Only getting spark to half of the engine. PLease help.

[Johnny-T]

So last month I was having some upgrades done to my daily driver 967. A DPI exhaust was added then we moved on to replacing my original fuel lines with braided SS lines. While in that area I had a tune up done as well. But while working on things we found my wiring harness had been cut and re-routed in several places and we were having to tape up and fix things as we went. Once everything was back together the car wouldn't start. It didn't seem to be getting any spark at all. After switching out distributor caps and plugs back and forth from the new ones and old ones we were able to get spark on the left bank but still nothing on the right bank. Obviously the car still wouldn't start so we came to the conclusion that some exposed wires on the harness had probably grounded on something possibly causing damage to the distributor.

A couple of days ago we finally got to putting in a new harness and distributor. We put in new plugs and everything but the result was the same. No spark to the right side of the engine. We tried switching out the ECU and that had no effect. The strange part was that when testing all the sparks, the 3 that weren't working would actually get a little burst of spark as the engine was turned off. We eventually messed with the mixture while cranking and got the car to start and idle. But still only on 3 cylinders. The engine actually idled pretty smoothly considering... But the car barely had enough power to get up my driveway. We then tried switching out the coil and ballast resistor but neither of those made any difference either.

Everyone is completely stumped. We have changed everything that could be causing the problem and nothing works. How can we be getting good spark on 4,5,and 6 on the left and nothing on 1,2,and 3 on the right until that last split second when the key is turned off? What are we missing? At this point we are considering putting in a new system that will bypass the ECU, coil, ect and give us a stronger spark and hope that it inadvertently fixes the problem. Has anybody ever seen or heard of anything like this before?

Any help would be great. As my daily driver, it is becoming increasingly difficult for me financially and emotionally not being able to get 967 back on the road.

[Bitsyncmaster]

That is really a strange problem. Only thing I can think of is your distributor cap is faulty since you have already replaced the distributor.

Edit: I see you already tried another cap, did that also include a new rotor?

[dmcnc]

You also changed your exhaust system. You could check the air-flow out of your new headers on the dead side. No airflow would kill all three cylinders on that side. Maybe troubleshoot with the original headers installed?

[Rich]

I think Dave picked up on the likely component.

With an odd-fire engine as in original D engines the symptom you describe is possible if the rotor/distributor and the plug wires are out of sync by one firing interval either way. Am not talking about the firing order. Long story.

Check that you did not install an even-fire distr. cap* (assuming that's even possible).
Check that the distributor is installed correctly per M:01:02 in Workshop Manual based off of TDC for #1. That is critical - assume nothing.
Check that #1 plug wire is on #1 TDC plug tower.
Check that the ign. timing is really set to #1 cylinder (rt front).

*Correct (odd-fire)cap looks like this, with the ignition towers sort of arranged in 3 pairs - looks weird but evenly-spaced towers (as used on even-fire PRV's) are bad for us:
http://store.delorean.com/images/Product/medium/102606.JPG

[DMCMW Dave]

Did this happen before or after replacing the distributor/cap etc.?

I don't understand how anything in the harness could "damage" the distributor. It just doesn't work that way.

The only part of the system that is separate right bank /left bank is the cap and wires. The ECU has no idea what plug it's firing at any point in time, and neither does the pickup coil in the distributor. Replacing the ECU won't fix this, you already proved that by swapping it with a known good unit.

Recheck your wiring, and make sure you don't have a bad (cracked or bad center spring/button) cap and rotor. I've seen new ones bad right out of the box.

What kind of wires are you using? What kind of plugs?

Did you try swapping the ignition coil itself with a known good one? Also be sure to verify that the +/- is connected correctly and that the condenser is on the right one. Go by wire colors, not position. It makes a huge difference.

[DMC-Ron]

I am new to DeLoreans, but regardless of car type this is a strange symptom. Here are some troubleshooting suggestions:

1. Get a spare (or temporarily remove) a spark plug and spark plug wire. Connect the wire directly into the coil and secure the plug where it is grounded and you can observe it firing (dark area). Crank the engine a observe the spark. Is it irregular (skipping) or regular? you might be able to detect an erratic pulse if the issue is with the coil or distributor firing signal to the coil ( this is because the firing order is 1-6-3-5-2-4 and, as such, does not uniformly alternate from left to right engine plugs). Erratic spark would let you focus on the coil and distributor. Nice even firing spark, start looking at the distributor cap and spark plug wiring.

2. If the coil spark checks out, you can take the same test plug, plugging one by one into each cylinder connection on the distributor and observing the spark.

All the testing should be done with the distributor cap in place. Use caution when testing exposed spark plug in the engine compartment.

Ron

[David T]

The only thing that would prevent you from getting spark to one side is if you damaged the ignition wires to that side. Check the resistance of each ignition wire or just replace them. If you are getting spark to one side the distributor, coil, ECU, wiring harness, etc is all working.

[FABombjoy]

Normally I don't like to add "hail mary" hypotheses, but this one is just weird enough to throw in another consideration:

Assuming:
-Proper distributor cap
-Proper rotor phase angle
-Known good ignition ECU

The trigger wheel inside the distributor does have a built-in asymmetry that will favor one side of the block. See part #8 on the diagram here:
https://www.deloreanautoparts.com/delorean-parts/images/ignition-dist-overview.jpg

You could scope the output of the pickup and look for a clean VR signal. Maybe there is a bent pole piece, flaky impulse coil, or something like that? Do you get 6 sparks / 720 degrees off of the coil?

[Ron]

( this is because the firing order is 1-6-3-5-2-4 and, as such, does not uniformly alternate from left to right engine plugs) I might be misunderstanding you, but just in case:
I like your thinking but with our engines it doesn't normally fire uniformly because the angle between each firing is different, while alternating from right bank to left bank ( 1-6-3-5-2-4 = R-L-R-L-R-L).

======

Johnny, you said it "didn't seem to be getting any spark". Did you check for spark actually getting to the plug wires and/or to the plugs?
I'd definitely check each position on the cap with a known good plug and wire as DMC-Ron said...

Also for, "3 that weren't working would actually get a little burst of spark as the engine was turned off", was this all 3 at the same moment? If so, that and you putting in a new distributor makes me suspect the cap/fit.

[DMC-Ron]

Ron,
You are absolutely correct, on both counts. If one side of the engine cylinders doesn't get spark, it just removes every other pulse and an irregular pulse would not be apparent visually. I had forgotten also that the spark, when fully working, is not equally spaced, hence the odd look to our distributor caps.

Thanks,
Ron

[Rich]

Repeating from post #4 - and you will need to go in this order....for example, you cannot check the ignition timing using #1 cylinder if there's no spark in the #1 wire due to a problem in any of the first 3 steps here:

Check that you did not install an even-fire distr. cap* (assuming that's even possible).
Check that the distributor is installed correctly per M:01:02 in Workshop Manual based off of TDC for #1. That is critical - assume nothing.
Check that #1 plug wire is on #1 TDC plug tower.
Check that the ign. timing is really set to #1 cylinder (rt front).

We know the distributor was replaced (but the replacement indexing accuracy is unknown so far) and we know there is no spark in the right bank. Spark may be generated for that bank but due to the odd-fire setup the spark could go nowhere if the rotor-cap sync is incorrect (off by one phase either way).

Especially note that when the distributor goes back in the spiral gear can affect the final rotor position/indexing.

[Johnny-T]

I have an update I wanted to share. I am sure that there is no fault with the cap, rotor, wires, or plugs. I just tried installing a new ignition system that had some effect but there is now a different issue that is just as confusing to me. I will try to explain everything in order in the hopes it points to a new clue.

So with the stock set up we found out we had good spark on 4, 5, and 6. No spark at all on 1, and 2. And a very weak spark on 3. But the car fires up and idles.

As mentioned before, we swapped out the ECU, resistor, and coil. We also tried different plugs, wires, and distributors components. All changes had the same results. Still only one bank with spark.

We then plugged in the new ignition system. It basically replaces the ECU, coil, and plugs and bypasses everything else. Once installed we tested the sparks and we finally got all 6 perfect and strong sparks. We don't know what it is that fixed the sparking problem because we had already tried swapping out all the separate components with no effect. In any case, the new system seemed to do the trick so we put everything back in order and tried to start the car again.

This time the car just cranked and cranked and then it would backfire/misfire with a loud popping metallic pinging sound and would cut off. It was acting as if the timing was off so we carefully checked and rechecked that the timing was correct. It was. We tried to start it again and still just got the misfire.

Finally we decided to switch back to the stock set up to see if it would still start again that way. We plugged back in the original ECU and everything except for the new plugs. Turned the key and the car fired right up but it was back to only the 3 cylinders firing again.

So we now either have only half of the sparks working with stock, and the car starts, or all of the sparks working with the new set up but then the timing seems off even tho we know it's good.

The only part of the original system we didn't swap out was the actual small harness that the new system replaces. (Jump harness?)

We now also know that the cap and wires are good because we were able to get good spark with them all. We just don't know what's causing the new misfiring problem when we are using the new set up.

I have videos I will try to add soon. But in the mean time, any other ideas or thoughts with this new information?

[kings1527]

I have an update I wanted to share. I am sure that there is no fault with the cap, rotor, wires, or plugs. I just tried installing a new ignition system that had some effect but there is now a different issue that is just as confusing to me. I will try to explain everything in order in the hopes it points to a new clue.

So with the stock set up we found out we had good spark on 4, 5, and 6. No spark at all on 1, and 2. And a very weak spark on 3. But the car fires up and idles.

As mentioned before, we swapped out the ECU, resistor, and coil. We also tried different plugs, wires, and distributors components. All changes had the same results. Still only one bank with spark.

We then plugged in the new ignition system. It basically replaces the ECU, coil, and plugs and bypasses everything else. Once installed we tested the sparks and we finally got all 6 perfect and strong sparks. We don't know what it is that fixed the sparking problem because we had already tried swapping out all the separate components with no effect. In any case, the new system seemed to do the trick so we put everything back in order and tried to start the car again.

This time the car just cranked and cranked and then it would backfire/misfire with a loud popping metallic pinging sound and would cut off. It was acting as if the timing was off so we carefully checked and rechecked that the timing was correct. It was. We tried to start it again and still just got the misfire.

Finally we decided to switch back to the stock set up to see if it would still start again that way. We plugged back in the original ECU and everything except for the new plugs. Turned the key and the car fired right up but it was back to only the 3 cylinders firing again.

So we now either have only half of the sparks working with stock, and the car starts, or all of the sparks working with the new set up but then the timing seems off even tho we know it's good.

The only part of the original system we didn't swap out was the actual small harness that the new system replaces. (Jump harness?)

We now also know that the cap and wires are good because we were able to get good spark with them all. We just don't know what's causing the new misfiring problem when we are using the new set up.

I have videos I will try to add soon. But in the mean time, any other ideas or thoughts with this new information?

Cranking, cranking, cranking, cranking, cranking, and then......BOOM.....misfire.....rinse and repeat, is symptomatic of the distributor cap being installed upside down. Very easy to make a mistake with that when you're not thinking about it. I'd go back and flip it around 180 degrees and try again. Very much a pain to do with the intake manifold installed again, I know.

[Ron]

Does the "new ignition system" consist of all OEM/Stock style parts?
Either way:
Does it include a distributor?
Please give us a step-by-step of the method you used to find TDC before dropping the distributor in.

I'm with Alex given all of that popping etc (180° off). You don't have to pull the manifold to tell, either.
(We can get in to that...depends on your answers to the above...)

[Johnny-T]

Cranking, cranking, cranking, cranking, cranking, and then......BOOM.....misfire.....rinse and repeat, is symptomatic of the distributor cap being installed upside down. Very easy to make a mistake with that when you're not thinking about it. I'd go back and flip it around 180 degrees and try again. Very much a pain to do with the intake manifold installed again, I know.

Is it possible for the car to fire up and run sparks on only 3 cylinders when the cap is upside down tho? Because if not then it can not be the cap. The cap is never touched when switching between the stock set up and the new system. And again, the car will start and idle when the original components are used, but it's still only on one bank.

The new system gets plugged into where the original ECM is. Then that has its own wires that runs to its own coil. That is attached to the distributor with the normal wire. So everything from the ECM to the wire going into the distributor is either replaced or bypassed.

Now it is possible that the new system calls for a different timing that we are unaware of. That's actually the next thing we are going to try. But we know for sure everything from the distributor to the plugs is correct and working. If they weren't we wouldn't be getting 6 good sparks with the new system.

The sparking problem was definitely caused by something between the ECM and distributor. We just don't know what since we had already tried changing everything with no effect.

It's only when the new system is installed that we finally get all of the plugs to spark but then the car acts like the timing is off. And again, the distributor remains exactly the same with either set up.

[Bitsyncmaster]

Maybe your new ECU has the pickup wires swapped. I found that problem with the FORD unit Bill sent me to test.

[kings1527]

Is it possible for the car to fire up and run sparks on only 3 cylinders when the cap is upside down tho? Because if not then it can not be the cap. The cap is never touched when switching between the stock set up and the new system. And again, the car will start and idle when the original components are used, but it's still only on one bank.

The new system gets plugged into where the original ECM is. Then that has its own wires that runs to its own coil. That is attached to the distributor with the normal wire. So everything from the ECM to the wire going into the distributor is either replaced or bypassed.

Now it is possible that the new system calls for a different timing that we are unaware of. That's actually the next thing we are going to try. But we know for sure everything from the distributor to the plugs is correct and working. If they weren't we wouldn't be getting 6 good sparks with the new system.

The sparking problem was definitely caused by something between the ECM and distributor. We just don't know what since we had already tried changing everything with no effect.

It's only when the new system is installed that we finally get all of the plugs to spark but then the car acts like the timing is off. And again, the distributor remains exactly the same with either set up.

I'm not sure what's exactly firing with an upside down distributor cap since I've never tested it but I also have no idea if you'd even get consistent results with it since it's out of the norm. Is it possible for it to run on 3 sparks with an upside down cap? Haven't a clue but it's much easier to ensure the cap is on correctly rather than try to hypothesize as to why or why not it would operate. SO MANY weird ignition/operation problems have been solved here simply by people going back to OEM plugs and wires without people actually figuring out why the car was running the way it was with the aftermarket stuff installed prior.

I think what's probable is you have two different issues going on.

1) your original ignition is not good (and therefor you're only getting spark on one bank). When you swap in the new ignition, it fixes that problem.
2) now that you get spark on all 6 cylinders with the new, good ignition, you have now most likely an upside down distributor cap that the system is contending with. That's when the misfire happens. Like I said in the previous post, putting that cap on upside down when you're not paying close attention to it is VERY EASY to do. Ask me later how I know that.

I have no idea with the history here on the forum of people having to adjust the timing due to a new ignition system being installed but I do know the topic of adjusting the timing is very rare.

Changing multiple components within the course of a "day's work" can bring on problems with troubleshooting a problem if one arises due to the fact many things were messed with. I think it'd be in your best interest to ensure without a shadow of a doubt that the cap is on correctly before investing the time and effort into a timing adjustment and then take it from there.

[DMC-Ron]

With no intention to beat a dead horse, but have you rechecked/verified the rotor timing position. Is it possible that the distributor is out of sequence/alignment? At TDC is the distributor rotor actually pointing directly at the #1 spark plug contact. If it were off, it might be close enough to spark some cylinders but not others.

Ron

[David T]

Not only must the rotor be synchronized to #1 cylinder you must point it to the #1 position on the cap. As previously stated, the cylinders are not evenly spaced around the cap so it is vital that you have the rotor aiming at the correct position of the cap and that it is for #1 cylinder. Not only is the cap asymmetrical, so is the reluctor ring in the distributor. The cap should have cylinder #'s marked on it and when cylinder #1 is at TDC at the end of the compression stroke it MUST point at the #1 marked position of the distributor cap. That wire then goes to #1 cylinder and then, following the firing order, each wire goes to the next cylinder to be fired. Just aiming at a cylinder on the cap when #1 cylinder is at TDC and then using that as #1 cylinder won't work on the PRV. Volkswagon Bugs had a similar issue, one cylinder (#3) was slightly different (it was ever so slightly retarded) so it wouldn't overheat. If you didn't install the distributor and cap so the correct cylinder, #3 fired when it should, you eventually burn #3 cylinder up. Maybe that's why you aren't getting spark to one side, you have the firing order out of index.

[Rich]

Not only must the rotor be synchronized to #1 cylinder you must point it to the #1 position on the cap. ..... Maybe that's why you aren't getting spark to one side, you have the firing order out of index.

+1 on what David T says, and also what posts #4 and #11 in this thread say, as well as Workshop Manual M:01:02.

The off-index or out-of-sync firing theory lines up consistently with the reported symptom - also is consistent with the fact that the problem started after the distributor came out.

It's easy to check/fix.

[dn010]

Does this "new system" have a name or is it going to remain top secret? It's a little hard to help troubleshoot when we don't know what you're working with.


Is it possible for the car to fire up and run sparks on only 3 cylinders when the cap is upside down tho? Because if not then it can not be the cap. The cap is never touched when switching between the stock set up and the new system. And again, the car will start and idle when the original components are used, but it's still only on one bank.

The new system gets plugged into where the original ECM is. Then that has its own wires that runs to its own coil. That is attached to the distributor with the normal wire. So everything from the ECM to the wire going into the distributor is either replaced or bypassed.

Now it is possible that the new system calls for a different timing that we are unaware of. That's actually the next thing we are going to try. But we know for sure everything from the distributor to the plugs is correct and working. If they weren't we wouldn't be getting 6 good sparks with the new system.

The sparking problem was definitely caused by something between the ECM and distributor. We just don't know what since we had already tried changing everything with no effect.

It's only when the new system is installed that we finally get all of the plugs to spark but then the car acts like the timing is off. And again, the distributor remains exactly the same with either set up.