Thread: Jerky on/off throttle transision and idle dip

I've got a '93 SE-R with an SR20DE with A/C and PS delete, all the idle control nonsense is unhooked and the main IACV is blocked off. EGR is also deleted.

My problem is that when cruising along in 4th gear at 30mph or so the car will do fine then I'll suddenly have a loss in power accompanied by extremely rough jerking when I go off throttle or get back on the throttle. After a while it will go away. Also, when coming to a stop and putting the clutch in my revs will fall to almost 300rpm before bouncing back up to 1300rpm or so. My only thoughts are it could be a vacuum leak or poorly-adjusted TPS but I have no idea how to check for either of those things.

The random loss of power and jerking is usually stressed out TPS wiring.

As far as the low/jumpy idle.... well you should not complain about idle issues if you delete your iacv. The car is pulling and adding ignition as well as fuel rapidly to combat the idle.

It idles fine, it just dips extremely low when falling from a higher RPM. Did that before I deleted the IACV as well.

I'll try continuity testing of the TPS wiring if I can find multimeter leads long enough. See how much resistance there is along the length of it.

It sounds like faulty TPS ground. That can lead to the ECU believing that you closed the throttle wile cruising along. This usually happens at low TPS %. Take a multimeter, and check the resistance on the ground pin. Should be close to 0 Ohm, but I've seen cars where it had 1-2 Ohms of resistance in it!

Oh, and deleting all idle controls will severely affect driveability. You can combat this by cracking the tb open slighly more, raising the base idle to closer to 1000rpm. This will make cold stalling less likely. Many people on this forum see the IACV as some kind of devil, but once you get the hang of it, the sweet idle is so worth the hassle.

Sweet, I'll check that out. If the ground has too much resistance would I just ground it to the intake manifold similar to the MAF ground 'fix'?

After deleting the IACV I messed around with the throttle blade stop to get my cold and warm idle in a decent range. Cold idle is 1300rpm, warm is 850 or so. It works rather well.

Thanks for the help.

If your going to run without the IACV / idle control devices your going to have to set the warm idle around 1000rpms..

This will give you 1500rpm cold start idle and will not bog down when coming to a stop. Having an idle of 750-850 is fine but its not enough to combat bogging down when coming to a stop.

and yes double and triple check the TPS voltage and resistance and re ground it also.

Just gonna say, it's better to be jerked off than jerked on..