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rpmdiag, Tech and Instructor
Category: Dodge
Satisfied Customers: 8065
Experience:  Since 1975
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I have a 02 Dakota with the 3.9 that after it warms up, it

Customer Question

I have a 02 Dakota with the 3.9 that after it warms up, it will not go over 40mph. When in neutral, it will not go over 2000 rpm. On live data stream, the only red is "1/1 adap mem factor" is between -9 and -15%
Submitted: 1 year ago.
Category: Dodge
Expert:  rpmdiag replied 1 year ago.

Hi, I’m Ron and I can help you.
I have been in this business since 1975 and also teach automotive repair. I am confident we can resolve your problem together. Please understand that I don't know your skill level. I can't see, smell, hear, or touch the vehicle either, so it may take a few replies to get to satisfactory results. Please be patient!
I also try to give all of the information you may need, expecting a “positive rating” in return. I will also continue assisting you after you have rated me, if necessary. If there is any reason I cannot get a positive rating, please let me know why “in advance”, so I can go another direction for you. I am sorry you’re having this problem; I’ll help you through it.

In this scenario, you need to check the MAF sensor for contamination, check fuel pressure and volume with a gauge and check for a restricted exhaust system like a plugged CAT.

Thanks, Ron

Customer: replied 1 year ago.
Well, there is no MAF the fuel pressure was constant at 55psi regardless of idle or stumble and upstream and downstream o2's are cycling like they should.
Customer: replied 1 year ago.
Drivers side exhaust above cat 1is 385 below is 300 pass exhaust above cat is 250 below is 185
Customer: replied 1 year ago.
What does the 1/1 adap mem factor being negative mean?
Expert:  rpmdiag replied 1 year ago.

It's subtracting fuel because it's too rich. I forgot this did not have a maf, sorry.

Pull a plug or 2 and see if they are black.


Expert:  rpmdiag replied 1 year ago.

If it's running that rich and the exhaust if free fliwing, then you m ay have jumped timing.

Please don't forget to rate me too, and keep this link for future reference for us.

Customer: replied 1 year ago.
As far as jumping timing, will that cause it to run ok cold and then poorly when warmed up?
Expert:  rpmdiag replied 1 year ago.

It can