idle is alil high....why?

[BEAST]

ok ive read pleanty of causes for it so ill tell you what ive done so far..

95 camaro 3.4 m5

after i replaced the intake,plenum, egr gaskets, the car will idle at about 1500 when cold and stay at about 1100 and normal tempt.....just for a tune up i replaced the coolant tempt sesnor, therm, and seafoamed the car....going to replace th o2s today....my car use to idle 1500 when cold but 800-900 when normal temp.

i tested the iac and it showed 52 ohms same as the new one i bought...but i still swapped it....and same....so i put the old one back....the car then sometimes creeps up slowly to 2000 and will go back but normal stay at 1200-1000.....im thinking its a vacuum leak but i cant find anything...other than the slow creep up of rpm...the car runs fine doest bog, or want to die....actually runs good...just scary that for no reason it will creep up slowly to 2000....i scanned it so i will post the codes when i find the paper....said something about "32 lose of signal" but i think thats the misfire i fixed....i heard of a spraying some sort of spray to see if the car revs idicating thats where the leak is at....

question has anyone heard of that? spraying something all around the vacuum hoses to see if the car will rev indicating a leak? plus how do you check the volts on the tps....i read it should be about 1-5 volts...is that true?

[gman2000]

Re: idle is alil high....why?

I have used starting fluid.

[Tech]

Re: idle is alil high....why?

Make sure there is not a fold or crease in any of your intake gaskets. My friends cavalier had a high idle and it ends up the throttle body gasket had a small fold in it from when we cleaned the whole intake and installed new gaskets.

[BEAST]

Re: idle is alil high....why?

but does anybody know how to check the tps sensor?

[vallentinerocks]

Re: idle is alil high....why?

I have had pretty much the exact issues as Beast with my 94 fireibrd. I also swapped out the IAC twice, the first time it may have been faulty, the second time i think its still something else.

I will do a vacuum leak test this week, should i use carb cleaner spray or starting fluid?

I can usually cure the idle change issues by disonnecting the battery and resetting the computer, but this is getting old. It ran fine most of the spring and summer and fall, but now as the temperature has gotten cooler, seems to do it more when its really cold outside. seems to do it less during the day when its a bit warmer. I dont know if the temperature really has anything to do with it or if its just by chance.

Normal idle is around 850-900. sometimes at stop lights or stop signs, idle will start fluctuating between normal and about 600rpms, sometimes the SES light will come on when it does this, most of the time the idle go backs to normal, and the light shuts off.

this week, the idle will sometimes jump to 1100-1400, even after the car is warmed up. the car never stalls it usually when actually moving the idle speed isnt affecting the driving.

im just sick of the unstable idle i get and dont know what to change next if i cant find a vacumm leak. Thinking of buying a new throttle position sensor next ($32 at autozone), then maybe have to look into MAP sensor, engine temp sensor, O2's? or something else.

I have come to the conclusion after talking to my friiend who owns a smog shop that the EGR valve is not to blame, because he said if the EGR was bad, then the idle would ALWAYS BE bad. He seems to think its a vacumm leak based on what i told him and by not looking at it.

hope you guys can shed some light on our idle dilemma. thanks

[slow6]

Re: idle is alil high....why?

I think its also a vacc leak because you said it only happens in cold weather.
Well, cold weather makes you run lean (its more dense).
Yes, you can use either/or carb cleaner or starting fluid or a fog machine...whatever.

If your EGR was bad, the computer would tell ya

Your friend may be right about

"if it were the EGR it would be bad all the time"....

well..

"If the EGR valve is malfunctioning you may experience reduced power, detonation (pinging), rough idle, or stalling and hesitation when accelerating."

EGR sends hot air into the intake.. so the pcm is set up for that hot air. Once you remove the EGR, your intake will see a nice (estimate: ~30F or more change in cooler temp). The cool dense air will make you run lean also which can lead to kr(reduce in timing)
(and I used to think that removing the EGR would make you run rich cause of less airflow hahaha I was a n00b)

suspect a vaccum leak or possibly some kind of fuel pressure problem?

[vallentinerocks]

Re: idle is alil high....why?

on my car, i checked for a vacumm leak today while thoroughly spraying carb cleaner..couldnt find anything that would indicate a vacumm leak. i went ahead and cleaned the throttle linkage with it and spraying cleaner into throtte body. after resetting the computer again, removing and cleaning he IAC, inspecting the TPS and bleeding the coolant for air, my idle is back to normal range again. drove for about 15 minutes around town today, and the idle remained normal. but this seems to be the case usually anyways. today was also warmer then it has been too.

could it be the pcm/ecu computer that continiues to malfunction itself causing the idle changes???? possibly dirty fuel injectors??? still stumped as i am almost sure the idle problem will return.

[Vanquish]

Re: idle is alil high....why?

If you feel that it is dirty injectors, then when/if the problem returns..........take your injectors off and give them a good cleaning.

[auto666]

Re: idle is alil high....why?

it probably tps. if its a vac leak check hard plasitc parts thats the only place you typically get such variation from a vac leak next time it does it put it in park and give it a tiny bit of gas if nothing happends you can bet on tps

[vallentinerocks]

Re: idle is alil high....why?

When doing the test for a vacumm leak, I sprayed carb cleaner pretty much everywhere i could think of and twice over, maybe three times and the rpm's never changed one bit. Of course in the throttle body when sprayed to clean, the rpms dropped everytime i pushed the nozzle. I once had a vacumm leak from a loose connection and my rpm's were high but ALWAYS remained high until i found what the problem was.

dont know if injectors being dirty could cause my scenario, just asking if it could be. Whats the best fuel injector cleaner i could use or do i have to physically clean the injectors??

perhaps I will go ahead and replace the Throttle Position Sensor and see what happens. My firebird does have quite a few miles on it so who really anything could be bad I guess.

thanks for your input guys.

[vallentinerocks]

Re: idle is alil high....why?

BTW, hey BEAST.........have you found anything out causing your problem?

sorry to piggy back your post...but real similar I believe...hopefully we both get it figured out.

[Die Ford V8]

Re: idle is alil high....why?

have you tried to just adjust the idle screw?

[vallentinerocks]

Re: idle is alil high....why?

uuhhhh.........idle screw??? come on..........i wish i could.

[slow6]

Re: idle is alil high....why?

will you all post your setups? you always should!
Is it Electronic Throttle Control?
Is it Fly by wire?
What?

[Die Ford V8]

Re: idle is alil high....why?

you should be able to adjust the idle screw, I know it is kinda difficult, but I did it on my friends 94 bird.

I know it seems super obvious, but yeah.

also, check to see if the butterfly is actually closing in the intake and not letting access air in. if your engine is letting air in the tps will add the right amount of fuel to make up for the extra air, aka high throttle.

good luck man.