...among other things

Basically the problem I have is really weird.

I have a HSR, still have my TPI small cap distributor, ignition, wiring etc.

What happens is my car loves to kill ignition modules, always after it has been sitting however, never does it when it is running or run weird.

I'll hop back in it after a week, a few months or 6 months and crank crank crank crank, nothing, and I know **** it is the ignition module.

Go and swap in another known good one, car fires right up and works great for another indeterminable amount of time.

Can someone explain to me why this might be happening and how to test my E-coil?

I keep hearing I should try to replace the distributor, but it looks to be in great shape.

All in all I figure if this is the worst my car can do (it really is), life ain't so bad, but it is rather annoying.

 

The biggest killer of ignition modules is heat. Are you using heat sink paste on the metal part of the module when you install it?

Do NOT use dielectric grease.

 

Yeah I use nothing but the heat sink paste now, have been for a while.

 

I have a 91 RS and have now gone through 5 Ing Modules.

Same senerio except this is my wifes everyday driver. After a month of intermitent opperation the original failed completely.

Change it to an aftermarket unit and it lasted about 2-months. Then when she stops at the store or maybe leaving from work it won't start.

I found that if I unplugged the module and plugged it back in it would work fine for a day or two maybe 3 or 4 but it would do exactly the same thing.

The last unit was a dealer item and it just failed again. I too have been using the heat sink paste. With this unit unplugging it does'nt work but tapping on the module does.

I have replaced the Mag Pickup coil for the second time last night in hopes that it may be bad but this is getting really old.

Now what????

 

a bad ignition coil can kill the module too.
its why when ever i find a bad module, i always replace the ignition coil.
i stay away from the aftermarket ignition parts as much as i can.

make sure your getting good voltage to the hot side of the ignition coil. low voltage can damage the module.
check the alternator output voltage at the alternator, also check it for excessive AC voltage.
also check all of the grounds under the hood, battery to motor, battery to body, & motor to body.

 

Thanks for the recommendations.

A little more history… This vehicle had a very inconsistent stalling problem. Usually in California freeway stop and go traffic on a hot day. It would always start and immediately stall several times then wouldn’t even start until it sat for 5-10 minutes then it would start and run fine until the next time.

At first, it appeared to be Vapor Locking but its fuel injected so that was unlikely. I figured the coil was possibly going out so I changed it along with plugs, cap, rotor, and wires.

The problem persisted so the next logical step was the magnetic coil in the distributor. That didn’t fix the problem either and unfortunately the problem was always away from home and any diagnostic tools with a hundred pissed off drivers trying to get around this GM roadblock. When the Ign module failed completely it was easy to identify.

After the module was changed, it didn’t quit while driving any more but a couple of months after the module was changed the car would not start after the car was parked. Some times, it would be in the parking lot of a store or leaving work for the day or after sitting at home for the weekend. The first few modules would work again after you unplugged the four-wire connector from the distributor and plugged it in. Module # 5 now in the car is an OEM module and when it acts up the unplugging trick doesn’t work but take a screw driver and knock it a couple of times does the trick.

Last weekend I checked the grounds and the resistance between distributor, engine block, chassis, and battery negative and that wasn’t a problem. The cranking voltage is between 10.8 and 11.2 Volts at the coil. For grins and giggles, I replaced the Magnetic Coil in the distributor again and now I’m waiting to see if it acts up again.

Can the ECM/Computer be causing the modules to fail? Also what about the Spark Control on the firewall?

The distributor is new from a component standpoint so replacing it seems futile. The only items left are the ECM and Spark Control.

Sorry for the Mini Novel, but this one has me stumped… I come from the automotive industry having spent 9 years with Standard Motor Products and usually don’t have to go beyond my own background or a few friends from the office to resolve an issue.

Any other ideas?

 

These things can be hair-pulling sometimes. Modules die becuase of heat OR becuase something else is KILLING them. When I have a car that likes to "eat" modules my first go-to is replace the entire distributor and the coil. Usually cheaper and simpler than trying to figure it out one component at a time.

Did your problem start after you installed the new-ish distributor?

If not, then perhaps your ECM of ESC is killing it, but I can't say I've ever run into that particular problem.

 

i fought with a problem on my car that sounds very similar to yours.
it would not act up when i had the time or tools to check it. when it did act up at work, by the time we pushed it in & i got the equipment out, it would fire right up.

a few years ago i had a problem with my car intermittently stalling when i let off the throttle or when sitting at idle in gear. sometimes i could let off the brake & touch the throttle and it would die just like you turned the key off. occasionally it wouldn't restart without a boost from another running car or a battery charger. also, sometimes it wouldn't start after sitting over night or a quick trip into the store without a boost. my motor would spin over fine without a boost, but would not start. a lot of times even with a boost from another car it wouldn't start unless the other car was running. i didn't always loose spark when it wouldn't start.
it was a very intermittent problem, sometimes not happening for several months.
it turned out to be an intermittent low voltage problem while cranking. i had checked and cleaned all the grounds and power feeds. i replaced the ignition switch and it was good for a couple of months, but it came back. again i had low voltage while cranking. i checked power into & out of the ignition switch, it was good going in, but low coming out.
another new Delco ignition switch took care of it, but only for a time.
i finally wired in a relay from the positive side of the battery to power up the switched side of the ECM and ignition. i haven't had a starting problem for about 3~4 years so far and it took care of 99% of the intermittent dying problem.

 

I havn't changed the Ingition switch yet but have been thinking about it. The only thing is that the Cranking voltage at the Coil is between 10.8 and 11.2 Volts, verified a good ground and still no spark until the module is tapped.

The last go around I change the Magnetic pickup again but not the Ign Module. Its been about 4-Days the the problem hasn't shown up again yet. In the past the problem would reoccure every couple of days once it began.

My wife is driving it this week so we'll see if the problem is going to arise.

Keeping fingers crossed.

Thank you for the reply.

I'll keep you posted

 

i had the same things happen withmy 89gta. it only started with a spark tester light and that was it for a while. or with a jump start. i had the car for 8yrs now and went through 5 of them. replaced wires, coil, cap, batt, everything it seemed. but it sits for the winter. i had a guy work on it aft a shop replaced it twice, and he showed me the old one. first it was made in hong kong, and second, like i thought, wasnt cleaned off the block when put the new one on. its a headache i know. trial and error, usualy error 4me. now my start noid is bad and i thought my mod or vats or ecm was bad. yea these cars are problem childs but ill never get rid of it.

 

Hey guys i was just reading this thread and i think i have the same problem. I made my own thread so i wouldn't hi-jack another one but seems like were all having similar problems. My '88 IROC-Z 305TPI does the same thing. It'll randomly start. It always cranks just fine but will never start. Also when you first begin to crank it you'll hear and feel the RPM's spike to about 700 then go back on the starter. Sounds as if it starts to starts then it just stops. I sprayed some carb cleaner past the throttle plates and it fires right up, so i'm to believe its not getting fuel. When your ICM problems have you tried the carb cleaner and did it help. And yes i know spark and fuel are completely different but i'm just trying to find a starting point for me to look. Thanks for any ideas.

 

Update from 91-F Body here.

So far so good. Since I replaced the Mag Pickup in my earlier post, the car has been working fine.

It looks like the earlier replaced modules may not have needed replacing however we'll know more once the weather heats up again.

Thank you everyone for your replies and assistance.

Happy New Year!

 

The problems described in the original post seem to the norm for failure of modules, especially if the engine is frequently operated under heavy load. Ive gone through dozens of modules and a few coils. The typical failure mode for the module is to work well for a while, then degrade, and finally die on a restart. I think part of it is the fact that the module can only get as cool as ~200 degrees F since the dist. is in the engine. The later vortec modules are actually mounted externally with their own finned heatsink. Looks like GM finally got the message that the modules cant stay cool enough in the dist. in demanding applications.

 

Possibly converting from in distributor to an external mounted module. The problem is extending reluctor coil leads which may be subjected to EMI (aka spark plug wires). All modern under hood automotive electronics is rated from -40 to 150C. It is still a challenge to design robust silicon!

 

That is exactly what happens to my car, I drive it very agressively and have an updated BIN with the Corvette spark tables which are more agressive I was told.

I have no idea whether that leads to premature module death but if external modules were the fix I am glad I did not spring for an MSD billet distributor for the late model small caps as it would have the same prob then.

Small update also:

Killed another module a week ago. I even popped it open to see if anything looked barbecued and it all looked ok, weird. Swapped in a new Niehoff from Kragens and it fired up like always.

I even pulled a few ESCM's from the junkyard, but really do not think that is the problem. Also I have not found a way to test those or the modules on here.

I might just try replacing the mag pickup or whole distributor / coil / module all at once when I get some more cash to see if I can get rid of this problem finally.

 

UPDATE:

Got towed today, module died and I even tried swapping in a spare and it still would not start.

This time I think the dist. or coil is fubar and am just going to replace them both...

Is there any way to test the mag pickup in the old distributor?

Also, does anyone know if I can buy an ACDelco TPI distributor new? If so what is the Part Number?

 

New dizzy fix it? Any more updates?