96 CX hatch, GSR swap with JDM ITR 98+ Trans. Running OBD1 with chipped P28.

From a cold start while driving, the car runs perfect, no issues at all.
BUT, if the car is warm, I shut it off, then restart and drive it, I get a jerking when i'm slightly on the throttle or from a stop and start going. Almost like the throttle is being sucked close, and it'll stay like that till I give it more gas.

I have no vacuum leaks, everything is tuned up and in good order. I do have a "typhoon" IM, and just put a (godspeed I think) 70 MM throttle body on it (I got it dirt cheap and it was brand new). This never happened with the stock TB, nor with the 70MM one until about a month after the install. I'm also using a Skunk2 Thermal gasket for the TB.

I had tried adjusting the idle, and the idle screw is ALL the way in, my idle is at about 1100-1200 RPMs.

I've don't some reading, but can't seem to find a solution, or at least one that has helped me any.

Thanks guys!!!

 

What i would look at first is the IACV that is the only thing that changes as the engine gets warmer...also i would just check the tps for correct voltage and make sure its not installed incorrectly....i dont know much else that would effect throttle response from idle besides those 2 which directly control it. Also if your idle screw is all the way in and it idles at 1,200 rpm thats pretty high.

 

I have tested the TPS and adjusted it to the OEM specs.

As for the IACV, I have cleaned it and made sure it's working properly. I have also had a thin plate between it and the IM during the summer because I can't get rid of the idle surge as well. With the IACV blocked of, the jerking still happened, which leads me away from the IACV. I had no issues with that valve before, without the blocking plate and with the old TB.

I'm more leaning towards the 70MM TB, but it has no leaks, it doesn't stick and works properly.

 

^iacv..clean it and go from there

-air in coolant system?
-vacuum leak
-tps

 

this isnt the thread i thought it was gonna be by the title

 

Like I said, TPS is to spec, with perfect sweep to WOT.
Have tried other IACV's that where on other cars that's worked fine, and I've cleaned mine numerous times.

I have no vacuum leaks, have looked over and over.

 

i had a similar problem on a d16y8, turns out the throttle stop (the adjustment screw on TB were the throttle arm rests at 0 throttle.) was adjusted up to high. so it was idleing high like yours and it was also causing my iacv to trip out bc my TB wasnt closing all the way at 0 throttle. once i adjusted it down to porper idle rpm, and TB closed properly it fixed problem

 

this is a good idea, I was going to re-adjust that screw after I installed it and it completely slipped my mind. I'll do this and post my findings!!

 

ok, so I re-adjusted EVERYTHING on the TB. changed the IACV again, re-bleed the coolant system, triple checked for Vac leaks. and still nothing.

This is weird how it ONLY does it once the car is shut off and re-started when it's still warm.

 

Maybe check to make sure coolant lines going to IACV arent clogged. or do you still have your stock TB? put it back on see if it stops.

 

coolant lines aren't clogged, I removed them when I changed the IACV last night, they were fine. I'm thinking I'll have to go back to the original TB and see what happens.

What causes a TB to make this issue? I know some aftermarket ones are junk and stick and have issues, but I looked all over this one before installing it and it looked fine, Throttle plate didn't stick or anything.

 

My civic would sometime do the same thing. I sometimes would stop the car, turn the key off and on right away, wait a few seconds and it would fix itself. Not sure what causes this but it happens rarely.

 

I tend to have this happen but I always questioned if it could be related to my clutch...

 

This happens to me as soon as my ECU throws code P0505. It can be so many things that its a real PITA to fix. Search for P0505 and youll find a few diagnostics/solutions.

 

p0505 is IACV, I have ruled that out because I blocked it off and the problem still occurred.

 

when is last time you changed fuel filter?


I am at its mercy on my car.

 

New fuel filter a year ago maybe?

Because of my aftermarket IM, the throttle bracket would only work using 1 bolt, and in doing that is causes it to move, which could be making the throttle get sucked closed. I made an adapter to make it not move anymore. I'll see if this does anything.

 

Should not be idling at 1200 RPM with the idle screw all the way in... start there.

 

when it revs high your temp stays same?

 

I know my rpms shouldn't be that high, but I can't find any vacuum leaks or anything.

And temp stays the same, fully warm it's just under 1/2 way and never moves. Fan comes on as it should

 

It jerks while in gear?

 

yes. once warmed and shut off. after restarting it while warm them driving, if you keep a stead speed, so the pedal is slightly pressed, it acts like the throttle gets sucked closed.

I'm thinking it was doing that while the throttle bracket wasn't right and was moving.

 

Hmm. Inspect the operation of your cable by having someone push the gas while you are outside.

Check your Throttle Position Sensor as well. Maybe even swap Throttle bodies to see if the issue still exists.

 

TPS is fine, I've checked it.

I didn't have any issues with this throttle body for the first couple weeks I had it on the car. I'm hoping my bracket fab. will work. I'm at work so I'll have to see after I get done.

 

ok, so it worked fine for the most part, but it's still acting up.

I'm going to change the throttle body out for the OEM one and see what happens. And look over the 70MM TB and see if I can see anything wrong with it.