Bill Ball

Exactly. The LH may be bad as well, but he has a large puddle of gas in the intake. When he first mentioned this to me, I said it must be oil, which is quite common, but Anthony insisted it is gas and a lot of it. So, the I started to focus on leaky diaphragms in the FPR and/or dampners. With the amount of gas he found, it should be obvious when he pulls the vacuum lines off these components, but from his comments, it isn't. Still, how else would a puddle of gas form in the throttle? For it to get there from the injectors it would have to be such a huge flood, the cylinders would hydrolock first.

SQLGuy

Well, if you replace everything, there's a pretty good chance you'll incidentally fix the problem. Landseer's list doesn't include all the fuel lines, and the injectors, and ISV, and regulator and dampers, and....

Personally, I prefer troubleshooting and fixing the problem, and evaluating the condition of other parts found along the way, rather than just shotgunning everything. Your preferred approach may also be influenced by whether you have $3000 to throw into it before starting any systematic diagnostics that might still be needed.

I'm sure I'll be flamed for this, but I'm particularly skeptical of all the suggestions I see to replace all the relays. I've never owned a new car, mostly owned German cars, and am currently on my 4th 928. The only bad relays I've had in these cars have been the A/C head unit ones.

outbackgeorgia

When my LH went bad, the injectors were constantly clicking loudly. Would not start, flooded. Wonder if this is the case, and flooding the engine?
This is a known LH failure symptom.
Dave

Landseer

$45 replaces all ten 53 relays. I'm on the 6th 928, all NE rescues. A few squirts of mouse pee on that panel, some sun shining thru the closed window of the car, and the garage, on the "always garaged".... those relays go belly-up. In fact, every plated interior bolt in the cockpit corrodes.

Fontana

I am curious...Where can you get all ten #53 relays for only $45? I replaced four #53 relays so far and the cheapest I could find one for was $13 bucks...

Fontana

Sounds like my problem, but the only symptom I know I don't have is the clicking of the the fuel injectors. Dr Bob believes the LH controller failed and the flooding of gas is caused by the injectors staying open due to the LH failure.
I am going to pull the plugs so the gas can dissapate, I don't want any hydralocking.

I know my problem here has progressed because I can't get the car started for nothing now! Before, I could spray a little starter fluid or pour a touch of gas in the throttle body and the car would start (run like crap, but would at least start). Now, it just cranks healthier than ever due to sanding of the grounds (particularly the main engine ground), but will not start at all.

Fontana

What about this infamous "Green Wire" that I kep reading about? Where is this located and could it also be a contributing factor?

WallyP

I would use a stethoscope to listen to the injectors and see if there is a regular clicking as the engine spins on the starter. If not, you have LH problems, relay problems, injector harness problems, etc.

I would also jumper the fuel pump relay and pull the vacuum lines on the fuel pressure regulator and dampeners (three units). Sucking (probably 5 psi of vacuum) might not show a leak that happens at 30 - 50 psi of fuel pressure.

"Green wire" is on earlier cars - not on the S4.

dr bob

The order of diagnosis at this point is to call Roger and see about sending the LH to him for evaluation, and rebuild/trplace if it shows the same symptoms in another car. Maybe in parallel, the FPR and dampers will get vacuum tested for leaks.


This car apparently has some history and hasn't run correctly for this owner, after the PO just parked it for an extended time. If there is anyone from the group that can stop by the owner's place and do at least some basic diagnostics on the car after the brain is evaluated, it will make things a lot easier for this owner. Anybody? Bueller? Bueller? Vacuum tester/MitiVac, fuel pressure gauge, voltmeter, ear for fuel pump running when it should, maybe an induction timing light to verify spark. Stuff like that.

SQLGuy

Well, I guess I've been lucky, then, although my current car lived for a while in NJ as did one of the previous ones. I also had a fair amount of water damage in the GTS (headliners, etc) due to a leaking sunroof.

Did you see only failures of the less expensive 53 relays, or also the much more complicated headlight relay?

SteveG

http://members.rennlist.com/pirtle/keepers.html

Link is to process for disabling ('90 GT) alarm; probly not the solution, but I thought it ought to be part of this thread;

I always get these confused, trickle vs maintainer, someone will correct me. 1.5 amps IIRC is the magic number, about $30, Schumacher is what I have. An unmolested system (minor drain) will 2-3 weeks and start, but most of us use a maintainer or disconnect battery, so I'm not surprised yours was down.

Get whatever batt they list with the most CCA, don't try to put something physically bigger than that in there, you risk arching to the battery cover, not good.

Landseer

Yes, I've replaced three of the headlight relays. The Ljet cars all get AFM and injection relays and foglight and Xrelays. Rest like intensive washer and rear defrost relay aren't so important to me.

The 53's came from Roger. Maybe they are $5 now?

Throwing parts to fix a problem is one thing. Replacing all known decay and wear parts on a refresh to both fix and avoid is another entirely. New fuel pump, strainer, tank cleaning, for instance. Not something I wait to do as-needed on a 25 old 928.

Fontana

UPDATE: I received a loaner LH from Rich Andrade (thank you Rich), plugged it in and...NO Start.

I started looking in engine bay and noticed someone had put some orange sealant where the Crank Position Sensor connectors join together in an attempt to basically glue it to a piece of metal as not to bounce around in the engine bay. This caught my attention and upon further inspection, I noticed that the wires coming out of the connector on the harness side were touching (brown and black) and the black wire completely broke off and was not connected. It was obvious that this has been that way for a while as the wire was completely oxidized. I thought I found my problem. I painfully layed on top of the intake, spliced new wires into the connector and tried to start the car, nothing!

The car cranks hard, but will not fire. The tach jumps up to 3000 rpm when I first attempt to start it then it will continue to jump a bit, but not as much as the initial cranking.

I tried to unplug the MAF with still no luck starting. Tomorrow, if I get a chance, I will pull a plug and see if I am getting spark. I will also buy some starter fluid and see if it will fire with a few shots sprayed in.

The Crank Position Sensor appears to be working as the tach jumps and it does look to be newly replaced (not by me, but previous owner). Not sure if it is that.

Temp II sensor appears to be new as well. I was hoping it was the LH but the search continues.

Could it be clogged injectors? I read a 9 page post from 2009 where one of the members "Tony" (Supercharged 928 from Vegas) had a similar problem and it turned out to be 4 clogged injectors and I believe a short in the harness.

I still have not been able to get to the two bellhousing grounds, all the others are done as well as a new battery ground strap that I put in last weekend.

This car is forcing me to learn it very quickly with the motivation being to actually be able to drive it for the first time...

Fontana

I might swap out the plugs for the 3rd time as well. Wondering if this is preventing me from starting it now. I may have fixed the problem or the loaner LH might be the solution, but if the plugs are fuel soaked, I would imagine the car would not start for nothing. Will check tomorrow...

SQLGuy

I'm not sure a jumping tach indicates a working CPS. The reason I say this is that, when I went to test drive the '88, it died half-way through the drive. The tach would jump when cranking, but no start. We eventually found that there was no power to the EZK relay because the dedicated line for it had come loose at the battery. No power to the EZK should mean nothing to read the CPS and nothing to drive the tach, but the tach was still jumping.