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Hey folks!
My 92 740 turbo wagon with 254k miles is having stalling problems. I've been trying to convey information cleanly and accurately with other projects I'm involved in and I will attempt to do the same here.
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Symptom Overview:
-While fully warm and at driving speed a "bogging" fuel or spark type stall occurs. The stall feels progressive as though I go from 100% power to 50% then quickly look for a spot to die with remaining 20% before its game over. It will try to start again and it briefly fires but its acting fuel starved (could be wrong assumption though)
-If its cool I can restart and go a ways further but that's becoming less reliable quickly. Yesterday I got about 1/2 mile from my house and died. Its been cooling there overnight because frankly we both needed it.
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Initial Diagnostics and Relevant Issues:
- I had it towed to my friends shop after the first failure last week. I didn't know it was an intermittent issue and I was dead on the freeway. First actual tow truck in all my years of driving (tow ropes are in a different class IMHO).
- - Their diagnosis?: out of gas - this is true AND possibly false. (i.e. a
red herring)
- - - I might have been siphoned because I always zero out my odometer when I
fill up. My fuel gauge has been unreliable lately, still showing empty
when I just filled up. Odometer reads 80mi on new tank (approx 250mi
average) but they said they added 3 gals and it ran fine. Weird...
- - - - I told them I wasn't convinced (it just didn't feel right). They kept
it for code checks and a day of parts runs around town. Not a single
problem occurred and the tech even complimented me on the running order.
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After a few more fun and exciting stalls, I pulled it into my garage for my little regular maintenance routine.
- Clean mass air sensor, flame trap, idle air control valve, throttle body,
etc (typical old engine oil blow off and grime)
- Check and clean plugs, grounds, sensor connections, etc (electrical
system simple stuff)
- Check hoses for leaks, clean nipples at intake manifold, turbo lines cleaned,
etc (air flow and pressure stuff)
It started fine, idled with very minor fluctuation and overall ran like a champ. On the road test it died 1/2 mile away, and there it sits right now.
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Possible Diagnosis:
Fuel Delivery?: - Unlikely IMO - In the last 15k miles I've replaced in tank
and rail pumps along with filter and fuel pressure regulator. No
fuel leaks detected anywhere.
Ignition?: - Seems like a more reasonable guess. Its acting like "hot start"
but its a quickly degrading version. Replaced cap/rotor,
alternator, plugs, battery, coil, fuel pump relay, in the last 10k
miles. Unlikely culprits IMO.
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Goals Today:
Get the bugger home. Try for stall in garage and test fuel pressure, spark at plugs, test coil resistance.
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Summary:
This is a great car when it runs and I can fix almost anything on it here in my garage/work shop. If I had more money I would gladly pay somebody else to fix or throw parts at it, but that's not really an option. I am a single Dad and busting my ass to make ends meet, so this car has to last a few more miles and I believe it can. I'd also like the dammed thing out of my shop because I have work to do. Thankfully more experienced people feel the way I do about these old bricks and I hope that someday I can return the favor.
Thanks for reading, the floor is now open...
Bruce
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