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Roughly a month ago our Dakota started running very bad. How bad? Really bad a couple of tanks gave 7.5 mpg.
Codes for bad crank position sensor followed by bad cam position sensor. Once the new cam and crank sensors were synchronized we got a low voltage, charging issue. New alternator and still a running issue but not as bad as before. Then another Evap leak which makes 11 hoses and fittings replaced. All codes cleared and running great most of the time. The running issue remained without a code. Shifting from 4th to 5th at 65/70 mph would start the truck to lunging like power on and off. After a visit to a Diagnostic center and hearing we will be able to tell you what's wrong for no more than $260. which won't include parts or repair I decided to push on. Reading everything I could about the systems and issues I developed a theory. A old racer I change one thing at a time so I'll know what worked. I ordered new TPS and MAP
sensors. I installed the TPS first and the truck ran great for three days. Then just like many times before the issue showed up again in the same location under the same conditions. OK, next I added the new MAP and have spent a full day without any running issue. I plan to replace the idle air and intake air temp sensors not because I have a running issue but each sensor removed appears to have been there since 2003. Steve
 

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Roughly a month ago our Dakota started running very bad. How bad? Really bad a couple of tanks gave 7.5 mpg.
Codes for bad crank position sensor followed by bad cam position sensor. Once the new cam and crank sensors were synchronized we got a low voltage, charging issue. New alternator and still a running issue but not as bad as before. Then another Evap leak which makes 11 hoses and fittings replaced. All codes cleared and running great most of the time. The running issue remained without a code. Shifting from 4th to 5th at 65/70 mph would start the truck to lunging like power on and off. After a visit to a Diagnostic center and hearing we will be able to tell you what's wrong for no more than $260. which won't include parts or repair I decided to push on. Reading everything I could about the systems and issues I developed a theory. A old racer I change one thing at a time so I'll know what worked. I ordered new TPS and MAP
sensors. I installed the TPS first and the truck ran great for three days. Then just like many times before the issue showed up again in the same location under the same conditions. OK, next I added the new MAP and have spent a full day without any running issue. I plan to replace the idle air and intake air temp sensors not because I have a running issue but each sensor removed appears to have been there since 2003. Steve
Well as we all nothing is as easy as it should be. Last night I decided to take the truck out and run it hard. Still running great and as smooth in each gear as good or better than since owning the truck. Parking in front of te house I noticed a new check engine code. Pulling the codes showed a P0300 and P 0303 a random misfire #3.I have no problem pulling a plug for a look. Compression test, leak down test a check of one year old wires, cap and rotor. I guess I should check the injector. And this brings me back to my eariler question about upgraded ignition coils. The other thing I'm interested in seeing if our repairs to the vacuum /evap system will reduce oil burning. OK, I read it on the net must be true. I'm trying to share, knowing how a running issue can mess up your day. Steve
 

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Well as we all nothing is as easy as it should be. Last night I decided to take the truck out and run it hard. Still running great and as smooth in each gear as good or better than since owning the truck. Parking in front of te house I noticed a new check engine code. Pulling the codes showed a P0300 and P 0303 a random misfire #3.I have no problem pulling a plug for a look. Compression test, leak down test a check of one year old wires, cap and rotor. I guess I should check the injector. And this brings me back to my eariler question about upgraded ignition coils. The other thing I'm interested in seeing if our repairs to the vacuum /evap system will reduce oil burning. OK, I read it on the net must be true. I'm trying to share, knowing how a running issue can mess up your day. Steve
Got to love it, riding around today I noticed the check engine light has gone off. Steve
 

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I did a oil change today and cleared the P0300 & P0303 which showed up right after changing my MAP. The check engine light went out and I wonder if that means it has no happened again and may not. Seems 303 is a popular code for these engines. Also today I was in touch with the Rostra cruise control people and they do have a correct kit for the 03 3.9 5 speed floor shift. Comes with a matching control arm mounting below the turn signal stalk. and the clutch kill switch. I'm seriously looking forward to this. I will report back it should arrive the first of the week. Steve
 

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I did a oil change today and cleared the P0300 & P0303 which showed up right after changing my MAP. The check engine light went out and I wonder if that means it has no happened again and may not. Seems 303 is a popular code for these engines. Also today I was in touch with the Rostra cruise control people and they do have a correct kit for the 03 3.9 5 speed floor shift. Comes with a matching control arm mounting below the turn signal stalk. and the clutch kill switch. I'm seriously looking forward to this. I will report back it should arrive the first of the week. Steve
It just gets better. it seems my cruise control order got lost and was never billed to my account. Just as well after two days of running great the idle had gone high. 1500 or 2000 rpm. Wait awhile and it will drop very slowly to 500. What the heck I replaced a very coked up IAC valve with new. I'm not sure it was a cure. Waiting for intake air temp and coolant temp senders. Once all in and checked I'll let them put it on a machine and tell me whats next. I'll reconnect with the Cruise people when I have it by the tail. Steve
 

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The new idle air valve did nothing to correct idle issue. Still crank up and tach runs up to 2000 or 1500. Turning off the AC lets it drop a few RPM which leads me to believe the PCM is sending info to the idle control valve. If you wait long enough the idle will drop back to 650 or there about. but give it a little pedal and right back up to 1500/2000. My water temp sender is lost in the mail. I took it to a shop and they don't want the job. Vacuum leak??? Steve
 

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Latest update, normal driving and highway she is running fine. The idle is still all over the place but mostly 1500/2000. It had been suggested to me to suck Sea Foam into the intake via a vacuum line and allow to stay after shutting down the engine.This has not been done even with several people telling me it's normal. I also was told to clean the throttle body. Just for the fun of it I removed the air cleaner and opened the throttle plates and cleaned from the top as well as possible. It is clear there is a lot of crap in there. While it did not clear the high idle problem on a ride around it now returns to 650 about half the time. Oh yeah, before cleaning such as it was I cranked up and right to 2000 RPM and I sprayed starter fluid all around the intake and hose connections. No change in running at all. Right after adding the new idle air control I got a P0305 code and the light went out within 12 hours.

I'm looking at an 03 Dakota, extended cab, 3.9 V6, 2 wd, 5 speed with 50,000 fewer miles. When I bought the current truck I replaced upper and lower front control arms. Hubs, everything brakes at all four corners. Everything AC related that could be gotten to without pulling the dash. Every vacuum hose and some twice. My 20 year old son uses the truck to haul his tuba and his sister's French Horn to music. They are both members of a local large stage band doing big band and pop. They are also members of the Orchestra so I'll let them have one and I'll keep one. Should be able to keep one going that way. Steve
 

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"It is clear there is a lot of crap in there".

If I were a betting man, I'd bet the plenum gasket is blown, allowing it to suck air and oil in.

RwP
 

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Discussion Starter #9
Thank you, wondering if I was here by myself. Sounds like it's time to pick up that spare power unit. I can remove the intake and throttle body do a mod on the intake and send out the throttle body for an upgrade. Once done I can make the swap. I don't like having my ride down for long. My Classic Mini resto shop is only 5500 sq ft. and this truck takes up to much room. Lots to do. Steve
 
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