Misfiring at idle

Dionikes · 06-22-2005, 01:57 PM

Ok, I have done several searches on this issue and I believe my problem is worthy of a thread.

I have been working on baselining my 911. This last week I replaced spark plugs, Clewett wires, cap and rotor. I also reset the valve guides.

Now I did this all backward. So I managed to change plugs and wires before I did the valves. I am retarded like that. So any it ran like a caged animal after I did the wires.

Yesterday we did the valve job and changed the rotor and cap. After we put everythying together it ran rough and after a couple of minutes started misfiring.

Troubleshooting done so far:
- ensured wires were seated on cap and plugs
- double checked order of wires in both places
- checked rotor postion at TDC
- checked the valve clearances twice before reassembling

What can I rule out? What can I check next? Any ideas? I know there have been problems with Clewett wires in the past...is it possible they are not seating?

Thanks for your help.

B D · 06-22-2005, 02:18 PM

Very basic but did you check or reset the timing, you did not mention that in you post? If not check it.

kqw · 06-22-2005, 03:53 PM

Setting the timing on the Carrera is not necessary....

kqw · 06-22-2005, 04:05 PM

Before you go back to re-check the valves,

I would put the old wires on again to eliminate an issue with the clewetts.

Dionikes · 06-23-2005, 05:07 AM

I had someone check my work. I had the 4 and 5 wires crossed. I felt like a total retard. Thanks for the reponse guys.

stlrj · 06-23-2005, 05:12 PM

I understand how easy it is to cross wires even when being as carefull as possible. So the question I have is why aren't the wires numbered to prevent this from happening?

I assume that Clewett wires are not numbered so how expensive would it be for these wires to come with numbers?

I suppose it's just as easy to number the wire ourselves with a ballpoint pen on both ends of the cable if I ever run into wires that are not marked.

Joe

Dionikes · 06-23-2005, 05:16 PM

The wires are numbered at the dist cap but not at the plug end.

kqw · 06-23-2005, 06:11 PM

Just a question folks....

Why are Clewett's and Magnabore's being considered over the original Bosch wires and connectors. My original Bosch wires lasted almost 15 years before they were replaced (again with original Bosch).

I see where folks struggle with fit, connections, separators etc....

Why go through this????

Again, just a question.

stlrj · 06-24-2005, 08:35 AM

OE Bosch? I thought Beru were OE at least from '73 on.

Joe

stlrj · 06-24-2005, 08:45 AM

Quote:

MSD's require a high level of EMI suppression to ensure that the ignition is reliable to 6K and beyond. Porsche uses solid core wires and puts their suppression into the notoriously unreliable Beru plug connectors. While its OK in some applications, using spiral-wound suppression wire works much better and prevents some misfiring issues that occur at high RPM.

__________________
Steve Weiner
Rennsport Systems
Portland Oregon
(503) 244-0990
porsche@rennsportsystems.com
www.rennsportsystems.com
http://forums.pelicanparts.com/showthread.php?threadid=223673&perpage=20&highlight=msd&pagenumber=2

Paulporsche · 06-24-2005, 08:49 AM

How can a car run like a caged animal (assuming you meant after it has been let loose) before the valve adjustment with the wires incorrect, but run poorly once the valves have been adjusted, with the wires still incorrect? Can anyone explain that?

Dionikes · 06-24-2005, 03:18 PM

The wires were right before thevavle job. I screwed them up when I put them back on. ;-)

kqw · 06-24-2005, 06:16 PM

Sorry...Beru...instead of Bosch...

Thanks

Dionikes · 06-24-2005, 07:51 PM

The Clewett plugs did not give me any trouble really. It was simply pilot error