Scott H

I drove through a puddle yesterday and soon after the car lost power and I pulled off to the side of the road. After a few unsuccessful attempts I got the car to fire again and went to Shell to get gas (where I was headed anyway). Filled the car up, went to start it, and it just wouldn't fire. Had the car towed home and tore into it this morning.

Checked:

DME Relay - Good
Coil - Tested good (used clarks garage method), but I'm somewhat suspicious since that's where I found water under the hood.

I charged the battery up some and got it to fire this morning but it's running really rich and the boost gauge does not read 1bar with the key switched to "ON," instead it shows around 10psi and stays there at idle. Revving it while in neutral makes it creep towards the 2bar line. I threw a real vacuum gauge on the engine and it shows 15mm/Hg cold, going to 20-22mm/Hg while off the throttle after a rev.

It seems to be running "okay" but I'm hesitant to drive it in its current condition. Any pointers as to where to look next?


And no, I wasn't running the plastic undertray, it was off so I could change the oil easier next week, kind of regretting that decision now.

Bri Bro

A common problem is the reference and speed sensor connectors. The sensor end of the connectors starts to crack and allows water into the connector. The signals are very low voltage so it does not take much to get a no start.

CPR

Yeah, but they are pretty high on the engine for puddle water to splash on to.

Perhaps the alternator got soaked & shorted? Does it have the rear shroud on it?

Scott H

The speed and reference sensors have been on my "take a look at" list for a while, the PO didn't replace the connector that broke and instead just hot glued the spade connectors into the remaining half of the connector... yeah, I keep finding these cheap *** fixes all over the place on this car. I saw 944 online has replacements for $20 so I'll be grabbing two of those or just two new sensors next time I make an order from there.

I thought about the alternator but it's up pretty high as well and tucked way up in there. The shroud is on, as is the cooling duct going to the rear of it. Maybe I have water sitting in there? I definitely heard belt squeal last night so water definitely made it onto at least the belt.

Any clue why the boost gauge would suddenly quit reading properly? Electronic casualty? Is there a MAP sensor for it anywhere or does it sense pressure some bassackwards way that only Porsche could engineer?

Bri Bro

I am assuming the factory boost gauge stopped working. There is a vacuum line that goes to the KLR. The KLR measures the boost and supplies a signal to the boost gauge. My guess is that it got disconnected.

Scott H

Went out and checked and it was still hooked up. Yanked it off and threw the mityvac on it and it held 27mm/Hg just fine. Is it possible that water got into the footwell and fried the KLR? Guess that's where I'll be starting tomorrow.

Bri Bro

What year is your car? There is a connector next to the KLR/DME computers that the boost gauge connects to. It is a good place to test the voltage out of the KLR. The connector is different after the 86 model.

DrZ1

May be a long shot, but do you have the factory alarm? I had my car in alot of rain once, and the drains under the battery were clogged. So the water went down the fire wall and filled my alarm module. I jumperd it and it fired right up.

Problably noit the issue but will put it out there.

Hope you fiqure it out.
Steve

Bri Bro

Factory alarm will result in a no start. A quick test is to bypass the DME relay with jumpers and see if it starts. The alarm disables the DME relay and the alternator.

Scott H

Found the problem: Water got in from holes in the battery tray and found its way into the KLR connector. Car works great again.

Glad it was something simple/free to fix this time, phew.

DrZ1

Glad to hear it, I need to pull my battery and make sure it will drian w/o being clogged. You also want to make sure that ther is not any rust holes. Usually a clogged drain, will allow water to settle and creat a rust hole, that will need to be repaired. I had it welded ( I think) then a black tar material coated over it from the welder.

Steve