gjpearce

I just was providing some loving care to my beloved 1990 928GT. I used Gunk regular foam and then rinsed off with regular hose water- not high pressure and i tried to stay away from the electronics. Then I left the hood open all day to dry. Now the car starts up for 30 seconds and then it dies. I can keep my foot on the gas and the RPM's have a mind of their own. I can press the pedal, RPM goes up, then it starts to go down. Every time I take my foot off the gas, it dies. any ideas?

MainePorsche

"...i tried to stay away from the electronics."

That's impossible.

Don't hose the 928 engine (compartment) to clean. Push it out in the sun, and give it ample time to dry. There are many harnesses/connections that didn't do well - The ones under the intake in the rear may not be obvious to see if they're dry (or still moist).

928mac

Check the connector on the passenger side fender.
put it in the sun with the hood up as suggested.
take an air line and blow the coil wire ends off.

MainePorsche

+1
Noo.. Lister.
Take the cover of the 'jumper' post on the passenger side. The all important 14 pin connector under there - don't disconnect it unless you disconnect the battery. Let it air dry. Consider all electrical connection still with water.

Mrmerlin

Never Ever wash the 928 engine with water.

FWIW the real damage from doing this water cleaning of the engine is that the throw out bearing may now be fully rusted and you will shortly be replacing it.
This happens when water is used to clean the engine it will run down the rear of the engine and then run down the release arm and this soak the TOB

While the hood is up look under the carpet on the PS side and inspect the CE panel for water , its quite possible you have gotten that wet as well. any relays or fuse thats corroded should be cleaned and the relays that are corroded should be opened

Clean the 14 pin connector,
remove both coil wires and inspect them no corrosion and they should not be touching anything in their run

mickster

Disconnect the ground strap at the battery and be prepared to do some triage. Don't start the car again until you follow everyone's advice above. Where are you located? You may need some extra hands...

Speedtoys

I will admit to being a water washer, but only because I've become intimate with everything electrical under the hood, and replaced it...but...that's not a license for anyone else to do it.

But..critically, what could be unhappy? TPS, AFM?

14pin plug...what in there is "runs ****ty" related?

Injectors...nah, possible the seal for the harness is out and doused the panel thru there and/or hvac box in the cowling, if the cowl was open. A bad temp2 sensor won't run that bad...

??

MainePorsche

We're just trying to get the Noo..Lister into good habits and educate him into what is where. We're also being descriptive - he wouldn't know a MAF or TPS if he bumped into one.

Mrmerlin

Speedtoys answer to your question is that most of the wires will leach water into the harness since most of the harness is crunchy,
the rubber wont seal well where the connectors are and once water runs into any of the harness and shorts out other circuits the engine wont run.

Speedtoys

Great points Merlin.

Just was curious..if you had to unplug sensors to dry them out..where would ya start/etc.


I do not disagree with ya.

Mrmerlin

CPS, knock, hall, TPS, MAF ,14 pin at hot post

depami

It might be wise to try and dry without touching anyting. Often unplugging connectors does more harm than good.

That's whats wrong with my 86.5 now. To many connectors turned to dust and too many wires cracked open.

If my engine compartment were to get watered now, the only hope would be complete new wiring with connectors.

Bertrand Daoust

Like everybody said, not a good idea to kleen the engine bay with water...

...But I did it myself and the car was running on 4 cylinder right after...
Let it dry and everything was good after.
Will never do it again.
Air and rag from now on!

gjpearce

the basic problem remains- I washed the engine on wednesday and today is Saturday. The car starts fine-idles about 20 seconds, then it dies. It has been sitting in my driveway and I am using another vehicle because I knew it was not running well from the startup when I first started the car on Thursday to go to work. So I have been using another vehicle ever since. I will move it to an air conditioned garage tonight to dry things out.

Bertrand Daoust

Sorry but I can't tell you what the problem is but I'm sure you'll find what's wrong with the help of everybody here.
Maybe it is something more than only water... But first make sure that everything's dry.

Interesting case for sure!