1987 l98, running in a 1985 t/a. auto trans. 165 maf ecm.

Car drove a good distance to my parents house on tuesday, no running issues, nothin ran a good as it always does, it's my daily driver.

i tore out my old interior, got a fresh one to go into it.
while cut some wires, i confirmed they were all unused stock speaker wiring.

i go to pull out today, car won't idle for ****, so far from spare cars, i've replaced the IAC, the TPS and the wiring plugs for both, set the tps to .54. i also tried the maf unlugged trick and no change, runs the same. at each step, nothing changes the car will sometimes idle most times not. you can keep the car alive sort of using throttle but often it dies. once you do get it to idle smoothly, which happens very intermittently, if you give it very light throttle it immediately dies, if you give alot of throttle, sometimes it breaks up, sometimes it's fine and pulls to 3k smoothly.

i've done everything i can, i have work tomorow and i need to find a definitive answer.

 

BUMP

okay i've put new plugs in, went back to factory tune, and tried unplugging the maf, no change, i need to know WHICH sensor on the fornt of the intake is the ecm CTS. the injector style plug, or the weatherpak one??

 

Im no expert on this kind of thing, or on anything for that matter, but if it will go when you hit the gas but not at idle, could it be a gas flow problem?
putting out enough pressure?
and dont you have a cold start injector with that model?
have you checked that?
does it idle ok after it gets warm? if so maybe its that cold start injector.

 

These cars are really fussy.
Mine used to do this while driving turned out to be the TPS.

 

i've replaced the tps, both coolant temp sensors onthe front of the block, and i've tried my stock tune wITH CSI and my arap tune without CSI..

i've tried maf plugged and unplugged at each stage and i've checked the FPR for fuel coming out, none.

i'm now making a post lookin for a new 165 ecm! since nothing seems to change each time, and when i tried to aldl log it it spit out a bunch of nonsense, i'm guessing it's a 165 failure.

discuss

 

back again, got sidetracked with another car and now i'm back trying to get the t/a running again.

so, i've replaced the ecm to no avail(new reman from advance not a takeout)

so far today i've tried replacing the ESC, the spark control module under the cap, and i've ohm tested the injectors.

none of that had any effect on the car being able to stay running, the injectors tested 17-16 ohms across the board but here's where it starts to make sense and also get crazy, i forgot to plug in two injectors at one point and tried to start the car, it started and idled the best it has, i mean a decent steady warm up idle. i shut it off and go to look under the hood and realize not only were two injectors unplugged but the pcv vacuum hose was also not attached.

so i'm getting WAY too much fuel. i support this theory with this example, if i give it gas when turning the key it'll spring to life and shoot to 3k, if i hold it steady on the throttle it'll slowly bog out and then quit over the course of maybe four-five seconds.

i'm going to try unplugging the maf again in a second and see what happens, but what else could it be? the fpr isnt spitting fuel out of the vacuum line so,, any thoughts?

 

the car runs better with the FPR disconnected and dies as soon as it's re connected. unplugging the maf makes things worse it seems.

also prefers runing with vacuum leaks.

seems like it has too much fuel but WHY!

 

What is the fuel pressure at? With line connected and disconnected. Stock original injectors?

 

i don't have the tool to read it but i gave playing with vacuum leaks a try and voila, it'll run with the fpr vac hose attached so long as it has another vacuum leak, so i'm starting to look at my parts car sourced IAC suspiciously. bout to try a know to work one that needed cleaned anyways.

 

seems to work a helluva lot better with the other IAC.

 

is your TPS bad? my TBI 305 was running super rich because the TPS was showing WOT at idle, ran like crap, replaced it, ran 10000x better.

EDIT: I see you did replace your TPS, I would check to make sure it's wired up right, and that it's not bad strait from the box.

 

gonna get a new tps and try that, the one i had was sourced from a parts car as a quick attempt but this is getting crazy.

new iac sorta helped but not so much car still quits and chokes and the like, tunerpro showes .55 v tps at idle but only 3.60~ at WOT.

 

sounds as if you dont have enough fuel pressure, if it runs better when you disconnect you vacum line from fuel regulator.when you do this the pressure jumps up higher. go rent a tool to find out

 

on my t.d. list thanks!