95 dak 3.9 auto, possible low idle
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95 dak 3.9 auto, possible low idle
my truck is low miles, only 34k.
When i start it up, no matter what the temp is outside, it idles at the same rpm. The same rpm it idles at once warmed up. It only ever idles at the normal idle for normal operating temperature, about 700 or so.
I'm trying to figure out if this is normal.
I've been trying to figure out the reason for my low gas mileage, and I'm thinking that if my intake air temp sensor is malfunctioning it would cause both the idle to be low when starting in cold weather and the low gas mileage.
can anyone give some info?
When i start it up, no matter what the temp is outside, it idles at the same rpm. The same rpm it idles at once warmed up. It only ever idles at the normal idle for normal operating temperature, about 700 or so.
I'm trying to figure out if this is normal.
I've been trying to figure out the reason for my low gas mileage, and I'm thinking that if my intake air temp sensor is malfunctioning it would cause both the idle to be low when starting in cold weather and the low gas mileage.
can anyone give some info?
Last edited by drussell4801; Nov 29, 2009 at 08:55 PM.
Thread Starter
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Registered User
Joined: Apr 2006
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95 318slt: yet again, thanks for the quick response..
My truck goes up to about 1500rpm when I first start it, and over a period of about five seconds it brings itself down to the 700 or so, and then idles steady at 700. It does this when its 90 degrees out and just yesterday it did this when it was 30 degrees out. So it seems to me that its opening the idle control valve at first, but just bringing it down right away. Now maybe its important for me to say that when it is idling at 700 just after startup, its idling smooth(regardless of ambient temp); no sputtering or missing that I can feel. (what i'd really like to be able to do is see on a tester that the ambient air temp reading is correct, because I keep feeling that the ambient temp sensor is the most likely issue. I'm thinking that the ambient temp sensor is damaged or just worn out in such a way that causes it to give a reading that the air is warm, regardless what the temp of the air really is; but then if that was the case, wouldn't it idle rough when its idling at 700rpm when its only 30 degrees outside? I can't seem to wrap my head around the fact that it idles smooth at 700rpm in 30 degree weather after cold startup.) Are there any tests that I could do that don't require plugging in a tester (which i have no access to).
I was considering things like:
-unplugging the ambient temp sensor should cause the idle to go higher..
-unplugging the coolant temp sensor should cause the idle to go higher..
yes I realize that both of these things should (and hopefully will) throw the check engine light, but I'm trying to see if there is anything I can do to force the computer to open up that idle control valve, just so I can rule it out? maybe unplugging the map sensor? maybe forcing the egr valve open and see if the computer tries to adjust the idle??
It may be important to note that this truck is almost like brand new. I think I still have the original tires on it from the factory
I bought it from my grandfather, who bought it from a used car shop in PA. The person who owned it before him had some aftermarket pioneer stereo equipment installed. I'm even considering that maybe he had the ecu chipped??
My truck goes up to about 1500rpm when I first start it, and over a period of about five seconds it brings itself down to the 700 or so, and then idles steady at 700. It does this when its 90 degrees out and just yesterday it did this when it was 30 degrees out. So it seems to me that its opening the idle control valve at first, but just bringing it down right away. Now maybe its important for me to say that when it is idling at 700 just after startup, its idling smooth(regardless of ambient temp); no sputtering or missing that I can feel. (what i'd really like to be able to do is see on a tester that the ambient air temp reading is correct, because I keep feeling that the ambient temp sensor is the most likely issue. I'm thinking that the ambient temp sensor is damaged or just worn out in such a way that causes it to give a reading that the air is warm, regardless what the temp of the air really is; but then if that was the case, wouldn't it idle rough when its idling at 700rpm when its only 30 degrees outside? I can't seem to wrap my head around the fact that it idles smooth at 700rpm in 30 degree weather after cold startup.) Are there any tests that I could do that don't require plugging in a tester (which i have no access to).
I was considering things like:
-unplugging the ambient temp sensor should cause the idle to go higher..
-unplugging the coolant temp sensor should cause the idle to go higher..
yes I realize that both of these things should (and hopefully will) throw the check engine light, but I'm trying to see if there is anything I can do to force the computer to open up that idle control valve, just so I can rule it out? maybe unplugging the map sensor? maybe forcing the egr valve open and see if the computer tries to adjust the idle??
It may be important to note that this truck is almost like brand new. I think I still have the original tires on it from the factory
I bought it from my grandfather, who bought it from a used car shop in PA. The person who owned it before him had some aftermarket pioneer stereo equipment installed. I'm even considering that maybe he had the ecu chipped??
Last edited by drussell4801; Nov 30, 2009 at 11:07 AM.