newworld

87s4aut. Hot stat issue for 5 min.

I made Some progress with this issue. Car will not start after hot shutdown for 5 min then runs like nothing happened.

I previously ruled out spark and focused on fuel. But I discovered it was my error. By the time I assembled my spark plug tester I think my 5 min window passed so each I got spark.

Today I got someone to crank car after hot shutdown and no spark.

Wait 5 min and you get spark.

I replaced some fuel items and now I am shifting to spark issues caused by heat....

That leads me to ignition coils or ignition module.


I am first going in to see if all connections are tight.

This explains why it starts when cold and warm but tough to start when hot.

Also depressing throttle has no effect etc for previous posts I read about flooding. Also when it starts no black smoke.

Is there a way to isolate coil versus module?

Hai gebissen

I don't know on these cars, but on Saabs that is a classic symptom of a failing crank position sensor.

John Speake

It's also a not unusual failure mode in the 928 either ...

newworld

I thought crank sensor as well but i changed it awhile back and I get a tach bounce on cranking.

I removed crank sensor again and it was good.

I pulled coil leads and tightened them I did find a couple of plugs not completely snapped in to distributor cap. I might have nudged them when I went in for other things.

Still hot start issue.

Then I looked at relay the ezk ignition relay. It was new, but I wondered if it was bad or got overheated when plugs were loose?

I saw it was a meyle but made in china...

I put a new one. And tested hot start. It started.

After 6 mo or so now I have found the culprit as of now.

I overlooked relay BC it was new.

My coils did not have signs of leaking. Also the ignition module in my experience would cause a stall cut out while running.

I never had that.

We will monitor and see if this fix holds.

Lesson learned. Make sure fuel or spark and then proceed down to troubleshoot. I went into fuel when I should have gone down spark path.

Also new parts don't guarantee that it works. Or it could be case where something I did caused new part to malfunction....

Hai gebissen

Nothing will drive you crazy more than a new part that is bad right out of the box. Back in my dealership days, I had (2) cabin fan control modules bad out of the genuine Saab boxes...back to back on the same car!

dr bob

Newworld, you have enough posts now to qualify for forum membership. It's a great investment.


Long time supporter Jim Bailey was the go-to guy at 928 International for many years before he started his carreer in front of the TV camera. Lots of wisdom accumulated and shared in that time and since. His mantra of "relay-relay-relay" is etched in the cerebral cortex of long-timers here, and it is even more applicable as the age of the cars increases. There are more than a few knock-offs of the 53B Bosch relays, and it's sometimes tempting to grab one while at the local chain parts rack. Many of us have discovered that using knock-off relays is a sucker's bet, and only buy reputable relays from reputable sources. Our 928 suppliers sell them from somewhere slightly less than $10 to slightly more than $10. Keeping in mind Jim's relay-relay-relay mantra, it's more than prudent to replace all potentially fatal relays whenever trouble starts. On the S4+ cars, at minimum it should get new fuel pump, EZK and LH relays. The X-bus relay is right up there for non-engine-related problems, since it feeds pretty much every accessory that comes on with the key. Then keep a few relays in the car for later, in the bag with the relay pullers and the jumper wire. They are on my 20-year PM program, mostly because I hate to get stranded by stupid stuff. Buy new ones, install them even if they aren't troubling you yet. Because they will. Why lay awake at night worrying about your relays? Peace of mind is cheap, much cheaper than a tow and a therapist.

(/rant mode]

Stromius

After checking and changing the relays, get your multi meter and check the posts on your Temp II sensor (each to ground) when you get a hot start issue. Had a few go south. Search for resistance specs in the forum or WSM.