Really low idle RPMs
23-Jan-2003, 12:14 PM
#1
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Really low idle RPMs
K I have a question thats plaguing me, it only happens when the car is cold so I figure thats the main cause of it. When I'm driving and I have to break hard, my rpms drop to like 200 or less once I complete the stop and the engine feels likes its gonna cut out. I'm guessing it's cause of the cold, but could there be any other reason its doing this? TIA
23-Jan-2003, 12:39 PM
#2
OK, the cold likely has little to do with it...auto or man?? Your booster is vaccum driven, so it's likely that the extreme use of vacuum for brake boosting causes the drop, but what should happen is that the vaccum loss would be read by the MAP sensor, which would tell the ECU, which would send out a signal to the IAC valve which would compensate for the change in pressure and idle condition...which in turn would make it all good, and this should all happen before you even blink. So...in other words, something in that loop is fooked...get down there with a scan tool and a multimeter and a wiring diagram and start probing your connections. But again, 5 SPD or AUTO!?!
23-Jan-2003, 06:16 PM
#5
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Originally posted by bbarbulo
OK, the cold likely has little to do with it...auto or man?? Your booster is vaccum driven, so it's likely that the extreme use of vacuum for brake boosting causes the drop, but what should happen is that the vaccum loss would be read by the MAP sensor, which would tell the ECU, which would send out a signal to the IAC valve which would compensate for the change in pressure and idle condition...which in turn would make it all good, and this should all happen before you even blink. So...in other words, something in that loop is fooked...get down there with a scan tool and a multimeter and a wiring diagram and start probing your connections. But again, 5 SPD or AUTO!?!
OK, the cold likely has little to do with it...auto or man?? Your booster is vaccum driven, so it's likely that the extreme use of vacuum for brake boosting causes the drop, but what should happen is that the vaccum loss would be read by the MAP sensor, which would tell the ECU, which would send out a signal to the IAC valve which would compensate for the change in pressure and idle condition...which in turn would make it all good, and this should all happen before you even blink. So...in other words, something in that loop is fooked...get down there with a scan tool and a multimeter and a wiring diagram and start probing your connections. But again, 5 SPD or AUTO!?!
you work for Haynes??
24-Jan-2003, 12:20 PM
#7
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Originally posted by bbarbulo
OK, the cold likely has little to do with it...auto or man?? Your booster is vaccum driven, so it's likely that the extreme use of vacuum for brake boosting causes the drop, but what should happen is that the vaccum loss would be read by the MAP sensor, which would tell the ECU, which would send out a signal to the IAC valve which would compensate for the change in pressure and idle condition...which in turn would make it all good, and this should all happen before you even blink. So...in other words, something in that loop is fooked...get down there with a scan tool and a multimeter and a wiring diagram and start probing your connections. But again, 5 SPD or AUTO!?!
OK, the cold likely has little to do with it...auto or man?? Your booster is vaccum driven, so it's likely that the extreme use of vacuum for brake boosting causes the drop, but what should happen is that the vaccum loss would be read by the MAP sensor, which would tell the ECU, which would send out a signal to the IAC valve which would compensate for the change in pressure and idle condition...which in turn would make it all good, and this should all happen before you even blink. So...in other words, something in that loop is fooked...get down there with a scan tool and a multimeter and a wiring diagram and start probing your connections. But again, 5 SPD or AUTO!?!
24-Jan-2003, 12:33 PM
#9
The higher idling when cold is like a choke on the old carb'd cars...it's normal. Helps warm up the catalytic converter to operating temps, as well as reacing closed loop mode sooner (lower emissions/more economical). Auto cars idle lower than manual, but 500rpm is a bit too low...600-700 for auto is normal. 700-800 is normal for 5 spd, but your manual or underhood sticker will have the exact specs on what it should be. I am stating in general...
24-Jan-2003, 01:31 PM
#10
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I had a similar problem even before winter
KS-R put in a d16z6 in my 4th gen and when I initially start the car the RPM's shoot up to about 2000 right off the bat. It will stay there and slowly make its way down to about 800-900 in about 3-5 mins. That's fine i guess b/c it warms up the engine faster but is it healthy? The other proble that has me concerned is that when i stop at a light the rpm's will fluctuate (if the stop is long enough). They will dip to about 300-400 and the engine will start to vibrate and then it will shoot itself back up to 1000 and then slowly dip again. I know that there is a clutch problem thoug b/c whe i disengage the clutch you can hear something scraping as it slows down and it also makes a noise scraaping noise when shifting. any ideas? Thanks
KS-R put in a d16z6 in my 4th gen and when I initially start the car the RPM's shoot up to about 2000 right off the bat. It will stay there and slowly make its way down to about 800-900 in about 3-5 mins. That's fine i guess b/c it warms up the engine faster but is it healthy? The other proble that has me concerned is that when i stop at a light the rpm's will fluctuate (if the stop is long enough). They will dip to about 300-400 and the engine will start to vibrate and then it will shoot itself back up to 1000 and then slowly dip again. I know that there is a clutch problem thoug b/c whe i disengage the clutch you can hear something scraping as it slows down and it also makes a noise scraaping noise when shifting. any ideas? Thanks
26-Jan-2003, 12:04 AM
#12
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Originally posted by precision4
I had a similar problem even before winter
KS-R put in a d16z6 in my 4th gen and when I initially start the car the RPM's shoot up to about 2000 right off the bat. It will stay there and slowly make its way down to about 800-900 in about 3-5 mins. That's fine i guess b/c it warms up the engine faster but is it healthy? The other proble that has me concerned is that when i stop at a light the rpm's will fluctuate (if the stop is long enough). They will dip to about 300-400 and the engine will start to vibrate and then it will shoot itself back up to 1000 and then slowly dip again. I know that there is a clutch problem thoug b/c whe i disengage the clutch you can hear something scraping as it slows down and it also makes a noise scraaping noise when shifting. any ideas? Thanks
I had a similar problem even before winter
KS-R put in a d16z6 in my 4th gen and when I initially start the car the RPM's shoot up to about 2000 right off the bat. It will stay there and slowly make its way down to about 800-900 in about 3-5 mins. That's fine i guess b/c it warms up the engine faster but is it healthy? The other proble that has me concerned is that when i stop at a light the rpm's will fluctuate (if the stop is long enough). They will dip to about 300-400 and the engine will start to vibrate and then it will shoot itself back up to 1000 and then slowly dip again. I know that there is a clutch problem thoug b/c whe i disengage the clutch you can hear something scraping as it slows down and it also makes a noise scraaping noise when shifting. any ideas? Thanks
28-Jan-2003, 01:19 PM
#14
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Greg, mine idles differently (lower I think) when the rear defroster's on too... just more load on the battery? I don't know how that relates to the idle though. All my Civics have had that attribute. It's so commonplace that I forget about it.
28-Jan-2003, 01:59 PM
#15
greg, have you checked out the things in the feedback circuit I told you about? I would check those components first...the defroster thing is a load on the alternator...but the belt would slip before it created enough load to actually slow the engine down. The defroster is like a 20A load. I don't use it unless I really have to.
28-Jan-2003, 06:07 PM
#16
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not yet B, still havent had a chance to really do anything cause of exams. I have to get my hands on a multimeter too, I'll get one from my buddy tomorrow, and I'll check it out friday.
28-Jan-2003, 09:09 PM
#17
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Originally posted by grego9198
not yet B, still havent had a chance to really do anything cause of exams. I have to get my hands on a multimeter too, I'll get one from my buddy tomorrow, and I'll check it out friday.
not yet B, still havent had a chance to really do anything cause of exams. I have to get my hands on a multimeter too, I'll get one from my buddy tomorrow, and I'll check it out friday.
28-Jan-2003, 10:19 PM
#19
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Originally posted by grego9198
Whatcha doin wednesday after 1pm? Busy? wanna help me do this?
Whatcha doin wednesday after 1pm? Busy? wanna help me do this?
