Cold Weather.. High Idle
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Cold Weather.. High Idle
Alright so since the cold weather rolled in the Bronc has been idling very high, around 1500 rpm. Before this cold snap it was idling around 6-800 rpm. Seems to be happening when the temps are down in the 20s.
The annoying part are the hard slams when I put it in drive/reverse from the high idle, but also that if I am cruising around 35-40 mph and let off the gas to coast it will then give a pulsing variance in rpms from 1000 to 1500.
Any ideas? Thanks!
The annoying part are the hard slams when I put it in drive/reverse from the high idle, but also that if I am cruising around 35-40 mph and let off the gas to coast it will then give a pulsing variance in rpms from 1000 to 1500.
Any ideas? Thanks!
Hotshot
Joined: Jul 2002
Posts: 14,285
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From: Bend,OR
are you letting the truck warm up good before you drive off? also do you have the antifreeze lines running to the throttlebody? if not you may have a tb that is sticking open due to the cold. I would pull codes
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Yes, I have been letting it warm up, the other day it backed down once the truck was good and hot, yesterday it did it all the time (although i never made any long trips)
I don't recall ever putting any antifreeze lines to the throttlebody when I rebuilt this engine, is that a standard setup on these engines?
Thanks for the help
I don't recall ever putting any antifreeze lines to the throttlebody when I rebuilt this engine, is that a standard setup on these engines?
Thanks for the help
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Ok I'm dumb - I went out and looked and there is a line running from the radiator to the throttle body, however even after running the engine to operating temperature that line was not really hot at all- coolant level is fine - is this typical?
Hotshot
Joined: Jul 2002
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From: Bend,OR
i wonder if that line isnt ran properly by chance. can you blip the throttle to make the rpms drop by chance? what temp Tstat did you install?
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Yes I can, like i said in the original post it hasn't been a problem until about three days ago when the temps dropped. Before that it had always idled fine, no problem like this. That line doesn't look like it could go any other way, so I'm not quite sure that it could be in improperly.
I am wondering though whether drunkdave may have had it right originally though on the vacuum leak idea as that is exactly how it acts, not so much a stuck throttle. A hard plastic line could have gotten brittle in the weather and snapped in the past couple days - this thing hasn't been driven in years. I think this weekend I will do some further searching around under the hood to see if there isn't a leak somewhere.
I am wondering though whether drunkdave may have had it right originally though on the vacuum leak idea as that is exactly how it acts, not so much a stuck throttle. A hard plastic line could have gotten brittle in the weather and snapped in the past couple days - this thing hasn't been driven in years. I think this weekend I will do some further searching around under the hood to see if there isn't a leak somewhere.
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From: Gateway to the West
The coolant line to/from the throttle body RETURNS coolant via the bottom hose to a point on the radiator just below the cap. However, the feed for the TB comes off a barb near the water neck If I am remembering correctly. Might want to make sure both lines are warming up.
The vacuum leak is the most obvious thing and with the hard plastic lines in some areas, they are adversely affected by the cold after a few years.
The vacuum leak is the most obvious thing and with the hard plastic lines in some areas, they are adversely affected by the cold after a few years.
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Alright so it turns out the cold weather just happened to hit as this problem became noticeable.. no relationship. I got the codes using the flashing check engine light method and got two codes concerning the tps. I replaced it today and bam.. like a new truck. The RPM fluctuations are gone.. and no more slamming into gear. Also no more sluggish starts off the line... a problem that I didn't even think was related. Amazing how much effect that one sensor has on an engine.
While I had the throttle body off I also cleaned that coolant tube as it didn't look like much was getting through there. Thanks for the heads up on that.
Thanks for the help.
While I had the throttle body off I also cleaned that coolant tube as it didn't look like much was getting through there. Thanks for the heads up on that.
Thanks for the help.
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