944 Turbo - No Spark !!

[Showtime]

Hi Guys - Newbie here ! ..Just bought my first ever porsche a few months back - someone began restoring and gave up..I took back to the garage and began the mystery of locating all the missing bits - and there were a few I can tell you. (400 quids so far and counting.

The gist is this - the engine was changed and never completed - I've re-connected everything and got to the 'turn the key stage' - no spark..thought it was the immobiliser/alarm - but engine wont turn if you press switch on the remote. press again and it turns over !!. Took out a spark plug and earthed it - cranked engine - no spark. Left the ignition on and connected 'power probe' - live to coil - nothing tho from HT lead. ..
HELP...
could it be the ECU ?, or the immobiliser still ?
Thanks Guys -(experts)

 

[Indi9xx]

Probably is the crank sensors at the back of the engine connected the wrong way round.

Does the rev counter move when you crank it?

It could be the immobiliser, or even the ECU, but if everything had been dissconnected its probable the two sensors are plugged in the wrong way round

 

[Showtime]

Hi Jon - Thanks for the reply,
I tried the two multi plugs both ways last night - still nothing, is it possible the sensors were bolted in place on the bell housing the wrong way round ?, is there an easy way to identify which is which.

Will check rev counter later too.

 

[Indi9xx]

Its possible the sensors have been installed with the wrong gap. but they are both the same sensor, so they can be swapped around. However one counts the ring gear (starter motor teeth) to get an engine position and the other counts a peg in the flywheel so it knows that its turned a whole rev.

So they can be swapped around, but the connectors have to go to the right one, otherwise your ecu will think its seeing the "Whole rev" peg so often that the engine must be reving at 30,000 rpm or something daft. (but it will not fire obviously)

If the gap is too wide then the signal will be too weak, if the gap is too close the sensors will get trashed or the signal will be full of noise... they need to be gapped to about 0.9mm.. However 0.6mm to 1.5mm normally works... we use a 0.9mm spacer which will be an actuall air gap of 1.0mm

 

[jimbob]

Hi Jon I own a 1990 944 S2 Cab. I have noticed only one sensor bolted to the bell housing on my car is this normal for a 944 S2? I have owned the car for 6 years and have had no problems .Car has only done 53,000 miles from new. Summer use only.

 

[Indi9xx]

Yes the S2 only has one sensor in the bell housing as it also has a sensor in the front cam pulley housing which looks at a gap in a metal disk on the back of the cam pulley to determin overall engine position. It was part of the step up to sequential fuel injection. (so the ECU knew not only if number one was at TDC but also if it was at the end of the exhaust stroke or the compression stroke)