Help Please 1989 S4 stops running like it got hot, but temp is good
#31
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So, what you describe is after warming up, the car will die, and during the process it acts initially like there is a rev limiter.
When you try to restart it without waiting 30 minutes, how exactly does it behave? You say it will die if you drive off. Does it die immediately after releasing the key from the start position? Does it idle? Does it idle but poorly?
I have seen problems from fuel overheating, but not in stock S4s - just a heavily modified car with a fuel cell, and that was only after extended driving at high altitiude (>5000 feet. How high is Vail? Sounds high.). As the fuel heated up, approaching 135F even on 80F days, the external Bosch 044 would slowly fail to maintain fuel pressure. We had remote fuel temperature and fuel pressure gauges, so we could watch it happen. The pump would get progressively noisier and the pressure would fall slowly over a couple of minutes...50...45...40..35...30..DIE at 135F fuel temp in the tank. Also, with our wideband O2 we could see the mixture lean out. The injectors would fail to squirt at somehere around 28 PSI. We eventually resolved this with a host of fuel system changes to keep the fuel cooler and the pump(s) from having to suck so hard.
Note that an 044 is overkill for a stock car and will result in much more fuel being recirculated through the hot engine compartment and returned to the tank at whatever RPM. This will heat up the fuel. However, the pump will let you know if this is the problem by getting very noisy as it fails due to vapor lock. An intank pump also makes this much less likely to fail. 30 minutes just doesn't sound long enough for this kind of problem to develop, but if you are at high altitude and it's hot out and you have an 044 with no intank pump...just maybe that's it. Once this issue started, we would dump 5 gallons of "cold" gas into the fuel cell and get maybe another 20 minutes down the road before it would heat up and fail again. And, of course, the lower fuel level, the faster it would heat up and fail.
I think as a policy, 928s at high altitude should not have 044s installed and should have intank pumps.
When you try to restart it without waiting 30 minutes, how exactly does it behave? You say it will die if you drive off. Does it die immediately after releasing the key from the start position? Does it idle? Does it idle but poorly?
I have seen problems from fuel overheating, but not in stock S4s - just a heavily modified car with a fuel cell, and that was only after extended driving at high altitiude (>5000 feet. How high is Vail? Sounds high.). As the fuel heated up, approaching 135F even on 80F days, the external Bosch 044 would slowly fail to maintain fuel pressure. We had remote fuel temperature and fuel pressure gauges, so we could watch it happen. The pump would get progressively noisier and the pressure would fall slowly over a couple of minutes...50...45...40..35...30..DIE at 135F fuel temp in the tank. Also, with our wideband O2 we could see the mixture lean out. The injectors would fail to squirt at somehere around 28 PSI. We eventually resolved this with a host of fuel system changes to keep the fuel cooler and the pump(s) from having to suck so hard.
Note that an 044 is overkill for a stock car and will result in much more fuel being recirculated through the hot engine compartment and returned to the tank at whatever RPM. This will heat up the fuel. However, the pump will let you know if this is the problem by getting very noisy as it fails due to vapor lock. An intank pump also makes this much less likely to fail. 30 minutes just doesn't sound long enough for this kind of problem to develop, but if you are at high altitude and it's hot out and you have an 044 with no intank pump...just maybe that's it. Once this issue started, we would dump 5 gallons of "cold" gas into the fuel cell and get maybe another 20 minutes down the road before it would heat up and fail again. And, of course, the lower fuel level, the faster it would heat up and fail.
I think as a policy, 928s at high altitude should not have 044s installed and should have intank pumps.
#34
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So, what you describe is after warming up, the car will die, and during the process it acts initially like there is a rev limiter.
When you try to restart it without waiting 30 minutes, how exactly does it behave? You say it will die if you drive off. Does it die immediately after releasing the key from the start position? Does it idle? Does it idle but poorly?
When you try to restart it without waiting 30 minutes, how exactly does it behave? You say it will die if you drive off. Does it die immediately after releasing the key from the start position? Does it idle? Does it idle but poorly?
I have seen problems from fuel overheating, but not in stock S4s - just a heavily modified car with a fuel cell, and that was only after extended driving at high altitiude (>5000 feet. How high is Vail? Sounds high.). As the fuel heated up, approaching 135F even on 80F days, the external Bosch 044 would slowly fail to maintain fuel pressure. We had remote fuel temperature and fuel pressure gauges, so we could watch it happen. The pump would get progressively noisier and the pressure would fall slowly over a couple of minutes...50...45...40..35...30..DIE at 135F fuel temp in the tank. Also, with our wideband O2 would could see the mixture lean out. The injectors would fail to squirt at somehere around 28 PSI. We eventually resolved this with a host of fuel system changes to keep the fuel cooler and the pump(s) from having to suck so hard.
I do have a second 044 sitting here. I can swap those and try that... or maybe just go with the other pump that works great on the other 89 and I drive it hard in all temps...
Though, now that I write, i have had a couple odd issues with BB that made it seem like I had no power... turned it off then back on and I was golden...
What happens when the MAF starts to fail? What are the symptoms there?
#35
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Did you remove the powder coating from the water bridge at the sealing surface underneath the hex-head part of the TEMP-II sensor?
#36
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#37
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Ah, I think Dave got it. It explains why this just happened after you did your powder coating.
It didn't fit what I was talking about. That was more just for general information. 3200 feet is not really that high. Don't bother with an intank pump unless you find there is really a fuel overheating or other delivery problem. I'd stick with the stock pump rather than an 044, but, like I said, I don't think 3200 feet is high enough for this kind of issue.
It didn't fit what I was talking about. That was more just for general information. 3200 feet is not really that high. Don't bother with an intank pump unless you find there is really a fuel overheating or other delivery problem. I'd stick with the stock pump rather than an 044, but, like I said, I don't think 3200 feet is high enough for this kind of issue.
#39
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Ah, I think Dave got it. It explains why this just happened after you did your powder coating.
It didn't fit what I was talking about. That was more just for general information. 3200 feet is not really that high. Don't bother with an intank pump unless you find there is really a fuel overheating or other delivery problem. I'd stick with the stock pump rather than an 044, but, like I said, I don't think 3200 feet is high enough for this kind of issue.
It didn't fit what I was talking about. That was more just for general information. 3200 feet is not really that high. Don't bother with an intank pump unless you find there is really a fuel overheating or other delivery problem. I'd stick with the stock pump rather than an 044, but, like I said, I don't think 3200 feet is high enough for this kind of issue.
I had issues with the flappy movement, had to file down the PC at the E-clip ends of the rod, and chased down leaks anywhere where there was water and something to hold it in...including temp2 surface, etc.
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Weve talked about PC and various bits of the intake at your house before.
I had issues with the flappy movement, had to file down the PC at the E-clip ends of the rod, and chased down leaks anywhere where there was water and something to hold it in...including temp2 surface, etc.
I had issues with the flappy movement, had to file down the PC at the E-clip ends of the rod, and chased down leaks anywhere where there was water and something to hold it in...including temp2 surface, etc.
#41
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Ah, I think Dave got it. It explains why this just happened after you did your powder coating.
It didn't fit what I was talking about. That was more just for general information. 3200 feet is not really that high. Don't bother with an intank pump unless you find there is really a fuel overheating or other delivery problem. I'd stick with the stock pump rather than an 044, but, like I said, I don't think 3200 feet is high enough for this kind of issue.
It didn't fit what I was talking about. That was more just for general information. 3200 feet is not really that high. Don't bother with an intank pump unless you find there is really a fuel overheating or other delivery problem. I'd stick with the stock pump rather than an 044, but, like I said, I don't think 3200 feet is high enough for this kind of issue.
#43
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I wonder how many flappys out there on PC'd intakes are stiff to open, or dont open well at all because of the space the PC takes, that the mechanism needs to rotate under the E clip.
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In this case that would have been to operate the engine until it began misbehaving and then run a test lead (two alligator clips on a length of wire) from the hex-base of the Temp-II sensor to a ground point like a (uncorroded) cross brace bolt. If the engine settles down with the test lead attached then the theory is proven correct, if not then the theory is proven incorrect.
Powder coating can be high-resistance and therefore interfere with the ground circuit. Initially, there's enough metal in the sensor to give a reasonable resistance reading. But as the engine runs, the ECU's circuits suck electrons out of the metal of the sensor body and with the high-resistance of the powder coating electrons can't flow nicely through the sensor to the ECUs from the body.
Basically, the LH and EZK ECUs begin getting a bogus temperature reading after a few minutes because of the high-resistance ground path. They think it is -20 degrees outside and mess with the fuel ratio and (maybe - haven't looked at Sharktuner maps in far too long) timing. Then, after a couple of minutes the 02 loop turns on trying to trim the air/fuel ratio and all idle-Hell breaks loose.
If you PC the water bridge you need to make sure to remove the PC from the sealing surface underneath the TEMP-II sensor and from the washer surface underneath at least one of the water bridge bolts.
Last, some PC can LOOK like bright aluminum when you Dremel it and provide a good ground path until it goes through some temperature cycling.
A multimeter resistance check from the TEMP-II to a ground point is not enough of a test.
Last edited by worf928; 07-24-2012 at 10:37 PM.