Hi all, I have a 2003 2.8 Diesel Jeep Cherokee Extreme Sport auto, (European model I understand) Now the dumb bit, I am told this jeep has four forward gears and a turbo, When I am driving and get to about 43 mph there is a boost in performance and the rev-counter drops by about 1000 revs. I am told this is the Turbo cutting in. When driving around town in the UK (speed limit 30 mph) the revs are about 1500 so the turbo never cuts in, so a lot of diesel is used. When I get the Jeep up to 40 mph say I have about 2200 revs and at 43mph I have about 2500 revs, when the turbo cuts in (43mph) the revs drop to about 1500. Is this normal (the turbo never cuts in when town driving) or is there a way to get the turbo to cut in sooner say at 30 mph or there about.
Ok I said it was dumb, but I had to ask,
Thanks,
Bill.
ps, by the way, thanks for all the other info, I have acted on most of it.

Go to Sam's NOOB guide and scroll down to the link to the manuals and parts fiche. Follow that link and get a copy of the FSM for your model year and the manual for the "export" diesel engine. You might also check the Jeep web site and see if you can locate a copy of the owner's manual if you lack one.

I assume you have an automatic transmission in which case it's likely the 42RLE (3 forward speeds plus an overdrive) and I think you are confusing transmission shifting with turbo performance. The turbo has no impact on rpms and that rpm drop you get at 43mph is likely the overdrive kicking in. The turbo runs all the time and provides "boost" (e.g. extra air flow) to the intake to enhance engine performance; exactly how much boost is provided depends on a variety of factors but I can assure you that a properly functioning turbo can provide added boost beginning just off idle regardless of the gear you are in.

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Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs

As papaindigo said...go to SAMS Noob guide and download the 2003 KJ Service Manual.

This however only covers the bodywork, transmission etc. ....not the fixed-vane turbo engine that we Export owners have..at least for the early CRDs.

Before you download that Service manual, first download the 2.5_2.8 Export Diesel supplement...that tells you all about our Export engines.

The turbo on our engine does not "cut in/out" although it does have a dump valve that may be malfunctioning...I agree that it is probably your transmission.

I am no expert on the automatic boxes as I have a five speed manual but I have seen from many posts that the first thing to do is replace the filters inside the transmission, replace the fluid, take it for a drive to get the transmission to re-learn!

Here is the link for the download in case you cannot find it in SAMS Noob Guide:

http://www.colorado4wheel.com/manuals/Jeep/KJ


And I like your User Id....I should have patented that one as well as my own

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2002 Export CRD 2.5 Sport

You may also want to contact GDE and ask about a tune to lower your shift points. The behavior (spelled CORRECTLY ) you are describing is a perfect description of the transmission shifting into 3rd, then 4th gear. Below 40mph, the shift points prevent it from shifting into top gear. The diesel however, should have ample power to handle this with only a moderate amount of "lugging"

If your turbo wasn't working, you would scarcely be able to accelerate past 20, and it would take a LOOOOOOONG time.

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Proud supporting vendor of LOST Jeeps
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Over 225 CRDs currently driving with my valves, timing belt, rockers, or ARP Studs.
Bad noises = REALLY bad things.

Thanks you very much all, I will take on board all you have said and when I have completed all the tasks I will report back, thanks again.