Bill Ball

Andy:

I can't come over tomorrow. Something about a mother. I can come over next weekend. You've done so much troubleshooting, I'm probably going to bore you repeating some things and perhaps doing them slower than you and puzzling a bit. We'll need to start at step 1. You've gotten a few new good suggestions above about grounds, ignition signal and power wires in the meantime. I've always regarded blue-gray smoke as oil, but excess fuel would make more sense.

John Speake

Faulty Hall or knock sensors won't affect starting or idling...

stuartph

Looking at the video of the exhaust smoke, that is what mine is doing but 10 times worse

borland

If yours is ten times worse, unless your smelling a strong scent of fuel, then it is probably motor oil or anti-freeze coolant.

The light grey smoke is usually soot, so it may not smell like gasoline.

Mongo

Hey Bill, of course not! Come to think of it, when I PM'ed you last I completely forgot about today. Let me know your availability next weekend. I'll take you out to lunch as well as just a small token of thanks for coming out to Marin and my appreciation for the help.

I am tempted to remove the whole CE Panel completely instead of pulling it down for pictures. I don't know if it was coincidence that the car ran like crap after I screwed it back in and reconnected the battery, or if there is really something going on in that board. I'll dive into it this week when I restore my patience again. I'm also thinking of yanking that airbox and redoing the ground back there even though I already cleaned it. The landseer approach of running to Napa and buying a new terminal, find some shiny copper behind the sheething and crimp all 5-6 of those grounds on to the new terminal and reinstall.

IcemanG17

Andy
http://www.electronikrepair.com/page6.html

I got a pdf "no start diagnostics" file from Rich that was around 9 pages long...I printed it and kept in the glovebox.....

I would start at the very beginning and check things off step by step....however since your problem is very odd I am leaning towards grounds.....for some odd reason certain 928's are just cursed with odd wiring issues.....since so many systems are tied together, one issue tends to effect many other systems....which also makes it difficult to solve too....

Where are you located.....I don't know how much help I can provide...but I'd be willing to take a look at it later this week!

taffelman

Noticed that the battery voltage was very low in the video. It looked like only 11 volt's or so before cranking, then dropping below 10 at cranking and while running it looked like the alternator barely gave it 12.5-13 volt, which should be between 13.8 - 14.8. The starter also sounded a bit slow compared to my car.

Have you checked the condition of the battery and the the battery ground strap?

Landseer

Last night Jadz928 solved an S4 random run problem at the CPS harness. Frayed, occasional contact, always tach bounce, though just couldn't decide any given day/minute if it would be enough shorting to stop it, or no-start it.

Mongo

Hey Brian and Bill, both of you are more than welcome to come over Saturday or Sunday this coming weekend. I am in San Rafael, across the Golden Gate Bridge. It will be my treat for food or beer, gas money, whichever works as I know I probably quite far away. I am greatful for any help with my headache right now. I don't have newer chips in my car so a diagnostic tool does not work on my LH as an FYI in case either of you have one. Feel free to PM me both of you to let me know your availability. And, thank you again!

Mongo

If it's not raining tonight, I am yanking the CE panel and cleaning it the whole week.

Mongo

Does anyone know off the top of their heads what gauge is the ground cable going from the engine to chassis under the car on the passenger side as well as the approximate length???

I have seen some aftermarket heavy duty ground cables at Napa and O'Reilly here. Last time I used one of these was on a 944 and I was amazed at how much of a difference a new ground cable made. I was thinking of using a 2 or 4-gauge ground strap of no more than 16" long.

Mongo

Bump for question in prior post.

I am considering replacement for ground strap under car from engine to chassis.

dr bob

Andy--

A 2ga would be nice but 4ga is probably enough. I looked at the one under the '85, and decided I'd look for something that doesn't have insulation to burn off. On that car anyway, it sits under and just in front of the pass side downpipe.

Do you have the ground wires from the cam cover area to the coil mounting brackets? I need to make a couple for the '85, since the originals are crispy and cracked. Also a reminder that FOE harness routing at the front right corner of the engine needs to be correct, away from the Hall sensorr wiring.

------------

If you want to see if your engine grounds are wimpy, you can use your handy DC voltmeter between the block and the chassis of the car. Turn on all the loads with engine running, rev the engine some as you test. You'll see the voltage drop on the ground strap displayed on the meter. Volts you drop there are volts that don't charge the battery, for instance. Consider that starter draw is more than 5x the available charging current, so consider that sarting will be some 5x the drop you see on the meter while charging hard.

jcorenman

Andy,

As I mentioned here, just crawl under the car and remove/clean the strap that is there. If it is corroded and falling apart then measure it and get another. But why spend money that you don't have to? (And ditto Bob's comment about insulation, it is close to the exhaust).

Bob's test is good, if there is any resistance in the engine-block ground strap then it will show up as a voltage drop between block and chassis. That is what I was trying to suggest here.

My suggestion is to measure the voltage drop between block and chassis with the engine cranking, if possible, rather than just running. Some of the problems you report (crazy tach while cranking, etc) are starting-related, and starting currents are much higher (close to 500A for these engines IIRC) so the ground-strap integrity is really important.

When I last did this test I saw a voltage drop of +0.16 volts when cranking, and -0.04 volts after the engine started (red probe on engine block, black on chassis).

Mongo

I neglected to mention that we did a DC volt test three weeks ago touching the block and positive post and got a steady 13.9v on my ohmmeter. Is that okay?

Hey Jim, the ground looks rather oily on the braided wire. It isn't shiny, but where the terminals are bolted into the engine and chassis, there is no corrosion on it that I can see. I still don't trust it. I have immediate access to aftermarket ones and I figure what the heck if it looks like it's been under there for a long time.

Oh and I have printed all of your posts and others that I have found very informative and keep them in a binder at my house that is dedicated to solving my running issue.