It sounds like you need to begin educating yourself on electricity & electronics - that's the long term project... get something simple from the city library or a community college. Then go to the library at USL (or whatever they're calling it these days). In parallet, find the Bosch booklets on the theory of operation of the stuff on your car and try to read thru them.

Sorry I don't have an easy solution - but not having a shop nearby means you are a DIYer, even if you don't want to be.

No, it can be while the car is running. You may be getting intermittent contact in the relay due to heat, moisture, or other issues that will give strange symptoms. I don't get the tie in here with the tach though...

ianc

I just PM'd you greg

How come no one questions the state of the CHT sensor like rcaradimos suggested?

I appreciate everybodies input - really, I do.SmileWavy

Ianc, hate to keep bugging you, but you mentioned the tach got its signal from the ECU, but doesn't the ECU pick it up from somwhere else. Does the flywheel sensor contribute to this.

I knew somthing was going on with this car a few days before the went wacko with the rough start and idle.

I know there is some sort of check valve that holds the fuel pressure, like i previously mentioned in the few times i started the car in the morning (the last few times) Its started rough and had to build up speed - almost like a locomotive before it got smooth. This led me - at the time - to believe it was fuel related - do any of the previous suggestions metioned by the various posters help key in on what this might be - I think its a clue to follow, but Im not sure what to check if it isn't the check valve bit.

Sorry for so many questions, but I'd rather be thourogh than sorry, again thank for the advise.

Yes, there is a speed sensor and a reference sensor. The reference sensor, IIRC, is only used when the car first starts up. The speed sensor gives the ECU RPM information, so logically it would send that to the tach. Both of these are mounted under the car on the driver's side near (obviously) the flywheel. Their electrical pickups are in the engine room on the driver's side in a small bracket to the left of the intake manifold.

ianc

Edited to say: if you don't already have the Bentley Carrera manual, I would jump on it ASAP...

Your symptoms didn't sound exactly like mine but it could be a possibility.

Try this link for info.

http://forums.pelicanparts.com/porsche-911-technical-forum/273451-finally-problem-solved-hesitation-etc.html

I have the Bentley and the Haynes, and im trying to understand the interconectivity of the whole system, but it helps to hear others input in conjunction with the books.

When my CHT sensor started to fail my rpm's were jumping from 2000 to 400 to 1800 to 800 etc. start no start etc. As JW puts it, rip the old one out and throw a new 2 wire in. I'll see if i can find the how to post.
Good luck

Lot of good info in this thread...
to answer one of your questions...

""Could a bad "barn door" MAF be intermittant?""

Yes, it was intermittant , but progessily worsened.

1 time a week became 1 time a day, became "Honey, follow me to the Mech shop...I hope it make it."

Here is an update:

1. the CHT is of the newer type, and looks to be rather new. Not much grime or dust on it compared to other compents in the car.

2. The flywheel sensors seemed pretty good to. The black rubber hosing isnt cracked and very fexible. I removed them and the only thing i noticed was that there was a small metal pile of filings (presumably from the clutch) magnitically attached the end of the senor. Could this cause a signal pickup issue?

3. the fuel pressure dampers vacuum line as barly in the flexible hose that attaches to the damper.

4. I tried to test fuel pressure, but my fuel pressure tester from autozone doesn't fit. Does anybody know where i might find one that fits? An observation that may or may not have any relevence. When I removed the cap to test fuel pressure the gas just dribbled out - didn't squirt out like somthing under pressure. I know there is a fuel pump check valve that is suppose to hold pressure in the system for start up. Remember, i have had problems with rough startups.


While resistance tests can only prove if a compent is broke and not 100 percent working here are the results:


IAT: 1.9K OHMS AT 80 DEGREES F
CHT: 2.01K OHMS
FULL THROTTLE SWITCH: .2 OHMS
IDLE POSITION SWITCH (42 AND 44): .2 OHMS
IDLE SPEED CONTROL VALVE: OUTTER TERMS: 42 OHMS, B/T CENTER TREM. AND EACH OUTER TERM: 21 OHMS