Ok, so here is my problem. recently i have noticed that my car idles around 1,500 rpms and hesitates when accelerating. i have read many posts about the 3,000 rpm hesitation so i double checked my car in higher rpms....and guess what.....it does it there too.

im parked with the car on and slowly rev the engine....and when i hit about 2500 rpms the car hesitates and drops between 2,000 and 2,500 back and forth. then i continue and it does it around 3,500 and then 4,000. the rpms drop about 500 rpms, then go back up, then drop, back up and so forth. so ifor example....it will reach 2,500 then drop to 2,000, then back up to 2,500, then down to 2,000. this is when i am trying to hold it at 2,500 rpms.

i have checked for vacuum leaks but havent found any. the car is non sequential and it started acting like this after switching the intake (installed mushrooms) and using a Mine's ECU. i switched back the ECU but havent removed the mushrooms because im thinking this has nothing to do with it...but i could be wrong.

sometimes the car will act normal and idle at around 750 rpms and when i try to make it hesitate...it wont do it.

so why would the car just randomly idle high, then sometimes idle normal? when warming up, the car usually takes forever for the rpms to drop below 1,000.

any ideas?

 

new intake could possibly throw off the tune set to the ECU. first thing to check are the basics, check the map sensor hose if that is still plugged in and operating correctly try going back to the stock intake and see what happens. the map on the ECU may not be able to compensate the added air.

 

actually, the idle would stay above 1,000 rpms from time to time....even before i changed anything.

 

have you tired to adjust the idle with the adjustment screw? but you said hesitation problems.. did the problems occur when you had the stock intake on?

 

I did try adjusting the screw and it helped. It idles at around 900. anything lower seems like it will die. Funny thing is that it takes FOREVER to warm up to those rpms. I can warm it up at home, drive to work and it will still be above 1000 rpms. At the end of the day (after work) it will eventually drop.

Dont know what could be causing this.

 

Start with the usual:

* Clean the ISC
* Make sure the TPS is within tolerances

 

Yeah def check iac and tps measurements. Also it wouldn't hurt to reset the ecu just in case.

 

well i have checked everything and it all looks good. My TPS is showing 1.26 at closed (narrow range). the range is from .75 to 1.25......so its off but just by a hair. reding 4.99 at open and the max is 5.00. I dont think this would affect it but i am not sure.

full range of TPS is within specs.

Everything that i have checked looks good . Maybe my ECU is affecting it? Im stuck!!

 

IIRC, 4.99 is the default reading when the PFC is not getting a signal (i.e. if you unplug the TPS, you should see 4.99). Is the 4.99 in black?

 

no, the reading is from the bottom wire. (not the black on) and thats when its fully open. I reads within range when closed too.

i dont have a pfc. just stock ecu

 

Sorry, I assumed you had the PFC. So let's back up a bit, does the car accelerate past 4000 rpms ok? Does it only do this when the engine is not at operating temperature or does it do it all the time?

When did this start? New engine install?

 

yeah, i can drive the car like normal, past 4,000rpms and even floor it and it runs good.

It has that slight hesitation when slowly to moderately accelerating or when idling (and slowly revving it). it will do this both when cold and at normal operating temperature. it will do it run sometimes without problems.....i would say about 75% of the time it does it though.

This happened when i changed the intake. (now have mushrooms but the top one has no pipe, just attached directly).

As mentioned, my idle takes a long time to idle below 1000 rpms. Like a REALLY long time. I have checked vacuum leaks, TPS, adjusted idle screws, checked IAC, reset ECU. Spark plugs are fairly new but will check them soon just in case. Not sure what it could be. Maybe grounds?

Right before this happened i did the non-sequential setup, but was running fine after.

Really stuck on this and somebody wants to buy the car. I dont want to sell it to him if it has this problem.

 

bump

 

If this started after switching the intake and you are selling the car, you could just put the original intake back but I think it's going to be a different problem. I don't believe your car will have a Check Engine Light on the dash, so have you attempted to us a LED or other tool to check for engine codes?

 

well i switched back to factory intake and still nothing. There are no check engine codes either.
I was looking around and found the idle adjustment screw....well the screw pushes up on a rod right? if so, i noticed that when I rotate the lever (the one holding the screw) there is no change in the idle. i pushed on the rod (still assuming it should push out and in) and nothing. its like its stuck.

so im thinking maybe this has something to do with it?

still not 100% sold on the ranges of my TPS either....but if you guys say its good then its good.

running out of ideas.

 

I would ensure the TPS is within spec, even if it's only a little out. Eliminating what is NOT the problem is the first steps of troubleshooting. If you make that within spec and you still have the problem, you can then leave the TPS out of the rest of your concerns.

When you did the non-seq conversion, did you also do any other removal like removing the double throttle?

 

yeah, im going to adjsut the TPS just in case.

No, my buddy did the conversion for me but i dont remember him doing anything with the double throttle.

 

well, i sold the car and the new owner said he would take care of it. I did adjsut the idle a little bit (didnt know i was adjusting the wrong screw) and now it idles a lot better and that hesistation wasnt as noticeable.

Thanks for helping though. this could be closed now.