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1988 tbi 3.9l constant throttle idle surge

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Old 05-22-2010, 04:48 PM
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Default 1988 tbi 3.9l constant throttle idle surge

My roomate recently bought a 1988 dakota with the throttle body injection. Ii had a bunch of vacuum lines that were run wrong and was throwing codes 24(tps) and 52(o2 sensor). Replaced both the o2 sensor and the TPS. Code 54 has since dissapeared but 24 remains. The fuel pressure regulator was connected with a odd looking vacuum line that actually wasnt supplying any vacuum. I found an open port and connected it. At idle and at constant throttle it likes to surge and jerk. If I punch it WOT it will hesitate a little bit at initial throttle then take off like a bat out of hell. Havent checked the fuel pressure yet (15 psi?) since the previous owner said that he has recently put a fuel pump in it. ( He could be bsing us ) Does anyone have a good idea at what this could be?
 
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Old 05-23-2010, 01:11 PM
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Sounds like a vacuum leak.
I will move this to the 1st Generation Dakota Sub-Forum.
 
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Old 05-24-2010, 09:42 PM
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I have since disconnected the MAP vacuum source and disconnected the connector to the Idle throttle control to make a manual idle stop and running the truck in limp mode ( open, closed whatever that is. NOT reading a proper signal from the MAP)

The truck is running very strong, albeit a high idle adjustment.

I will try to change the MAP and hose this weekend.

I would be able to figure this out if it was a ford, just not a chrysler guy. If anyone has any good idea of whats going on ( MAP source interpretation, signal from computer, Anything between the MAP and its surrounding system)
please let me know. The roomie could really use a dependable vehicle for work and I could use a truck for the shop and yard.
 



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