NEED serious help with ECM theory and batch fire problem

M

montecarlofast

740 ftlb Rocket Couch
Joined
Oct 23, 2006
So I am trouble shooting a problem on my car that has been a problem for 14 years.

Symptoms are The car shuts down at random moments and wont start back up for a few days. just pops and backfires and then shuts down.

Things ive already tried.
Spring cleaning (GNTType.org)
Replacing fuel pump/tank (they were caked with rust), Cleaing fuel system, fuel filter, and new injectors
Installed a new fuel pressure regulator
replaced cci and timing modules with known good ones
Known good ECM and injector driver chip and Eprom chip
New caspers complete engine harness
New sesnsors, All caspers or AC delco. TPS IAT IAC, MAF, CPS, Cam sensor, O2 sensor,
I installed a fuel pressure gauge at the rail and I have fuel pressure even when car starts to sputter
ALL grounds are in place and are good.

When I installed the new cap. (caspers with led light) I noticed the light is on solid. and does not blink. So im wondering if it is going into batch fire mode and why. when I discontent the sender wire from cam sensor then it blinks, and it blinks while I crank the car, but when it starts, it goes solid. On a strange side note, I was trying random things to see if i could get it to stop, I unplugged the alternator excite wire, and the cam sensor began blinking. and battery voltage is at 11.8 volts. when i plug it in and the alternator starts charging, the cam sensor goes solid.

This car came to me from my uncle and he bought it in Canada 14 years ago. It has had this problem that long and no one has been able to enjoy the car since. ANY, ANY, help and ideas will be greatly appreciated. Thanks!!
 
check the condition of the wires in the plugs on the ecm- my T Type would die at random times, and sometimes restart right away and sometimes take a little bit to recover and start again.. turns out that the pin in the ecm that the orange power wire goes to had rusted to the point where it had broken off and it would lose contact from time to time.. it was caused by the drain in the heater box being plugged, which caused it to fill full of water until it found a hole to escape from, which was at a point where it would run right down on the top of the ecm... i started looking at the ecm when i noticed that the check engine light wasn't on with the key on/engine off and the fuel pump wouldn't prime up when i turn the key on after the car died... i would wiggle that connection and the light would come on and the pump would prime and then the engine would start... i could then kill the engine by wiggling that plug... my fix was to clear out the drain and upgrade my 84 to the 86/87 ecm and a TurboTweak chip...
 
Have you checked the tightness of the harmonic balancer bolt? Torque on it is over 200ft#.
If it is loose it will allow the interupter ring to move in & out of the crank sensor. When it moves out it will shout doen the engine until it moves back in. This will cause pops & backfires.
Another thing, is the battery to start the original cable? If so there maybe corrision under the hard red plastic on the battery end. When this corrision gets bad enought it will shut down all power. You can ohm out the cable or just cut with a sharp knife or use a dremill tool with cutter blade.

Still another thing to check is the vehicle speed buffer output. I used my direct scan to check the output of mine. It was giving different mph speeds ever 1/16 of a second (mol). From 10 mph to over 200 mph. If your chip has a top speed shut off of 160 or 180mph, then when mine exceed 180 it shut off the injectors till the reading went under 180.
If your is going bad, there is no telling what numbers it is giving the ECU.
Scan Master will NOT show this reading. Plus it is changing ever 1/16 of a second (more or less).

I have had all three of these things occur on mine and these are my experiences, your maybe different.

Gary.
 
Key switch?
Bulkhead connector corroded?
Crank thrust brg hammered, allowing the crank interruptor ring to move out of the sensor.?
 
The indication that you're getting from the LED cap are normal. It should blink during cranking, but when the engine is running, the blinking is too fast to see and appears as a steady light.
 
Check this connector behind the glove box door for the pink wire on both sides, on side is fatter than the other.

Give the pink wires a lot of wiggles and see if the car sputters or dies and if not see how it runs under boost again.

It should take 5 minutes tops to check it out, it provides power to things like the MAF and CCCI module.

 
Thank you all for taking the time to reply. On my other 87 gn the cam sensor blinks so you can see it until higher rpm. But maybe its just that car.I will check the plug behind the glove box for sure. the cables are new and in good shape. Crank thrust is a good point. I will have to look at that too. The motor had an rebuilt motor in it when it was bought 14 years ago. That's a very good question. I will check all of these and get back on here. Thank you again!
 
So, I got back to my car this sunday. Started it up, Ran Like sh#t, Visually inspected the crank pulley. everything looked fine. seemed tight. pulled the aluminum cover off, and looked inside........... The bolt was a third of an inch out of the crank pulley.... and the reluctor ring was not in the crank sensor enough to make a signal... I couldn't believe it. pulled the bolt and washer out, Loctite'ed the threads and impact gunned it back on. started car up, runs good. drove all day yesterday and today without any problems. It does make sense. im sure before my uncle bought the car, whoever rebuilt the motor did not torque the bolt down. and its been THE hidden problem on this car ever since. THANK YOU ALL FOR YOUR HELP. cant wait to start dumping money into her.
 
Glad you found it. I have a freind that his car started making a knocking sound and sputtering so he tried this and that and finally decided it wasthe bottom end.....pulled the motor for a rebuild and got to the crank bolt to pull the bolt and....it was loose and that what it was the whole time making the noise and sputtering....LOL
 
I had a customer that bought a car with a nasty rod knock for next to nothing since the owner did not want to rebuild the motor. He brought it to me to check out I took off the inspection cover and tightened the convert bolts and it was all fixed. The balancer bolt has happened more than once had e stumped for a few days once. Glad it is fixed.
Mike
 
now that its loctited, you may never get it back out.... :)

But, the keyway may be beat-to-death. You may want to check the base timing.

Glad its fixed.

Bob
 
How funny I was doing a rear main seal the other day and when I went to turn the crank by hand notice the bolt was loose now keep in mind motor had just been rebuilt.
 
The torque spec is something like 250 ft lbs for the balancer bolt. Most torque wrenches don't even go that high. :eek:
 
The torque for Balancer Bolt to Crank is 219 ft-lbs
 

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