eng lost power at intersection, rpm wont go above idle 500 rpm. disconnected battery thinking computer would clear itself and run normally. no luck. please help
I think I saw fail safe mode light on dash
eng starts most of time but wont rev at all.
scanner shows tps to be workibg.
I feel like the problem is in the computer system somewhere. please help, thanks Ralph

 

Certainly sounds like failsafe mode. You said the scanner shows the TPS to be working, but that doesn't preclude it from tripping somewhere (fighting the same myself). Were you able to scan to see if there were any codes stored? Not sure if the tool you has can, but if so, it might help. The fact that a battery reset didn't clear it, makes it sound like something is certainly out of whack, but you would normally expect some codes to be thrown to give a hint.

 

First thing that came to mind was throttle body. You'll have to pull the intake tube off and with key on/engine off, have someone floor the gas pedal and see if the butterfly valve opens up. When the key is on, can you hear a humming noise coming from the TB? When turning the key off, it'll do a open/close test. If it's unresponsive, you may need to check for a blown fuse first. I know there's a dedicated TB relay so there's a fuse somewhere. The fuse however, may be shared with something else.

 

It has a mechanical cable and throttle shaft which appears to turn properly from the outside

 

Is there any way to reset fail safe mode?

 

Yes - fix whatever is causing it. Otherwise, not really and anyway you might destroy engine/etc.

 

I have no codes, how can it recode itself if it wont rev up?, just sitting and idling?
thanks Ralph

 

Disconnecting the battery may have been a mistake as you lost data you may need. Car now probably has unset monitors and may well be in Catch-22 where it can't set codes due to unset monitors and can't set those due to fault(s).

 

Agreed- Does any one Know how or what is required to reset the computer from this condition???
thanks Ralph

 

It can be hard, since the whole idea is not to cause it. If you check sensors for plausibility, check which OBD monitors are unset and try to figure/guess why (refer to drive cycle etc for clues), and so on, with effort and maybe some luck you can perhaps get it happy again. If not, consider a jag expert (indy) as not only should they know the cars intimately but also have in-depth diagnostic & test gear.

 

Thanks Jagv8

 

This seem to be a real challenge to deal with..


If you saw the fail safe message on the dash, that obviously means that the car is protecting itself from getting something seriously damaged, the engine or the automatic gearbox.. nothing else really.


Since it happend suddenly and without warning, my Money would be on a "loss of imput" somewhere.. I would have checked the main connectors to the gearbox and engine, throttlebody, airsensor and VVT's..


What did you do just prior to the problem? Braking or accelerating?


Any previous faulthistory in this matter?


Any meintenance that have been done recently?


/E

 

Thanks Einhead, it was braking slowly to a stop at a red light on a hot day, no maintence recently, trans code shift sol about 1 yr ago, solinoid replaced, no prob since then.
prob will tow to dlr for diag tomorrow
thanks for your help
ralph