Odd starting on my 3.2

[911hillclimber]

Just ordered a new DME relay.
If that fails to fix this then will buy 2 new crank sensors for £150.
Bitch to make the change but stories abound that these can cause my kind of issues!

 

[Motorhead]

Looking online it does sound as though the DME relay could be the source of your problem Graham.that sorts it!

Trial and error unfortunately, but maybe you could return it for a refund if it doesn’t work?

Jeff

 

[911hillclimber]

Just might have found the issue Jeff.

With the aid of YouTube checked the DME relay.

The two I have (original @ 1985 and the one Bob Watson fitted in 1995) both check out perfectly.
Soon I will have a nice new one too, so can compare that to the two I have, but I suspect I will soon have 3 DME relays that pass!

Moved on to the two engine sensors fundamental to the DME system, the RPM sensor and the TDC Sensor.

The resistance of each should be 600 ohms to 1600 ohms.
Checked both and the RPM sensor is 860 ohms so good, BUT the TDC sensor is roaming around at 15.000 ohms +/- a house brick.

I think this is the culprit.
ordered one and hoping this will do the job.

Has been a long time since I spent £230 on this car!

 

[vitesse]

Have you considered checking the coil resistances -is maybe the coil starting to fail or have I missed this point being resolved back in your thread?

 

[911hillclimber]

Thought about that, but I don't know how to check the coil and what parameters are the specs to meet.
If you know, please advise.
When the engine did start it ran perfectly.

 

[vitesse]

Not information I keep in my head but I have figures somewhere for a 4 cylinder engine.I have a spare coil in the garage which I'll check with a multimeter-you just check primary coil resistance & secondary coil resistance -normally one of them breaks down when the engine gets very hot but can annoyingly resolve itself when cold.just a thought thats all

 

[911hillclimber]

Google came to the rescue this morning, so once all the system is back together I'll check both circuits on the coil, but thank you for your thoughts.
However:
I think you can call that a bitch of a job, and I'm not finished yet after nearly 2 hours replacing these engine sensors.
Rather than moan (too much) the old sensor is out and the new in followed by the one I changed some time ago that almost dropped out of the housing, the bad original 1985 sensor did not pop-out....
Access is NOT easy.

Just need to button all the damper/heater hose, DME relay and a run of battery isolation wires to, I hope, the new idolater motorsport type that's 'in the post'.

The condition of the original part was poor, the outer loom sleeve all broken and much of the wires going into the sensor.
The other one, maybe 15 years old looks new.

I think the design of the 3.2 engine and all these parts are when engineers in Production Engineering decided to make things easy to assemble in the factory, and to hell with serviceability, a movement still in full flight today.

Just might get to see if it will start tomorrow.

If not it must be the DME unit itself, heaven help me.

 

[Motorhead]

Goodness me Graham … what a trial! Aged wiring and components are always a cause for concern.

Hopefully now you’re on the last lap to resolving the problem.

Jeff

 

[911hillclimber]

Time will soon tell Jeff.
When these things happen to me they are never simple, bit like the sorting of white start-up smoke on my Boxster.

When all is done I'll do a resume of the things that have been done and the costs.
Good job I'm very very cheap.
(something my wife does not agree with!)