hey guys, i need some help, i've done a bunch of searching and nothing seems to fit my particular issue. so i need help before i go on a part replacing binge!! please read all

ok: i have an 89 iroc 350TPI. my problem is when cold i have to hold the gas pedal a few seconds for it to begin to idle on it's own and sometimes takes a couple seconds to start. when i take of from a stop it hesitates and/or boggs.

when warm, the car runs and idles great although it smells a little rich.
recently when warm, at a stop the idle would jump to 2500rpm for no reason... ses set code 21 and 32 (this happend 2 times).

what i have done: I did an ohm check on injectors hot and cold and all are good right around 16ohm. i checked all my vacuum connections and all seem ok. fuel pressure ok. code 21 TPS - i checked all my voltages to TPS and all were ok, ground circuit ok, i replaced it anyway and set it to .55V at idle. i replaced the IAC and "TRIED" to set minimum air using the instructions in tech articles --- the problem i had is it would not hold idle in service mode with IAC disconnected unless i really cranked up the idle screw. so i couldn't set minimum air properly. (yes i did this while the engine was warmed up).

what reasons would it not idle in field service mode???

after done with that i ran the car and adjsuted the idle screw to around 1000rpm (it would not go any lower even with the idle screw not touching the throttle blade) in park but when i put it in drive the idle doesn't change.

can anyone help? what should i do next??

i am thinking injectors and all new vacuum lines. (i don't have any vacuum test equipment).

 

I would like a little more info before I even attempt to say anything. What exactly is your fuel pressure at with the vacuum disconnected, and how long does it take for the pressure to bleed off? What is your base timing at? What is your battery voltage at idle with your headlights on or any other moderate electrical load? Also, does the idle improve if you raise idle about 100 rpms? What exactly is your vacuum at idle?

After you answer these questions, we could have a better idea. The problem is that, we can't actually see the car and the more info we have, the better the members can help you.

Also, did you try to unplug the MAF sensor to see if your idle improves? That is the super common thing to check, probably the next thing to check after ignition timing and fuel pressure.

 

just an fyi, just because your injectors ohm out ok doesn't mean that you do not have a problem with your injectors. if they are clogged/leaking they will still ohm out ok. Dirty or leaky injectors will affect the atomization and spray pattern of the fuel. They can stick closed and not supply any fuel, and or spray more fuel in one direction than another, they can leak fuel continuosly, or deliver different amounts of fuel to the individual cylinders. I am not saying that your problem is due to your injectors, just wanted to let you know that by having adequate ohm readings doesn't necessarily mean that you do not have a problem with your injectors.

www.southbayfuelinjectors.com

 

ok. update... still need help by the way...

i ended up changing the TPS which took care of my engine light, which apparently had ZERO to do with my cold start/idle issue.

i jsut changed the injectors with Bosch III from south bay fuel injectors. the car runs better in general but still the cold issue. also, during this cold issue phase, the idle goes up and down sloly like i give it gas and let off...

i checked timing and it is ok at 6* advanced. i set minimum air, turns out my RPM gauage is way off so i used the timing gun to read RPM's

i replaced any cracked vacuum lines and with vacuum gauge at idle it reads a 12 when cold and then 15 consistantly when warm. is this normal vacuum operation??

fuel pressure is normal and holds 39/43.5psi (vacuum on/off). it takes about 20-30 minutes for pressure to bleed off.

i also changed the temp sender for ECM (and fixed PO's fan wiring).

i'm not sure about the vacuum, but other than that i'm led to the EGR, MAF or ECM - no codes stored, no engine light.

i am in process of getting a laptop and ALDL cable so i can look at things. until then, any ideas or help is appreciated!!!!

 

sounds awfully similiar to what minedid before replacing maf sensor and my gm/sec were perfect.if you have access to a known good maf sensor i would definitely give it a shot.my car was all over the place cold and after it went into c/l it it wwas fine.

 

sound alot like a vacuum leak to me. my car does the same and i did a smoke test and found that i have a large vacuum leak on both ends of my throttle shaft in my throttle body

 

Did you disconnect the "Set Timing Connector" when setting minimum air?