before I throw money at it.....

[john baldwin]

1989 3.2 Carrera, ~100K miles...Seems to be running on 4-5 cylinders from idle to 2500, cold or warm. Idles steady at 800 after a cold or hot start.
New cap, rotor, & NGK coppers.
Wires (Beru's-original?) all check between 2.65K and 3K (cyl 6) ohms; connectors screwed on tight, dielectric grease in boots before snapping over plugs.
Plugs: #6 comes out wet every time I check.
Injectors: all vibrate when running; leads all @ 2.5K ohms; 0.09mV at connector with ignition on.
No vac leaks...confirmed all hoses are connected; sprayed carb cleaner with no affect, removing oil cap does cause idle speed to drop as it should.
CHT sensor checks in at spec, despite it being single wire.
Coil...haven't checked R values (how to pull off cover without breaking fastener???)...but checked a grounded plug using wire to #6 and #2 cylinders...got spark on start up to both.
Grounds..all wires removed, cleaned, reattached and verified.
1/2 can Seafoam directly into the TB, definite improvement; balance of can into the tank with Sunoco Ultra.

When I pull connectors off the plugs or the injectors, the only cylinder that seems to affect the idle speed is #2...every other cylinder seems to have no affect on the idle speed or when I rev the engine with the connector off!

Guessing I may have a double whammy...insufficient spark and clogged injectors?
Still don't understand why new wires may be part of the answer, given that R values of the Beru's are in spec. Magnecors or Clewitts? (and why?)
Also, if injectors are clogged, is it better to replace with the metal tipped Buick look-alikes (@$35) rather than have the plastic tipped (prone to clogging) Bosch originals cleaned (@ $19)
Any thoughts, suggestions are appreciated. Not sure how to pull an injector while engine is running to check....read an earlier thread recommending spraying water on each cylinder from below to see which ones do/don't "steam"...I'll be sure and try that.
My Italian tuneups have been fun, but unsuccessful thus far!

[ossiblue]

Regarding the wires, they may test correctly but the Beru connector is notorious for shorting out (losing continuity) during use or vibration. The connectors have internal resistors that can go bad and will show up only intermittently. Replacing the original wires with a new set of known good ones will eliminate that variable in your problem.

[Porsche_monkey]

Possible. I think double whammy is statistically unlikely. Could be just a bad injector?

At 100k new injectors might be a good starting point. Or send them for service.

[Por_sha911]

Explain what you mean by "#6 comes out wet every time".

[Zeke]

My '88 runs on 5 if it sits for more than 3 weeks. Go figure, but that little diddy has been "documented" here.

[ischmitz]

How do you know it's running on more than 4 above 2500. It is possible you have the order of the plug wires on the cap wrong?

Ingo

[john baldwin]

Porsche Monkey
Possible. I think double whammy is statistically unlikely. Could be just a bad injector?
[I]If so, why doesn't engine stutter when I pull plugs OR injector wires?
Por_sha911
Explain what you mean by "#6 comes out wet every time".
[I]After sitting overnight, I frequently pull plug #6 which has fouled since I bought it...It's always "wet"...not burned, caked carbon, but oily, unburnt fuel....
ischmitz
It is possible you have the order of the plug wires on the cap wrong?
Triple checked firing order...it idels steadily at 800 hot or cold.

[stlrj]

Originally Posted by john baldwin

Still don't understand why new wires may be part of the answer, given that R values of the Beru's are in spec.
Any thoughts, suggestions are appreciated.

Would you believe the values of these Beru's are in spec?

[DanielDudley]

I expect that if the car was an MG, and the wires were 19.00, we wouldn't be having this conversation. OEM wires for a 928 are around 400.00, and I can't tell you how many people have come to 928 boards with running issues and 24 year old plug wires that nobody had ever bothered to replace. Usually after a major service, I might add.

Replace the wires. What have you got to lose when you perform basic maintenance ?

[john baldwin]

Interesting picture on the Beru's arcing...I checked mine for a light show... everything was dark...
Thanks for all the input... just trying to narrow down the probabilities to avoid forking over $ to replace components that might still be perfectly good...
Any thoughts on the coil? Haven't checked R values as I can't seem to get the cover off the top without destroying it.
Wires...Clewitts or Magnecors?
Injectors...clean them or buy new Buicks?

[69911e]

Compression test, wires, swap injector 5&6.

[tharbert]

A leakdown test!

[ischmitz]

I am confused: I assume this is the same car - so did this fix it: Motronic Distributor removal & cleaning or are you still having the same issue? I can see where a stuck dizzy causes issues like yours

Ingo

[john baldwin]

Originally Posted by ischmitz

I am confused: I assume this is the same car - so did this fix it: Motronic Distributor removal & cleaning or are you still having the same issue? I can see where a stuck dizzy causes issues like yours

Ingo

ischmitz,
Yes this is the same car, and no this did not fix it. Weights spin and move smoothly when shaft was rotated....

[john baldwin]

Originally Posted by 69911e

Compression test, wires, swap injector 5&6.

69911e,
Swap 5&6 just to be sure it's injector 6 at fault? Once the injectors are out, anybody know how to test?

[Steve@Rennsport]

John,

How old are the wires? (I've had enough trouble over the past 25 years with Beru wires & connectors that I don't use them anymore when there are better alternatives)

Is #6 coming out fuel or oil fouled?

[porschefool]

Maybe you can borrow a known good wire for #6 and see if that's it...
I put on a new set of Clewitts for Christmas and I love them.

[john baldwin]

Originally Posted by Steve@Rennsport

John,
How old are the wires? (I've had enough trouble over the past 25 years with Beru wires & connectors that I don't use them anymore when there are better alternatives)
Is #6 coming out fuel or oil fouled?

I'm the fourth owner, and nowhere in the maintenance records (limited) is there any mention of the wires being replaced....
It appears to be fuel...wet electrode and porcelain; dried right up with a rag...not oily...plugs look clean after

[john baldwin]

Originally Posted by porschefool

Maybe you can borrow a known good wire for #6 and see if that's it...
I put on a new set of Clewitts for Christmas and I love them.

I'm thinking the whole kit of wires is bad, despite resistance being in-spec and the lack of a light show...
how else do you explain the lack of any response when I pull each wire while she idles and there is no affect at al??

[Porsche_monkey]

Originally Posted by john baldwin

If so, why doesn't engine stutter when I pull plugs OR injector wires?

If it's not firing, then pulling the plug wire, or cutting off the injector won't make a bit of difference. It could be spraying a stream of fuel, I'm leaning more toward an electrical issue now.