Still Can't Answer This One

altarchsa · 07-19-2007, 12:46 PM

I have some new details, so I am re-posting this question.

Please Help!!!!!!!!!

'89 C4, 109,000 mi+, stock

Bought the car last year with $11,200 bill owed the mechanic for battery/ECU replacement, top end, then top and bottom rebuild when rod problems were discovered, A/C, clutch, etc. Replaced battery and alternator before finding mechanic had left starter wire loose. Drove the car 2,000 mi with no significant issues until broke valve in #2, bent rod in #3.

Replaced #2 piston, cylinder and head, #3 rod, rings, etc. myself (my 5th 911 rebuild). I'm worried about other valves, but I'll save that for later. Motor sounds and runs really good re: repairs, but now I'm getting lights, lots of lights, in different patterns.

Most consistent pattern is: On, Normal light up, Start, Lingering Anti-lock and PDAS, but then lights go out. After short time (a few seconds or 10 minutes) moving or not (usually moving): Horn, Warning light, Anti-lock and PDAS, then horn stops after 5 seconds, but all 3 lights remain on. Common problem, right?

Now for the fun part. Washed engine the other night and then had perfectly normal operation for 30 minute drive. Next morning, back to previous pattern on drive to work. After a brief rain while at work, perfectly normal operation again for short drive, then back to warnings upon restart. This morning's drive to work was perfecly normal except for Fan Belt warning light in clock. (Fan belts are OK.)

Connector/sensor problem that's fixed by water in the connection/sensor?

Some of you may know the answer so far, but wait, it gets better.

I'm also getting other lights, weird patterns, weird sequences as with teh Fan Belt this morning. Most often is: After start up and driving off, all warnings blink. May blink again a few seconds later. Then I may get warnings described above, but sometimes get Christmas tree - Gas and W.Washer warning lights in gas gauge, all warning lights (except Anti-lock - usually) in Oil Temp/Oil Press gauge, and fan belt warning in clock. Sometimes get one light or other combinations. Last night, got the blinks then Brake warning only, nothing else. Previously got alternator warning with nothing else.

Combination yesterday afternoon was no horn, solid Warning light, solid Low Fuel and blinking, yes blinking, Washer Fluid and Spoiler lights. this was after a 15 minute or so period of absolutely no lights, normal operation. This series of events was both preceded and followed by the previously described more "normal" Warning/Anti-lock/PDAS warning and the erratic Christmas trees. I did notice that the Christmas tree started once with a jolt from a speed bump. Got only Fan Belt warning on 30 min. drive this morning, nothing else. (Fan belts OK)

I'm beginning to think wheel sensor for the "normal" warnings and short (pinched or damaged wire) for the weird combinations.

Or,

Did I switch a connector?

The only other thing I can think of is "Are the connectors in the right places?" I'm 99.9% on all but the Head Temp Sensor and Ping Sensor, I think it was.

Does anyone know if these connectors are interchangeable so that they could be inadvertently crossed at the bracket at the front left of the engine compartment. I can't tell which is which on the cabin side. Any guesses what would happen if they're crossed? Any way to tell which is which on the cabin side?

I'm sure if they were crossed, it would result in erratic behavior, if not blow the thing up!

Side issue (I think) is Speedo works for short time when cold, but flutters and slowly goes dead after a few miles Spoiler works when Speedo works, get spoiler warning otherwise.

Hammer was recommended by one Forum member and may be the the best idea at this point.

OK!! OK!! OK!!

When do I get to enjoy this car? Oh if I only had my SC again. Even my '75S.

However, this one does have scary pull at 130......when it runs.

PLEASE, ANYONE, HELP!!!!!!!!!!!!!!!!!!

My Responses to Previous Help:

Replaced DME relay and did a DME disconnect for about an hour. I checked the connection at the DME, no corrosion, no apparent problem. I did the 2-3 min. warmup / spirited drive routine, during which it ran great, but Warning, Anti-lock and PDAS lights came on as previously described.

No Katrina flooding in this case. Car was held for ransom for nearly a year by the mechanic who was owed the $11,200. I believe that would have put it in his 2nd floor storage garage in Corpus Christi, which wasn't hit hard anyway, during Katrina. Besides, none of these problems, except the lingering lights, on startup only, and dying speedo, were evident in the 4-5 months I drove it before dropping the valve. I believe the valve getting jammed into the head and through the piston resulted in the bent rod in the adjacent cylinder. It was nasty.

The mechanic said the ECU replacement was probably necessitated by careless jumping of the dead battery. Again, the ECU seemed to work OK before the engine rebuild.

Groesbeck Hurricane · 07-21-2007, 02:31 PM

I would start checking wyres. Sounds like a ground may be loose or some rats/mice could have had dinner from some locations. Just my two bits which could be very wrong. I've seen these things before and they were always ground related. Does not mean this is the case here.

altarchsa · 07-22-2007, 01:41 AM

Good suggestion. I noticed that mice had gotten into the car while it sat on blocks for quite a long time when I was doing the engine work. I don't know where to start, but I'll begin looking for damaged wires.

altarchsa · 07-23-2007, 06:13 AM

Well, no sign of mice damaged wires under the dash. However, I still get the relief from the warning lights, both ABS/PDAS and Christmas tree, after an egine wash down. Any suggestions anyone?

gamma · 07-28-2007, 10:31 AM

I would make up some leads and start grounding things that should be grounded just to make sure that what looks like a good ground is a good ground. Kevin.

MobileWrks · 07-28-2007, 02:10 PM

It never hurts to add a few exsisting grounds to help and see if it betters.. I have had 3 88-89 Carreras fuel pump system act like that where it comes and goes.. I added a ground to the chassis, and loop wire ground at pump! Problem gone!! Shop even replaced the FP 3 times with charging him everyother month for it...

altarchsa · 07-29-2007, 05:35 PM

Thanks MobileWeks and gamma. Sounds like good advice. I went through some high water last week and no problems until it dried out. Seems like a bad ground could be fixed by a wet condition, so maybe your advice is right.

Groesbeck Hurricane · 08-04-2007, 10:18 AM

Can you get the car on a lift? I'd be looking for damaged wires in the engine compartment (top and bottom) and anything you can get to under the car. I had a disconnected ground wire in a tail light once. It did wierd things to the car until I found it. Lights coming and going, warning lights coming on and off. Very strange behaviour.

altarchsa · 08-04-2007, 05:34 PM

Thanks Hurricane. I can get it to a lift but I'm one of those hard headed cheepo's who likes to do everything himself. I can get it up on some good ramps I have though, same ones I used to pull and rebuild the engine.

I think you all are right about the grounds or shorts. I'm going to start a methodical process of going through each group of wires. Since I'm having trouble with the the speedo, I'll start with the speedo sending unit wire group that goes up over the top of the trans, to the starter and into the engine compartment. Then the tunnel cover / console on the inside. Then the alternator area.

After the engine work, the shaft on a nearly new alternator broke, just like the photo in Streather's book. The pulley bearing had worn out, or I had the belts too tight, or both. Anyway, I installed a new voltage regulator in my old alternator and put it back in. (It was still good when I installed the new one because I had misdiagnosed the problem and replaced it unnecessarily.) I installed a new voltage regulator.

Could this be causing the Christmas tree effect if it's not working and allowing over voltage? Anyone ever have this problem?

Groesbeck Hurricane · 08-05-2007, 05:47 PM

Bump.

Have you checked on Rennlist? This is quickly going out of my knowledge base.

I would think that over generation of electrical current could create gremlins but I just really don't know so much...

altarchsa · 08-06-2007, 01:03 PM

Thanks Hurricane.

kirkf · 08-06-2007, 06:44 PM

1. There is a ground between the engine and the chassis. It connects at the edge of the 'firewall' lip behind the air cleaner, to a bolt near the starter. Its easy to forget this.

2. Replace your plug wires. I have read several posts where aging plug wires have caused issues like the ones you describe.

Kirk

altarchsa · 08-07-2007, 08:07 PM

Thanks for the additional ideas. I did get the ground at the starter, but the plug wires are the originals, so that could be it. I noticed I had a cracked boot, so I ordered a new one, but I had forgotten it was the unique #3 exhaust so I will have to reorder. Will try that first before all the wires. They're pretty expensive.

kirkf · 08-08-2007, 07:14 AM

Honestly if it was me I would just order the whole set and replace them. They are 18 years old if they are factory. If you see deterioration on one of them, they are probably all in rough shape.

You could run the engine run in the dark an spray some water around and check for arcing.

Kirk

altarchsa · 08-08-2007, 11:46 AM

You're probably right, although I've tried watching in the dark for arcing. Didn't see or hear anything, even at the cracked boot, but I didn't try water. I guess it could still be arcing, but so closely that you couldn't see it.

Not your average Porsche-money-to-burn type. Saving up for new wires.

FRED/LI · 08-12-2007, 03:57 AM

Faulty plug wires caused a meltdown of my DME on the '90
C2 I had a few years ago. Had to have it rebuilt. Same varying symptoms you have.

altarchsa · 08-12-2007, 07:00 AM

Thanks Fred. Looks like plug wires could be the problem. However, I was reading a Bentley Publications Forum last night and Adrian Streather had replied to a similar question with a list of possibilities. First on the list was over/under voltage caused by poor battery performance, then plug wires. I'm going to do a complete battery check followed by plug wires, if the battery is OK.

Thanks again for your help.