jbmozer

I just completed a TB/WP replacement, installed a Porkensioner and eliminated the Air Pump. Now I have a definite misfire condition. At higher RPMs (>3000), the misfire goes away momentarily (suddenly, not gradually--it is like a flipping a switch). On top of that, there is a definite stuttering as if running lean.

The sparkplug wires were pretty old and the nighttime "fireworks" test showed that they were in poor shape, so I figured that all the bending and shifting around while I was doing the TB job triggered a failure--so, I replaced all the wires and plugs. Alas, when I started it up, I still have the same problem.

Still thinking that it must have been something that happened during the TB job, I rechecked the tics on the cam gears and everything lines up just fine (at least not apparently off by a tooth on either gear).

I've checked the rotor caps, coils, etc, and think that the ignition system seems solid.

When replacing the spark plugs, I noted two interesting things. First, the number 6 plug was fouled with carbon deposits (perhaps a bad injector?) and, when I took the left-side air plenum off, I found it had about 1/4-cup of motor oil in it. I'm not sure where that came from, but surely it can't be good.

Having run out of diagnostic patience (and time), I took the car to the local Porsche mechanic who called me back after a couple of hours to tell me that it was running lean and told me to put in some injector cleaner and go for a long drive. He said that if that didn't solve the problem, I should bring it back to him and he would start replacing injectors. This all seems a bit unsatisfying.

So my questions are:

1) Is there anything else obvious that I should check in association with my TB/WP/AP job? The car ran fine before, so I'm highly suspicious that I screwed up something during the procedure.

2) The carboned-up number six spark plug seems to point to something wrong there. I've tried disconnecting the wires to that injector, but the car is running so rough, I can't really tell if it makes any difference.

3) Whassup with the oil in the intake box? Should I be worried about a contaminated MAF?

4) I'm willing to follow the mechanics advice and drive it a while. Can anyone recommend a good injector cleaner?

Thanks in advance,
-joel

SeanR

Year of your car please?

jbmozer

Oops, sorry. 1986 (early) S

WICruiser

Not to be a wise guy but are you sure the wires are connected in the correct order - sounds a lot like two are firing at the wrong time.

Some oil carry over into the intake seems to be normal, how much time did it take to accumulate the amount of oil you noted?

AO

+1 on the wires. Happened to me - had #6 and #7 swapped.

Rob Edwards

Plug wire orientation:

Overall:



Passenger side (4671):



Driver's side (5238):

zoltan944

ya almost ALWAYS wires, always have to check 3-4 times before I throw the organ pipes back on. check again and let us know.

rexpontius

also here +1 on the wires.

When doing my TB / Pkensioner job I took pictures before removing the wires.
When reassembling everything I was really glad I had the pictures, their are pretty easy to mix up.

good luck

jbmozer

I double-checked the firing order (and that was also the first thing that the mechanic did). Plus, I had the problem before I put in the new plugs and wires. So, I am pretty sure that I am good there.

Cosmo Kramer

I would check the wiring at the coils. Something could have been disturbed when you were pulling the covers off. Also check the 14 pin connector by the hot post. Sounds to me like you have a bad connection and once the alternator hits 3000 rpm it provides enough juice to overcome the resistance.

SeanR

Check your plugs to make sure you didn't close the gap in them upon installation. Don't ask me how I know.

Also ensure your timing is correct, Kens 32vR is a fantastic tool to use.

Brett Jenkins

Might be irrelevant, id you plug the vacuum line that was associated with the air pump?

jbmozer

By Jove, I think that's it. I took apart the 14-pin connector, cleaned it up, pluged it back in and it is running MUCH better. I suspect that I got it wet when I was washing the grease out of the front end before I started the TB job.

The misfire is gone, but I still have a bit of a stutter at low RPMs. It still feels to me like it is leaning out a little. I still suspect that I have at least one injector that isn't performing to spec. But, at least it is driveable at this point. Thanks much for the tip!

-joel