Adam Geist

Hey Mike,

I do not remember seeing any blue smoke out of your exhaust last Fall for the few seconds it took me to catch up to you in the gold '86.5......that's IF you let up on the throttle to let me pass you!

I've replaced valve guide seals on Honda/Acura 4 valve per cylinder engines without removing the cylinder head. Can the same be done on the Porsche 4v cylinder head?
Adam

hacker-pschorr

I'm sure the guides will be worn too (at least the exhaust), I'm not sure how those can be done without removing the head.

AO

Mike,
Didn't you have a bad LH recently? Could this be a result of that thing shooting too much fuel? I know you're going to say, "Andrew, the 928 is batch fired, so wouldn't they all be in similar condition?"

To which I say, yeah... but I'm trying to think of other potential causes.


(I know it's a weak suggestion.)

heinrich

that looks a lot like oil. and massive amounts

AO

I don't know enough about this stuff, but wouldn't a compression test reveal if this is an oil control ring issue?

Adam Geist

I have a leakdown tester - would that help?

WallyP

Given the way that the car has been driven (not driven?) over the last few months, my action plan would be:
- Check the plug wires and cap.
- Road Trip! Vigorous driving for long enough to really clear out the engine. These cars don't like being run for short periods, never being fully warmed up, never seeing full throttle.

Check the plugs and compression again, and then decide what to do.

It is easily possible to have stuck rings that will free up with some enthusiastic driving.

SharkSkin

+1 on checking wires and cap. The extra resistance from the deposits would have encouraged the spark to find another path, potentially making that wire fail a bit before its time if it was already marginal, or leading to arcing in the cap.

Mike Frye

Thanks everybody,

Adam, of course I let up on the gas to let you pass me, but not abruptly (more like from 4500 rpms down to 4000 or 3700 or so) I'm not sure. If I remember correctly, we both had to take it easy because your nephew's eyes were as big as saucers and he was going to leave fingernail marks in your dash if we went any faster.

Andrew, I thought it was an LH problem and I plan to re-update that thread, the surging when warm seems to have gone away and it idles more smoothly in general, but the surge is still there when cold, and the idle could be attributed to switching chips at the same time as we switched the LH, so my test wasn't conclusive on that one.
That's what I thought. My compression numbers were listed in the OP, no significant difference between cylinder 3 and the rest.
I don't know how to use one, but more information is always good.
Plug number 3 had some oil on it after just 1 day (about 40 miles of driving with higher than typical shift points, about 3500-4000. I'll have to plan on blowing it out a bit this weekend and see what I get.
Will do, thanks.

Does anyone think it could be caused (or exacerbated) by a bad ignition coil? I think #3 is the farthest one on the DS distributor, maybe if the coil is weak, the voltage isn't quite getting to the last plug when I'm at idle? The plugs, wires, caps and rotors are all new as of 10/06, but I've never replaced the coils and don't know how old they are. Maybe that and marginal cam timing could combine to cause it to miss enough to get sludged up at idle?

Mrmerlin

if you have coil questions just swap them as well as swapping the igniter plugs, but do one thing at a time to narrow down your testing.
A free test would be to run the car in the dark and look for sparking at the ignition wires

hacker-pschorr

It usually doesn't hurt to spray a little water mist too.

Mike Frye

I really doubt the wires themselves are bad, they're the good ones and they're barely 2 years old. When I looked inside the boots two days ago, they looked brand new with no corrosion or 'arc' marks. I'll check at the distributor end tonight. I think I might just get a set of ignition coils and replace them just because I haven't done that yet. Plugs are all new as of yesterday (Bosch WR7DC).

I hadn't heard that trick. Thanks for the tip.

So this weekend I plan to:
>Adjust the timing using Porken's timing tool
>Run it like I stole it for at least 50 miles or so
>Go through the entire LH/EZF test plan start to finish again, without skipping anything that was 'good last time I checked' like the grounds, temp sensor readings and TPS test.
And as soon as I can get a replacement set of coils I'll swap those out too.

Hopefully one or all of these things will help me isolate it, and if it turns out I need to pull the engine to pull the heads to do the valve guides and seals (and valve job...) then I guess that will go on the list. I'm getting good at pulling the top end off of this engine. This will be the third time in the last 6 months.

Lizard928

One thing to keep in mind for the oil is the crankcase breathing system on these cars allow them to pull oil into the intake.

Pull the MAF and look for oil in the base before the TB.

As well pull off and empty the two side plenums and clean them out.

Mrmerlin

you may not have a coil problem, I would close the wallet for now.
Add some marvel mystery oil to the crankcase about 1 qt should do. Add some Techron to the fuel.
for the ignition wire test although water is suggested, I have found that ignition leaks are easily seen at night in dry conditions,. and you could always spray water after first observing the dry system.
make a few short trips so the let the different oils/cleaners do their job. then report back,
Based on the condition of the other spark plugs i would say the colis are fine, more so a possible problem with the wires that go from the coil to the caps

Mike Frye

Close the wallet for now! Blasphemy! I thought you were a mechanic. Now I can see you for what you truly are: An imposter who clearly doesn't understand the basic economic concept of working on other people's cars.

I've used the marvel mystery oil before, but not on this car. I just topped off the oil when I did the plugs, so I may have an issue with that one for now. I hate trying to removing 'some' oil from the car. Will do the Techron and the next time it needs oil I'll add some MM oil.