ebs

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 assistance.

Thaddeus

Start the thing up at night, hood up, in the garage, with all the lights off. (be safe, and make sure you have adequate ventilation). If you see a light show on your engine wiring, you may have found your culprit. Or "a" culprit. It may not fix your specific problem but any error condition is one error condition too many for these cars.

Rez

Sounds to me like a fuel injection problem. I assume the injectors were checked when cleaned, so I'll rule those out.

Check is the green wire from the ignition box to terminal O7 on the bottom of the Central Power Panel.

This wire triggers the fuel injection relay and the injection control unit.

P.S. did you check the fuel injection relay?

Jim bailey - 928 International

It would help to determine what is lacking ....fuel or spark once that is determined it will greatly narrow the possibilities. So crank the engine then remove a spark plug and see if it is wet with fuel. Take out the plus 4s and put in Bosche new original copper plugs just because. The green wire mentioned is a prime suspect for ignition issues. And as always ....RELAY RELAY RELAY The alarm you mention is an aftermarket add on and as such is only as good as the installation. The car may ALSO have factory alarm which arms when you lock the doors /hatch with the long key so try unlocking the doors and rear hatch prior to cranking the engine.

dr bob

I'll chime in on this one. Bosch admits that they 'invented' the Plus-4 plugs to support 100k maintanance intervals required on new cars. They don't run better, and on pent-roof combsution chambers may actually run worse. Plus, there's no good way to check or adjust the gaps. If a plug is dropped at any time, there's a risk that the ground electrodes might be evere-so-slightly bent. You need an ignition 'scope to spot a log that's firing at a lower voltage, generally an indication that the gap is smaller.

I know I'll take some flak from those-who-believe-all-advertizing-claims, But I'm ready to pull the +4's from my car, to go back to the original copper plugs that were in there when I bough it. It barely passes smog (high NOx) with the +4's, but easily passed before that with copper plugs. Film at 11 when I'm due for smog again.


Good 'tip' Jim!

ebs

Thanks for all your posts. I'm still struggling. I checked relevant fuses with a fuse tester. I pulled the relevant relays, but not sure how to check a relay. Can someone please explain what to do to check a relay. Are any of the non-essential relays inter-changeable? (or maybe with my 951?)

I had someone turn the ignition key and I listed at the fuel pump, but heard nothing. Shouldn't the pump be buzzing when the ignition is turned? I could smell fuel when the key was being turned. The fuel pump is only a year old. What do you think?

Can someone please elaborate on the green wire and exactly where I can find it please.

Thanks.