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Weird Idle when cold (1994 prelude VTEC)
Hello all. I need opinions. Car is a 1994 prelude VTEC.
On cold starts, idle climbs to 2 to 2.5K RPM. All is well it seems. Then after a while, when the engine starts to warm up, the RPM will go down, then up, down then up (you get the picture). When the car is fully warmed up, RPM stays at the same place normally. Opinions? Thanks! Ben |
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#2
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Weird Idle when cold (1994 prelude VTEC)
Bendit wrote:
> Hello all. I need opinions. Car is a 1994 prelude VTEC. > > On cold starts, idle climbs to 2 to 2.5K RPM. All is well it seems. > > Then after a while, when the engine starts to warm up, the RPM will go > down, then up, down then up (you get the picture). > > When the car is fully warmed up, RPM stays at the same place normally. > > Opinions? > > Thanks! > > > Ben check coolant level inside radiator. must be full to the top. if diluting antifreeze, use distilled water. |
#3
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Weird Idle when cold (1994 prelude VTEC)
On May 4, 10:24*pm, jim beam > wrote:
> Bendit wrote: > > Hello all. I need opinions. Car is a1994preludeVTEC. > > > On cold starts,idleclimbs to 2 to 2.5K RPM. All is well it seems. > > > Then after a while, when the engine starts to warm up, the RPM will go > > down, then up, down then up (you get the picture). > > > When the car is fully warmed up, RPM stays at the same place normally. > > > Opinions? > > > Thanks! > > > Ben > > check coolant level inside radiator. *must be full to the top. *if > diluting antifreeze, use distilled water.- Hide quoted text - > > - Show quoted text - Thanks for your reply! I did check the coolant level IN the radiator. Full to the top, but the expansion tank was empty. So I added some in there. My "instincts" tell me that the RPM "dance" is not related to the radiator. Perhaps something about fast idle valve when cold or something? (I don't know much about cars, more motorcycles). It seems the car cannot transition well between cold and warm status. Know what I mean? Cheers and thanks again for any information!!!!! Ben |
#4
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Weird Idle when cold (1994 prelude VTEC)
Bendit wrote:
. . . . . . .but > the expansion tank was empty. So I added some in there. > > My "instincts" tell me that the RPM "dance" is not related to the > radiator. Perhaps something about fast idle valve when cold or > something? (I don't know much about cars, more motorcycles). It seems > the car cannot transition well between cold and warm status. Know what > I mean? > > Cheers and thanks again for any information!!!!! > > > Ben ========================= Expansion tank has to be kept at MAX so there's a RESERVE to replace the AIR that's going to burp out next time the engine warms up.. Computer gets confused if the sensors aren't immersed, idle goes up and down. Been covered a million times. 'Curly' |
#5
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Weird Idle when cold (1994 prelude VTEC)
On May 5, 10:01 am, motsco_ > wrote:
> Bendit wrote: > > . . . . . . .but> the expansion tank was empty. So I added some in there. > > > My "instincts" tell me that the RPM "dance" is not related to the > > radiator. Perhaps something about fastidlevalve when cold or > > something? (I don't know much about cars, more motorcycles). It seems > > the car cannot transition well between cold and warm status. Know what > > I mean? > > > Cheers and thanks again for any information!!!!! > > > Ben > > ========================= > > Expansion tank has to be kept at MAX so there's a RESERVE to replace the > AIR that's going to burp out next time the engine warms up.. Computer > gets confused if the sensors aren't immersed,idlegoes up and down. > Been covered a million times. > > 'Curly' Thanks for the information. Filling the expansion tank did not fix my problem (even though it needed to be done). Any other ideas? (keep in mind idle maintains itself just fine once the car has reached operating temperature) Thanks again! |
#6
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Weird Idle when cold (1994 prelude VTEC)
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#7
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Weird Idle when cold (1994 prelude VTEC)
On May 6, 9:39*am, E Meyer > wrote:
> On 5/5/08 8:27 PM, in article > , "Bendit" > > > > > > > wrote: > > On May 5, 10:01 am, motsco_ > wrote: > >> Bendit wrote: > > >> * . . . . . . .but> the expansion tank was empty. So I added some in there. > > >>> My "instincts" tell me that the RPM "dance" is not related to the > >>> radiator. Perhaps something about fastidlevalve when cold or > >>> something? (I don't know much about cars, more motorcycles). It seems > >>> the car cannot transition well between cold and warm status. Know what > >>> I mean? > > >>> Cheers and thanks again for any information!!!!! > > >>> Ben > > >> ========================= > > >> Expansion tank has to be kept at MAX so there's a RESERVE to replace the > >> AIR that's going to burp out next time the engine warms up.. Computer > >> gets confused if the sensors aren't immersed,idlegoes up and down. > >> Been covered a million times. > > >> 'Curly' > > > Thanks for the information. Filling the expansion tank did not fix my > > problem (even though it needed to be done). > > > Any other ideas? > > > (keep in mind idle maintains itself just fine once the car has reached > > operating temperature) > > > Thanks again! > > If the expansion tank was empty, did you also fill the radiator itself > (which most likely is also low)? *The problem you are trying to fix is to > get rid of the air bubble in the cooling system that is isolating the > temperature sensors and making the engine computer think the temp of the > engine is something other than what it actually is.- Hide quoted text - > > - Show quoted text - Thanks for your reply. Yes, I did check the level of coolant inside the radiator. It seemed to be full (all the way to the top). Perhaps it will take time to get rid of the air then. I do not currently drive this car every day (but will start on the 23rd of this month when I return my leased car). I will post back progress once I do (and see if the air problem fixed itself). Question: where exactly is the temperature sensor(s) ? Thanks again guys! |
#8
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Weird Idle when cold (1994 prelude VTEC)
On May 5, 10:47*am, Bendit > wrote:
> On May 4, 10:24*pm, jim beam > wrote: > > > > > > > Bendit wrote: > > > Hello all. I need opinions. Car is a1994preludeVTEC. > > > > On cold starts,idleclimbs to 2 to 2.5K RPM. All is well it seems. > > > > Then after a while, when the engine starts to warm up, the RPM will go > > > down, then up, down then up (you get the picture). > > > > When the car is fully warmed up, RPM stays at the same place normally. > > > > Opinions? > > > > Thanks! > > > > Ben > > > check coolant level inside radiator. *must be full to the top. *if > > diluting antifreeze, use distilled water.- Hide quoted text - > > > - Show quoted text - > > Thanks for your reply! > > I did check the coolant level IN the radiator. Full to the top, but > the expansion tank was empty. So I added some in there. > > My "instincts" tell me that the RPM "dance" is not related to the > radiator. Perhaps something about fast idle valve when cold or > something? (I don't know much about cars, more motorcycles). It seems > the car cannot transition well between cold and warm status. Know what > I mean? > > Cheers and thanks again for any information!!!!! > > Ben- Hide quoted text - > > - Show quoted text - yeah, my guess too. don't know preludes, but the civic uses a small idle air valve that gets opened and closed to regulate idle speed (as opposed to other cars which have a little motor to open and close things) which gets gunked up, and might benefit from attention/ replacement. |
#9
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Weird Idle when cold (1994 prelude VTEC)
On May 13, 12:12*pm, z > wrote:
> On May 5, 10:47*am, Bendit > wrote: > > > > > > > On May 4, 10:24*pm, jim beam > wrote: > > > > Bendit wrote: > > > > Hello all. I need opinions. Car is a1994preludeVTEC. > > > > > On cold starts,idleclimbs to 2 to 2.5K RPM. All is well it seems. > > > > > Then after a while, when the engine starts to warm up, the RPM will go > > > > down, then up, down then up (you get the picture). > > > > > When the car is fully warmed up, RPM stays at the same place normally. > > > > > Opinions? > > > > > Thanks! > > > > > Ben > > > > check coolant level inside radiator. *must be full to the top. *if > > > diluting antifreeze, use distilled water.- Hide quoted text - > > > > - Show quoted text - > > > Thanks for your reply! > > > I did check the coolant level IN the radiator. Full to the top, but > > the expansion tank was empty. So I added some in there. > > > My "instincts" tell me that the RPM "dance" is not related to the > > radiator. Perhaps something about fast idle valve when cold or > > something? (I don't know much about cars, more motorcycles). It seems > > the car cannot transition well between cold and warm status. Know what > > I mean? > > > Cheers and thanks again for any information!!!!! > > > Ben- Hide quoted text - > > > - Show quoted text - > > yeah, my guess too. don't know preludes, but the civic uses a small > idle air valve that gets opened and closed to regulate idle speed (as > opposed to other cars which have a little motor to open and close > things) which gets gunked up, and might benefit from attention/ > replacement.- Hide quoted text - > > - Show quoted text - Problem solved. I have replaced both temperature sensors and now all is well. |
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