Birty Dastards Jeep Club

Tech Forum => Workshop => Topic started by: mr s on January 06, 2011, 09:00:27 PM

Title: Gearbox?
Post by: mr s on January 06, 2011, 09:00:27 PM

Hi all, I'm afraid I need to pick your collective brains.

I've had my Cherokee for about 3 months now and I think I'm getting the bug; expect questions on springs & lift kits very soon!

First though I need to get this little niggle sorted.  The car is a 97 XJ 4ltr auto with 86k.  The car drives well and changes through the gears smoothly but there seems to be a heat related issue with the gearbox.  When the car has been at operating temperature for say 20 minutes or so I've noticed that it will not rev past 3k when in gear, even at full throttle.  It doesn't seem down on power, from a full throttle standing start it races to 3k then changes, it's almost like the 'redline' has been electronically adjusted.  Likewise this has affected the kickdown; flooring the throttle at say 35mph when cold results in a downshift and hard acceleration, however with the engine hot the car still goes, but does not change down.

At the moment by money is on some sort of engine speed sensor issue (does that exist?) or (god forbid) and ECU problem.  As I've said before, the engine doesn't seem down on power at all.  The only other bit of info i can supply is that the engine revs happily to the redline when out of gear, even when hot.

If anyone has any ideas or solutions I'd love to hear from you.  I should add that i don't make a habit of hard driving but there are occasions when I've needed the extra oomf :jump_125:

Title: Re: Gearbox?
Post by: Dave69 on January 06, 2011, 09:31:14 PM

disconnect battery  for 10 mins to allow the ecu to reset as an initial cheap test.

have you checked the level of the gearbox oil ?  

Title: Re: Gearbox?
Post by: mr s on January 06, 2011, 09:42:38 PM

Hi Dave, thanks for the tip, I'll give that a try at the weekend.  I've checked fluids and everything looks fine.

Title: Re: Gearbox?
Post by: mr s on February 21, 2011, 09:54:25 PM

Little update on this topic.  Been a little busy of late with a tempremental MX5 so I only managed to take the battery off this weekend.  Left it off for a good half hour to be safe and, fingers crossed, it seems to have sorted the issue.  Not only has the main bugbear gone (so far so good) but the shift points in general seem better.

Incidentally i noticed that the retaining nut on the battery wasn't metric (12mm to small, 13mm too big).  Am i likely to find this a lot on the car & if so what do i need to by buying?

Title: Re: Gearbox?
Post by: Bishops Finger on February 21, 2011, 10:10:46 PM

Replacement nut...?

Title: Re: Gearbox?
Post by: mr s on February 21, 2011, 10:35:32 PM

I was thinking more along the lines of imperial spanners but i guess i asked for that lol

Title: Re: Gearbox?
Post by: JamesH on February 22, 2011, 08:54:40 AM

You need a full set of imperial and metric to work on an XJ - the joy  :icon_rolleyes: