I finally finished building my motor and put it in this weekend. It runs awesome except for one wierd problem. If I start it cold, it will idle and jump between 1700 and 2000 rpm's until the fan comes on and the motor is warmed up. Then, it idles fine just below 1000 rpm's..... But, when i rev the motor up, it still wants to jump around consistantly between 1700 and 2000 rpm's until i step on the pedal enough to bring it past 2000 rpm's, then it revs up perfectly smooth. It also does this while i'm driving, i'll be going in 1st gear, and once it hits 1700 the car jumps around until i get it past 2000 rpm's....
WTF?? I thought it could be the iacv but why would it do it after the car is warmed up and while i'm driving it?? plus, it still does it when i unplug the iacv.... i also changed computers and it still remains... any opinions on this bizarre problem would be appreciated. thanks,
-Justin

 

AH HA! I was thinking the same thing.... but, my JG throttle body came with a brand new tps that was supposed to be "set perfectly" from the factory.... although this tps has room for adjustment back and forth, and it is currently adjusted all the way to one side... i thought that was weird... any other ideas, or anyone know how to properly set a tps?

 

my iacv got ripped out and it idles fine. the wires are just chillin hangin in the motor bay. but my timing is also off by 18 degrees retarded.

 

What exactly do you mean? i was thinking the same thing, that maybe it was something with the butterfly at 2000 rpm's and one of the air bypasses.... I have a brand new JG 65mm tb and brand new skunk manifold... any ideas??

 

well actually, I calibrated the tps a few days ago... it's a perfect .500 volts at closed throttle and it reads a smooth voltage increase to appr. 4.8 at WOT... i've changed the iacv, changed computers and replaced cap and rotor.... right now i'm completely perplexed... any other ideas guys¿¿¿¿... I definately have been doing a whole lot of trouble shooting... just wanted to know if anyone has heard of this problem because it's got me stumped.... i thought it could be the tb, but at closed throttle when the rpm's are coming down after being on the throttle, it tends to stay at 1800-2000 and jump around... although if i hit the gas really quick, it drops fast enough to sometimes get through that spot and idle normally... with the GSR computer the problem isn't as bad, when i accelerate slowly the car jumps at those rpm's, but only sometimes... with the skunk2 program (p2 it does it really bad and wants to always idle/jump around at those rpm's.... so i'm guessing it's electrical, not vac/throttle related... any other suggestions??