Loses all power when uphill/overtaking

[Mattyjee]

Hello crew,

I've had a long standing issue with my CRD JK Wrangler which is slowly getting worse. I've searched and found nothing, hope someone can help.

When driving for at least half an hour or so, if I need to gun it to get up a steep hill, or overtake at speed, my Jeep cuts out and loses all power (to idle). If I back off on the throttle to idle, then after 10 seconds or so it will allow me to go again, but I have to go easy on the throttle or it will do it again. It only does it when the engine is hot such as after a country drive, I struggle to replicate the issue in the city.

I've had a turbo hose blow before, and the loss of power feeling is very similar.

I don't get a fault code when it happens, the only time i get a fault code is if I dont back off the throttle and hold it down - then after a while i get "turbo underboost" but i think this is caused by the issue, not the cause of the issue.

It's not a fuel supply issue - filters are clean and it doesn't do it when the engine is cold - only after an extended drive.

Does anyone know anything about this? Alternatively, does anyone know a good place in Perth that will help diagnose this? They will need a dyno if I am to replicate the issue.

Cheers.
Matt.

[GR_76ers_Iverson_3]

Curiosity, is it an auto gearbox and what year model?
I have had a similar problem but haven't totally diagnosed yet.

[Mattyjee]

2007 model - Auto.

[Paul-JK]

You say it only does it when it's hot and you drive it hard. I have had mine cut back to limp mode when it overheats. That for me has only been on long (long) winding steep hills when loaded up. If yours is doing it more frequently could it be your engine or transmission cooling system is stuffed in some way......fan motor not working, radiator blockages etc? That's just a guess as I'm as mechanically minded as an earth worm but might be worth a look.

[MRGC]

Check your trans temp at the time of when it happens.


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[Mattyjee]

My OBD connector does not show auto transmission temperature - does the vehicle's ECU know the temperature and just not reporting it, or is it blind to the temperature?

I assume that the auto trans pumps the fluid through the radiator to cool. I notice an upper and lower connection on the side of the trans. Does anyone know which is the supply and which is return? I might try to prove there is no blockage somehow...

[Paul-JK]

I know the scanguage (and similar) can read auto trans temps, or at least they can on my MY10. Not sure about the earlier models.

If the trans was overheating in theory you should get a hot oil warning on the dash I think. That said, as the cooler is shared (with the air con I think) and all the radiators are close together, overall cooling is compromised anyway. I've never seen the trans getting hot without the engine temps going up with it, and I think it may be the engine temps that trip the shut down before the tranny. I'm pretty sure that's what happens on mine. On the few occasions that it's done it, it goes into limp mode but I don't think I have seen the hot oil light so i'm assuming it's engine temps that are tripping it.

Can't help with which hose is which though.