Twin Plug-no spark
 

I got my 3.5L done, on the ground, and tried to start it this afternoon. After cranking for a while (multiple times). Nothing happened, so the troubleshooting begins.

It's got an Andial splitter in it with a 964 dizzy. I have +12V to both coils confirmed. I've got fuel pressure confirmed (injectors were tested and cleaned). So we pulled a plug and cranked it over with no spark (yes, the plug was grounded).

The biggest question I have is the Andial install paperwork shows a white wire and I was shipped one in the same position with a green wire. Anything to this?

We also isolated the coils (which are brand new) and they appear to be doing their job. So what is causing the loss of spark? Anyone?:confused:

When you cut the signal #1 green wire at the dme plug that one goes from the dme to the #5 on the splitter.

Here is the original setup: you have one power wire (black) and one signal wire #1 (green) going to the coil. You use these two wires (one already hot) and make the green that you cut 12v and run them to the power side of the coils. You run two new wires back to the coils and make them the new signal wires from the splitter #2 and 3 on the splitter

Ground the splitter

Then power up the splitter with 12v

You only cut one wire in the dme plug, thats the #1 green
You have to strip back the harness further from the plug (where is dme wires go into the main harness) to pickup the original black power wire that works with the key

It should work.

Is the red light, light up on the splitter with the key on?

http://i30.photobucket.com/albums/c3...alSplitter.jpg

Yes, the #1 Green wire in the DME loom is the one that is running to pin #5. It's just that on my splitter (on the splitter side), the wire color is green not white as the Andial picture shows. I'm sure it makes no difference, but want to be sure.

I'll take a picture of the set up and include it a little later.

I just pulled up an old picture of mine and my #5 is also green on the splitter.

http://i30.photobucket.com/albums/c3...1/IMGA0059.jpg

Thanks cgarr. Thought it was nothing, but wanted to make triple sure. Occam's razor applies in cases like this. Check simple stuff first.

Off to the shop/garage to take the seat out and check previously done triple checked work. I'll post some pics shortly.

http://forums.pelicanparts.com/uploa...1309721200.jpg

Here's a shot of the wiring I did.

Quick review...stock config is to have the +12V (in wire harness that sits on the floorboard to the left of where the driver's calf would be) to go to the #15 post of the single coil. I cut this and ran the upstream (end the goes toward the front of the car) side to the Red wire on the Andial splitter. The downstream side is still connected to post #15 of coil 1.

Found the green wire that ran to pin #1 on the DME control connector and clipped it in half. The upstream end (side that goes into the large/long DME connector) is now landed on the Green wire on the splitter. The downstream side (used to be on pin #1 on the single coil) is now connected to the Red wire on the splitter and the other side was moved to pin #15 of coil #2.

You can make out the black and white 14 AWG wire/cable I ran to the engine compartment (one black, one white) connected to the two Purple (they are more blue really) wires at the splitter.

My ground (which is the brown wire at the splitter) is running to the lug located on the front stud of the DME mount.

This all seems as the wiring diagrams prescribes. Correct?

When I turn on the ignition, the Red LED on the large box on the splitter turns on. The two ignitor LED's do not. Normal?

I took some Ohm measurements for reference. Taken at the connector on the splitter. Ignition off, bat connected, DME connected.
Between either Purple and Red=about 0.7 ohms
Between two Purples=1.2 ohms
Between Brown (gnd) and door jam=0.3 ohms

Do you see anything screwy? What else should I check?

Do you have two new wires running from #1 term on the coils to the splitter #'s 2 and 3?

What I did with my black hot wire was just T off it and run that into the splitter term #1 and also put the green wire that goes back to the coils in term #1 on the splitter and each of these wires gets hooked to term #15 on each coils.

I dont have led's on my ignitor.

Where is that black wire from thats hooked to the splitter #5 post? That should be the green wire from the dme plug..

Dont make me take my seat out! lol

#5 on the splitter (my black wire their green wire) goes to pin #1 on the DME (verified with a volt meter cont test 10 times, might check 20 times before I know for sure :)).

Yes I have new wires running to #1 terms on coils.

Verified I have voltage going to both coils, and have verified they aren't firing when the engine is turned over.

I'm betting something in the electronics is screwy which sucks rocks cause that's where the $$$ is!

Could be in the splitter unit, I have had parts go bad in them but usually you will not even get a light on it then. Pull the cover off it and take a look see if anything is toasted! I have had loose soldier joints before too!

I have all the spare parts except the ignitors.

http://i30.photobucket.com/albums/c3...IMGA0038-1.jpg

I know it would be a PITA but you could put it back to stock real quick to see if you get spark just to rule out some other problem.

One other thought: You didn't happen to remove the power to the dme unit its self by any chance? I'm sure you know this but only one wire is cut in the dme plug.

I'm sure you know the old cliche, "check 500 times, cut once". Got close to 100 time before I cut any existing wires.

Yes, the only wire that I cut in the main DME harness was the green one that went between its pin #1 and the old coil. That was the ONLY wire I touched in that harness.

Just checked the reference and speed sensors as well (I put new ones in on the rebuild just because I'm like that). They both create 0.96 kOhms between pins 8-27 and 25-26 on the main DME harness connector.

You're right I could put the old set up in there with one set of plugs, but F I don't want to think I can't find the issue without doing so. I'm sure it's something stupid. Always is!!!

I've asked Wong to help me troubleshoot the DME here somehow to make sure it's doing what it's supposed to.

I need more thinking fluid :)

I've scratched a hole in my head trying to figure out what the issue is on this one.

Cranked the engine over for enough time to put some fuel in the cylinders. Stuck my nose up the exhaust pipe (I feel like such a fool). No fuel smell. F!

Checked the power to the injectors. Looks good...+12V. All grounds very good. Injectors were cleaned and tested before installation. Haven't had an extra set of hands to test them installed by pulsing them, but all 6 can't possibly be bad. That's the only way no fuel smell would appear anywhere as I've noticed.

Checked the signal from Pin 1 on the DME to ground w/ignition on and it reads a little over 4.2V. Checked with the engine cranking and it doesn't seem to pulse. Seems to stay at 4.2V. F!

I think my DME may be hosed. Dammit! Not sure how that could be unless the damn splitter shot it in the head the first time it was powered? The only connections to it that have been changed are the Pin 1 wire and a custom chip from Wong. Guess I'll have to send the whole unit out for him to test.

I'm still perplexed as to why the LEDs on the igniters, on the splitter, don't light or flicker or anything. Maybe because the DME isn't sending a pulse there?

So now I have two problems, no injector firing and no spark. Has to be the computer. Carbs may have been better :mad:

ECM sent to Wong for eval this morning.

I took a peak at the parts on the splitter board as cgarr suggested and they all look brand new. All solder joints look great.

Checked and double check all signals coming to and from the DME relay. Everything perfect. Power going to the pins on the ECM connector. All to spec.

Beginning to seem like something ain't right in the silver box with Motronic embossed on it. Wong will confirm I bet.

Do you have the reference sensors connected to the right plugs? If backwards, it won't fire.

Sure thought I did:confused:

ECM checked out with Wong. No problems found. When it gets back here I'm going to try swapping them and see if it fires.

Before it gets here, I'm going to check the connectors themselves to see if they are OK.

Next I'm going to take the splitter out of the equation.

It's got to be something dead stupid! I've even checked to make sure there actually is a distributor on the engine.

Is your dizzy timing correct?

You didn't happen to not have the coil wire hooked up when you tried to start it did you? That will blow the splitter unit, if you want to check each side firing unplug one ignitor at a time to test it.

Yes, the coils were definitely hooked up and secure before trying to start. I must have checked the wiring on that part a couple dozen time to make sure it was all hooked, continuity confirmed, grounds perfect, etc...

I checked and rechecked (with a separate pair of eyes) that the dizzy timing was correct and plug wires were going to correct cyls. Must have checked this over a dozen or so times. I'm going to check the dizzy timing one more time, but I expect it's good. This wouldn't explain no spark though.

It's got to be a connector somewhere. Pushed pin or something. I should get a chance this afternoon to look at it again.

Thanks cgarr for your input.

If the rotor in the cap was not close to the cap pickup on TDC then you would not get spark, otherwise you would at least get spark even if you had it timed to the wrong cylinder.

Too true...

Checked resistance at the DME connector. Both speed and reference sensors at the connector read 970 ohms, so I've got continuity all the back to the DMe connector.
The cylinder head temp sensor also reads 2.54 kohms at the DME connector, so I've got continuity all the way back on that as well.

Going to pull the dizzy caps and recheck that as well. It's a new/rebuilt 964 dizzy so unless they are not tightened down or out of spec that should be good.

Can't try a start again until I get the ECM back sometime in the next couple of days.

I think there's a little man in that engine compartment somewhere laughing his little rear end off!

Thanks again cgarr for the input.

Yep, look at the ref and speed sensors connectors carefully, I had a carrera stump me for a little bit yesterday. Car came in dead, with no spark, no injector pulse, and no signal from the ref sensor. Replaced both sensors, started right up, but after puttting the air ducts back on, car did not start again. I checked, and again had no signal from the ref sensor. I unplugged it and the dme, and was going to check for continuity, when I noticed a pin pushed out of the ref sensor connector on the harness side. Would be nice if this is your issue

All connector pins look good...darn, wish there was something wrong with one. Never thought I'd say that.

Awaiting return of ECM, then more testing and measuring.

ECM is back from S.W...Thanks for getting it here quick Steve :)

I was 99% sure I had plenty of fuel going to the injectors, but I got a glycerin filled gauge and made an adapter to get it on the system.

http://forums.pelicanparts.com/uploa...1310232217.jpg

Tricky to get my handheld camera to focus in the odd lighting in the engine compartment, but it says 26 psi. This is the residual pressure as the ignition was off when I took this picture.

Going to put a noid light on next and see what happens.
Then going to try defeating the splitter and run on one coil.
Then going to try same with my old coil and old plug wires.

If none of this produces an answer, I guess I'll just have to get it back up in the air and check the speed/ref sensors air gap yet again and delve deeper and deeper into the electrical system with scopes and prayers.

Check that...actually it reads 32 psi. Seems like plenty of go juice going in.

I took all the wires out of the splitter and took some measurements.

No coils connected at all, nothing attached to the splitter. +12V wire (one that was stock going to the #15 pin of the original coil) to ground and I got 5.2 ohms with ignition off. 1.2 ohms with it on. Is this normal? The battery was disconnected on the neg side. Why would this lead test with such a low resistance to ground? Odd... Wires I ran for the second coil all show infinite resistance to ground so they aren't pitched or cut anywhere.

Tried connecting just one coil without the splitter in the circuit at all. Crank and crank and crank....no life.

Still have fuel pressure and plenty of it. 38+ psi residual.

So now I went to checking silly stuff, again! Both dizzies have rotors and they turn with the crank. Check dimensions from rotor to cap, all make contact with each other.

Also tried (for kicks) swapping the connectors for the speed and reference sensors with the splitter defeated. Crank and crank and crank....nothing. Moved them back.

Now to obtain a friend's scope and check the speed and reference sensor signals while cranking. Also going to get my hands on a noid light to see if the injectors are firing.

Nothing is showing it's ugly head yet.

Nothing is a substitute for perserverance and hard work kids!

I got it running!

Check your sensor gaps and check them again and again and again and again.

Put the car back up in the air, contorted myself around the headers and loosened the sensor bracket. Move the sensors to as close to the right gap as I could again, retightened the bracket. Then I stared at it for quite a while. Shoved a small mirror up there and eyeballed it as best I could (no room for getting a gauge in there).

Put the car back on the ground and presto chango alla kazam, she turned over a couple of times and announced life with a loud burst of straight head rumble!!!

Haven't had a chance to run it on the road yet, but I'm really jazzed now.

I found a willing soul to watch for leaks and noises and ran it for 15 minutes.

No problems...idle stability was iffy, but it's way out of its element so I'm sure it needs some adjustment on the valve to get it stable.

A couple of minor oil leaks. One at the return tube from the engine mount oil cooler. Probably will replace with new rubber because I'm sure there is a small crack in it somewhere. The other was at the driver side tensioner line where it attaches to the case. The compression fitting probably isn't seated great. Both easy fixes.

No case parting line leaks or cam tower leaks. Amen!

Now I need to find a spotter as I take it out on the road. Tranny was rebuilt as well so it should be interesting.

I will sleep well tonight.:D