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  #1  
Old 04-28-2005, 09:36 PM
engineer_comp_geek engineer_comp_geek is online now
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truck idling too low and stalling

I have a 95 Dodge Dakota pickup truck that is idling too low and tends to stall a lot when coming to a stop. If it were slightly older I could just turn the idle set screw up a bit and call it a day, but since it's computer controlled there isn't an idle set screw on the throttle. Is there any relatively easy way to make this thing idle a little faster? It idles around 250-300 rpm (according to the tach) and idles a bit rough, and if I give it just a little gas it runs smooth at about 400-500 rpm.

Otherwise, it runs ok and has plenty of power. This problem showed up after the stuff inside the catalytic converter came apart and was rattling around and blocking the exhaust. I thought the stalling was just due to the exhaust being blocked, but I had the catalytic converter replaced and it still idles too low and stalls (the engine was starved for power though, and replacing the catalytic converter did fix that).

It's an old beater truck with a hundred and plenty thousand miles on it, and I just use it to go to Lowe's and get stuff that won't fit in the car, and to get to work on snowy days. I'd rather not put a lot of money in it, so I'm looking for a cheap, quick, and dirty fix if at all possible.
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  #2  
Old 04-28-2005, 10:15 PM
Gary T Gary T is offline
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There's a reasonable chance that cleaning the throttle body will help. This site has good instructions: http://www.allpar.com/fix/throttlebodycleaning.html
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  #3  
Old 04-29-2005, 03:10 AM
DougC DougC is offline
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- - - For the most part, modern computerized auto engines don't need to have their idles manually adjusted. Idling too low is often caused by a dirty air filter (8$) or fuel filter ($4).
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Old 04-29-2005, 06:11 AM
Gary T Gary T is offline
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Sorry, Doug, gotta disagree. Long before an air or fuel filter would even marginally affect idle speed, it would dramatically reduce power under acceleration. And while many fuel filters for carbureted engines might be around that price, I wouldn't expect to find one for a fuel injected vehicle that cheap.
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Old 04-29-2005, 09:49 PM
engineer_comp_geek engineer_comp_geek is online now
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After driving around for a couple of hours today the check engine light came on (this is the first time it's ever come on). When I got home I checked the computer code, and it gave me a fault code of 32, which in my Haynes manual has the description of "EGR system."

According to Haynes, the EGR system consists of the EGR valve, transducer, and solenoid. My Haynes manual also has the following paragraph:

"Symptoms of problems associated with the EGR system are rough idling or stalling, rough engine performance during light throttle applications, and stalling during deceleration."

Yep, that sounds exactly like the problem. I wonder why the stupid check engine light hasn't come on before now. Oh well, at least now I know where the problem is.

The book also has about half a page devoted to how to figure out which component is bad. It looks to be fairly simple.

Thanks for the replies.
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Old 04-29-2005, 10:26 PM
danceswithcats danceswithcats is offline
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If you'd like some help with the repair, send me an email-c'mon up to the hills. Glad to assist.
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  #7  
Old 04-30-2005, 06:32 AM
wheelie wheelie is offline
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Quote:
Originally Posted by DougC
- - - For the most part, modern computerized auto engines don't need to have their idles manually adjusted. Idling too low is often caused by a dirty air filter (8$) or fuel filter ($4).
~
I priced a fuel filter for my '94 Dodge Ram once, it was $170 from the dealer. It's part of the fuel pressure regulator and lives inside the tank. I got the whole pump assy, including regulator & filter, aftermarket for the same price. I'll never do that job myself again!
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  #8  
Old 04-30-2005, 11:25 AM
Gary T Gary T is offline
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Quote:
Originally Posted by engineer_comp_geek
I wonder why the stupid check engine light hasn't come on before now. Oh well, at least now I know where the problem is.
Maybe. Maybe not.

That code 32 may relate to low EGR flow and have nothing to do with the low idle speed and stalling. It may not have come on before because the conditions to set it weren't present before, those conditions not being the other symptoms you mentioned.

Both the poor idling and the code 32 might have been ultimately caused by buildup of carbon deposits in the throttle body and EGR tube, respectively.

Or might not. It could be that the EGR valve is hanging open and affecting the idle -- just don't count on a code to reliably tell you what the problem is, or even what area it's in. Sometimes they do, sometimes they don't.
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Old 04-30-2005, 02:44 PM
Eleusis Eleusis is offline
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I'm definitely not an expert on these things, but when I had these symptoms once, it was the oxygen sensor.
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  #10  
Old 04-30-2005, 05:36 PM
Tuckerfan Tuckerfan is offline
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I had a Ford Ranger with nearly identical problems, it turned out that the throttle cable had too much slack in it. Tightening it up fixed the problem. How I figured it out was I noticed that when I pressed on the accelerator, it didn't respond until the pedal had traveled a certain distance.
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  #11  
Old 05-01-2005, 07:22 AM
enipla enipla is offline
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I had a similar problem with my '93 Pathfinder. My air cleaner box had come loose and dirty air got to my oxygen senser.

Aparently, there is a secondary filter in front of the O2 senser, and that got clogged. Once that was cleaned up, it ran like a charm.
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  #12  
Old 05-01-2005, 08:11 PM
engineer_comp_geek engineer_comp_geek is online now
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Quote:
Originally Posted by Gary T
Maybe. Maybe not.
Good point. Personally I'm leaning towards the EGR valve being mucked up since this fits in with the earlier problem of the catalytic converter self destructing. I'm thinking that the excess exhaust pressure probably mucked up the EGR valve. But I'll definately keep an open mind going into it.

Throttle cable: Definately not. This is ok.

O2 sensor: Possibly.

Quote:
Originally Posted by danceswithcats
If you'd like some help with the repair, send me an email-c'mon up to the hills. Glad to assist.
What are you doing next weekend?
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  #13  
Old 05-01-2005, 11:50 PM
danceswithcats danceswithcats is offline
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Nothing planned at present-shoot me an email-we can exchange phone numbers and go from there.
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Old 05-07-2005, 10:01 PM
engineer_comp_geek engineer_comp_geek is online now
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It turns out that the EGR transducer was majorly hosed. My best guess is that the exhaust pressure (from the catalytic converter being mucked up) caused the feed tube into the transducer to burst, and the resulting stream of hot exhaust just cut through the bottom of the transducer. That's what it looked like anyway, just lots of melted plastic.

Thanks to all who helped and gave suggestions, especially danceswithcats for helping with the actual repair.
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  #15  
Old 05-07-2005, 10:57 PM
Jake4 Jake4 is offline
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Since the problem's fixed, I've got a similar situation. What does it mean if your 86 Olds Cutlass starts up the first time you turn the key but promptly dies, requiring more key turning and gas? Then when you get to the first traffic light and begin to accelerate, the engine sometimes stalls, and when you press the accelerator just a little bit, it seems as if the fuel flow goes down relative to the idle, rather than up.
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  #16  
Old 05-01-2014, 08:31 PM
silver jet silver jet is offline
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my 77 GMC won't idle

I recently bought a 77 GMC 4x4. Now it won't idle. At first it would idle Ok but seemed slow. Then just once in a while it would die when I'd stop at a light, but would start right back up. If I put it in neutral or park it would idle. But now it won't even idle when it's first started.
Any ideas folks?
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  #17  
Old 05-01-2014, 11:58 PM
Ranger Jeff Ranger Jeff is offline
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Replace the fuel filter. Even if it doesn't fix the problem, it couldn't hurt. And it's the sort of thing people ignore until the vehicle stalls out on you.
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  #18  
Old 05-02-2014, 12:41 AM
engineer_comp_geek engineer_comp_geek is online now
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Man, sometimes I hate it when these old threads are resurrected. RIP Paul.

Anyway, a blockage could cause those symptoms. I would start by checking the fuel filter and air filter. If they haven't been changed in a while it might be a good idea just to change them anyway even if they aren't the problem.

You can usually hear an exhaust blockage, at least I could every time I had one. You can hear the constricted air whistling. Of course this would require someone inside the truck to press on the accelerator enough to keep it running while you stand outside and listen. 77 was one of the first years to have a catalytic converter, wasn't it? My truck's problems (mentioned in the OP of this thread) really started with an old catalytic converter that corroded inside and came apart, causing an exhaust blockage.

How old are the spark plug wires? A weak coil or bad wires can cause problems like this. An easy way to test the wires is t wait until dusk and open the hood and spray some water from a mist bottle (an old windex bottle or something similar). If you see a fancy light show then the wires are shot.

A 77 has a carburetor, doesn't it? That could be causing you all kinds of problems. It might just be gummed up, in which case taking it apart and spraying it with carb cleaner could do wonders. It could also have a choke problem or a float problem or all kinds of things.
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