EDIS help with miss on one cylinder

[flosho]

Ok, I've been trying to diagnose a problem I've had the last few weeks.. Seems that my car is only running on 3 or 3.5 cylinders instead of all 4. The reason i say this is because I have low vacuum when idling, around 12 InHG. I can get it to idle decent where its not shaking the entire car, however, I am also able to pull the #1 spark plug wire and it doesn't miss a beat!

If I pull any of the other 3 plug wires it'll chug and die. I've swapped injectors and plug wires, new plugs. I've also done a compression test on this cylinder and it has good compression. What could cause this cylinder to misfire? When I pull the plug, its black and sooty.

[flosho]

Sorry, this is on a Porsche 924 Turbo. I'm running ms1 3.0 with edis4 ignition, 36-1 trigger wheel, etc.

[kritip]

Is it a wasted spark coil pack, or Sequential COP, or wasted COP?

//edit -- missed the edis bit...i know nothing about edis. Please ignore me ;)

Cheers,

Kristian

[flosho]

No worries, thanks for the post. ;)

[vinister]

Disconnect the SAW line from the MS so that the EDIS gives you 10 degrees advance. This way you have removed MS from the equation, if the problem still persists, it has to be a problem with the EDIS.

If it was a problem with the module or the coil, you would have 2 cylinders misfiring because they are grouped together.

it must be a problem AFTER the coil, which means either leads or plugs.

if you have swapped both the leads and plugs... then its really hard to say.

I had a problem with EDIS when I used Bosch plugs, it was arcing from the lead end straight over to the block, arcing out, bypassing the spark plug entirely. I couldn't figure it out until I looked at it at night, and could actually see the spark jumping over to the block. I fixed the problem by going to NGK plugs one step colder.

[Minami Kotaro]

Standard question: are you using resistor plugs. If you aren't switch to them and it may help.

Did you make your own plug wires? Could be that one of them isn't working.

[flosho]

I am using standard Autolite Copper cored plugs with resistors.

I am using ford ranger EDIS plug wires.

[flosho]

Ok, changed plugs, plug wires, injector clips and still the same thing. The idle idles pretty smooth, but when I pull the injector clip or the plug wire for the #1 cylinder the car doesn't miss a beat...???

[vinister]

what if you pull the #1 fuel injector plug while its idling, does it still not notice?

[flosho]

That is correct. I can pull either the plug wire OR the injector clip for the #1 cylinder and the car will idle the same.

Like I said before, compression is solid, injectors cleaned, new plugs, new wires, new injector clips, freshly wired.

[flosho]

The other thing is, the #1 cylinder is getting good spark for sure, because if I pull the plug(s) and leave them on the valve cover, you can see a good strong spark coming from it.

It seems to foul or at least blacken the plug pretty quickly as well...

[Minami Kotaro]

The other thing is, the #1 cylinder is getting good spark for sure, because if I pull the plug(s) and leave them on the valve cover, you can see a good strong spark coming from it.

It seems to foul or at least blacken the plug pretty quickly as well...

Your injector may be staying open all the time. I had a stripped spot on an injector wire that was grounding it out and keeping it open all the time, and my problem was similar to yours. It would idle decently, but when I gave it gas it would barely run. Took me forever to figure it out.

[flosho]

That could be but, I've swapped injector spots, and made a new injector harness and they shouldn't be grounding out at all now... How else would I test to see if its staying open?

[JWX]

The injector itself could be stuck open. Pull it out of the fuel rail and see if it clicks when you apply 12v.

[flosho]

Took the coil to NAPA today and they tested it, said it was a-okay.

Took a long screw driver to each injector and could clearly hear them all clicking, and they should be since I had them tested and reconditioned about two months ago!

[flosho]

Any other ideas? I tried to attach a datalog but it said the board was over its attachment quota??

[flosho]

Ok, could this be a problem with the MS unit internally? Or possibly the VR sensor gap or alignment? Would that cause it to miss in this way.

I'm absolutely stumped as far as why only #1 cylinder has this miss..

[flosho]

Ok, I just switched the #1 and #4 plug wires and it runs exactly the same? What does this mean?

[Matt Cramer]

The only things that could cause one cylinder but not the other to drop out are ignition problems or a bad injector.

[flosho]

I did some more tinkering, and found that the front TWO cylinders are being worthless right now. Meaning I start the car and it idles, I shut the car off, pulled plug wires for the front two cylinders (1,3) and it idles exactly the same.

Firing order is 1,3,4,2. I have injectors wired 1/4 and 3/2 , so it can't be the wiring for the banks(I just rewired them as part of my troubleshooting). Also 1 and 4 and 2 and 3 are the ignition coils on the EDIS coil pack, not to mention if I pull the wires it has good spark.

The plugs for the front two cylinders are black/sooty. The plugs for the back two cylinders are perfect!

I just ordered new injectors and maybe a new FPR.