ebs

Hi I previosuly posted what you see below. I couldnt get the thing to start no matter what I tried, and this went on for days. A few days later, after trying periodically throughout the day, it just fired up as if nothing was ever wrong. 2 mechanics have been unable to diagnose the problem. Now the car is fine, but the problem will return, as it does. I am not sure if this is relevant, but it seems if I drive the car very gently (keep it below 2000 rpm) the problem stays away. I never drive it that hard, but give it the odd burst to between 4000 and 5000 rpm, maybe once every couple of weeks. Could this do it?

Sorry for what has become a long post. What can I do please to fix this???


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"Hi, my 928 is basically a 1984 US spec engine, but in an S2 body as it was delivered new to Japan. I've had it for a year tomorrow, and one problem keeps coming back every few weeks. Its driving me crazy!

Basically some days when I turn the key, it won't actually fire up. You can hear the starter motor cranking, and even see the oil pressure guage go up, but just won't turn over. One minute its fine, the next its not. Some days its fine, the next it just wont start. Sometimes after trying for like 5 minutes, it will start, other times nothing, and I then try the next day. Outside air temp seems to make no difference.

To fix this I have tried the following:
1) had all spark plugs changed (to Bosch super 4's)
2) checked coil and plug wires are on. They are kinda old, but have all been checked to see they work. There is a slight misfire though, which I'd guess could be a plug wire breaking down???
3) changed fuel pump to a new genuine unit (the previous one that was on when I bought the car was the wrong one)
4) changed fuel filter
5) had fuel injectors removed, professionally cleaned by machine, and the surrounding hoses replaced on the fuel rails.
6) cambelt was changed 3,500 odd miles (5,500 km) ago when I bought the car anyway
7) checked relevant fuses are okay (eg, fuel pump)

One friend who is a mechanic said he thought it would be the immobolizer/alarm. But when I click the key fob to turn off alarm/immobiliser, it appears to work fine and the electrics come on when I turn the key, which is not the case if the immobolizer is still on. Could this be it?

What else can I possibly do? It just comes and goes. One day its fine, the next day it won't start. The slight misfire is always present though (when its running, of course). Please help. Thanks for any ***istance."

Garth S

Aftermarket alarms have caused problems for many - mainly due to a botched up job on the tie-in to the cars wiring harness more so than the alarm system itself. It may be worth the time to investigate this - and (temporarily) defeat the system.
Also, it is worth pulling and cleaning/reinserting all the critical relays. My '80 died in a similar fashion : the cure was pulling and reinserting the FI relay - which cleaned the contacts .... see https://www.928gt.com/default1.htm for great relay charts.

John Speake

I agree with Garth - this type of intermittancy sounds typical of relay trouble. Treat the car to 3 new relays - Fuel pump, LH and EZK. these are all essential for the motor to run.

bigs

I'd maybe consider replacing plug and coil wires. They are old. Get some red ones - they'll make your engine compartment look better anyway!

Thaddeus

Could be a bad ground also. Clean where the grounding rat-tail attaches to the body in the trunk, clean it up thoroughly. It may be letting enough current through to run your accessories, but not enough to turn the starter motor over. Similarly, check where the hot cable attaches. Clean and tighten.

ebs

Thanks for all your thoughts.

Bill51sdr

I agree about the relays, btdt, but does an '84 have an LH or EZK relay?? I thought the '84 was L-Jet... Anyway, I would ABSOLUTELY completely remove the aftermarket alarm system. They are well documented for causing just the kind of intermittent problem you are having.

ebs

My car is L Jet, euro 84 had LH.