i have a 1986 trans am with a 305 v8 5.0 tpi with automatic transmission
100,000 miles on it

im not sure if i want to go to a mechanic or dyno shop to tune my car for a s*** load of more money on this car

or is it better to get a scan tool and figure it out myself? and what kind?

i want to get what i can out of my engine life and performance.

and i dont want to run the engine and have fun with the car if theres something stupidly wrong that will hurt the engines life/performance that could be easily tuned/tweaked/fixed

i want to bring my idle down but i did set my iac to my best capabilities and using the most common instruction tech articles since non can agree on some steps like in park or drive or when to pull the jump wire from a-b terminals etc...

when i start my car the tach shoots up to 2000(never did that untill i did the min air adjustment and not sure if its good) and then dies down quickly to settle around 1100 and then dies down to 800-900 once it warms up

i rev the engine and it sounds great once i let go it dies down and almost stumbles slightly to catch itself and idle goes back up to 800-1000

its not eratic and doesnt search up n down its a steady idle with i think a steady vacuum leak.

anyways i believe i have a vacuum leak but cant find it and my car is running a lil rich to compensate.

i just want to make sure i get everything i can out of my used engine since i cant buy a new one.

no engine codes present

new iac, rebuilt maf, tps reads .54v, rebuilt/refurbished throttle body, fresh gaskets for tb/runners/plenum, installed a crane afpr set back to stock psi or slightly higher, air foil installed in the tb

new egr valve and regulator

fresh/new pcv valve and hoses on both valve sides for crank case ventilation

k&n filter/cold induction kit

replaced more than half of the rubber hoses.

done a number of oil flushes and i use 91 gas with fule injector cleaner

i like doing things on my own and i hate spending money on labor that i can easily do myself but i need to be pointed in the right direction.

the whole wd-40 thing isnt helping with finding a link but i heard a scan tool or vacuum gauge may help but not sure


you engine guys what do you think?

 

well for one, try that IAC again and make sure your throttle blades are closing all the way. make sure the idle screw isnt turned up all the way

that car should idle warm at 550-600rpms, if its mostly stock

You could get tunerpro RT and a scan cable that plugs into the ALDL to read what the ecm is seeing as far as coolant temps, idle rpms, and IAC steps. Monitor all those and see if that IAC is reading right at idle

cold first startup idle should only go to like 900-1000 and slowly work its way down to 550-600 as coolant temps warm up

 

Sorry to jump in. With an automatic transmission, would the 550-600 engine warm idle speed apply if the car was in gear or in park? Thanks.

 

not really, the rpm in gear is only 50 or so rpm difference than neutral/park and both are around 550-650 rpms

 

OK, thanks. I'm about 600 in gear so I guess I'm in range then.

 

my car is in the 700-800 in drive and 800-1000 in park,

 

my car is 750 on idle and 625 in park..

 

at 2-300 on idle.......

 

anyway... after you adjusted your IAC, did you readjust your TPS? if not, theres your prob

 

With a completely closed IAC, bypassed EST, and transmission in DRIVE (with a stock torque converter) the throttle mimnimum air position should be ajusted to obtain 500 RPM. That's the factory specification. I prefer to run it closer to 550 RPM just in case there is an IAC problem, but anything higher is going to be a problem. Decode the factory binaries and you might discover why. The factory programming also has an RPM adder for when the transmission is in PARK, so it must be set in DRIVE to do it properly. Tech articles be damned, that's the proper procedure.

If the IAC is clean and able to move freely, it should maintain idle once it is active. Coolant temperature and VSS also affect the target RPM. If the minimum air is set corectly, and the TPS is adjusted correctly (Good call, Nater!), the rest is up to the ECM and IAC.

Was the IAC replaced or cleaned & lubricated?