Why does my car stall ? (video of tachometer)
09-05-03, 07:05 PM
#1
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Why does my car stall ? (video of tachometer)
OK I mentioned this before, but now I have a video to show all.
(download here - www.ldvg.com/idle.mov (6MB)
Here's what happens-
PASS #1 - I'm idling in (P)ark. The A/C is on. I rev to 1200 RPM. I let off the gas pedal and the RPM's drop to around 380-400 RPM. This is below the programmed 600 RPM idle at this point the car gets shakey but corrects itself.
PASS #2 (important part at 15 secs into video)- This time I rev to 1400 RPM. Notice closely the RPM's are dropping by itself. I let OFF the gas and the RPM's drop to 200, car ALMOST stalls. All the engine error lights come on and in this shot you can see the coolant light come on (like if ignition was on ACC but not started). The engine speed goes up to 600RPM VERY quickly then drops to 400 again. Slowly the RPM's climb back up to 1000 RPM.
Other notes- Watch the RPM's "skip" up inbetween passes #1 and #2. If you do see it, that's not me having a figedty foot, the car does that by itself (which I think is a TPS problem).
Lastly, A/C idle is not 1000 RPM, but 1200RPM for this car. It always has been until this problem started occuring. I have gotten it to stall a few times.
(download here - www.ldvg.com/idle.mov (6MB)
Here's what happens-
PASS #1 - I'm idling in (P)ark. The A/C is on. I rev to 1200 RPM. I let off the gas pedal and the RPM's drop to around 380-400 RPM. This is below the programmed 600 RPM idle at this point the car gets shakey but corrects itself.
PASS #2 (important part at 15 secs into video)- This time I rev to 1400 RPM. Notice closely the RPM's are dropping by itself. I let OFF the gas and the RPM's drop to 200, car ALMOST stalls. All the engine error lights come on and in this shot you can see the coolant light come on (like if ignition was on ACC but not started). The engine speed goes up to 600RPM VERY quickly then drops to 400 again. Slowly the RPM's climb back up to 1000 RPM.
Other notes- Watch the RPM's "skip" up inbetween passes #1 and #2. If you do see it, that's not me having a figedty foot, the car does that by itself (which I think is a TPS problem).
Lastly, A/C idle is not 1000 RPM, but 1200RPM for this car. It always has been until this problem started occuring. I have gotten it to stall a few times.
09-05-03, 08:14 PM
#2
my guess is the idle air control assembly is not responding fast enough. Could be a few other items, like dirty TB, or TPS as you stated. Toyota/Lexus idle like crap when the air tube from air box to TB has cracks or pinpoint holes in it. It thows off the MAF readings and the fuel air ratio is wrong (ECU doesn't know of the extra air coming in).
the CEL and other lights in pass# 2 are probably coming on when the crank sensor triggers a fault code cause the RPMs dropped below the cutoff number (usually in the ball park of 350PRM). The ECU thinks the engine has cut out and goes into a shut down or increases fuel and the rpms shoot up in a recovery attempt.
It would be interesting if you could hook up a scan tool and then repeat you experiment. You would then know the sequence of codes that are triggered. This may help you to pinpoint the problem.
steviej
the CEL and other lights in pass# 2 are probably coming on when the crank sensor triggers a fault code cause the RPMs dropped below the cutoff number (usually in the ball park of 350PRM). The ECU thinks the engine has cut out and goes into a shut down or increases fuel and the rpms shoot up in a recovery attempt.
It would be interesting if you could hook up a scan tool and then repeat you experiment. You would then know the sequence of codes that are triggered. This may help you to pinpoint the problem.
steviej
Last edited by steviej; 09-05-03 at 08:16 PM.
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