OTR18WHEELER

You say it feels electrical, leads me to think bad coil, coil wire, or that module thing on the core support in front of the radiator, without discounting a bad relay in the CE panel. It's one of those gremlins, probably will be the last thing you check before you find it.

bureau13

Ha ha I'm sure that is true, it will be! I'm just worried it's something like grounds where I'll never really know for a fact that it's fixed.

Not sure what module thing you're talking about though.

MrMerlin, noted! No stickers on my radiator...

Wisconsin Joe

I have to agree that it seems electrical.

The easiest way to check for spark is with an induction timing light if you have one. A spare plug into a detached plug wire will work, but beware the current, as MrMerlin says. It's a pretty strong "zap" (betcha can't guess how I know that )

If you have (or can beg or borrow) a noid light, checking for injector pulse would be a good idea too.

Finding that one, the other, or both isn't there when the engine dies would be a big help in solving this.

Cleaning the grounds is a good idea. Intermittent electrical problems can often be fixed by making sure that there is good connection to ground.

And on that subject - Have you thought about your ground strap? They have a nasty habit of corroding inside the insulation. It looks just fine, and even passes enough current to make an ohm meter show that it's ok. But it's too far gone to carry all the current that the car needs.
This can be checked with a jumper cable (just one side of a set) connected between the negative post on the battery and a good ground point on the car (substitute ground strap, more or less).

bureau13

I have discounted the ground strap since the starter is cranking over the engine very strongly. Wouldn't that not happen if the ground strap were the problem?

I was actually looking at timing lights and noid lights the other day...I didn't get any (I've never used them actually) but maybe I should rethink that. I'm pretty sure I can borrow those next time though.

OTR18WHEELER

while I'm trying to figure out what I am talking about, this is a very informative link to help troubleshoot most common problems.
http://www.nichols.nu/cat03.htm

WallyP

So far, I don't remember anyone mentioning an intermittent ignition switch...


If you get desperate enough, buy a bunch of 12-volt LEDs or tiny light bulbs. (Don't laugh, but a good source of cheap ones is a string of Christmas tree lights - many of them are 12-volt.)

Get some of the super-thin telephone cable wire. Run a common ground wire to one side of some of the bulbs. You can pull a fuse - say, the fuel pump fuse - and stick the bare end of a piece of the 24 or 26 gage phone wire into the load side of the fuse so that the fuse leg holds the wire in place and makes connection. Run the wire to the other side of one of the tiny bulbs. Repeat with other bulbs on a switched ignition connection, the load side of the EZK relay, the LH relay, etc., etc. When there is power, that bulb burns. When the power goes away, the light goes out. Use a hot-melt glue gun to mount the bulbs to a small board, and stick the light board where you can see it.

Note which, if any, of the bulbs go out when the car quits.

Wisconsin Joe

If it's cranking well, then the ground strap is probably not the problem.

The noid light is about as simple as it gets: unplug a wire from an injector & plug the noid light in. It will blink if the pulse is there.

The timing light isn't much harder. Power goes in (two battery clips in the ones I've used). The inductive clip goes around a spark plug wire.
You aren't worrying about the timing itself, you just want to see if the timing light blinks as it senses a spark pulse through the wire.

OTR18WHEELER

have you checked this thing?, I couldn't find a related thread, so I just used one of my pics for reference.

good luck, I have nothing else to offer., sorry

bureau13

I have certainly not checked that thing, I'm not even sure what it is! I will have to go research it now, I'm curious.

WallyP, now that is a seriously creative diagnostic tool right there, love it! Regarding the ignition switch, someone did mention that to me off-line. I may not fully understand how they work, but wouldn't it also fail to crank if it were the problem?

SteveG

That module can cause a no-start. You might want to pm wyatt's ride, he went through an R&R of it. There is something about heat paste that you must reapply if you remove the unit, even if it checks out OK.

I agree about the ground strap if it cranks strong, but know that these electrical gremlins are very tricky and devious. And the fact that this car is demanding ignition-wise. A dicey connection in the most unlikely place can sap electrons and if the system doesn't get what it wants, it acts up, and can present as intermittent. Last time I checked a strap was 11 dollars. Anything that frees the flow can make the difference.

bureau13

Anyone know the size of the bolt that connects that coil ground wire to the block? Anything that fits through the wire terminal is too small and won't thread into the block.

I thought the WSM would have this info to be honest, but I can't find it anywhere.

Landseer

The engine computers ( and the injectors), MAF and CPS shield wire are some of the items that are grounded at those two ground points at back of the engine valley. Those and the ones over the CE panel are the critical actors. . Also, removal and re-fuse of CE panel, plus replacing 10 or so regular relays are some of the things that should be done upfront,. When its out, checking the back for any wire melts is a good idea. I've had a situation where two completely separate systems were connected, intermittently, because a pair of wires subtly melted into each other. Not even visible until I was plucking around and found it.

MAF wire short can cause issues. CPS can fail with and without tach movement. New ones aren't in my opinion bonded as well metal to plastic, so if a new one is twisted in the bell housing during installation its possible it could be damaged inside.

Noid light (can order one from Lisle online) is an important tool.

bureau13

For what it's worth, I just ordered that Noid light and a spark tester (basically the "spare plug" technique mentioned earlier, but since I don't actually have one lying around, this thing should basically do the same thing in a dedicated package).

It also started again briefly, and then died. So whatever is failing, is now failing with greater regularity, which I consider to be a good thing.

uncre8tv

Sounds exactly like mine before I cleaned the grounds (is it colder this week in S. Fla? temp can impact grounds a lot.)

WyattsRide

That is the ignition modules/amps. There are two under the black plastic cover. One for each bank of cylinders. I don't know if they would be the cause of your intermittent no start or the engine to just shut off. What I can tell you about them is, don't unscrew the two screws that hold the module to the base and pull apart. You will more than likely ruin the module. There is a thermal/silicone paste between top and bottom of the amp and very small thin wires that make connections on a type of circuit board. That paste becomes hard over time and if you pull apart you will ruin the connections within . My experience with the modules is if one is bad, then the engine will only run on 4 cylinders. Both bad, I would say no start. Good used module/amp sets are not very expensive.