Rough idle and stopping

Asked by Mar 02, 2017 at 09:25 PM about the 1989 Dodge Dakota

Question type: Maintenance & Repair

I have a 1989 dodge Dakota 3.9 v6.  I am
having issues with idle and stopping.  It idles
very low in park or neutral but when I out it in
reverse or drive it wants to sputter and die.  
Also loses power while driving.  Have to
feather pedal at stop sings and lights to
keep running.  I replaced idle speed control
motor, throttle position sensor,  replaced all
vacumn lines,  and removed cat converter
and straight piped it.  No change at all.  I had
about 1/4 tank of gas and I filled it back up
and it ran fine. When I got back down to 1/4
of a tank again problem started back up so I
figured maybe a bad tank of gas.  So I filled
it back up and put a bottle of heet in it and
no change at all.  Any suggestions will help.

18 Answers

72,235

Should check the fuel pressure, may have a bad fuel regulator or fuel pump. Sounds like a fuel regulator to me, but I like doing some testing before putting forth money into it.

1,595

could be vapor lock , as you use the gas in the tank the volume needs to be replaced with air , I guess loosen the cap to see if it makes a difference , Spray some carb. cleaner down the throttle body that can help , see if there's any codes , let us know what happens

No check engine light showing so can't read codes it did it for a while then put new gas in with a fuel treatment then started again drives fine going down the road but in idle and stopping no luck

72,235

Driving good down the road, then it is not a fuel regulator or fuel pump. The idle air valve and port in the throttle body may need a good cleaning.

72,235

Also there is a idle speed control motor on there. Should look at that.

I replaced the idle speed control motor just released gas cap and No change

Sometimes going down the road it will lose power like something is clogged have to release pedal and push again

72,235

Oh, I see you replaced the ISCM, sorry, but check out that Idle Air Control Valve. It is best to take it out, and clean that port. Best to take the throttle body off to do this. Probably just replace it, but it is important to do a good job cleaning out that port. And the red bottle of Heat is what you want to use for moister in the gas. Not the yellow bottle.

I used the red bottle yesterday I made sure all battery cables were tight

72,235

Idle Air Control Valve needs to be looked at.

If I unplug the idle speed control motor it idles fine but does the same with starting and stopping where is the valve located google didn't show much in pictures

72,235

It should be around the throttle body. This is what it looks like..... https://www.carid.com/crown/idle-air-control-motor-mpn-83502375.html?singleid=293752923&url=731374

I replaced that bran new (idle speed control motor)

72,235

https://www.carid.com/standard/tru-tech-idle-speed-control-motor-mpn-sa4t.html?singleid=23790156&url=731374

Yes all is bran new

72,235

Ok then, another cause would be the EGR system, or the air injection pump system.

72,235

The EGR Valve can affect the way it idles and make it die. If the EGR is all carbon up not allowing the pentel to close it would idle rough and can make the engine die. If the EGR is good and all related parts, then it is just a matter of taking it off and cleaning the Valve and the port it sits on of the carbon deposits. You may need a vacuum pump to see if the EGR is good or not.

Ok will check it

Your Answer

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