ok i still havnt figured out what my issue is with my 98 spyder gst. i have a stang idle issue that i cannot seem to fix. I have tried the IAC 4 times and nothing has seemed to make a difference. so today i went threw and pulled all the code/car info from the OBDII connection. the CEL was not on but i was still able to pull the codes. this is what i got:
@ engine idle i have a load at 30%
CEL- P0505= Idle air control system. (i have 4 different sensors and not 1 has fixed this issue)
car goes back and fourth between open and closed loop at any temp
short term fuel trim switches between 0%-24.2%
long term fuel is at 12.5%
spark advacne is around 16*
air flow from mass air flow sensor to turbo 1.265 @ 1500 rpm
oxygen sensor: Bank 1 0.02 volts, Bank 2 0.02 volts

this is what i have gotten of of my OBDII engine reader from craftsman. the car has trouble creating boost at low RPM's and the only time i can get a good blow-off is after 5,00rpms. which to me isnt normal but i may be wrong.

anybody know what might cause this issue?

things i have replaced within last 6 months( car hasnt run properly for over a year):
O2 sensor #1 on turbo
IAC (4 times- no difference)
TPS

All this started after i had my headgasket replaced. i also replaced all of my timing belts, water pump BS belt, and all new gaskets.

There is some whine that i cannot figure out. someone once mentioned that it sounded like it came from the turbo. but they were not 100% nor were they a mechanic.

thanks for any help

 

check your coolant temp sensor

 

what do you mean coolent temp sensor? the highest it got that i can remember was 206* and that was before we shut it off. I do know that my collent level is low and thats one thing that i havnt taken the time to get yet so thats probly y its a little high. would this cause a high idle?

 

i mean the coolant temperature sensor (CTS), it senses the temperature of your coolant. the low coolant is definitely the reason for the temp getting that high, as for a high idle, its possible, fill it up, bleed out the system, and see if that fixes it, if not my bet is on the cts

 

anybody else got any other ideas. im gonna fill up the coolent today and see what it does. but i dont think thats the issue

 

maybe some vacuum lines werent hooked back up correctly after then put the head back on

 

this is what makes me think its your coolant temp sensor, if that went bad, your car wouldnt know when to switch between open and closed loop

 

ok, im about 99.9% sure that all the vacuum lines went back the right way. i have checked that many times because i thought that was the issue. couldnt find a single one that was out of place.

i dont think that a vacuum line would cause the engine to work so hard at idle like it is. its also got a very rich fuel mixture that i cannot figure out y.

 

you know what might cause a crappy idle, and cause your fuel to be pig rich? a faulty coolant temp sensor

 

ok im gonna pick one up today if not i will have it ordered today nad i will let you know on my progress