I think I have a bad ignition module

[JeepsAndGuns]

After not being able to get it running on a stock chevy (ASDU) bin, and still not getting it to run with a howell bin I got from another member, I am looking for my problem.
If you have read my other posts, you may remember it will start and run, but just barely. It surges bad at idle, pops and backfires and dies after about 30-60 seconds, or if you touch the gas. If I unplug the bypass wire (like you would to set the timing) it will start and run (not the best, but semi smooth) it will stay there and run as long as I want, but if I rev it up any past 2000 rpm it spits and misses.
It seems to me there is something bad going on with the ignition. I have the base timing set to 10*, I have it set for that in the bin too. But with it running with the bypass unplugged, and not with it plugged up, makes me think I had a bad ignition module. The one I have I pulled out of a random truck at the junkyard. The truck looked pretty rough, but it was the only one I could find.
Looking at diffrent parts stores, these little buggers are expensive! Is there any way to test these things? I googled it without any luck. I dont want to drop the coin on a new one if its not the problem, but I dont want to buy a cheap one just to see if thats the problem, then be stuck with a cheap module. If it is the module, then I am gonna buy a quality replacement. But I dont want to drop $70 on a module if its not the problem.
I have the module on a nice heat sink with the proper paste between it and the sink. I have a ground wire run from one of the bolts to a good ground, I also used a multimeter to check the ground and make sure its good, and it was. Other than that I dont know what esle to check.

[Billygoat]

Your dizzy trigger wires could be backward, try switching them and see how it runs. It won"t hurt anything if that is not the problem, I have done then backward a time or 2... It throw the advance to far is all, and you systems are making me think that now.

[FSJ Guy]

With the bypass wire CONNECTED, do you get a Check Engine light? If not, the module is probably fine. If the module is bad, you will usually get a Check Engine light.

[JeepsAndGuns]

Your dizzy trigger wires could be backward, try switching them and see how it runs. It won"t hurt anything if that is not the problem, I have done then backward a time or 2... It throw the advance to far is all, and you systems are making me think that now.

Just tried that and it wouldnt even start. It poped a couple times, but would never fire. Swaped them back and it wouldnt start. Had to unhook the battery to clear the computer before it would fire back up.


I restarted it with the bypass CONNECTED and it sat there running uber bad, loping so heavy the whole jeep rocked back and forth and popping/backfireing out the exhaust real bad. The check engine light never came on though. I let it run like that for about a min and the check engine light never came on, sooo idk. Any chance it could be the computer? The check engine light came on for a few seconds when I turned on the key then went back off, so I know the bulb is working.

Think hooking it to the laptop and trying to get a datalog like that could do anything? I mean, with the bypass and everything connected, I should be able to right?

With it running/acting the same with both the ASDU bin and the howell bin, I'm thinking its something other than the bin. Any ideas?

[Billygoat]

Sounds mechanical not electronic.
back to basics...

If you dizzy in correctly?
Plug wires if the right order?

You did mod your dizzy to lock out the mechanical and vacuum advance right?
(I don't know the details of your rig, so I have to ask, not trying to sound like a prick.)

Are you running a standard cap and rotor?
I don't know if the chevy coil is to hot for the small cap or not, I have a TFI cap and rotor on, don't know if the stock cap will cross arc??? - anyone?

[Chris P.]

I've run the chevy coil with a stock cap for over two years and so far it has been fine. I did adjust the phasing on the distributor because under full advance the rotor was a little too far from the contacts for my liking although it seemed to run fine with the stock phasing.

[PlasticBoob]

You need to datalog and check the pulses that the computer is receiving from the module both while cranking and running. They may be dropping due to noise/interference, though I do know that some aftermarket module of lower quality will not pick up good VR signals and thus put out a signal with missing square waves.

[JeepsAndGuns]

The module is a factory GM one I pulled from the junkyard. I am using the large TFI cap and rotor and a aftermarket chevy TBI coil.
When I removed the dist to convert it, I found the plastic around the pickup was cracked (but it still ran fine) but I didnt trust it. So I installed a new pickup coil, I removed the advance weights and put a couple tack welds on there to hold everything still. Its reinstalled correctly and the firing order is correct as I never removed the wires or the cap when I converted it. Vacume advance is not even on the dist anymore. I used another screw and locked the pickup to the baseplate.

Looks like my next order of business will be to try and datalog. Might be a couple days before I get some time, been woking 10 hour days.

[babywag]

I'd be suspect of the replacement pickup-coil...wouldn't be the 1st time a new ignition part was faulty right out of the box.

[Billygoat]

dizzy locked out and installed in the correct orientation, with plugs and wires in order - verified!

I'd be suspect of the replacement pickup-coil...wouldn't be the 1st time a new ignition part was faulty right out of the box.

This is a good thought and something to test...



tried reversing the dizzy pick up wires, would not start...hmmm, IIRC when I had mine backward when I put the TBI in Thumper it would not start when I switched them because the base timing changes when you switch the wires - meaning you have to turn the dizzy again to get the base set.
With the engine at #1 TDC compression stroke, where is the rotor pointing in relation to the cap post? It should be a tough after the post.
You simply could have put the dizzy in 1 tooth off as well.

The way the engine runs really seems like ignition timing, you can try a data log, but I can't think of anything in the log that will give much information to the problem....there could be, I just don't know what.

[FSJ Guy]

I have a spare rotor cap with a hole drilled out over the #1 wire. With the bypass disconnected, you can shoot your timing light at the hole and verify rotor phasing.

[JeepsAndGuns]

I brought the engine up to TDC before I removed the engine. I removed the #1 plug and confirmed compression stroke by holding my finger over the hole. I did the mods to the dist and droped it right back into place.
Its not one tooth off because I only had to turn it a smudge to get it to set at 10*. Even if it was off, all I would have had to do is turn the dist till its lined back up.
I have the pickup wired to how I saw several places list it. Attach the orange wire to the P terminal and the purple one the the N terminal. In my google searching I found one place that said to check a ford pickup coil is to test the resistance. It said between 400 and 1000 ohms is good. Mine tested at around 675 (if I remember correctly)

I still am wanting to think its something electrical. Cause with the bypass plugged up, the computer is controlling timing and it runs like poo. With it unhooked its running off only base timing and it will run for the most part ok (for a completely un tuned system that is)
Could the spark controll module be causing it? I tried unhooking the knock sensor to see if that effected it any, and it didnt. Could that module be bad and be telling the computer to retard timing?

[FSJ Guy]

Does your Howell bin actually have a timing curve created for an AMC engine?

If you don't request it, I don't think they change the timing from the factory Chevy specs.

[Billygoat]

Does your Howell bin actually have a timing curve created for an AMC engine?

If you don't request it, I don't think they change the timing from the factory Chevy specs.

Yes it does, I can attest an amc 360 runs fine on it

[Billygoat]

Attach the orange wire to the P terminal and the purple one the the N terminal.

Ok Yes that is correct, I remember I so wanted P to be purple and I had to swap it

I still am wanting to think its something electrical. Cause with the bypass plugged up, the computer is controlling timing and it runs like poo. With it unhooked its running off only base timing and it will run for the most part ok (for a completely un tuned system that is)
Could the spark controll module be causing it? I tried unhooking the knock sensor to see if that effected it any, and it didnt. Could that module be bad and be telling the computer to retard timing?

As far as I know the spark control is only suppose to do stuff when the knock sensor register, but if bad if could be going goofy, try unplugging it and see how the truck runs. Also did the CEL kick on with the knock unplugged?