engine surge

[intern8tion9l]

well this has been a problem ever since the swap but i kind have been letting it slide although it is very annoying. the car will surge at idle and continues to do so when gas is applied; also it kicks up for a sec between shifts. i know this is a feature on newer cars, but pretty sure this is too old for that to happen. varies up and down 400-500 rpms i'd say. i've gone crazy trying to find a vaccuum leak with no luck. i think someone mentioned leaky injectors might be the culprit? i also recently fouled a plug so maybe all this is related?

[Invasion1]

would this be the "bucking RPM's" some of the 5-speed swap guys have run into?? (myself not being one of them)

know josh had that bothering him also..if thats what it is.

[twinturbosedan]

i have exactly the same problem.  drove me absolutely nuts....to the point of considering going back to an automatic.

i thought the problem was the chip i was using, but Kenny burnt me another one and the problem got even worse when i put that in.  my only guess is that you'll have to do alot of datalogging & tuning to eventually find and eliminate the problem.  i myself would rather put an automatic back in the car than dick around with that for months and months.

i think one problem could be that the Getrag 282 is so poorly mounted in a W-body.  good luck

[Invasion1]

he has almost the same chip programing i have (since i made it) and mine does not do it at all......

i r

[twinturbosedan]

that pretty much rules out the chip being the culprit then.  i really have no idea what the problem could be :confused:  i thought i fixed it by replacing the ground cable but at best it only made it a tiny bit better.

mine is by far the worst in 1st-3rd gear.  the lower the gear the worse the problem is.  it is the worst when i'm trying to maintain a steady speed but also very noticeable in decel conditions.  trying to maintain a steady 30mph in 3rd gear can be very aggravating.  usually i will just get up to 30mph and then put it in neutral and coast just to avoid the bucking.

idle RPM is messed up too...it will surge like crazy.  RPM will also "flare up" during shifts.  i've also noticed that if i'm coasting in neutral (at any speed) the RPM will surge between 1500-1800 RPM.

i guess i'm leaning towards a vacuum issue.  i've looked for vacuum leaks and found none; although my engine had low vacuum at idle - around 10-12" IIRC. 

[intern8tion9l]

well looks like i have all of your symptoms minus the bucking TurboSedan. if i'm driving i don't even notice it unless as you said, i am coasting and the idle remains high. i mean its annoying but def not to the point where i would even consider an automatic! especially since this 5spd is factory and its one thing that makes my car unique

[twinturbosedan]

that's wierd i'm the only one with bad bucking.  i think Luke mentioned something about having that problem too but since then i guess Kenny has fixed all of that with chip tuning.

one thing that i've thought might be the culprit is that i'm using an LH0 shortblock unlike anyone else.  Jud posted some pics a long time ago showing that the LH0 crank has something like 1.5 degrees difference in crank timing.  i don't know if that 1.5 degrees could cause this bucking problem or not.  maybe the LH0 crank isn't compatible with TGP code?  who knows maybe when i finally get my real TGP engine out of the garage and in the car the problem will go away.

[intern8tion9l]

lets hope so, i can imagine that must piss you off pretty bad