ok so all i have done to this motor is open element K@N. and no its not a vacuum leak. i have replaced all the sensors except the O2, on the tbi. Does anybody have any ideas. and I also wired the fan to run all the time. and put a 160 thermo in it(yeah i know its a little low but help with the 1/4 et).

A few ideas....

Did you replace/remove any of the components on the TBI unit itself? (TPS or IAC) If the TPS was touched, you'll want to make sure it's adjusted for the correct voltage at closed throttle. If the IAC was removed, you'll want to go through the minimum air procedure outlined in the tech area of this site.

If the above isn't applicable, I'd ask at what temperature the engine is operating. It may be possible the engine is idling at 1500 because that's the desired idle speed at whatever coolant temperature the ECM is seeing. If you have some sort of scan tool, you should be able to see the desired idle speed.

I second what was posted above by TTA. Also, look at your throttle linkage. Make sure that your open element is not hitting it or causing it to fully close. Check for vacuum leaks around the base of the TBI unit since you had it off. I assume you used a new gasket?

Id suspect a stuck IAC, hanging throttle, or possibly a problem with the PCV.

my formula is doing a similar thing to this. not quite 1500 rpm but in the morning when its cold and I crank it up it jumps up to 1300 rpm for about 5 minutes. I tried adjusting the idle screw and it didnt matter how much I turned it. I put on an open element and kept the IAC inside (I drilled a hole to bolt it inside the aluminum container)

Is it really idling at 1500 or is the tach saying its idling at 1500? I thought i was having the same problem then i realized, along with many other third gen owners, my tach is off. Do a search on "Tach problems " and you will find your answer.

ok, no its not a vacuum leak cus i pluged all the outlets(dont worry i put all the lines back) and it still idled high. no its not the tach i can hear the difference. my engine is running under 200 degrees 24/7. no i did not use a gasket with the open element. cus my 70 chevelle has a open element with no gasket and it runs like a bat out of hell and idles a nice 900rpms. and i relocated the air sensor to up close the the fire wall. away from engine heat. i drove the car today to school home and then to work and home. and the car is supposed to get 17mpg city. i lost a quater and a half.
oh pcv? positive crank vacuum? or something like that. your talking about that little tube with a filter on it? on the passenger side valve cover? the filter is a little dirty but i think it is fine. that is the least of my worries.

Did this check out?

Although it's good you checked the vacuum hoses for leaks at the TBI, it's still possible to have a vacuum leak at the base of the TBI as Shifty mentions. Did it pass the old carb-cleaner-spray-around-the-TBI test when the vacuum lines were plugged? And, have you checked to make sure your vacuum leak isn't coming from some other "hole"/port/hose in the intake manifold. (Not sure if you have any others on your engine. But, just in case.....)

Ironic! i started mine up for the first time in 2 months and it maxed out on RPMS way past 8000 grand it pegged the tach and the engine cutout, kinda made me nervous at first, it started up just fine and idled at 1500 rpms or about there, i suspect my problem is in my chip, i believe my fueling is off, because when you press on the thottle it hesitates and then picks up from there, im thinking it might be too much air and not enough fuel, like the A/F ratio is way off, i dont have a cat installed at the moment. next task is to datalog.

The hesitation is not enough delta tps and/or MAP AE. The stupid smog crap where they double the MAP AE at high throttle to reduce the ammount of AE needed is part of the problem. In your chip this can be disabled by maxing out the threshold needed to cut the AE in half. After that start tinkering with the AE to see if you can reduce/eliminate the hesitation.

BTW, the car is supposed to idle around 1400 rpm when cold. Its just the way the stock computer is.

er...in the morning (EVERY day) when i start 'er up, i get that 1400-1500rpm
idle for 6-8 minutes or so, then it slowley drops down to the norm 750-800rpm.
Is this normal or a sign of some mis-adjustment?

ok I probibaly should read all the posts before asking a Q. dimented24x7
nailed it for me already


-Aydin

ok i still can not find the problem, could if have anything to do with the fact that i took off the smog pump and lines? still leaving the egr valve and the peices on the header

is this the problem?

I turned the target idle down on my chip, dont think that helped. I check the TPS and IAC for adjustment made the nessary moves but it now idels at like 1000 rpms and then down to 600rpms which i dont think is high enough to keep it running it surges all over the place, dropping down past 500 rpms and then up to 1500 and then it pops and quits.

Im gonna restore the values in the chip and retry it, the only time that this occured is when i got my cat-back on, i doubt that it the problem. When i press the pedal down it stops fueling-hesitates then starts fueling. but since i made some changes on the IAC it doesnt do that anymore, keep in mind that i have driven the car plenty and had no problems whatso ever. the exhaust smells like its lean, so maybe its a fueling thing.

Itll cause the car to possibly run rich. Put pipe caps in place of the one way valves.

ok i think i have found the problem. by the way i replaced the pcv valve and the O2 senser. did not do a thing. still idles high. but since i work at a local tire shop. I had a friend look the engine over. he tinkered with the trottle position sensor and has come to the conclusion that it was not put on correctly or something. So all i have to do is put it on correctly and i should be good. the O2 sensor did seem to make my car a lot smoother.

just how much of the idle can be programmed in a tbi chip. I heard for the most part nothing can be done in the prom...

You heard wrong. Pretty much anything can be done to your idle in the prom. When you can program your own proms you have complete control of your fuel and ignition timing everywhere. Look into it, it's a worthwhile tool to have.

I have a camaro 1992 z28 tpi
and it idles high when i start it, the idle is 3000 then it dopes
to 1500 sometimes, but most of the time it stays at 2000-3000 rpms. SO i ran a computer on it and because the check engine light kept going on, but would never stay on.It might turn on for about 30 seconds and turn back off,or sometime it would stay on for 15 minutes then cut back off.While back to the subject the computer said it was the tps sensor so i changed it but same problem but the idle would now say at 1500-2000 rpms
i was reading a couple of threads and it said that when your engine is could it should idle at 1400-1500 but once it heats up it should drop to 750-800
"nidyanazo"er...in the morning (EVERY day) when i start 'er up, i get that 1400-1500rpm
idle for 6-8 minutes or so, then it slowley drops down to the norm 750-800rpm.
Is this normal or a sign of some mis-adjustment?

i had a mechanic adjust my idle and some problem it also hestates
alot i change the fuel filter and did alot of them things you recommeded, can somebody please help me

I had a similar problem to yours (hesitation) I replaced the pickup coil and ignition coil and it fixed the problem...o and before i replaced those i got new sprk plug wires..which is prob the first thing i would check even though in my case they werent the issue.

i dont think it's that because i just recently got a tune up 3 months ago replace wires put ac delco spark plugs and new distributer cap

Yes, that wasn't it for me either, so now look at the ignition coil and pickup coil..

Anyone get the problem resolved?