fraggle

yep. Rebuilding, cleaning and debugging the relay board can be a daunting task.



I worked on all this and it didn't even change anything! At least it is done.

Sab

After another rainy day the car started acting up again. First the check engine light and the started to sputter on the highway under accelleration.
changed the relays again, change the fuel pump fuse... nothing. Poor idle and AFR shows way lean under any acceleration. Car puffs out black smoke at idle.

Let the car sit in the sun for 5 hours and try again... hurray perfect , no problems... ?????

I talked to John Speake he suggested a bad ground point on top of the bell housing. That sounds like a major project to even look at.

The fuel pump fuse feels a bit looser then the others though, but wiggeling the fuse did not do the trick while it was running poorly. Can I re tighten the contacts un that socket?

928drvr86.5

If the suggested ground point on the bell housing is the same as the ground point on my '86 it's not hard to get to at all, just remove the airbox and it's below and right from the MAF. Maybe more difficult on your GT especially if you have an intercooler in that spot.

Royal Tiger

Take alot of photos when disassembling, it will make it easier if you forget where something was. I'm sure you know this but I wanted to throw it out there.

worf928

I don't know about a ground point ON the bell housing. However, there are two ground points at the back of the block. Each 'half' of the LH harness has a ground on the block. One is underneath the fuel pressure regulator (or is it the dampener? I forget... definitely on the left-hand side.). One is next to and not quite underneath the throttle cable pulley. That one I have once seen cut almost in-two by the cable because of poor routing vis-a-vis the throttle cable by a previous 'professional.'

Both of these are a minor PITA to get at comfortably. You need to get the airbox out, MAS out, disconnect the dampener and regulator, and swing them out of the way.

Either way since your symptoms are 'rainy day' symptoms(?) it sure sounds like a loose/exposed electrical connection. In what condition are the injector connectors? MAS connector? Any wetness in the fuse panel area? Final injection stage connections? Ground point near the injection stages?

Tony

Sab has to pull the SC off to get at it i believe. Although IIRC you have the Eaton and you may be able to just pull the rear inlet.? Thats one thing i did before bolting mine all up...cleaned the 2 grounds back there. Did it on Darriens car a couple of days ago as well....they were all green, crusty etc.
Sounds like a real Gremllin Sab...let us know what you find out.

Sab

OK, I think I found the ground point and it looks spotless. Is this the one?

I also found a seriously corroded wire in the harness going to the right side of the engine compartment. I cut that one as far back as I could and resoldered it. What does that harness do or control?

SharkSkin

That's most of the important connections to the engine IIRC -- alternator, gauges, etc.

worf928

And 12v power to a LOT of stuff.

Sab, there's one more LH ground under the throttle cable pulley.

AO

Wow! That harness looks pretty rough... hopefully a little tlc will help. There's another ground point on the bottom of the engine too.

Chris

Hey Sab that harness looks like a real mess, there should also be a plastic shroud covering that area to protect it.

Have you done Wally's ground cleaning servie procedure? MIght as well do them all while you are in there.

Chris

Sab

I cut the corroded wire and soldered a fresh one onto it. taped it all back up, cleaned and placed the cover back in place. Pretty scary how fragile and partly corroded these harness wires are...

Where do I find Wally's ground cleaning procedure?

Chris

Here you go (from the archives):

You can either try to find the problem, or you can do the routing yearly electrical maintenance and see if that solves the problem.
Annual maintenance:
1) Open the hatch and remove the tool panel. Remove the carpet and spare tire cover. Remove the spare, tools, etc. Open the battery box.
2) Disconnect the ground cable from the chassis. Remove the negative battery terminal. Remove the positive battery terminal. Remove the battery. Use extreme caution to avoid getting battery acid or residue from the top of the battery or cables in your eyes. Goggles are recommended. If the battery brushes against your clothes, you can end up with holes.
3) Clean the battery terminals until they are bright and shiny. Dull gray won't do. If it is possible to check the fluid level in the battery, do so. Fill to the rings. Wash the battery. Put it on a charger if possible.
4) Clean the battery box, removing all corrosion. Wash the battery box. After it dries, touch up the finish as required.
5) Clean the battery cable terminals (all of them, inclucing both ends of the ground strap) until the connection area is clean and shiny. Dull gray won't do. Clean the connection area on the chassis.
6) Clean the speedometer/odometer drive electrical connector in the right forward corner of the spare tire well (pre-'90 models).
7) Raise the hood (bonnet). Remove the protective cap from the jump start terminal and pull the protective plastic cover from the terminal. If you are missing the cover or the cap, replace them - they are critical items. If there is no cover, water will enter the connector and corrode the connectors and wires, causing serious electrical problems.
8) If the connections are clean and tight, replace the cover and cap. If the connections show any corrosion or looseness, disassemble, clean and reassemble.
9) Jack the right front of the car so that you can SAFELY work underneath.
10) Remove the ground cable that runs from the right side of the engine to the chassis. Clean both ends of the cable, and check for corrosion in the cable. Clean the connection points, and replace the cable.
11) Check the heavy cable connection on the starter solenoid for looseness or corrosion.
12) Check the moderately heavy wires on the same connection for corrosion and breaks inside the insulation. These carry the charging current from the alternator.
13) Check the small yellow wire connection for corrosion and tightness. This wire triggers the starter solenoid.
14) Lower the car. Fold back the carpet and open the central power panel cover.
15) Check the main power connections at the top of the panel for tightness and corrosion.
16) Check the ground connections above the panel for tightness and corrosion.
17) If you are having electrical problems, remove each fuse and reinsert three times. Check the fuses for the proper value, and examine them visually for damage or corrosion. Test them if desired. Later cars have a fuse tester built into one of the relays.
18) If you feel that it is necessary, remove and reinsert each relay. This won't be easy, as they fit very tightly in some cases. Porsche sells a relay removal tool, but I am not impressed. It is basically a pair of pliers with square jaws, and will pull the relay apart. One tool that works well is a spark plug boot removal tool. It is a thin but strong sheet metal tool shaped like a "J" with the top 1/8" bent over at a right angle. You can put this angle under the bottom edge of the relay and lift it out - IF the battery is disconnected!
19) Close the panel and replace the carpet.
20) Replace the battery. Install the positive cable. Install the negative cable. Put a drop of oil on each nut. Connect the chassis end of the ground (negative) cable. Lubricate the battery box latch and close the box.
21) Lubricate the wiper drive shaft and hatch latch mechanism.
22) Clean the spare tire, jack and tools. Put a couple of large heavy plastic garbage bags in the spare tire well for emergencies, along with a tube of hand cleaner and some paper towels. Install the cover and carpet.
23) Lubricate the jack, and put it inside the tool panel. Clean and lubricate the tools. Reinstall the tool and tool panel.
24) Reset the clock and radio presets.
A couple of hours of quality time with your 928 once a year can forestall many problems.

Sab

I think I finally resolved this problem.
During my t-belt replacement I saw that the leaft and right wires from the coils to the distributor where completely desintegrated. (plug wires look great, so whoever changed the plug wires skipped the coil wires..., probably 15 years old...)
I replaced them and the problem has disapeared.

928SS

good job sab!

mine is now hard starting when cold. plenty of spark, so I'm suspecting a fuel ck valve that's letting fuel drain back to the tank. seems even more likely now, cause it easily starts cold if the tank is full - which I suspect is probably preventing fuel from running back... fun, fun, fun!!! guess the in-tank pump and lines above the tank are going to be replaced - bout the only stuff that hasn't been on this old gal, so what the heck.