[Jono]

Hmmm, well I finally got around to replacing the DME relay and the car started, yay! But then I put the old relay back in....and the car still started....so I'm none the wiser. If I'd thought about it I should have tried starting before I changed the relay to make sure the problem was still there. It's possible the relay is failing intermittently, I've replaced several relays on the car and they all exhibited intermittent failures before I replaced them, most notably the fan relay (which is horribly expensive) which caused the fans to start in the middle of the night......

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[Stilly50]

Further to my starting problems, we never isolated the problem, so we were never able to prove the cause, however a series of eliminations narrowed it down to probably being the injectors. My mechanic thought that because the vehicle had spent periods of it's life unused there may be gum or corrosion on the injectors. He put all of the injectors through his ultrasonic injector cleaner twice to be sure. We are not sure that that was the problem, but the vehicle has started every time since the clean, which was three months ago.

Stilly50

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[Grandpa#3]

The Fan Relay Cover can be removed by lifting the tabs and the points inside can be cleaned. This is not a hard job to be accomplished.



Cheers,

Larry

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[Stilly50]

The dammed thing refused to start again three weeks ago. My son now calls it my "push". I put the engine analyser on it and it showed a fault with the Temperature sensor and that the engine temperature was -31degees C. The Porsche fault code list says that a faulty temperature sensor can result in starting problems. I presume that a faulty temperature reading will result in the computer adjusting the fuel mix incorrectly. Anyway I fitted a new one and she fired first time. Hopefully I no longer have a Push and have my Porsche back again.



Stilly50

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[wildcat]

My car, which was originally sold in California new, came with a manual that mentions the "immobilizer" and try as I might I never found it. I concluded that the cable that runs to the transmission that is part of the steering wheel locking mechanism, is what they meant by an "immobilizer". I have a Tiptronic transmission. I do have the standard alarm but there is no arming after the key is removed. There is a connection between the transmission and removal of the key, as the key cannot be removed unless the shift lever is in "park" and the button is up. You can't get the transmission into any gear without the key in the ignition and the steering wheel unlocked. FWIW.



My car "no start" was not intermittent. It just failed to start one morning. I ultimately traced it to the "ignition coil driver" which on 944 is called the "ignition coil module" and a separate unit. In the 968 it is incorporated with the DME computer. Once replaced, haven't had a start problem. May not be relevant to your situation.

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[ds968]

After my ( tiptronic ) car sits for more than a week , starting is always a hassle. It either 1) starts and within a second or two it stumbles and dies, but then starts right way on the second try and no problems afterward , or 2) as was the case today , it turns, and turns and turns but the engine refuses to engage until I go through that shut off and restart a few seconds later routine several times..today it was on the seventh attempt that it started. The blink test showed 1-1-2-3 which is " oxygen regulation " , not to be confused with " oxygen sensor " which is an entirely different code , but no one seems to know what exactly oxygen regulation translates to and what to look for . This is a code which has appeared a couple of time s in the past on the tip, but the symptoms always resolved on their own ( eventually ..) so I did not follow up on that. No idea if the oxygen regulation issue has anything to do with this starting problem , but thought I'd post today's experience since this is by far the most difficult start experience yet..

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[Waylander]

Fault code 1 23
The oxygen regulator cannot operate within its control range if extreme problems of mixture preparation occur, e.g. due to an excessively lean setting because of unmetered air, or due to an excessively rich setting because of a faulty injector valve. The oxygen regulator then moves up to the stop position.

Oxygen regulation stop too rich:

Oxygen regulation stop too lean:

Check intake system for leaks (Test point 29)

Check fuel pressure (Test point 28) Check injector valves for leaks

Fault, Fault Code Possible Causes, Elimination, Remarks

 

 

Page 157 of the workshop manual

under DME diagnostics

 

I would take a guess at the ICV

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[unknown4u]

First off all. Jumper dme to rule out. Because this symptoms are familiar with a faulty dme.
The icv is powered by the dme.....you csn see this in the wire diagram.

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[ds968]

The dme is relatively new, but since I keep another new spare in each car, that's easy to test.   At first I thought it may be the fuel check valve since the symptoms would suggest the car does not retain sufficient fuel in the lines / rail and it slowly all drains out after several days, but I changed that valve not too long ago either so low probability of it acting up in that manner.  So when I drive the car daily, starting is no issue at all, it's only when it sits around for about a week.

If the ICV is faulty would it manifest in this manner ( never a problem on daily starts, but lack of activity for a while makes it "stick" somehow ) ?            

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