Darien

Alright, as a jet mechanic I know trouble-shooting a problem without physically working it is like "shooting in the dark". But, any ideas would be greatly appreciated

Last night I stopped by to see a friend; I over shot his house so I put in reverse and backed up approx 200 ft. When I put it in drive I notice a hesitation, so I put it in park and reved the motor, it sounded fine. Later, on the way home the she started idling and running rough, like it lost it's timing or missing spark I got her home and did a quick inspection of the plug wires and plugs. The #4 plug was dirtier than the rest so I cleaned off the electrode and gave her a crank. She ran smoothe so I drove around the block and it felt fine. This morning on the way to work after approx 15 miles, it started the same ****. Unfortunately, I'm at work and can't investigate.

Just a quick note, it started after driving in reverse, and this morning it started after it heated up. No issues prior to last night

SHE IS MY DAILY DRIVER

Fastest928

cheick plug wires .. bad wires often are the source of ignition issues
When was the last time you got gas? Moisture in the gas is always a consideration
is there any moisture in the air .. did it rain recently? check all ecu connections. It is good to pull all relays and fuses, clean contacts and reinsert every 5-10 years

Darien

Thanks Marc,

I have the Nology wire set, I haven't tried the "lights out" test yet The plugs, caps, and rotors all have less than 5K miles. I did wash it yesterday, I concentrated under the rear end due to all the construction mud from the last rain which was last week. I filled up gas last week and currently have 1/4 tank left....

Darien

Anyone else??

I read a few other threads discussing the coil possibly going out?

FlyingDog

If the coil goes out completely, you will be running on four cylinders. The car will idle a little rough, but anything above idle will feel and sound like you're driving an aircooled VW that's about to fall apart. You can try running the engine and pulling each plug wire and replacing to see which cylinder(s) are not firing. You can also do that with the injector wires (although they may be under the covers on your 32V). If several cylinders are at fault, see if those cylinders match up to one of the distributers.

If it's just one or two cylinders it's not a coil, coil wire or rotor.

Tony

My guess is the LH Darien. The Brains.
We can try a swap if you like?

mulik51

I always suspected brains in the Electronically Injected cars, but what I found out-usually it is not it. Brains re very hard to brake unless you physically brake them(or put them in the wrong conditions).
Just my 2 cents...

Klim

Darien

I got her home and this time the strange happenings started @4 min after engine start. 2 new observations:

1. It reminds me of when I had a few spark plug wires crossed in the wrong distro caps after changing the t-belt. 2. Also, it smells very rich!

FlyingDog

Remember, if it smells rich and some plugs aren't firing, you're dumping raw fuel down your cylinder walls. That's not good.

If you have the WSM, run through all of the diagnostic checks. My 84 did this a few weeks ago and I was confused as hell when it wasn't the dual distributor belt. It turns out I sheared the little screw holding the left/rear rotor to the shaft.

Darien

I'm starting to wonder about marc's question about water. It seems to be intermitent now?? I'm curious if I could've got something electrical wet yesterday when trying to wash the under carriage? I wish it would just show it's ugly head so I can fix it

Rich9928p

Tony,

You're very kind, but you have bigger brains than Darien (don't most pilots have big brains?). Seriously, the S4 and newer 928s use a 35 pin LH Jetronic, the 1984 (Euro ONLY) and 1985 - 1986 US 928s use a 25 pin LH. The 25 pin LHs have fewer problems then the S4 and newer counterparts.

So Darien would need to swap brains with an earlier 928 [but NOT a 1980 - 1984 US L-Jet, which is also 35 pin].

I'd bet that his wash job did get something wet or cause some ground problem. Or, another problem like a failing relay could have just occured BY CHANCE at this time.

heinrich

I agree with Marc. Check the throttle body for water. Pull the plugs and look for water. If none, check for shorts along the coils or more likely distributors or wires. Cracked cap will give this result. Agreed check at night.

hlj821

If it comes down to a brain swap, mine will work.

Tails

The LH brain failes on a time basis due to a hybrid tile fitted to suit the 928.

I recently had a problem with my my car, I swapped out the LH ECU with a borrowed one and it proved it was the ECU.

I had the ECU repaired by JDSPorsche of UK, however I believe 928 Specalists stock these rebuilt LH ECU. Excellent service and work.

Tails 1990 928 S4 Auto

Rich9928p

To clarify just a bit, the 35 pin LH for the 1987 and newer 928s has the LH failure problem due to the "tile" (ceramic hybrid circuit). Bosch used hybrid circuits in many LH-Jetronic units, including those fitted to Volvos and Saabs too - and these cars also are suffering a greater than normal failure rate.

The 1986 and older 928 25 pin LHs do not have this hybrid chip and therefore do not have the associated failures.

Darien's 86.5 LH is hybrid circuit free. His LH could be failing, but the odds are somewhat lower.