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Dave C
Dodge Dakota
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8/18/2005
15:29:00
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 Subject: My truck is idling too fast..........
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I have a '89 3.9 4WD. When it gets warmed up, it idles way too fast. Sometimes if I "kick" the gas pedal it helps, but most of the time it doesn't help. I have tried turning the "threaded nut" on the adjuster as far down as it will go. But that only seemed to help a tiny bit.
Is there something that I need to clean or replace?
I did a search for this problem, but didn't really find anything other than some things about the IAC (idle control valve) and the throttle body sensor. One of the posts said something about maybe cleaning one of these two parts.
Any ideas would be greatly appreciated.
Thanks,
Dave
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Joe M.
Dodge Dakota
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8/18/2005
16:48:39
|  RE: My truck is idling too fast..........
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a vac. leak could cause poor and or high idle also
and to clean the IAC its easy a torx driver and some carb/choke cleaner
it's located in the back of the TB
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Dave C
Dodge Dakota
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8/18/2005
16:51:35
|  RE: My truck is idling too fast..........
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Thanks, I'll give it a try, and look for some hoses that may have come loose or are split.
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daddio
Dodge Dakota
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8/18/2005
16:59:29
| RE: My truck is idling too fast..........
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i don't think an '89 is MPFI? no IAC.
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Relf
Dodge Dakota
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8/18/2005
17:00:49
| RE: My truck is idling too fast..........
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Dave C, what "threaded nut" on what "adjuster" are you talking about? On the throttle body? Did you just put a V8 throttle body on? If not, what modification did you recently do?
Joe M is right, carefully remove the IAC and get some carb cleaner and a toothbrush and gently clean the plunger thing on it. Be careful and do not press in/pull out on the plunger. Sensitive area! While you are at it, maybe you need to remove the throttle body and clean it all together.
Relf.
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Dave C
Dodge Dakota
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8/18/2005
17:00:59
| RE: My truck is idling too fast..........
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What is MPFI, please?
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Dave C
Dodge Dakota
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8/18/2005
17:04:10
| RE: My truck is idling too fast..........
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There are no mods. Completely stock. The
"adjusting nut" is on the Idle Speed Control Motor. At least that is what they are calling it on the Autozone site.
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cuzindoug
GenIII
8/18/2005
17:05:12
| RE: My truck is idling too fast..........
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Multi-port Fuel Injection, and no on an 89 you wouldn't have it. The high idle is most likely cause by a vaccuum leak, whether it is on the manifold or one of your vaccuum lines is cracked.
If it ain't broke, fix it til it is.
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Dave C
Dodge Dakota
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8/18/2005
17:09:11
| RE: My truck is idling too fast..........
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What is the best way to check for leaks? And which sizes of hose am I looking for?
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cuzindoug
GenIII
8/18/2005
17:27:56
| RE: My truck is idling too fast..........
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The easiest way is to listen for a "hissing" sound under the hood with the engine running. I also heard someone say in the past(I tried it and it works great) is to take a propane torch and attach a length of small diameter tubing to it and just barly crack the valve. Carefully (while the engine is running) pass the tubing close to vaccuum lines and gaskets. If the RPMs change(go up), you have found your leak. For your other question, the vaccuum lines are about the size of 10-12 AWG(gauge wire) or about the size of an individual lead on your basic extension cord. The most likely will be black in color and depending on the age, very brittle due to dry rotting.
If it ain't broke, fix it til it is.
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DaveC
Dodge Dakota
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8/18/2005
18:31:14
|  RE: My truck is idling too fast..........
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Thanks everyone - I'll try all of these and let you know what I find out.
Dave
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Joe M.
Dodge Dakota
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8/18/2005
19:25:39
| RE: My truck is idling too fast..........
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sorry guys didnt know the 89's didnt have an IAC
OK Dave C then yepp move onto checking for a vac. leak the propane torch is the method i use
(un-lit) of course i dont even use a hose on it
just the brass neck, also know of another method
and thats a can of WD-40
but anyway your going to want to go over every vac. hose and your intake (gasket area)
first start by checking the larger ones espec. the one off the power brake canister
with the truck at idle go over them and your listening for a change in the idle
unless your lucky enough to hear a hissing like cuzindoug had said, good luck and give us an update .
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Dave C
Dodge Dakota
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8/18/2005
20:09:22
|  RE: My truck is idling too fast..........
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Stupid question here: I am not real automotively inclined, so I really appreciate all the help you guys (and maybe gals) are giving me. But my question is - why would the engine rev when when the propane or WD-40 finds a leak? I warned you I'm not automotively inclined!!!! Probably a real simple answer that I will kick myself in the butt for.
Thanks,
Dave
P.S. I case you haven't guessed it by now, I don't want to sink a lot of money into this truck. It's got almost 200,000 miles on it. But it is my only way to work and I want to get it running "good" before winter. I may be asking more of you.
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cuzindoug
GenIII
8/18/2005
21:34:41
| RE: My truck is idling too fast..........
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Internal combustion engine:
**(normal)Fuel+Air+Compression+Spark=bang(low idle speed)
**(with propane)Fuel+Air(ladden with an extremely framable gas)+Compression+Spark=BANG!!!
If it ain't broke, fix it til it is.
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Relf
Dodge Dakota
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8/18/2005
23:38:09
| RE: My truck is idling too fast..........
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The way I have checked for a vacuum leak is by spraying a can of carb. cleaner onto the ends of the vacuum lines while the truck is running. When the truck's idle changes, then you have found your leak.
Relf.
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Dave C
Dodge Dakota
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8/22/2005
16:03:59
| RE: My truck is idling too fast..........
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I couldn't find a vacuum leak. By the way, my truck does have a IAC. I think I will try to take it loose and clean it. I also read somewhere that it could be the EGR valve? Possible?
Thanks,
Dave
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cuzindoug
GenIII
8/22/2005
17:52:06
| RE: My truck is idling too fast..........
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You truck is TBI correct?(Throttle body injected)
If yes, you do have one, but I think it is one of the gear driven type. You could try cleaning it, but be careful not to damage it...I think they are about $100 last time I checked. It could also be an EGR related problem like you read, they run off vaccuum as well.
If it ain't broke, fix it til it is.
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Dave C
Dodge Dakota
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8/22/2005
18:39:50
| RE: My truck is idling too fast..........
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Maybe what I will do this weekend or before, is take some digitals of various parts of my engine and show them to you. THat might help.
Thanks for your help so far.
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thomas
Dodge Dakota
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8/23/2005
22:03:38
|  RE: My truck is idling too fast..........
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hey man i had a car that idle up to like 4 or 5 grand and i didnt know so i got it fixed and 4 or 5 sensors blew or shorted out and that could have caused a problem
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93dak4x4
Dodge Dakota
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8/23/2005
22:18:52
| RE: My truck is idling too fast..........
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Just some general knowledge here. Any vehicle that is fuel injected will have an IAC unit. It is the only way the computer can make the vehicle idle under varying weather conditions. Your high idle is most likely the IAC or like they said a vacuum leak. The Egr valve, I am skepticle about that being the culprit but I would try playing with that as well. Good luck
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