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Ken
Dodge Dakota
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4/06/2005
19:01:23
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 Subject: High idle on 87 Dakota 3.9
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Message:
Hi,
I have a recently (total) rebuilt 3.9/w carb. Brand new everything. New carb, alternator, starter, battery, just about everything bolt on is new.
The mechanic who did the work tried a couple times to get it to pass smog, but replaced the carb after failing. (I suspect he even cheated n the smog test in some way to get it to pass, though I was not privy to this information)
My issue is with the idle speed. I dont have a tach in my truck to see what it idles at, but it seems way too high and I know its killing my gas mileage, and at 2.60 a gallon for unleaded, mileage per gallon becomes priority.
The set idle screw on the carb is all the way out so I cannot adjust the idle down anymore. Theres another large straight slotted set screw on the front side of where the throttle sits on the carb that I believe is the idle down control. As it is, the setting is almost completely turned to the right (counter clockwise). Will adjusting this in affect the idle speed?
It also diesels randomly when I shut the motor off, the only constant is that the engine has been running for w while, hot and cold weather.
One other thing, on the driver side exaust manifold, there is some sort of ?valve? that sort of pops out from the exaust and has a spring for returning to position. Is this part of the smog hardware, some sort of emmissions return? Would this overtly effect my idle?
Please email me with info: cochino1@hotmail.com
Thanks in advance.
Ken
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vern
Dodge Dakota
JOIN HERE
4/06/2005
20:10:51
|  RE: High idle on 87 Dakota 3.9
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Message:
Ken does it have a electric idle solinoid?[i don,t remember]see if thats working
check for vaccuum leaks,hoses,gasket under carb,loose carb bolts
in the front of carb,down on the very lower part of the carb are two plugs that can be removed[not easily most of the time]sometimes you can drill these out,just go slow and easy,
behind these plugs should be two jets that can be adjusted,these adjust air/fuel ratio
this is the only things i can think of
good luck
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Ken
Dodge Dakota
JOIN HERE
4/06/2005
20:33:14
| RE: High idle on 87 Dakota 3.9
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Message:
The solenoid you spoke of, does it have a plunger that is depressed by the throttle linkage? The adjustment screw, I believe sets the distance the plunger sticks out...
If thats what you are refering to, then yes, I have one.
Any ideas on what the thing is on my exaust manifold?
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87 4x4 dak
Dodge Dakota
JOIN HERE
4/06/2005
22:03:04
| RE: High idle on 87 Dakota 3.9
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Message:
Im just curious, what happens to the idle speed when you unplug the pcv valve? Does it stay the same or does it go down noticibly. The base idle on 87s is supposed to be set with the pcv valve unpluged, and I believe the vacume line that goes into the computer should be unplugged. On my 87 having the PCV valve unplugged is a big difference in RPM. If with these items unplugged the idle speed is correct then I dont think the carb is the problem, although I absolutly hate the carb on my 87, they should have made the first year with TBI.
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geobar
Dodge Dakota
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4/07/2005
15:49:27
| RE: High idle on 87 Dakota 3.9
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Message:
The high idle and dieseling are symptoms of a very lean gas/air mix most likely due to a vacuum leak, but also could be a carb mixture adjustment.
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Bob Lincoln
Dodge Dakota
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4/07/2005
16:02:48
| RE: High idle on 87 Dakota 3.9
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Message:
The thing in your exhaust manifold is the heat riser valve, which assists in heating the intake manifold when engine is cold, by directing exhaust gases through a passage across it. It isn't causing your problem.
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Ken
Dodge Dakota
JOIN HERE
4/09/2005
17:38:56
| RE: High idle on 87 Dakota 3.9
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Message:
Any suggestions on which vacuum lines to check first?
I'm pretty much a novice when it comes to anything water cooled. I'm a VW gearhead, and most PICT carbs on vw's have either 1, 2 or no vacuum lines :D
Another thing, my truck originally had problems passing smog (I live in CA). I know there are tricks mechanics use to coax a vehicle into being able to pass.
Are there certain things I should consider trying to correct my high idle issues?
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Ken
Dodge Dakota
JOIN HERE
4/09/2005
17:39:52
| RE: High idle on 87 Dakota 3.9
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Message:
Besides the vacuum lines, that is. heh
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