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-   -   Transmission Double Downshifting (http://www.jeepgarage.org/f203/transmission-double-downshifting-40338.html)

DrLocke 04-05-2012 11:14 PM

Transmission Double Downshifting
 
Hey Jeep guys...
I just replaced my radiator in my '04 WJ I6 and decided to take trip to Payson. It is a 75 mile trip mostly up hill from my house in Mesa, AZ. I was checking the temp for possible air contamination. (the old story)
I had cuise set at 60 and would take it out of O/D when it would downshift. On steep hills it would double downshift and the RPM would shoot up to 5k before I had a chance to take it out of O/D.
Any idea what could be the solution to a more civilized downshift?
Also while I have you on the line...my mpg was 17.2 on the way up (understandable while going up hill) and 19 on the way down. I used to get better gas mileage. Any mileage solutions?
Thanks.

01grand 04-06-2012 10:18 AM

Re: Transmission Double Downshifting
 
Could need an intake cleanup to help with the mileage, or new O2 sensors. Mileage is such a subjective thing though, so many different factors can play into it.

As far as the downshifting on cruise I remember my old 4.0L ZJ would do that and I never really tried to do anything about it. I always thought it was a combo of the smaller engine/transmission and cruise control not reacting quickly but steadily, it seemed like cruise would "stomp on it" causing it to downshift sharply momentarily. Lol not sure if I made much sense here but hopefully this helps somewhat, maybe someone else will chime in with a solution.

JeepMe 04-06-2012 05:33 PM

Re: Transmission Double Downshifting
 
I think that's a pretty normal action for the tranny behind the 4.0L engine. Mine does that when it's on cruise control, but a normal civilized downshift when I'm controlling the throttle.

I believe that the top of 2nd is right around 45-50, so you were 10-15 mph below the set cruise control level and it's trying to make that up.

cheapjeep 04-06-2012 09:06 PM

Re: Transmission Double Downshifting
 
Yep Doc 4.0,cruise and especially overdrive don't go together in the hills.

DrLocke 04-07-2012 08:54 AM

Re: Transmission Double Downshifting
 
Thanks for all your replies. After driving with a leaking radiator for over a month I was glad to be able to make a longer trip. It is great to be able to relax and not worry about being stranded or worse.
I will be cleaning my TB next time I have time to dive into the engine.
Sea Foam sounds like fun. I don't know if my neighbors would share my enthusiasum. lol


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