Ok I installed a hotcam, 1.6 rr, new springs, etc, etc. w/ PCM4less tuning.

The car runs great, except my idle is a little high....around 950 or so(6speed). I have a new program, just gotta get it loaded..however I think the current problem is totally unrelated to this.

Anyway, I had a hard/sticky spot in my throttle. So I took the throttle body off cleaned it up real good with 3M Throttle body cleaner and put it back on....the hard spot in the pedal is gone, but now my throttle wants to "Hang" up around 1500.
It does this when coming to a stop, start up, and is very slow to come back down to normal idle. Any suggestions on what might be causing this.

Thanks,
Nick

 

My 97 Z does the same thing. When I am in neutral and coming to a stop, the idle stays around 1500 RPM until I stop. But it only takes a second to go back to normal (~800 RPM) once I stop. All computer controlled cars start up at high RPMs, so that's normal. The idle will be higher if your A/C is on too, but I guess you would know that one

 

my car started doing that after i got it reprogrammed. I think its pretty normal for the idle to come down slow in neutral. I have a problem that my car does that when its cold, but when it warms up, the idle will die down to about 500 then right back up when coming to a stop. I have no clue why it started doing that.

 

My idle is programmed higher because of the cam. It's set to 900, but usually shows around 1000-1100 on the tach. When coming to a stop, it stays about 1500-1600 for a second, but then drops slowly back to normal. It seems to drop in about three increments over a few seconds. Every once in a while, it will stick and not drop down. With a quick blip of the throttle, it then drops back down.

 

mine does the same thing , cept mines and auto so I only see it when Im in neutral . As soon as I put it in neutral it it goes to 1500 then in what seems like 3 step increments as well it backs down to 900 (set at 850) . Also when I start the car it does that.

 

Have you checked for a vacuum leak...start with the simple things before you move on to computer programs and stuff, also check the iac motor.

 

I have checked for vacumn leaks, there are none. I can blip the throttle and it goes right back down...maybe its just something I'll have to deal with.

Thanks for the replies,
Nick

 

Yeah I'm starting to see a pattern here b/c my car does the exact same thing as everyones. And we all at least have a cam and prog as one of our mods.

 

Either your blades are sticking on your throttle body, which is likely if you ahve an aftermarket one, or you need a new TPS sensor.

-Shannon

 

My car has been doing this same thing for a while now too... I don't think it's normal as the car never used to do it.

Sometimes it runs fine other times the thing sticks at either 2,000 or 1,500.. hot or cold it doesn't matter. Whenever I take my foot off the gas and put the clutch in the throttle will sometimes stick for a sec and then suddenly drop to 2,000 then stay there for a bit and then abruptly drop again to 1,500.. it won't reach idle until I come to a complete stop however.. and the car has always idled high - 1,000 on the nose (before and after reprogram).

Sometimes I can put the clutch in and the rpms will even climb up to 1,500 or 2,000 before dropping back down again. I find myself putting the damn thing in gear and pressing the brake to slow the engine down (not good.. I know).. it's becoming a nuisance what with how loud the car is.. that and my city mileage is like 12 mpg (I baby the hell outta it too) but interstate I still get 27 or so..

How hard is it to remove the throttle body for a good cleaning? Do I need to remove the TB to take out and clean the IAC also? And the TPS, clean it or replace it? How much do they run?

Sorry to thread jack you.. hope the problem I'm having is the same as yours (sounds like it at least).. if you solve it let me know because I have urges to blow the car up when it starts doing this

 

the throttle body isnt that hard to take off , just remove the throttle cable , the vacuum lines , and the coolant hoses (this is a good time to do the t/b bypass if you want , but remove the hoses somewhere you done mind spilling some coolant. After that its only like 4 skrews. I cleaned it all , but it didnt fix my prob altho it did fix the surging my car was doing after I started it.

 

a certain amount of whatcha would call snap throttle return or throttle follower is programmed into our cars. its there in manual cars to either a greater extent or some have less even among the same factory flash or calibration number. you said the plates seem to want to hang till you cleaned the thing, thats bad. is the hard stop (minimum air) screw turned in enough to keep the blades fron closing completely and contacting the t-body bores inside? if ya want to pull it off again shine a flashlight in and look thru the bores from the opposite side and a slight amount of light should be seen at the top and bottom of the bores with the throttle closed this is ball park stuff but its just to determine some rough ideas of where to start the diagnostic tree, can also slide a feeler gauge in the bore top and bottom with the body still attached to the plenum to get a rough guess to too closed or too open-im thinkin too closed. anyhow check it out and if that basic setting isnt correct you will be chasing your tail trying to sort it out. ecms have a certain idle iac count programmed in that makes em "happy" plates too open or closed or too dirty gives headaches like this. after these basics are established you can perform a minimum air adjust procedure-im not explaining the whole thing-check yer factory manual for how, varies from car to car. pull off the iac motor check for wear (shiny) on the pintle shaft and also crappo on the pintle itself and the pintle seat. i gots more things to have you try but look at these things first. stuff like disconnecting the vss and iac but we will get there only if this other stuff checks out good. later