Streetfighter

I am having a hell of a time trying to figure out what happened to my car over the last few days. Earlier this week everything was running well, accelerated well, idled, no problems. Thursday was driving and the cars idle speed dropped to 300-400 rpm at stop lights. Then at idle a check engine light comes on and the revs jump up to 1200-1300 rpm. When I accelerated it hestiated between 2-3k rpm and bucked back and forth. It was running like crap so I parked it.
I first looked at the dist. caps, a little arcing, but otherwise very clean. Next looked at the dist. belt, teeth looked good no fraying or cracked belt. Next I hand cranked the dist. belt and it moved. I cleaned the ISV valve, no effect.

I recently replaced the DME relay with a 993 part. Battery is 3 years old, but otherwise runs okay. I cleaned the dist. caps and checked coils everything seems okay. I start the car and now it idles at 300-400 rpm and when I hit the gas it dies. There is a check engine light on start up.

Fuel filter? Fuel pump? Battery terminal clean? I am at a loss right now.

Eric Kessel

Take it somewhere dark, with the engine idling, mist the distributor with water, and check for bright arcing (you may hear it before you can see the arc, but if it's bad, it will be obvious)..... Did you try getting the blink codes for the check engine light?

Streetfighter

No, not yet. I am thinking its the coils, they are original to the car. The car has 100k miles on it. From what I have been reading this sounds like it could be the culprit? If it is, I need to buy 2 coils? I know about the spray test, but I believe the dist. is working correctly.

Eric Kessel

The spray test is to find a bad wire. How old are the spark plugs? If you disconnect one of the coils (leave the coil wired up, but disconnect the wide connector on the "amp thingy" bolted to the front of the coil, it slides down once you press the wire clip in) see if it runs better on one coil versus the other. I'd bet you have a bad wire or two, and it's screwing things up. I had a hell of a time tracking down erroneous O2, and knock sensor errors, and absolutely crappy running issues that went away when I replaced the spark plugs and a few bad wires.

Streetfighter

Spark plugs have about 50k miles on them. O2 sensor was replaced also about 50k miles ago with caps, dist. belt etc. When I intially try and start the car it sputters for a couple seconds and won't fire. After 10 attempts it finally fired and idled low 300-400 rpm and when I hit the gas after 50 seconds of idling it died. Maybe it is a bad wire?

Streetfighter

For the spray test I am aiming at the top or bottom dist cap? By pulling the wire you mentioned I am pulling one of the black caps off on one the 6 six wires, on top of the dist. cap?

louisifis

You said you changed the DME relay recently-firstly, double check the applicability of the part number. Should be 993.615.227.00. Next do a DME reset-some people have had no luck using the battery disconnect technique so I would suggest using Vag or the Hammer.

These are the easiest/cheapest things to do first before changing parts. See how you go...

Streetfighter

I need to find someone in the area who has a hammer. The DME you mention is the one that I have in the car. It was replaced 3 months ago.

Eric Kessel

50k miles on the plugs? Really? That could be a problem...... For the misting, use a spray bottle, and spray around the tops of both distributors. Leave all the wires attached to the coils and caps, but disconnect the wide connector that goes to the piece of electronics bolted to the front of a coil. Unplug one at a time, and see if the cars runs better on one or the other. If you really have 50k miles on the plugs, the whole system will have to be running pretty hard..... if you search the internet, you can find the bosch plugs for around $3.00 each.

Eric Kessel

Check out the following to see if you can get the check engine blink codes:

http://efinnegan.com/Porsche/Repair%...faultcodes.htm

Streetfighter

Would that mean I may need to replace the ignition coils? Buying a set of 12? What do you mean Bosch part for $3.00? Is that the small pin in the dist. caps that looks like a spark plug sticking up? Replace those things at $3.00?

Streetfighter

My fault, I see you mean spark plugs! Maybe I should replace those, since it is easy and cheap to do. Do you think at 50k they would be shot?

Eric Kessel

Don't worry about the coils for now, get the fault codes (although if it's an ignition wire issue, the fault code may be bogus anyway). The spark plugs that screw into the cylinder heads are not good for 50k miles. You need 12 and the Bosch part # is FR5DTC, they can be found for around $3 each. If the spark plugs are worn, that puts extra strain on the rest of the ignition system, and can lead to the wires breaking down. Try misting the wires, and if you hear any loud snapping sound, then look around in the dark to see which wire is bad. The pin in the top of the distributor cap is not replaceable. It's part of the cap.

Streetfighter

Thanks Eric, I would say my culprit maybe the spark plugs. That could be why it is difficult to fire up and is running like crap right now. Anyone in the Chicago suburbs that has a hammer? Currently car is not driveable.

newsboy

Your due for a plug change, so I would do that 1st. Next on my list would be the coils. 100k is allot of miles.
Even coils that test within Porsche specifications, can produce electrical problems. Check all of your grounds also.