Towers

After getting my dad's car up and running last summer I returned it to him in working condition, only to have another problem spring up;

Sometimes when you put the key in the accessory position before starting, the dash doesn't light up and the interior fan wont start. When that happens the car will turn over but not actually start.

I haven't been able to isolate the problem because sometimes you just need to turn the car back off and on again and its good to go, and sometimes I can't hang around and wrench on his car and my dad is not the best at remembering what he's done between it not starting and starting again .

I *think* it might be related to the battery since it was a much more reliable starter last summer after replacing the corroded ground strap, and it seems to happen less when the battery is straight off the charger, but I don't get why sometimes you just need to flick it off and on again to get it working.

Any suggestions what it might be or what to start isolating in order to narrow down options?

Kiln_Red

Likely another failing ignition switch.

MainePorsche

^^

FredR

Sounds as though it could be the ignition switch- not a big job.

If you are going to post on this list it usually helps if you can identify the model and year of manufacture.

Rgds

Fred

Towers

Thanks guys.

I'll replace the switch and see what happens.

dr bob

Be aware that the dash should not light up and the interior fan should not run with key in position 1 ("accessory"). Thos don't happen until you get to position II, the "engine run" position. Further, the fan shuts off when the key is in position III, the "engine start" position.

Make sure you are chasing an actual problem as you start throwing parts at the car.


I spent some time chasing minor electrical gremlins related to charging, and decided to replace the ignition switch prophylactally just to eliminate it from my possible-causes list. New switch did nothing really. So I have a perfectly good original spare in my "original parts that came on the car" bin. It was an interesting excercise changing the switch, with blind access and angle-drive screwdriver, but in the end it was no better than what I had original from the factory.


How long does the car sit between uses? The fuel pump runs only after the engine controllers sense that the engine is actually spinning on the starter. Further, it might be two full engine turns before the pump starts, depending on where in the rotation the engine happens to stop, particularly if there's a fault in the Hall sensor just behind the passenger's side camshaft drive sprocket. If you can get access to one of the diagnostic tools, it will tell you if the Hall sensor has a stored fault. Meanwhile, often the first cranking is enough to re-pressurize the fuel system. Then the car starts right up on the next crank turn.

Kiln_Red

I consider an ignition switch replacement preventive maintenance on our 928. They've failed on every car I've owned. I had a 928 for just 3 months once and, of course, the ignition switch failed. That's what I get for trying to be courteous in a drive-thru I guess. I hate to holler my order out over the exhaust note.

Mrmerlin

More than likely the issues your having will be fixed by doing a CE panel and ground refresh.

I can understand the temptation to swap in a new IG. switch.

But really the running relays and fuse failure rates are much higher than the IG switch is.

Swapping in new running relays would be a better choice than the IG. sw.

Make sure you use Deoxit on the CE panel connections and the fuse connections,
also clean the battery terminals and the wires secured to the terminals.

As Dr Bob points out, you may be looking for system operations while not fully understanding the key position operations.
A look at your owners manual will bring you that info.

This will be a useful guide.

http://api.viglink.com/api/click?for...anel-refurb%2F

Kiln_Red

Stan, those are good suggestions and every 928 deserves that attention if you expect reliability.

If you're going to daily drive a 928, I would suggest following Stan's advice AND keeping a spare ignition switch. But, that is just based from my experience. The ignition switch is just one component of a many that I keep as spares for the 928s I have driven. I plan to daily drive the car in my avatar after I finish re-assembling it. Just installed a new ignition switch maybe two weeks ago and I'll be keeping the old as a spare as it still works.

If terminal 50 doesn't get energized at the same point in time that X or 15 doesn't, then that pretty certainly isolates the problem to the switch IMO. Especially when the symptoms are described as intermittent in nature and collective in that they affect multiple circuits that all rely on the function of the ignition switch.

Mrmerlin

from all the wont start issues I have had the opportunity to work on,
most are fuse and relay related, with bad computers or bad green wires filling in the rest

My experience with Ignition switch issues have resulted in swapping two new switches,
with one of these being sent back due to a bad switch,
and tightening 3 more from loose hardware.
So thats what I am basing my recommendations on.

Bmw635

Thanks for this CE panel refresh tip and link. I am getting intermittent no firing but cranks all the time summons. It comes down to the connection in my new FP relay in the CE panel when I wiggle the relay, it fires up. Thanks.