posted by
someone claiming to be Brian
on
Sat May 24 14:02 CST 2003 [ RELATED]
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The subject line just about says it all.
When it first happened a couple of days ago, it would only cut out under boost pressure. The engine would momentarily die for a fraction of a second, and then it would catch and keep accelerating.
Now it's happening regularly, and even during acceleration when no boost presure is present. It idles perfectly, and does not actually stall (just cuts out for a fraction of a second, and catches again).
The problem coincides with a new tank of gas, so I'm wondering if I picked up bad gas. But I bet it's not that simple.
It's pretty much undriveable now, although it was an erratic problem at first.
Any helpful diagnoses? Thanks!
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posted by
someone claiming to be Brian
on
Mon May 26 14:01 CST 2003 [ RELATED]
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Thanks to both of you.
The rubber intake tubing appeared to be ok, although I know that leaks in these things can be a bear to spot. These tubes were replaced 2 years ago, so I'd be surprised if they failed so soon.
The tachometer follows engine speed exactly as it starts to miss. So if the stumble sounds like it was killing about 500 rpm of speed, the tach drops about 500 rpm.
Today it started dying at idle when waiting for stop lights. Car actually stalled, and took about a minute to restart. Then it ran great for 10 minutes, then back to the stumbling & now stalling. Obviously the problem is getting worse rapidly.
Possibly it is a coincidence, but I just filled up with a fresh tank of gas before all the trouble. I intend to analyse the fuel - maybe I picked up a tank of bad fuel &/or water.
I'll keep you informed, even if I break down and have my indy mechanic look at it!
Thanks again.
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I'm not sure if this helps or not, but I once filled up the car with what turned out to be 'very' bad gas. My car would fire up fine, then after a few minutes it would go into lengthy tangos with the rpms, occasionally stalling and dying completely. It was scary driving it. Once I finally used up the gas and filled up with good gas, the problem dissapeared completely. Ask around the neighborhood where you filled up for reports of bad gas at the station you filled up. In my case, I heard several people has similar problems.
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posted by
someone claiming to be Brian
on
Tue May 27 10:48 CST 2003 [ RELATED]
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That sounds very like my problem.
However, I broke down today and took it to a mechanic, who analysed the gas in the tank, and it is fine. Apparently he could find no induction leaks in the intercooler plumbing either. And the spark is good. So his thought now is a fuel delivery problem, although he has yet to test the fuel pressure. So, relay, pump(s), regulator, injectors, or... ?
I'll post the results, assuming he gets to the heart of the problem. If you've read this far in the thread, I'm sure you're curious to know the final result.
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posted by
someone claiming to be Brian
on
Wed May 28 08:42 CST 2003 [ RELATED]
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The problem turned out to be that when the engine was cold, I had a nice factory-spec 42 psi of fuel pressure. But when the engine warmed up, the fuel pressure dropped right down to about 20 psi! Yikes.
That's a good warning to do a fuel pressure test only on a fully-warmed engine. Initially, the test showed the fuel pressure was fine, throwing off the diagnosis.
Most of the fuel system is original to the car, so I think it's time for some serious renewal. I'm replacing the fuel pressure regulator, the main fuel pump, and the fuel filter. I assume this will catch whatever it was that was killing my fuel pressure, and whatever might have killed it again in the future on this old car.
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Next time that this happens, pay close attention to the tach. Had a similar problem with an '84 245, where the car would cut out (buck) every "x" number of seconds under load. When this happened, the tach would do down (but not to 0) and then shoot back up. Turns out that I had a loose connection at the coil. Mechanic replaced the two "clips" on the leads that connect to the coil and have had no problems since.
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posted by
someone claiming to be Brian
on
Sat May 24 14:21 CST 2003 [ RELATED]
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I wanted to add that the tachometer stayed up when the car misfired, and did not drop to 0. The boost gauge does drop to 0 for a second until the car catches again.
So I don't thinks it's Hall or power stage related.
Thanks.
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You probably have an induction system leak. Remove, clean and inspect the hoses. The intercooler discharge hose wears out on the bottom, where it can't be seen. The elbow at the throttle body breaks on the outside.
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