MFJ

I am working on my 87 gta 5.7 it's 100% bone stock, and I am at my wits end. This was my dad's car and after some guy killed my car I had to steal my dad's. It had been sitting for 12yrs, we got it up to speed and she was loving life. Passed smog like a champ after a good tune up. My pop got it smoged and then drove it an hour away to my house. On the way(about half way to me) the car started acting up, misfiring, spewing black smoke, and not idling well. After many new parts which I shall list below, my car dose not like starting(5-10sec before it catches) and when it dose it idle very rough. at start up the RPM will be around 1300 for 15-30sec, then drop to 850 and sounds like it has a cam. Randomly at stop lights it will surge, with my foot on the breaks it will almost loose traction, it will also idle at 450 and die at lights( it's like a game: surge or stall). The intermittent stall is what is really keeping me from driving it. Last week it stalled after going over some railroad tracks, wouldn't re-fire had it towed home to find out the fuel pump had died. I replaced the fuel pump and re-wired it (the ground was in some bad shape).Last night on the way home it stalled going up a hill and re-fired right away. I checked the SES light and it gave me code 21 TPS out of range, adjusted my tps to no avail. I am stumped, any help would be greatly appreciated if you need any other info let me know.
NEW PARTS TO THIS DAY:
fan temp switch
coolent temp switch
fan motors
fan relay
crank position sensor
EGR valve
o2 sensor
ECM
cap
rotor
plug wires
plugs
coil
fuel pump
fuel pump relay
fuel filter x3
cleaned injectors
new gaskets for TPI (all from plenum to injector o-ring)

Thanks, joe

88gta_hiflyer

iTrader: (1)

Have you cleaned the throttle plates and the IAC valve? If not I'd take about a full can of carb cleaner to those. After you remove clean and replace your IAC readjust your tps. Also make sure that it is working properly because a bad one could cause the symptoms youre describing. Another possibility is a clogged egr. You said you just replaced the fuel pump but have you put a pressure gauge on it since? Also replace your fuel filter if you haven't already and check the resistance on your injectors. Hope this helps.

MFJ

I have cleaned the throttle plates, but not the IAC, the IAC is my guess. I checked the injectors they are all at 15.8 ohms, I have changed the fuel filter three times, last one was changed on sunday. I bought a fuel pressure gauge this morning on my WALK to work and will check the fuel pressure when I get a RIDE home. Thanks for the help.

88gta_hiflyer

iTrader: (1)

When you have the iac out be sure to clean the housing out really well too. The location of the egr on tpi engines causes the throttle body and everything close to it to get really dirty fast and it makes them idle like absolute crap...if at all.

ocsurfer999

have you replaced the control module in the distributer? Sounds like the problem i had w/ my 92 GTA. Inexpensive part that many people overlook when having ignition issues / stall

BluFBdy

iTrader: (1)

that wouldnt cause black smoke, unless the motor is highly carbon coated and its just kicking it out, the tps might be to blame, if its shot adjusting it wont help much, but im thinking its elsewhere in the system

MFJ

BluFbdy:the TPS range was from .054v to 3.3v, at about 95% throttle the TPS zero's out. is this acceptable or my problem? Is there a way to test the distributor control module? thanks for all the help I may live on the coast of CA but it was a cold walk to work this morning.

ocsurfer999

No way to exactly test it but if it is bad you can have the start stop and stall issues. If you replaced the cap, rotor, and coil with anything other than stock ac delco you should replace the control module. I put an accel cap rotor & coil on my car and ran into a problem with my control module. The module was stock and who knows how old when i replaced the coil which shorted the module. When I checked codes I had code 33, replaced the module and cleared codes, and have not had a problem since. Accel control module $45-60. Even if this does not solve this problem, I recommend changing the control module because you could have the same issues come up if the module goes bad.

BluFBdy

iTrader: (1)

oh dude trust me i know how that goes, im in AZ freezin my nuts off right now, we had an issue with the DCM on my friends 89 GTA we rebuilt, theres no actual way to test that im aware of but i just swapped his out, takes 5 mins, and the problem ceased, always worth a shot i just pulled one out of an extra dizzy i had layin around, i dont know how but its like they multiplied on me lol

rgarcia63

95% of 5volts is 4.75v replace the TPS because the high end isn't adjustable.

Autoparts store will test the ICM for free.

ineedtorun!

Sounds like the problem im having. Started out wanting to stall when coming to a stop and triggering the check engine light. I have replaced the fuel filter, cap and rotor, plugs and wires and ran fine for a few weeks and started over again. The car has sat for over six months. I have put new gas in but it doesnt even want to idle. I checked fuel pressure off the log and it was 44lbs. I have put in a new tps and set it accor. to specs. Still runs like crap. Suggestions ANYONE

Thanks
ineedtorun

MFJ

Redundant part have a way of stacking up in the corner of my garage, it started with one and now there is half a motor in the corner, How? Gonna replace TPS tonight, I'll let everyone know how it goes in the morning. Thanks to everyone that has offered help I needed it. F-Body peeps rock!!!!!

MFJ

So replaced the tps sensor and ICM and no change... well it stalls every time I try and move it now.... I'm just gonna set this car on fire and enjoy watching it burn!!! Thanks for all your help. I'll post pics of the burned carcass of my GTA.

gallaleo

An auto parts store should be able to test an ignition module. I use to work at one, that is how I know this. Not to mention I had thatsame problem( only on a v6) and replacing the module did it for me.

BluFBdy

iTrader: (1)

dude wtf dont burn the damn thing! its a GTA for christs sake atleast sell it to someone who will pay good money for it and fix it this might sound kind of insulting but have you checked the firing order??? make sure its set right we rebuilt my friends GTA and managed to misplace a wire somehow and it did this! make sure you set it according to the firing order on the manifold under your plenum its worth a shot

MFJ

yup! I have checked the firing order. Some of the wire were routed improperly and I have re run them. I am at a loss... I can no longer pull codes from the ecm. The TPS is adjusted properly, ICM is brand new, ECM is new...WTF? As you can probably tell I am frustrated. I can see no other option than to take it somewhere, and I don't have the money to do that. I'm speachless.

BluFBdy

iTrader: (1)

well if youre not getting any codes its possible youre not throwing any, if you hook up the paperclip or whatever youre using and it flashes code 12 3 times then youre still ok, the only thing i can say is hook up the fuel psi gauge and watch it as the car runs, my friends iroc had a bad fuel signal in his ECM but the chances of that are remote from what i can tell, i dont wanna send you on a wild goose chase, hook up the gauge and watch it as it idles and stalls out or whatever its doing, if youre getting a consitent psi it shouldnt be fuel, its hard to diag a car if its not in front of you but give that a shot and let me knwo what you find

MFJ

so... did a fuel pressure test and I am good. 44 psi @ idle, 56psi @ wot, 38psi while driving. I cleaned my IAC with electronic cleaner and it helped the idle a lot. It will almost idle properly! Last night I ran it for 15min, after about ten min it started idling really rough and then stalled. when it did this the SES light would blink(as it was about to stall) but the ecm recorded no codes. It only stalled once, however once it stalled the idle was bunk from then on. Could the IAC cause the sudden stall? Like I have said, the IAC and the MAF are the only sensors I haven't replaced yet.

rgarcia63

Looks like your delta psi is about (56-44=) 12.
WOT and Key-On/Engine-Off while priming both should be the same 44 psi.
Idle shoudl be about (44-12=) 32. Crusing should be anywhere in between 44 & 32.

The stock regulator shouldn't be any higher than 47psi.
Do you have an adjustable FPR, are you running larger than stock injectors?

TheAdmiral

just scrolling through, saw some things. I work at an auto parts store so i know a little about what im talking about. replace your Idle Air Control Valve, the get a lot of carbon build up and the spring gets worn out and either stays open or closed. Along with your IAC replace your Throtle Position Sensor. Located right on the other side of your IAC. Both should be replaced at the same time. Good luck.

MFJ

nope everything is 100% OEM (the old man would have it no other way ). I ran the car with the fuel pressure gauge on and tried to get it to stall, but you know these thing never act up when you need them to... So no idea if the stalling is fuel related or not. I will replace the IAC since there isn't much on my list of thing to change.

MFJ

I have replaced the TPS sensor and properly adjusted it. The IAC got cleaned up and that solved my idle issue. But the stalling is driving me nuts...since it stalls at idle randomly could that be a faulty IAC? or would it more likely be electronic?

TheAdmiral

are you idling at about 500 to 400 then stalls?

MFJ

when cold it idles at about 950rpm, once warm it drops to 650. After it stalls and I re-start it, it idled very rough at 650-500rpm. Last night it only died the once, however I didn't take it out for a test drive(no money for a tow).

Yes when it stalls it dies at about 500rpm. but when it dies while driving it just shuts off. no chug, stumble, or anything to warn you it's gonna die, it just dies.

TheAdmiral

are you fuel injected?(TPI, TBI) or are you carb?

palric

iTrader: (1)

MFJ check your injectors.

This is exactly the situation I have had with two cars both plagued with those POS multec injectors. Your car is a bit older for multecs but never know. If you have light gray injectors chances are they are multecs which = immediate replacement.

assuming you have bosch (GM used these in '87) lets run thru a bad injector:

- injector flows too much fuel, drips gas, runs rich
- stopped at light ECM sees you are idling, TPS is closed, IAC locked, O2 open loop, VSS says under 5mph, and so on.
- but ECM reads O2 rich because of leaky injector so retards the timing looking to reduce rpms/lean exhuast, rpms drop, motors almost stalls, ECM reads enexpected low rpms and compensates thru IAC, timing and fuel which surges the motor and so the cycle begins
- under load the engine runs rich due to leaky injector, retards timing and cuts fuel up to stall/fuel starve, almost stalls and surges to recover
- ECM idles engine at near stall so engine vibrates, runs rough

sound like what you are experiencing?

when you are encountering surging during idle have you hooked up a timing light and watched the advance? In my case it was bouncing between minus 6 degrees timing then up all the way to +28 degrees and back down up/down/up/down... my ECM was trying to deal with (in this case 2) fouled up injectors.

BluFBdy

iTrader: (1)

just to throw it out there, if your MAF is coming up with screwey readings (since you havent touched it) that sends info to the ECM on how much fuel to meter into the cylinder, ECMS only deal with information in/information out. Sooooo to sum it up your MAF has a possibility of telling your ecm you either need more, or less fuel. As far as the IAC goes they can be disassembled and cleaned ive done it to mine multiple times and it always does the trick. Id check into the MAf but thats a pricey possibility, i run MAP, same idea just used vaccum readings instead of air flow but it jacked up my ecm and made the car run really rich, then really lean and stopped me from idling properly and i had that pull up to a stop and it dies, wont start, crappy throttle response the whole 9 yards

MFJ

TBI

MFJ

when idling if I tap the MAF my idle will bounce around for a second and then will smooth out. I can't remember if that means it's working or broke? Don't answer that question, I can do some research. thanks for all the help it is much appreciated.

MFJ

that kind of sound like whats happening, I have run an ohm test on the injectors (all 15.8ohms) and four months ago(100 or so miles) I had them cleaned and flow tested. One injector was down 5% from all the others, but didn't think that was a problem. I may have been mistaken apparently.

MFJ

Replaced my MAF last night. Ran reasonably well, but thought I would clear the SES codes. Un-pluged neg bat cable waited 5 minutes, no start! WTF! I am so very done with this car!!! It makes no sense to me. If anybody wants an 87 GTA they can pick it up in felton,ca **** this car! not my headache anymore!!!!!

BluFBdy

iTrader: (1)

if its free ill take it lol just let me know ill pack up and head out there asap

entrig00

iTrader: (1)

LOL....what the hell? Just like that LOL.....

BluFBdy

iTrader: (1)

the worst you can get is a no lol

MFJ

So the Car has been taken to a farm up north, they tell me it will be able to run around all day and lead a good life. Never got it fixed had to replace the ECM twice, But to no avail the car just won't start now. I gave up, I don't like being defeated but I was. So I have resurrected my Big Block Plymouth Belvedere, "Mopar or no car!" and my third gen made that point evidently apparent. So in closing I want to say thanks to all the people whom helped me, without your help I would have given up much sooner. Esp BlueFbody- Thanks Boss.

Dizturbed One

too many parts, not enough testing or logic used. so sad to see a car die for no reason.......

Sounds like it probably just needed a new IAC and a clean throttle body along with a Minimum Air Adjustment procedure...

MFJ

Well sir, seeing how I have replaced all the parts you suggested and did all the proper procedures, not really sure why your rubbing salt in the wound. So sad that all the peeps that gave me GOOD advice weren't able to help. Do you have any nuggets of wisdom that may help? Or are you just trying to re-hash old wounds? Read the entire post and you may see something others missed, but I feel I had some super stars helping me so if you think you "Mr. Bigstuff" give it a shot.

timonator

iTrader: (4)

Wow, what a waste of time. I just read through all of that for nothing.

1987CamaroZ28

ha, was thinking the same thing.
Hey, i read lots of threads, go to post something and have to keep signing back in. That's very irritating, but I still post! Although, it's easier to sign back in than diagnose a computer controlled engine. I just put together an LB9 and she wants to quit when cold. That is how i ended up here in the fist place. I may go with replacing the IAC and EGR because those are the only sensors/emissions that haven't been replaced.

timonator

iTrader: (4)

Does yours have a cold start injector ?

SteelWolf319

Okay, I had the same issue as MFJ but tonight when I started it up after work it repeatedly tried to stall out and my power steering didn't seem to work. I'll check it in the morning to see if the pump seized, but it sounded like I was only running on three or four cylinders. Luckily it was just a couple minutes from work to home. Any ideas?

SteelWolf319

Okay, never mind about all that. Found my problem, for now. The entire left side of my pulley system broke off. All three bolts broke off in the block. Once I get this fixed, I'll see if it's doing the same thing with stalling and surging.