Might want to test the ICM. easy test take it off and take it to advance,oreillys or autozone.

 

my mechanic has already tried that...along with trying another coil pack....you think it's possible it could be a fuel problem?....he said something about it stops getting injector pulse also...but still no source of the prob?

 

so he told me today it might be te ECM....i swapped that today with a good one and sure enough it ran perfect until about 180 degrees....

 

I'm confused a bit

at first blush, your posts sounds like you are doing these things yourself or instructing a "mechanic" to do them. Who is doing the diagnostics? Is the "mechanic" just following your instructions or does the "mechanic" have the necessary diagnostic scanners?

Please define, gets to op temp and then "dies"

 

sorry it's my mechanic doing all the work and yes he has the the diagnostic equip...and the engine will reach approx 180 degrees and the it completely shuts off

 

then the problem occurs when you go into "closed loop" when the sensors kick in and send readings to the computer. May we assume that the engine runs great before reaching operating temp? Do you throw a service engine soon light and the fans kick on before the car just dies?

what are the codes he is reading? Does he have an OBD1 scanner? This is a 95 which has an OBD1 computer but an OBDll connector

 

yes the car runs fantanstic up until the engine warms up...i'm not sure if i throw a lite or not i'm almost positive that i dont....so your thinking it might be a sensor somewhere?....ive been told from a few people to check the MAF and MAP and TPS sensors..

 

Have your mechanic take a look at the EGR valve also to make sure its operating correctly.

 

Should have replaced the entire opti, cap and roter fixes are fine if your taking a new gm opti apart and putting it in a new msd cap and roter other then that I think they are waste of money.

I want to say the opti but it shouldnt just cut off at 180, it would stumble and do a bunch of other crap before it dies, but since you didnt replace your opti Im going to say opti.

 

Well i would say a few things. Unplug the maf and start it up. Let it get warm and see what it does. That or it is still the icm.

It should go into closed lope before even getting to 180 degrees. If it were the opti it wouldn't run at all or right. Check the fuel pressure when it happens. Though i doubt that is the problem. The egr wouldn't be the problem either. As it will still run just not good.

I say the icm even if it was new. Opti or coil. That or the wiring to it but i doubt that would be the the problem as it wouldn't wait till 180 to do it. With temps doing it though it would be the icm.

 

i talked to my mechaninc and said we replaced the entire opti.....so ill mention upplugging some sensors to him and seeing what that does

 

IMHO, that is part of the problem. Is there another shop where you can go? Your mechanic should know these basics.

 

Unplug just the maf. What brand opti and icm did you use. You also need to ditch this mechanic. As he doesn't know his but from a hole in the ground from the sounds of it.

The only thing that will screw up a lt1 running once warmed up some would be the maf,coil and icm. Unless a relay is getting hot.

Other than that there is nothing else that i know off. Beside maybe the fuel pump. It could be the relay for it. Will it start right back up?

As for going into close loop when it uses all the sensors it should happen in like 2 mins or when the temp gets to like 100 degrees or something around that. By the time it gets to 180 it should have in closed loop for a few mins.

 

no it will not start buck right away its like you have to wait for it to cool off it ususally takes about an hour if you try to start it before it cools off it' will sit there and crank crank crank all day long but never fire

 

it's losing all spark and all injector pulse...i've resorted back to doing the work myself...i have ordered an ACCEL opti replacement today...that should be here in a few days i'm gonna try that...according to my mech he bypassed to opti somehow for the injector pulse and it worked by bypassing it....so hopefully this works....it's literally all i can think of and yes the orginal cap and rotor i bought was from auto zone....

 

call and cancel that accel opti, DO NOT get any other opti than a GM AC DELCO one for to man issues with aftermarket ones! man where are you located?? you really need someone on here that lives close and knows what their doing to help you out!

 

i already cancelled it due to the funding situation...i bought a GM direct otpi....i'm in southern illinois...

 

Buy a freaking new icm. That is the classic problem of it. Which i believe will cut fuel also. That or it could be the opti but not the problems it does. Either way don't buy accel optis. Gm or msd.

 

ok my new GM opti should be here anyday i'm going to try that and if that still doesnt fix it ill but a GM ICM....but i'm praying that the new opti takes care of it...it's just been a neverending money pit so far and it's really start to drain the wallet and putting a really good strain on my nerves....lol

 

How did it go?

 

what is IMHO?

 

In My Humble Opinion ^

This is the first thread that came up when I looked for this problem so I will answer here when I figure it out, Ima start with the ICM.

 

http://www.ls1lt1.com/forum/faq.php?faq=generaltech#faq_acronyms

 

hey i know this an old post but my car is doing about the same thing what did you do that ended up fixing it

 

Hmmmm must've been the opti. Or fuel pump relay-.-

 

I just bought a 1996 TA formula for a insane steal of a deal because of this problem. So far I've replaced the ICM, tested the coil resistance hot and cold, tested the TPS and harness, replaced spark plugs and opti spark, not the wires though, I have them and that's next on my list though. I took the ICM to autozone and they aid it tested bad so I was so sure that way my problem, but unless the new one is bad too then it made no difference at all. the car will run smooth and great until it gets warm, then it studders horribly, It just yesterday started to actually die on me though, so whatever the problem is it's slowly escalating. I'm about to get a new coil even though it tested good just because i know sometimes they can be bad when hot even if they test good.

My main question though is, I've considered the closed loop idea as well, but I was under the impression that even warm the car had to at least start before it would jump into the closed loop. Being as the car won't start when hot at all it doesn't give the computer the chance to say hey, i hate life, I'ma take a nap for a while. I was thinking cps or coil, but idk if the cps is effected by the engine warming up or not. If anyone has figured this out let me know, and I'll do the same if I do. I'll also keep the thread updated with what I test or replace to help narrow it down for anyone else struggling with this.

 

Hmmm



Have you tried hooking it up to a computer to see if any codes are produced? I think the water sensor can cut it off too.

I just spent 1100 dollars getting my Opti/ICM and front seal replaced because she had the "dies when warm" problem and that fixed it right up. They used the computer to tell them what was wrong and a 359 dollar NAPA distributor but I have heard horror stories of people putting in brand new BAD distributors. How confident are you that the one you put in is good?

From what I can tell from my own situation and others the most likely causes of the "shuts off when warm" problem are in order of likelyhood:

ICM
Opti
Water Temp Sensor
Other sensors (particularly ones that tell the car to do something different once it reaches a certain temperature)
Brain Box

Hope this helps!

 

Wait? so the water temp sensor can cause a no spark? Where is that located? and how can i test that? can i just unplug it?

 

No it won't cause it to not spark but it is one of the things that kicks on at a certain temp. If there is a short in the fan wiring etc it may cause the car to stall, there are a million things you need to check after you have ruled out (fore sure) the ICM and Opti.

Have you checked for codes? That is the reason they started with the computers and codes because of the ECS on these machines past early '80's was a troubleshooting nightmare.

It could be a simple wire short, and finding all the wires in that cramped old engine will be a really pita!

Have a mechanic or friend check the codes when its cold and then HOT to find the bad guy.

By the way how confident are you that the Opti you used was good? I know it sucks but it needs to be asked bc many many many have had to replace those 2+ times to get one that worked.

Keep us updated!

 

The coolant temp sensor (CTS) does not "kick on". It constantly provides feedback to the computer. If it were way out of range, it might cause fueling issues. Anything wrong with fan wiring is only going to cause fan operation problems. There really is not anything to do with fans that could possibly cause the car to stall.

Try to get some live scan data. I would advise you to invest in some sort of scanning solution. Test for spark and fuel pressure when it won't run to narrow it down.

 

Hmmm



Yeah I am only speaking from second hand experience on that one, one guy said his sensor water temp sensor was causing his car to stall on warmup.

Said it had to do with faulty fan wiring which shorted out something, but who knows maybe he was wrong.

What I know for sure is I had this exact problem and replacing the Opti and ICM fixed it up. The mechanic did a code test before doing the work and that's what he based the repair on. Trouble shooting without coding is really like firing at a buck in the dark... sure you may hit the buck but you may shoot your partner too

Go get that free scan!!!!!! You don't have time?? It takes like 30 to 60 minutes You will spend 3x that troubleshooting randomly.

 

Well the guy I bought it from said he replaced the opti, I can't verify if it was tested or anything but i can tell you that the water sensor looks brand new (if you mean the one on the water pump) the opti was a bit dirty from oil or what not, but the cap and rotor looked new, I doubled checked with the guy who assured me he replaced the whole thing not just the cap and rotor, a little brake cleaner and it looks brand new as well now. I don't think I have an continuity on the harness that goes to the opti, although I checked for continuity and resistance on the harness that goes to the pcm from the opti (the wire connector by the intake) while I had it disconnected (is was easier to get to than the plug on the opti itself) and 3 out of the 4 prongs have a really high resistance and one has a really low resistance with another, I'm not sure if this matters, I assume that becasue it goes to the pcm that that's why they have continuity, that or that's my problem.

All I know though is when it gets warm the coil will eventually stop sparking after running like crap for a while, I tired a different coil, still no spark, so I'm not sure how the opti can be the issue, unless the opti for some frustrating reason controls the ICM?? My next test is to check the icm harness for current while cranking. I've also got the MAF off and o2 sensors unplugged so that I can keep the list of problems narrowing.

 

The opti IS the first thing in the hierarchy that tells the coil to fire. Without it, the coil will do nothing. Also I would leave everything else connected, instead of what you are doing. It only adds complexity and variables to the troubleshooting, because the computer has to make allowances for them not being there. I will also reiterate that you need to get it on a scanner.