kylehorn09

I have an 87' Trans Am GTA. 350 TPI, auto trans.

heres my issue. The car starts. But has a really rough idle. really rough. And when i push the gas or move the throttle body just the slightest bit. it acts like it wants to die. needless to say. i haven't been out in 2 days. it has done this before but only for a minute or two then it was fine. I checked for loose/cracked/ripped vacuum hoses; none. Took out all the spark plugs, they're all fine. My uncle said i should tap on the mass air flow sensor when it's running and see if anything happens. nothing happened. I just bought this car. any suggestions?? Thanks in advance

kylehorn09

Forgot to add, but i can get it to rev up if i pump it a couple times or hold it open for a couple seconds and it will all the sudden rev up. also, while trying to do that. i'm pretty sure i heard and felt it backfire through the intake.

cIaRmOaCrZo

does it have any codes??

kylehorn09

if it does, i dont know how to get them. ? and i think the service engine light is burnt out. cause it's never come on.

cIaRmOaCrZo

well if its burned out, just pull the dash bezal off and throw a new bulb in. but if you just turn the key to on, without starting it, the check engine light should be on. if it isnt, then like i said just replace the bulb.

2c2g

I've got the same problem with my 88 i unplugged the maf and it allows the engine to idle smoothly but at 1100( to high) and drops down to to 750 when i put in gear, but it run like crap at highway speed .Does anyone know if this is a bad maf or what else is causing the extremely rough idle?will a odb 1 scanner help diagnose this problem?

kylehorn09

god....lol that is gonna take forever. luckily i dont work tomorrow. haha

cIaRmOaCrZo

i can help you guys, but im trying to do a process of elimination. FIRST being, what codes do you have?? after you tell me that, then i can start throwing suggestions and more advice. so first things first.

kylehorn09

mine idled at 1000 now that i think about it. now its way down into like 600-900, but really really rought.

kmd

i just had the same problem with my 88 camaro. i cleaned off my IAC and it actually runs now. my problem was a combination of bad ignition timing and the IAC, i don't know if that's the same issue with yours but maybe it'll give you somewhere to start.

kylehorn09

well it seems as though i solved my problem. it was the maf. I got to looking around about bad mass air flow sensors. and ended up on an audi site lol. they were tellin some guy to start the car with the maf disconnected and if it ran better that was the problem. well...i thought wat the hell, so i did it. thinking the car wouldn't even start. but it did, and it ran better. so i had an extra maf at a buddies house. replaced it. and the car runs. no reall rough idle. or anything. also, i saw that on the maf i took out of the car it had the engine side screen taken off on it. maybe that was a contributing factor? also, can anyone tell me how to properly drop the idle on my car. it idles around 1000-900 rpm. any help is appreciated.

cIaRmOaCrZo

can anyone tell me how to properly drop the idle on my car. it idles around 1000-900 rpm. any help is appreciated. [/quote]

thats normal....

kylehorn09

thats normal....[/quote]

i know its not supposed to be that. hi. maybe minimum idle speed should be around 650-600. warm up idle should be that. but i got it dropped. the right way. here is a link. this is after you hve determined you have no vacuum leaks, and you have set your time.

http://www.hotrodhandbooks.com.au/eB...Line-11-5.html

cIaRmOaCrZo

Man I'm not tryin to be a **** or anything but a 1,000 rpm is generaly the desired rpm for ALL cars. Mine runs that too and it's just great. Yeah there are a few cars that may run a lowwer idle and with cam change, higher. Usually. Too low of an idle affects oil pressure alot, which MAY not matter but it would worry me...

DENN_SHAH

iTrader: (1)

IAC and TPS Adjustment,
https://www.thirdgen.org/tpimod2

rgarcia63

The baseline idle of 450 is just a reference point for the ECM. The ECM actually takes control of the engine at 400rpm taking into account all the the other parameters like temp, load, battery voltage...etc, and the Desired RPM versus Temp table in the EPROM.

My 383 starts around 900-1000rpm and almost immediately settles down to 700-850rpm, the higher the coolant temp the lower the idle rpm.

The Minimum air rate procedure in the 700r4 link is the same as in the manual. You'd think this site would have the same information in it's IAC tech article, but it doesn't.
I would also suggest for the procedure the use of a scanner, TunerCat, TunerPro, or similar program, or a precision tach because the OEM tach when new was at best reasonably accurate, unfortunately it does degrade overtime. So, if you use it to set your idle it mostly likely won't be correct.

y84pauloflondon

600-650 rpm's is where it should be on a V8!!! STOCK!
And about 400-450 rpm's in DRIVE and foot on brake.

y84pauloflondon

At 450-500 rpm's my oil pressure sits at 350 kpa.....at that high amount of pressure, I'm not worried at all!