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Feelin' Solexy
 
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Join Date: Oct 2003
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Unhappy My car croaked in the carwash

So we've recently had unseasonably warm weather here in the boston area, and I decided to treat my 944 to a nice car wash.
I decided that, given the salt on the roads here in MA, I would splurge for the undercarriage wash.
So my car is working fine as I pull into the carwash....engine is thoroughly warmed up, idle is steady at 1000 rpm, everything seems fine. this particular carwash is about 6 carlengths long, and it's the type where your car is pulled along a sort of track. Anyway, I have the car in neutral and I'm in the wash for about 6 seconds when things get a little weird. The tach goes up to more like 1500 for a second or two, then falls for the next second and the engine stops. (Little side comment here: The carwash was sort of loud, so I can't gaurantee that the RPM actually went up versus some sort of instrument screwup. In cold weather my tach has a tendency to sometimes read about 20% high until the car warms up, at which point it will suddenly correct itself. I will be driving along and the tach will indicate, say, 5000 RPM and suddenly the needle will fall to the correct 4000 RPM. Haven't figured it out yet)
Anyway, I have a bit of a heart attack because there are cars in front of me and behind me, and I'm really worried that if I can't get the car started again I will end up with a disabled car at the exit of a carwash where the cars are literally being pushed out the exit.
I tried starting the car a few times, but no luck. As it turns out, there was a bit of slope at the exit, so I was able to push the car a bit and drift to a safe spot. I popped the hood, and took a look around. Here are the facts:
The dist. cap was bone dry on the outside, though I did't pop it to look at the inside.
The coil was totally dry
plug wires were practically brand new (about 250 miles on them) and dry from cap to plugs.
Inside of fuse box was dry
DME relay was fairly new (about 500 miles) and had been replaced as "preventative maintenance", replacing with old relay had no effect.
So I gave the engine a few minutes to hopefully dry out and then tried to start it again. When I cranked the engine, it wasn't firing at all no matter how much or little gas I was giving it. BUT, when I stopped cranking it would hit on a cylinder or two. I could crank for 10 seconds with not a single cylinder firing, and then after I let go of the key one or two cylinders would fire.
After about 20 minutes of this, I gave it another shot and the car started, but it was sputtering and when I tried to increase RPM it just stumbled at around 2000 and then stalled again. Finally after waiting another 5 minutes I got it going and warmed it up and drove home, no problems after that.
So, here's what I've looked at since:
Battery tray: I've heard of trays leaking and letting water hit the electronics below, but when I looked at mine it was clean as a whistle. Actually, probably the cleanest battery tray I've ever seen. The drain hole was clear.
Fuel pump: I figured maybe the pump was shorting out or something. However, when I went to take a look at the pump itself it was not exposed like on earlier cars but rather coverd by a pretty solid/ water proof looking cover thing.

So I've pretty much run out of ideas. I'll probably do some experimenting this weekend with jacking up my car, starting it up and then hitting various parts of the undercarriage with a hose to see if I can get the engine to react.
One idea I had: my rubber plug for the "peep hole" for the clutch in the bell housing is missing, would it be possible for water to enter there and get splashed by the flywheel up onto the speed and reference sensors? Also, do the speed and reference sensors provide the input for my tach?
Anyway, any insight or suggestions would be greatly appreciated. Thanks!
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1974 Vespa Rally 200, 1974 Vespa Primavera 125, 1963 Solex 2200, 1938 Buick Special, 2008 Mini Cooper S, 2010 Mazda CX-9, 1986 VW Vanagon Syncro Westfalia, 1989 VW Doka Tristar - in the stable
1989 Porsche 944, 1973 VW Beetle - gone but not forgotten
Old 03-01-2004, 07:55 AM
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well i am not an expert, but my guess is that you had water running into your dme box... did you check if the area was wet? the only other thing I can think of is the ignition components getting wet, but you say they are bone dry.


perhaps this is just some weird cosmic coincidence and your car would have died if you were just driving on the street?
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Old 03-01-2004, 08:08 AM
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Quote:
Originally posted by CJFusco
well i am not an expert, but my guess is that you had water running into your dme box... did you check if the area was wet?
Isn't the DME box the one that gets wet if your battery tray is leaking? I didn't look closely at it, but assumed ( you know what they say about assumed ) that if the battery tray looked good after the fact that it was unlikely. Is there a possibility that the DME computer would get wet anyway? In any case, the carpets were dry so if there was a leak into the cabin it must have been small. Hmmmmmm
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Grant
1974 Vespa Rally 200, 1974 Vespa Primavera 125, 1963 Solex 2200, 1938 Buick Special, 2008 Mini Cooper S, 2010 Mazda CX-9, 1986 VW Vanagon Syncro Westfalia, 1989 VW Doka Tristar - in the stable
1989 Porsche 944, 1973 VW Beetle - gone but not forgotten
Old 03-01-2004, 08:23 AM
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Ground strap comes to mind. As well as the ground located on the Xmember. Sman
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Old 03-01-2004, 11:07 AM
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The crank pulley opening will let water into the belt box. The balance and timing belts will throw the water around the belt box and then into the back of the dist and also through the vent hose and into the air cleaner.

The cover on the coil will capture water and short the HV coil wire out.

Even the HV coil wire to dist can have cracks in the weather boots and let water in resulting in grounding.

As you relate the tach doing strange things I would check the DME first to see if it's wet from water leaking trough holes under the battery.

Then start checking the dist cap and coil.

I've also seen the speed and reference sensors fail when wet when there is cracks in the insulation or the connectors.
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Old 03-01-2004, 02:01 PM
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I tell you, this sounds like what happened when I decided to give my engine a bath. It ended up being moisture in the distributor cap shorting and then finally buring up my rotor (see pic).

Water in the belt housing steamed up when the engine warmed up and collected in the cap as condensation. After swapping in a new rotor and cap I still couldn't get it to light off. I ended up tracing and swapping just about everything in the electronic ignition chain, thinking I had burned something else out, only to discover in spite of available diagrams, I had plugged the plug wires into the distributor cap upside down. Duh!!!
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Old 03-01-2004, 02:16 PM
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Can you post a larger picture of the rotor?

Like to add it to my bent parts collection.
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Hugh - So Cal 83 944 Driver Person
NOT a 'real' Porsche -- Its Better!!!!
When was the last time you changed your timing and balance belts and/or cam chain and tensioner?
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Old 03-01-2004, 04:37 PM
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I would also check to see if you got water in your air flow meter, It is possable you got some water in there from bad seals or shorted it out until it drained out. Checked to see if the little black lid is sealed on the air flow box.
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Old 03-01-2004, 04:45 PM
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Maybe check the flywheel sensors on the bellhousing?
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Old 03-01-2004, 04:55 PM
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Quote:
I will end up with a disabled car at the exit of a carwash where the cars are literally being pushed out the exit
I understand that sort of panic.

It's just my luck to end up in situations such as those.
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Old 03-01-2004, 05:14 PM
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My AFM has a good bead of silicon around the cover, so I'm not worried about it unless the water was already in the air system somewhere. I'm not sucking water from the belts to the airbox because I removed that hose and capped both sides, had heard previously that it was detrimental.
My ground strap appears OK from the outside, although I haven't seen the core and can't think of a way to do so without destroying the strap in the process. FWIW, all of my engine grounds have been cleaned up recently with a wire brush etc.
As for the sensors....I've been worried about them for a while, just because I've never had them off the car to look at them etc. If they malfunction, what happens to the car? Does one of those sensors give the engine RPM signal for my tach, or is that generated elsewhere?
Thanks for all the input guys, I'll be sure to keep everyone updated.
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1974 Vespa Rally 200, 1974 Vespa Primavera 125, 1963 Solex 2200, 1938 Buick Special, 2008 Mini Cooper S, 2010 Mazda CX-9, 1986 VW Vanagon Syncro Westfalia, 1989 VW Doka Tristar - in the stable
1989 Porsche 944, 1973 VW Beetle - gone but not forgotten
Old 03-02-2004, 06:14 AM
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Well if it was the sensors I believe it would give crazy rpm readings then the rpms would drop and the car would die. Did you try jigglying the sensor wire? Maybe a bad connection there? That would cause it.
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Old 03-02-2004, 08:27 AM
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I went through the engine bay and took apart each comnnector and plug, and sprayed them with dry wire, then filled them with di-electric grease and plugged them back up. haven't had a shorting problem since.
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'85 (Early) 944 - Beater
'87 924S - Crunch/Rebuild
'76 924 - Long Gone
"If everything seems under control, you're just not going fast enough."
- Mario Andretti
Old 03-02-2004, 02:12 PM
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