[Mokchirnaff]

I come here trying to save an engine in a vehicle that I have had half of my life. If I can't get through this problem myself I will have to do the dreaded deed of feeding it to the wolves (taking it to a garage) where they will no doubt charge me inaccordance to whatever they want, if they can even fix the problem themselves.

Whatever help I can get here will be deeply appreciated.

This is a Chevy Van 305 V8 with an hei ignition system that is producing no spark. I have replaced everything at one time or another. At this time it now has a pretty much new ignition system. New ignition switch, distributor (which came with a new module, pick-up coil and capacitor), new distributor cap and rotor and a new coil. There is also now new spark plugs and wires.

There is 12 volts present (with switch in 'run' position) at the connector which plugs into the 'bat' terminal of the cap. While trying to crank the engine it drops to around 10 volts. I would think this is normal, no?

Please help. I am at my wits end. Does anybody have any suggestions?

 

[docvette]

No Spark?

Doc here imp:

This is a no Spark condition?

Remove the Cap, invert it, and using a DMM set on auto-range Scale, measure between the "Batt" terminal and the rotor Button pickup.

It should read between 6K and 30 k on the scale, If its less, more or infinite, get a new coil..

The same reading should be between the "Tach" and the rotor button pickup.

The Tach to Batt should read 0.00 ohms.

Also Don't rule out the module just cuz it's new... the come in "Floods" of bad batches...Take it to your Auto parts store and have it tested. (usually free)

BTW, what year? Fuel infected? TBI? Carb?

Try that and let us know..

Doc imp:

 

[Mokchirnaff]

Thanks so much, Doc, for your reply.

It is an '83 carbed engine and there is fuel being sprayed into the throat when accelerator is depressed.

After plenty of thought last night, I decided to quit putting off researching these four wires that are coming out of the distibutor. That's probably why I never mentioned them before. Three of them connect into the input side of the electronic ignition module along with the two pick-up coil leads. Following these wires out of the distributor leads into a small metal box with a circuit board inside. It is underneath the drivers seat. My manual is calling it the ECM. Apparently all it is for(with my vehicle) is to receive one input from a knock sensor. I began messing around with this and low and behold the engine started?!!?

The problem is still intermittent, though. I stopped and started the engine several times. Sometimes it wouldn't start again (meaning absolutely no spark) until after some flexing and bending of the wires. A couple of times without even touching anything the engine just stopped!!

So I think I have isolated the problem but I do not know if it could be this ECM (hope not, $100.00), the knock sensor or bad wiring.

Any suggestions?

 

[docvette]

ECM

Doc here:imp:

The first thing you want to do is carefully (with the battery disconnected) pull the harness plugs from that unit, and using a good electrical cleaner (no residue) and a small acid brush or Emery board, Clean & Burnish All the pins , using care not to deform them, and inspect for fraying at the pins and plugs.

Next Clean the edge card connector pins on the box ... Don't flood it with cleaner, just enough to clean them and Emery cloth to burnish them.

Inspect and continuity Check that harness between the distributor and the box for bad connections, or cut or shorted wires..repair ANY that look suspicious...

Finally, Try putting a HARD ground wire from that box To any frame/engine ground...mine, On the 80 Vette, had a loose one and would throw codes (check engine light) about every lope of the engine..until I added the hard ground..Drove me Nutz...

Hope it helps!
Doc imp:

 

[Mokchirnaff]

I checked the continuity of the few wires that run in and out of this ECM and nothing triggers any flags. There already is a solid ground wire to the engine for the ECM. Without knowing and being able to monitor what the outputs of it are I don't think there is anything else I can do.

There really is no way to get a known good ECM without buying one. Autozone told me that once I do, it is mine to have and hold and the only thing they would do is to replace with another one. The same holds true with the distributor I got from them.

So I have reached the point of no return. After many failed attempts to again restart the engine I am now giving up. I can't get a consistent spark and the sparks that I do see are kind of orangish/whitish, of which I understand indicates a weak spark.

Instead of throwing more money/new-parts at it I have been recommended a reputiple and well-equipped garage that I will have to tow the van to and more than likely pay out a large sum of money to get it back on the road. Ho-Hum.

This is a big blow to this one do-it-yourselfer. I thought I could get to the bottom of any problem with this vehicle but after doing all I am capable of all I get is "errrr errrr errrr errrr errrr errrr errrr".

Thanks for all your help again and I'll be sure to let you know what ends up happening.

 

[docvette]

I checked the continuity of the few wires that run in and out of this ECM and nothing triggers any flags. There already is a solid ground wire to the engine for the ECM. Without knowing and being able to monitor what the outputs of it are I don't think there is anything else I can do.

You can get a Haynes or Chilton manual at the auto parts store that will tell you What the wires are and where they go.

If moving the harness kills the engine, that's the problem plain and simple...

you have wires that are losing connection.

THE solid ground wire going to the engine, may not be enough...

The ENGINE could have a high Resistance to ground too(it sits on rubber mounts!) BE sure your ground cable from the battery bolts Directly to the ENGINE around the starter.

There really is no way to get a known good ECM without buying one. Autozone told me that once I do, it is mine to have and hold and the only thing they would do is to replace with another one. The same holds true with the distributor I got from them.

If you really feel you need a computer to test with, Go to the Bone yard and pull one from a "Runner" In FACT ask the guy if you can SWAP your computer in their car first and see if it runs before you buy it in case you don't need it...If they are cool guy's they might let ya do it..Although, I really don't think its the computer..

So I have reached the point of no return. After many failed attempts to again restart the engine I am now giving up. I can't get a consistent spark and the sparks that I do see are kind of orangish/whitish, of which I understand indicates a weak spark.

Here is something to try...run a "Hot" wire directly from your battery to the Battery terminal on the HEI, crank it, If it starts you have Harness / plug issues...and a good suspect is corroded plug at the firewall...

Instead of throwing more money/new-parts at it I have been recommended a reputiple and well-equipped garage that I will have to tow the van to and more than likely pay out a large sum of money to get it back on the road. Ho-Hum.

If you do that, your going to end up with a new computer, sensors , and all the parts you've already replaced...

Some Shops (not all, but some)have a tendency to "Parts" change or "Shotgun" when the problem is not in evidence and hope you won't B*tch about it when you get a $1000.00 bill...and then tack $99. an hour labor to that...

So you'd be $100. to the good if you bought The computer and installed it yourself...Even though I don't think that's the problem...

To show you how Rugged those Baby's are.. My Bro'~in~law's nephew was driving tow truck, picking up a car in So. Cal. (Story on this thread under electrical "Dig this") When he, and the Truck were struck with lightning...Good enough to hospitalize him and Kill the owner of the stranded vehicle hooked to the tow truck...BOTH computers survived the strike of Millions of volts with no malfunctions...in fact the tow truck was in service the day after the incident...

Computer's "Is or they I'snt" rarely inbetween...and usually only the prom needs changing not the whole unit...and if you buy a new computer, (or have it installed) You'll have to buy another Prom ($50 to $100 OVER the Computer price)...or use your old one which if was the problem , your "New Computer is going to do the same thing...A Bone yard computer off a "runner" will have a good prom already in it and I'll bet (If they won't let you test yours first) you can score it for about $50......


This is a big blow to this one do-it-yourselfer. I thought I could get to the bottom of any problem with this vehicle but after doing all I am capable of all I get is "errrr errrr errrr errrr errrr errrr errrr".

If you have the time, and patients I wouldn't throw in the towel just yet...Unless it absoulte that you need the transportation now...Besides...how will you learn if you don't tinker? When you find it, next time you hear of that problem you'll be able to say "Dude , Change this..." and it will run...

Of course If you have to have the car now...Then The shop is the short term (but expensive) answer.

Doc imp:

Thanks for all your help again and I'll be sure to let you know what ends up happening.

 

[Mokchirnaff]

I know, I thought I had it nailed. I got it started after messing around with the ECM. I don't know exactly what I did. Just found it. Looked at it. In the process flexed and bended the wires. Suddenly it started. Now it won't again. Very, very frustrating.

My manual shows a wiring diagram but it is obvious the diagram is not specific to what I physically have in my vehicle. So that doesn't help. The ECM I have is very limited in its functionality (knock sensor is only input) and it obviously effects the electronic ignition module (EIM) because it provides all three of the EIM input terminals (two of which are also joined by the pick-up coil leads). I have been told the ECM can completely disable firing of the plugs if its output is not correct.

I measured over 10 volts across the ECM's positive and negitive terminals so that tells me its getting a ground.

The shop I take it to is NOT going to change one part without my consent. If they tell me the problem has anything to do with the new distributor then that is covered under the Autozone warrenty. If they tell me its the ECM I will then get one MYSELF from somewhere, maybe Autozone again.

I'll let you know, Doc, so we both maybe will learn something. Thanks again.

 

[Mokchirnaff]

Good news, Doc!!

If you can imagine Garfield's big sh*t eatin' grin, Snoopy's dance and Steve Martins happy feet all mixed into one, you've got a vision of me now!

Thanks for prodding me into a "you've found it already" ... "now fix it, for Pete's sake" type attitude. It was right at the connector on the ECM. I was in the process of putting the circuit board back into its metal box and then back underneath the seat in preparation to tow it to a garage when I decided to try and start it again. It fired. OK!! ITS GOT TO BE HERE!!!

Looked at the zinc terminals on the card again. Decided to look at them through a magnifying glass. Those gouges that I mentioned earlier that were telling me there was a good connection turned out to be canyons, instead. Upon inspection of the connector terminals there was evidence of the same thing. SO!! maybe the current has finally decided that it could not consistently bridge the gap. I got out the trusty soldering iron and layed a layer of solder on each gouge to fill them in. BINGO!!
After some fiddling with the distributor, she's purring like a kitten.

WHEW!! I even took back some parts from shotgunning my problem that I was left over with to Autozone and they gave me my money back. $125.00 worth!

So my soldering iron fixed the problem. I end up with a new distributor (which also includes new ignition module, new pick-coil and new capacitor) new cap and rotor and new plugs and wires. NO PROBLEM! I might never need to be concerned about them again.

So all's well that end's well. Thanks Doc, for that last little pep talk!!

 

[docvette]

KEWL!

Doc here imp:

I just KNEW ya'll could do it!!

really happy to hear you got it on the road again! and you saved the shop and tow costs...

Now... Take some of that $125 and get 'er washed & Waxed, and when you get home , invest in a good adult beverage..you Deserve it!!

Thanks for posting back!

Doc imp: