LS6 always idled better in OL!!

[Jayrcr3]

My cammed Camaro sounds mean as hell when it starts up cold. Once it warms up, it doesn't sound quite so choppy. It also stinks up the garage quite a bit.

[turbo_bu]

My cammed Camaro sounds mean as hell when it starts up cold. Once it warms up, it doesn't sound quite so choppy. It also stinks up the garage quite a bit.

I can't remember, but is there an easy way to have a tune with OL idle, but closed loop during normal driving?

[macca_779]

That's not a big cam and will have no issues idling at 800 in closed loop. Your bucking could be a lean or even a really over rich condition there. Throw half a point at it either way if your not tuning with a wb and see if it clears up. If it does you know where the issue is so clean up the VE from there or if closed loop sort that out by either fixing it or going open loop.

[quik95lt1]

well i finally got back on tuning this thing after buying an EFI Live book and installing an LC1 in the car..........i went into open loop SD mode with it and Auto Tuned the VE after gettting it close manually.............the car runs absolutly perfect in SD mode even in the 30* weather here now....i cannot beleive the difference in the car.......my low speed and idle VE was WAYYYYYYYYY too high like almost 15% in areas.........car started instantly and idled perfect on its own this morning and it was 23* outside.......drives great at low speed also.....i also dialed in my idle to 900rpm and my WOT to 12.8 across the board car makes great power now also, new issue is in the cold air i cant get any traction untill im in 3rd gear lol.....thanks for all the suggestions and help from everybody that replied in this thread..........next im going to plug the MAF back in and auto tune the maf table........then i should be good to turn on the O2's again and be done with it :D