Thanks Wally and Lizard. That sounds do-able. I'll check tomorrow/over the weekend.

Wally, I had a look at the manuals, but as far as I could find they described the steps of taking the whole time belt out. But I’ll check again. Thanks for your write up and the links!

 

Couple of other things to check (from experience). My '90 GT went into 4 cylinder mode while idling after startup. Once it had cooled down the car wouldn't start.

The 4 cylinder mode was finally found to be caused by a corroded coil connection, but once the coil was replace the engine STILL wouldn't start. It would *almost* start with a few "chugs" but just wouldn't catch. After describing the problem on the PacNW928 list a member mentioned that a mechanic friend of his had told him of many 928's coming in with no-start issues which turned out to be flooded cylinders.

Since it had been a long time since the car had received new spark plugs I put in new plugs and then *unplugged* the fuel pump fuse. After a few cranks the engine fired up strong (and immediately died since the fuel pump wasn't running). Plugged in the fuse and it fired right up.

Might be easier to check some of those things before heading in to check the belt?

David

 

That sounds like a good idea to check thoroughly David, thanks. I must admit that I only checked 2 sparkplugs for sparks, both being on the left side. It is possible that the right side has a problem.
The time belt is a plausible explanation, because I just spinned on the track. No hits no bumps, nothing. I think all other things would be a coincidence, but a possibility of course.

 

I checked all the spark plugs now and they are OK. All the spark plug caps popped out of their sockets when cranking without plugs, so assumable compression is OK. I checked the timing and it’s OK (see picture). The car has ignition, so I guess the brain is OK? Or anything power related? I put some WD40 in the inlet while someone cranked the car, but no life whatsoever.

Any other things to check? Vacuum lines maybe?

 

Andre,
So far,so good !

You are right that with spark, the EZK ECU is OK, and also the flywheel sensor. The LH ECU could be faulty, but it's difficult to reason why your "off track experience" could damage it.

Have you been able to hear the injectors clicking when cranking the engine ?

Did you go over some hard kerbs or bumps, when leaving the track ?

 

Andre,

You said that you heard possibly the fuel pump when you switched relays, then, switched back, no noise. That sounds like the fuel pump relay is bad. Open the rear hatch to listen for the fuel pump noise when you turn the ignition key. If you cannot hear it, remove the 2 nuts that hold on its cover. The cover is about a foot wide at the right rear, looks like part of a fuel tank.

Clean all wire connectors and grounds. Something could have come loose,… like the connectors beneath the black plastic cover way up front. A ground from the engine to the coil may have broken,… one of mine did. Here are some of my procedures:

Maintenance:

Coat all electrical connectors with DIELECTRIC GREASE after cleaning/polishing them to enhance conduction and prevent corrosion. Assure that all connections are tight, but not over-torqued.

I would clean every electrical connector I could find. The blade connectors are self cleaning. Cycle them in and out a few times to shine them. You can also use scotchbrite, sandpaper, point files, tiny round files, etc. to polish connectors. For the plugs with 8 or 10 round pins, I use scotchbrite on the male side, and a small round file on the female side.

Replace all old fuses with new ones even if they work perfectly. Be sure to use the right ones. Cycle fuses and relays in and out to polish connectors. See this link, courtesy of 928 Specialists, for fuse and relay charts: http://www.928gt.com/928specs/85-86relay.htm

Ground Points:

Note: Brown wires are solid grounds.
Brown/white wires are switched grounds.

There is a ground, and various connectors beneath the plastic cover, in the spare wheel compartment, above and forward of the battery. Thoroughly clean and coat all of these to help with starting problems. Of course the battery terminals and the bunch of wires attached must be clean, coated, and tight.

2 engine ground cables attached at coil brackets:
- Right side cable goes from coil bracket bolt to topmost front timing belt cover bolt.
- Left side connects at bottom rear of back timing belt cover.

There are a total of 7 ground points. Some easy to get to others you will need to lift the car and climb under. I will try and get you in the right area.
1) Battery negative pole to body in the trunk.
2) Two points separate points above the central electric board.
3) Engine ground to body on right side member. (about a foot forward of firewall, and a foot deep on right hand fender well)
4) Ground point on front left cross member.
5) Ground point on front right cross member.
6) Ground point underneath instrument panel next to steering column.
7) Ground point in trunk at rear right underneath trim panel. (you have to remove the trim panel for access)
This was taken from the shop books.

Listed as follows in the manual:
-Battery negative to body
-Above and behind central electrical panel (2 points)
-Engine to body (under passenger's side)
-Left front cross member (to left of headlight motor)
-Right front cross member (passenger's side)
-Under instrument panel by steering column
-Under right rear side trim panel (inside)
Additionally, my fuel injection harness is grounded to bolts on the passenger's side valve cover.
'83 US 928S 5sp

 

https://rennlist.com/forums/showthre...5&pagenumber=2

https://rennlist.com/forums/showthre...ghlight=ground

 

John,

Yep, I heard the injectors clicking. I took a copper pipe and pressed it against the block and could hear them clearly. Or at least I heard the clicking (that couldn’t have been the spark plug could it?) I did not hit any curbs or anything. Also not when leaving the track. When leaving the track and the car was cooled, it car was town and I put it in second for about 1 mile. It did not do a thing. All the light went of as if the car was normally running, but in fact it wasn’t.

Thom,

I clearly heard the fuelpump when my girlfriend cranked the car (I thought it was OK fur her to sit in the driverseat as long as the car isn’t running ). The groundpoints are a good point, but at this time when resuming; we have compression, we have fuel and we have ignition, but no lift off. Because there is a spark, I think I can forget all the electrical. My guess is there is not enough fuel for some reason. That could be the brain. The injectors do click though and the sparkplugs are wet when I take em out. Hmmmmm. Just to make sure I’ll get some new spark plugs tomorrow.
Thanks for the write up Thom, I’m gonna check them all just to make sure.

Any other suggestions?

 

Once again, have you checked and tested the green wire to make sure it is good??

 

One more thing, if you dont have a timing light buy one. Hook up the timing light to one plug wire at a time and have someone crank the car over. Make sure that the light flashes while the car is cranking. Do this to every plug wire to make sure all have spark. If you have spark and fuel then the engine should start or sputter or backfire or something. If you feel that your injectors are not opening then spray some starting fluid into the air box and see if it will sputter or backfire when using that stuff.

Thats all for now.

 

Ehhhhhh, what green wire is that Curt? Have we spoken about this before?

I could use a strobe light to check all the spark leads, but the sparking spark plugs says it all.

I sprayed WD40 in the airbox (removed MAF first, not disconnected) but no go.

 

Hi
My car had exatctly the same problem, it turned out to be a fault in the ECU.
I got it reapered at ATP Electronic.
http://www.atpelectronics.demon.co.uk/index.htm
I think this problem is very common on 928 between 87-89?
--------------------------------
Johan ' 88 S4 euro

 

Hi
My car had exatctly the same problem, it turned out to be a fault in the ECU.
I got it reapered at ATP Electronic.
http://www.atpelectronics.demon.co.uk/index.htm
I think this problem is very common on 928 between 87-89?
--------------------------------
Johan ' 88 S4 euro

 

Andre,
try turning the engine with the plugs bak in, just to make sure there is compression.

Crank the engine on the starter for a while an check that the plugs are wet with fuel. If they're not, then (carefully !) release the cap on the end of a fuel rail to check you are getting fuel pressure at the injectors.

If you are running out of ideas, I will check your LH (fuel) ECU on my test jig for the cost of return postage to you.

 

John,

This weekend I changed the spark plugs just to make sure. It had no effect. When I take a sparkplug out after cranking it is wet with fuel and smelling accordingly. But after cranking the car for about a minute my guess is that the spark plugs should be much wetter. So I’ll have to check the fuel pressure.. When you release the cap of the fuel rail, what do I see? Is it a pulsating flow or should it be a constant squirt?

Thanks once again for offering to check my ECU. I’m having a friend over soon who has a ’90 S4, and we’ll exchange ECU’s. Do you think that could give a problem? When it appears to be faulty, I’ll let you know. Any idea of the costs for repair yet?