Hi all. It was about 95* out yesterday when I was driving my '86 GT w/ 2.8 and 4T60 trans. I was driving about 30 miles when the car started to buck some and then it stalled. I rolled to a stop on the side of the freeway and restarted it a minute later after *something* had cooled off. I had suspected that my ICM was getting cooked so I decided to try to make it into the next town with a parts store.

So I keep driving it, it stalls again but this time I had to wait about 10 minutes for it to cool off. So I continue on my way another 15-20 miles, stopping every few miles (either by choice or by being forced to by stalling) to let it cool off. I got to an Autozone where I removed the ICM and had it tested. It was tested about 20 times and it passed but I still suspected that it was the culprit so I bought a Duralast ICM for about $40. So I continued on my way to my destination, about 20 miles and all was fine till I was about a mile from home when it stalled yet again.

Needless to say I was annoyed. Either I didn't fix the problem and the stalling went away because it had time to cool off while I was checking the ICM or the Duralast ICM started to fail as well.

OR.... after a search in the forum The Ogre suggested to a person with a similar problem that the ECM may be overheating. This is very possible, especially because I have my engine bay insulation removed (was chewed up by mice anyway) and I don't have AC in my car, just the windows down. The Ogre's cave suggests that I remove the insulation from the inside of the ECM surround to help it breathe better.

So, does an overheating ECM sound plausible or should I start looking into other possibilities? Also, should I replace the ECM now that it may be damaged?

I just pulled my center console out. I ran the motor for maybe 10 minutes about 10-20 minutes before I pulled the console and the ECM was quite warm to the touch. I pulled out the insulation from in the console, took off the console door (warped badly and broken anyway... I wonder if the warping is caused in part by the ECM heat?) and removed the two vents on the side.

I think I'm going to remove the metal plate over the PROM too to help get the heat out of the ECM.

Then I'm going to put it back together and hope for the best.

Go ahead and install some insulation behind the ECM,, tho this is not your problem..You probably damaged the fuel pump <<I read the other post about missing going up hill,, this over heated the pump,,unless it is fairly new ,,Now when the pump heats up ??
you diagnose this by having some quick start,,or gas in a squirt can,,gas is better because it will not evaporate so fast ,,when it stops you remove top of air cleaner a quick squirt/burst of quick start ,, attemp starting,, if it fires then will not run fuel pump suspect ..
aluminum foil make a good temp insulation,or cardboard or wrap cardboard in foil,,make sure all the holes are plugged ,,wires and cables have proper surround plug even if you make it.

often loose pieces of bike inner tube, pieces of rubber come in handy,,never throw away the insulation from an old Fiero shift cable ,,some thing like a large sturdy plastic bottle cap has many uses..

[This message has been edited by uhlanstan (edited 07-17-2010).]

What happens with the Tach when this trouble is happening? If the tach works fine while cranking when you are having the problem, then it's NOT a pick up coil or ICM problem. If the tach dies when the engine dies then it IS a pick up coil or ICM or related problem (could be loss of +12 power to the coil also). It could be a tach filter problem The tach filter is the capicitor looking item attached to the engine by the coil. Unplugging it will disconnect it (and the tach). If that cures the problem when it is happening then you have a bad tach filter. Leaving the tach filter unplugged will disable the tach so don't leave it unplugged and then preform tests involving looking at the tach.

If the engine dies but its still on the highway and turning over that is for sure when you want to look at the tach. A dead tach before the engine stops turning over

[This message has been edited by phonedawgz (edited 07-17-2010).]

The tach doesn't work Its really never worked right, but I've got a new tach filter to go on so maybe that will fix it.

The distributor is a rebuilt part that I bought used from another forum member. Its the newer style star-shaped version so I assume the pick-up coil is fairly new. Could still be bad, of course.

Yep could be bad - Ohm meter is a good check. Make sure you wiggle the wires around when you check them. Make sure when you put the coil wire clip onto the ICM that the metal connections feel tight (you should feel some resistance that is not caused by the plastic latch while pushing the connector on). Wiggle the coil to ICM wires. Test the Ignition coil with the meter. Unfortunately with an intermittent problem when you check with your meter and/or other tests everything might test fine, only to have the parts be bad when heated up. If you can bring a meter along with you along with the print out of the tests, then when the car fails you can preform the tests. Would be good to bring starting fluid along also and see if the engine will fire on the starting fluid. The engine firing on the starting fluid would point to an ECM/Fuel injection problem.

Bring a fuel pressure gauge along if you have one. Who knows, maybe your fuel pump is running on only one of the two switches (Oil Pressure or ECM/Relay) and the remaining switch is failing when hot. Do you hear the fuel pump running while you are having this problem? You could perhaps have a fuel pressure problem that manifests itself when something gets hot. If you are checking fuel pressure on a hot engine make sure you bring along enough rags to totally encase the schrader valve area when connecting/disconnecting so you don't spray gas onto a hot engine.

Leave your console bolts out for now. I'd leave the cover on the ECM until you have the problem figured out. What you want to do is to get the car to fail and then see what fixes it. If you try a bunch of things, and the problem goes away, then you're not sure what the fix was, and not sure if/when the problem will come back. So if the ECM IS overheating then after the problem occurs, then removing the console cover would most likely make the problem go away. That's when I'd look at what can be done to cure the KNOWN problem.

Don't assume or rule out anything till tested.

[This message has been edited by phonedawgz (edited 07-17-2010).]

DIAGNOSTIC..The best diagnostic set up for fuel check .. is to drill or poke a small hole in a plastic soda or bottle cap then you put gas in the bottle and a simple squeeze , squirts fuel into snorkle or TBI.

grounding a spark plug on the block will show spark..

..the problem is doing this when engine stops
Diagnose ,, Fuel or spark..
when the engine will not run,,if you squirt fuel into the snorkle and it runs and dies this indicates fuel,!!in doubt do it twice
spark or fuel

I need to pick up a new multimeter, my old one has dissapeared. I'm going to leave the console apart for now and just set it back in place. As of now I'm suspecting the ECM is overheating but I'm totally open to other possibilities even if the parts are newish.

I do have a fuel pressure gauge so I'll have it with me. After it stalls, it only takes 1-2 minutes for whatever is overheating to cool off enough to restart for another 10 minutes or so of driving, at least when everything was good and hot already.

One thing to watch out for - when using either starting fluid or squirting gas into the throttle body - When squirting the fluid in - open the throttle so you squirt it past the throttle plate. Then put the rubber intake hose back on before cranking it. Sometimes the fuel in the intake can backfire - and if there is an accumulation of fuel in the intake, it can be blown out of the intake by the backfire. Of course that fuel will be on fire because of the backfire. Putting the rubber intake back on will keep that from blowing buring fuel all over your engine/tranny. Good thing to have a fire extinquisher handy too!

My car stalled out after driving maybe a half mile on my way to work( figures too, I just told my dad how awesome the car has been running the day before). It just cut out instantly at 55 mph. After I pulled off it started and I got home with no problem. Hope we both get our cars fixed.

I'm up at Brad's and he's got a bunch of spare parts so I'm trying a rebuilt delphi ECM and I'm taking a couple spare coils and ICM's with me. If the car stalls, I'll swap in another coil. If it stalls again then I'll swap in another ICM. If it still stalls, then I have issues elsewhere and have at least eliminated some parts. At least I've got enough parts to start troubleshooting now.

Its really running different with the replacement ECM so I'm really wondering if thats the problem. I hope it is, but I guess we'll just have to wait and see. Then again, I haven't had a chance to run the ECM during the heat of the day nor for long distances.

My car stalls at a stop after getting hot! It will re-start again though. If I blip the throttle some of course it won't stall and then at the next stop if I shift into neutral and let it idle she's ok what gives??

Let us know what you find. It's always good for everyone to hear.

rundlc do you have an automatic transmission??

So far I've swapped in a different ECM and went for a 50 mile drive. It was at night so it was somewhat cool out, but so far nothing has happened.

I'll be driving in the heat tomorrow so I guess I'll just see what happens.

@ uhlanstan,, No it's a 4 speed manny. hmmm r u thinking bad clutch switch?

RUNDLC, No !! common problem with 3 speed Fiero automatic ,,you need to make sure your idle is over 850rpm,steady & you have no vacuum leaks,,
you could pull the EGR vacuum hose, plug it,,then see if engine performs better,,
if you can pull a vacuum hose and see if it makes no real difference in the way the engine performs..
a leading cause of engine stall is dirty pintle on EGR,,easy to clean
..check engine while running at night to see if there is arcing along the wires if they are older..
..remove snorkle ,,clean IAC area inTBI,spray jismi n hole
Fiero,s love great negative/ground connections,make sure the small wire that runs from the battery to the inner fender ground is cleaner than you would be if you had a double date with Reese Witherspoon & Jennifer Anniston,,check the big thick one to..
..do a check and make sure the coil,plug wires and vacuum hoses are connected
your problem is not serious,but anoying..NOW

FIERO & GOOD GROUND ??a life long affair
a hard tooth brush is most excellent for cleaning battery terminals/battery cable terminals

[This message has been edited by uhlanstan (edited 07-20-2010).]

Hey guys we shouldn't hijack this thread for a seperate problem. RUNDLC - If that didn't fix your problem it would be good for you to start a new thread with just your problem in it. Also if the problem is still happening - if you could copy and past what was already in this thread to the new one it would be helpful.

Thanks

Sorry didn't mean to hijack this thread, just thought why start another one on the same topic. Will move on though, don't want to step on toes.

I don't mind the hi-jacking as long as its with a related problem :P

Today I tweaked by TV cable and the trans is shifting much better but I don't think it has anything to do with it stalling when hot. Still haven't drove the car long enough to get it hot and stall yet though.

I hate it when problems just 'go away"

Cause they tend to come back at the worst times.

Drove it about 20 miles today and it started stuttering again. Pulled over before it died and swapped the coil, ignition module, and coil wire. Drove it the rest of the way home without any problems so go figure.

Drove home tonight about 100 miles with no problems either, but that was at night when its relatively cool. Everything in my engine bay seems to be significantly hotter than that of Brad's 3.1 car so maybe I've got something causing the heat? An exhaust leak or the timing is off or maybe my elusive vacuum leak is causing it? Maybe? Not sure?

I was thinking that maybe the engine was just running too hot and was heat-soaking all the electronics so I burped the coolant. Then I remembered something.... I had the GT nose off for some repairs before painting and when I put it back on, I never put the lower trim and air dam back on. So...

I bet the lack of an air dam was keeping the radiator from cooling properly so that the engine ran hotter than it should. Couple that with 100 degree temperatures and driving long distances and my electronics were failing due to heat soak. I finally got my temp gauge to work and I drove the car around some and the needle hovered about the center of the 220 mark and the start of the red zone... so maybe 240*? Its not super hot, but perhaps hot enough to overheat the electronics over time.

Does that sound like a possibility?

Nope - The electronics are designed to work at least up the the temp redline of the engine. You never boiled over. You are operating within the normal range of temps.

I guess we'll just have to see then. After I burped the coolant I ran the car this afternoon while it was hot out. At this point it was without the air dam and it ran above 220 for pretty much the whole trip.

I finally got the air dam back on tonight and went for a drive and it stayed at 220 or just a hair over it for pretty much the whole drive. It did jump up once so I may still have some air in the coolant but for most the part it was stable. I'll have to run it tomorrow and find out how it does heat-wise now that I have the air dam back on.

I currently have Rodney's lower temp coolant switch with a stock 195* thermostat. I used to have a 180* thermostat in it but I took it out a while back to do some troubleshooting. Would this combination cause me any major issues? I plan on putting the 180 back in as soon as I find it.

The car should run fine with either thermostat

I ran it today in the heat and no stalling! It is slow to accelerate though after it gets warmed up but with the air dam in place it doesn't run too horribly hot. I think I just need a proper AC Delco ignition module and I'll be OK now. I think I have an old one floating around somewhere that I may try just to see if it works better than the one I have now.

I'm tempted to use a bottle of "Water Wetter" in my coolant. Supposedly it can reduce coolant temps by up to 20* but its also like $8 for a little bottle of it. Meh, we'll see.

Wedging your thermostat open will do more to make your car run 20deg cooler than anything you put in the coolant. I don't remember seeing the thermostats marked with an asterick (note this thermostat is marked with the temp without water wetter, subtract 20 deg if the crap is in your car)

Well, no water wetter and I'm still running the 195* T-stat.

Drove about a 100 miles non-stop to Tulsa this evening. Ran pretty decent except that I would get the occasional drop in RPMs like something was wanting to start to fail and then decided not to. Could just be related to my vacuum leak though (got a code 44). The temp gauge needle stayed just a hair above the 220 mark the whole trip.

I also checked my coolant level at the t-stat before I left and it needed maybe half a cup of coolant to top it off. Probably insignificant.

re Code 44 - lean.

Does your 2.8 idle too fast? If not you most likely don't have a vacuum leak. A vacuum leak would cause idle problems long before causing a code 44. Have you checked your fuel pressure lately? You should have over 40 after prime, engine not running. Also if you could check the ALDL fuel pump pin G voltage, make sure it's close to full voltage.

Have you changed your fuel filter lately?

Fuel filter is new as of 6 months ago. Fuel pressure has been checked as good with two different gauges. Idle varies from about 900 to 1100 (it hunts). The idle is a tad high and it never really learns the mix. I've got a snap-on scanner that I hooked up and my O2 seems to be in working order as well as my CTS so I've either got one of the following:

-vacuum leak -- most likely with all the lines on the Fiero, however I haven't found it yet via the spray carb cleaner everywhere and listen for it method
-bad/dirty injectors -- the car sat for 8 years, I have ran lots of fuel system cleaner though them but they could just need a professional cleaning
-an exhaust leak upstream of the O2 thats throwing off the O2

The vac system and the exhaust can be tested for leaks with a fog machine. I'm going to make one by rigging a party fogger that I'm going to borrow from my brother.

I've never seen the light come on the dash while I'm driving, just a stored code. Not sure if that means anything though.

quote Originally posted by 02greens10: figures too, I just told my dad how awesome the car has been running the day before.

There's your problem. It happens whenever we brag about how great the cars are running. Fieros like to keep us humble and remind us exactly who is really in charge.

------------------
Jim Martin
White '86 GT
California

Check the CTS that feeds the ECM. This may be your problem.

The temp sender that runs the gauge and one that turns on the cooling fan are seperate from the one that feeds the ECM. If the ECM one reads high you may have an issue there. If the ECM sees a high enough temp it will shut down the engine to protect it. This sounds like kind of whats going on to me.

Its a simple test but you need an ohm meter and thermometer to do it. Lean conditions increase engine temps and may be complicating the problem or causing it. Ideally I'd want to get a scanner on it also to see what temps the ECM is reading compared to what you guage is saying.

[This message has been edited by Fieroseverywhere (edited 07-27-2010).]

The CTS is new as of about a year ago and the fan switch is new from Rodney Dickman as of about 6 months ago. I have a Snap-On scanner that I can use to better verify their readings though. I think I'll try that if the fog machine doesn't find any leaks.

How are your engine to frame grounds?

Grounds:

-braided cable from head to trunk hinge bolt
-battery cable from head to battery tray

Should I add more?

Anyway, I ran down to Tulsa couple days ago. Its about 130 miles round trip and I did it at night, about 9-11 PM. The car stumbled a couple of times but otherwise ran OK. I checked my fuel economy and got a 21 MPG at 75 MPH or so w/ the 4T60.

I came home today and left about 2 PM and did't get back in till just a few minutes at about 5.30 because I had to stop after the car stalled on me a few times. It was about 95* out when it stalled in coffeyville KS, which is about 80 miles away at 55-65 MPH. I stopped at the local gas station, got a soda, and let the car cool down for maybe 10 minutes and decided to just keep going.

Maybe 10 miles later it stumbled and stalled out again and I rolled over to the side of the road. Since I was quite annoyed that it had died again, I figured I might try swapping the fuel pump and AC compressor relays out that sit behind the air canister. So I swapped those out and I also had a new air canister that I swapped in because the old one was rusty.

Well, the old one must have been rustier than I thought as it may have been part of my vacuum leak problems as my fuel gauge practically quit moving and I almost doubled my fuel economy from Coffeyville to Pittsburg. I'll go and fill up the tank to check it against my mileage here in a bit. However, it didn't solve all my troubles.

About 70 miles down the road of the car not stumbling and apparently getting better fuel economy it starts to stumble yet again and it eventually stalled. I lucked out and pulled off on a country gravel road with some shade and popped the trunk. I noticed that I had forgotten to screw down the clamp on the air snorkel from the filter can to the intake, but I don't think that it was causing any trouble.

I did notice a LOT of heat coming out of the engine bay as though the exhaust heat isn't able to escape and is heat-soaking into everything and eventually stalling it out. I probably made it 70 miles because I was stopped about 20 minutes and it must have been able to cool down.

The whole time I was running the temp gauge read about 220 or just a hair over it so the coolant is running correctly. I don't think swapping the relays did anything so those are ruled out. The ICM has been changed about 3 times now so I think that can be ruled out. The coil has been swapped once so I think that can be ruled out.

Theories left:

-my ICM is still overheating because its not AC Delco (Its been suggested to me to buy a heat sink to put on it, not sure if it would do me much good when the whole bay is heating up)
-my fuel in the lines are getting turned into vapor by the heat build-up (exhaust maybe?) and needs some kind of heat sheilding
-my exhuast Y pipe needs heat shields. I got the car as a basket case without them and I have just been running the car with the Y pipe covered in exhaust wrap. The rear manifold has the stock heat shield, the front manifold has nothing. I'm missing all other heat shields and insulation.
-the fuel pump is overheating, as thats kinda how the car is acting before it stalls. The pump is TRE PERFORMANCE pump, not AC Delco or Delphi. TRE pumps are supposed to be really good though and it has tested good on a pressure gauge.
-I have a code 44 leak, exhaust or vacuum, thats causing to motor to run hotter than the electronics can stand in the heat of summer and is causing them to fail when hot, everything works fine when its cool(er) out at night.
-my aftermarket EGR valve from Autozone sucks and I should swap in my OEM valve that I got as a spare somewhere.
-not enough grounds?

Thoughts? This is really driving me nuts...

[This message has been edited by Alibi (edited 07-28-2010).]

When it stalls - does it stall like you turned the key off? or does it stumble? - (edit - Never Mind - I see it stumbles)

When it stalls - what happens with the tach? The important part will be, specially if it stalls like the key is off, what is happening to the tach while your still on the highway and the car and engine are still turning over. If during this time the tach dies, then its for sure ignition.

EGR would not kill the engine

If you have a fuel pressure gauge it would be handy to know what the fuel pressure is 1 - Key on engine off, 2 - idling, 3 - Key on, engine off, return line blocked

It would be nice to know whats happening to the fuel pressure during one of these events. I'm not sure about screwing a fuel pressure gauge onto the schreader valve while the engine is hot, and I'm not sure about leaving a standard fuel pressure gauge with its rubber tubing on while running. It would be damn nice to have a screw on one permantly attached.

http://www.google.com/produ...m=3&ved=0CDcQ8wIwAg#

[This message has been edited by phonedawgz (edited 07-28-2010).]

The damn tach doesn't work. I put in a new tach filter and it didn't change anything. I have an extra tach that I need to swap in and maybe it will work. The one I have now the needle sits at 12 o clock when the engine is off but then when I turn the key to give it power it just pegs out on the needle stop at about 2 o clock.

When it stalls the first time it stumbles for about 20 seconds as though its not getting gas. I can goose the throttle and it will rev a tiny bit and then stumble again and then stall. If I don't give the car but 10 seconds or so to restart it, it just turns over and wont fire. If I wait about 30 seconds it'll sputter and try to fire. If I wait about a minute, it'll fire and I can drive it but after a mile or two it stalls out again (but this time it just quits like someone turns off the key). If I let it cool down for about 10-20 minutes then I can drive it much further before it stalls out again.

About all I have left that I haven't swapped out ignition-wise is the pick-up coil. I have a rebuilt/new distributor I bought used off another PFF member with the star-shaped magnet on top instead of the old-school version the Fiero came stock with. The wires coming off the pick-up coil look kinda small compared to the ones on the old distributor. Could that cause anything?

A bad EGR won't over-heat the engine bay would it? It just feels really hot under there like the air itself feels like its burning the tips of my fingers when I'm poking around in the bay.

So swap the tachs

Would also be nice to do the pick up coil resistance tests during the time of the failure.

[This message has been edited by phonedawgz (edited 07-28-2010).]