help! rough idle and hesitant to rev

[driftin'180]

hey guys i have a blacktop s13 sr20 that i swapped about 2 months ago and everything ran perfectly. anyways i just plugged my aiv hole and all of a sudden my motor shakes like crazy at idle and when i rev it it revs extremely slowly like im accelerating. i haven't driven it yet as it is still up on stands so i dont know how it is when you drive it but i really dont like how much the motor shakes when in neutral. please help all i did was plug the aiv hole in my exhaust. and i tried fiddling with the idle adjust screw and it smoothed things out a bit but it is still bad.

[Ni2s4s0aSnX]

Why would you plug the aiv?

[driftin'180]

ummmmmm lets see because the tube that connects the aiv mounted to the head to the turbo outlet runs directly through the steering column thats why. im not the first to do as there are a few shops that sell plugs just for this. its either remove it or dont put the sr in, im not gonna go through the trouble of fabing up a device that is useless if you srent running a cat which im not

[Ni2s4s0aSnX]

Oh, we're talking SR here, I guess I wasn't paying much attention the first time I read your post. But I can't think of anything, but I can tell you that it most likely doesn't have anything to do with plugging the AIV, because the AIV really serves no purpose in terms of engine performance.

[D2180SX]

Sounds like a couple of things could be at fault:

If your setup is normal/with turbine/intercooler:

- Check your air flow meter (AFM) (if you run FCONV or other AFM-less ECU, skip this step). Is it dirty? Remove the AFM and shoot brake cleaner through the screen. keep shooting until you get no more residue/dirt. Reinstall and put your air cleaner back on.

- Check your intake behind the AFM (skip if don't run with AFM). Is it fully seated? Check for holes/cuts

- Your intercooler piping may have a leak. Check your sleeves for holes or slits and ensure your piping is fully seated. Some people really over-wrench the clamps, causing cuts.

- You've got a major vacuum leak on the intake side on the intake pipe. With engine running, feel around the pipe. If you come across a hole/cut/unplugged area, you'll feel a sucking sensation and your engine rpm will jump back to normal.

- You have a bad ignitor. You can check by removing each ignitor at a time while the car is running. If the engine drops in rpm even lower than what it is doing now (or even dies), it means that ignitor is good. If you remove one and there is no change in rpm- that's the bad one.

I doubt it is the exhaust side because the rpm's would be constant and there wouldn't be any "nervousness" in the engine, just a low unbaffled sound with reduced backpressure.

Hope this helps.
Modified by D2180SX at 2:58 AM 11/20/2005

[The Mic]

hey guys i have a blacktop s13 sr20 that i swapped about 2 months ago and everything ran perfectly. anyways i just plugged my aiv hole and all of a sudden my motor shakes like crazy at idle and when i rev it it revs extremely slowly like im accelerating. i haven't driven it yet as it is still up on stands so i dont know how it is when you drive it but i really dont like how much the motor shakes when in neutral. please help all i did was plug the aiv hole in my exhaust. and i tried fiddling with the idle adjust screw and it smoothed things out a bit but it is still bad.

If your engine continues to idle real high after it's warmed up, check the air regulator unit. There's a hose connecting to it. Pinch the hose when your car is idling high. If the idle speed drops, there's a problem with the unit. Also check the electrical ground connections on the engine for looseness and oxidation.

Another thing to check for is an air intake leak somewhere along the intake plenum between the Air Flow Meter and the Throttle Valve. Check all the nuts for tightness that fasten the intake system to the engine.

[Chezedik]

boost leak?

[driftin'180]

i dont think its a boost leak or mafs problem cause i had both of these happen to me when i finished up my swap 2 months ago and i havn't touched any of these things since. plus my motor revs to redline not to around 2500 which is when it stops with these problems. anyway i noticed that a wire (brown wire by where the harness from the car plugs into the engine harness by the brown connector) had come undone. i soldered it and the car ran fine i adjusted the idel to 900 and took it out for a spin. it worked fine but the idel kept dropping when i pushed the clutch pedal down to around 500 or lower and stayed at about 700 but it ran fine. the next day i went to go to work and it was doing the same thing with the hesitant rev.