XJ 98' 2.5TD VM Power loss

[agwhiteb0i]

Hey, i recently bought my first car, a jeep cherokee XJ 98' model. Its a great car, in great condition, however it was sold with a somewhat major power loss problem.

The power problem is that when driving, it seems as if the turbo isnt kicking in as it takes forever to build up revolutions, which is even worse on hills. IT DOES, get over 2000 rpm as most say if it doesnt, this is the dreaded limp mode, it just takes a while to build up past 2000. You can still hear the turbo spool however its as if its not applying the boost to the engine??

Things that have been changed/looked at:
-Fuel filter replaced
-Turbo checked (holding 16psi) being further assessed
-MAF replaced, however there was no change plugged in and unplugged so am looking or another one (bosch?)
-Mufler been cut off.

I've been told that it may be a fuel delivery problem so am looking at ordering a facet pump and also a going to fit a provent to help clean up oil mess. Also on that note, the turbo seems to be constently covered in oil

Has anyone run into this sort of issue, or have any ideas what else may be causing it?

[Deezelweazel]

Turbo checked?
This raises my eyebrow.

The turbo itself?Compressor side? exhaust side?
The wastegate only? Or the complete intake system?

For me it sounds that you have a boost leak. Oil covered turbo? Did you look inside the outlet of the compressor wheel?
Oil on the outside of the turbo is quite normal if the hose clamps do not hold boost
Take a couple of pictures and show us:
- the fuel filter head
- the turbo
- the EGR
- the intercooler with the clamps (oil drips down there?)

Forget about the facet fuel pump. Either you have enough fuel or you don't have enough fuel.
Do you still have braided intercooler hose protection on the hoses? get rid of them and inspect your boost hoses.

Taken from the manual:
"If the boost pressure sensor fails the PCM records a DTC into the memory and continues the engine to operate in one of the three limp-in modes. When the PCM is operating in this mode, a loss of power will be present, as if the turbocharger is not operating. The best method for diagnosing faults with the boost pressure sensor is the DRB III scan tool."
This means a trip to the dealer to read out the DTC. DRBIII tool is around 6900 US $, so its cheaper to go to Jeep.

You already exchanged the Maf- Did you also check the wiring for continuity????
Disconnect the battery and use a DMM only to check the resistance of the wires!

Before you are going to invest into a Provent:

I would check from where the oil is coming.
From The charger itself?
Under low or no boost conditions the oil seal does not work-it stopps leaking with boost.
Remove the intercooler and check the amount of oil in there. It can collect down there. a small shot glass full of oil is ok.
Remove the crankcase ventilation line and put it into a soda bottle. Cross check the amount of oil delivered from there.
Make sure no unfiltered air enters the charger!


Aaah, I forgot: welcome to the site...

[layback40]

it would still be worth checking the #1 injector sensor ~ What is the resistance of the sensor?
When does this lack of power or RPM build occur?
Do you have good power for a short time & then it gradually dies like 1/2 way up a hill?
Whats your air cleaner like?
Where is the 16 psi being measured?

[agwhiteb0i]

Originally Posted by Deezelweazel

Turbo checked?
This raises my eyebrow.

The turbo itself?Compressor side? exhaust side?
The wastegate only? Or the complete intake system?

For me it sounds that you have a boost leak. Oil covered turbo? Did you look inside the outlet of the compressor wheel?
Oil on the outside of the turbo is quite normal if the hose clamps do not hold boost
Take a couple of pictures and show us:
- the fuel filter head
- the turbo
- the EGR
- the intercooler with the clamps (oil drips down there?)


Taken from the manual:
"If the boost pressure sensor fails the PCM records a DTC into the memory and continues the engine to operate in one of the three limp-in modes. When the PCM is operating in this mode, a loss of power will be present, as if the turbocharger is not operating. The best method for diagnosing faults with the boost pressure sensor is the DRB III scan tool."
This means a trip to the dealer to read out the DTC. DRBIII tool is around 6900 US $, so its cheaper to go to Jeep.

You already exchanged the Maf- Did you also check the wiring for continuity????
Disconnect the battery and use a DMM only to check the resistance of the wires!

Just got the car back from the mechanic/exhaust guy. Turbo was measure with a boost gauge and that's the 16 psi. The waste gate is opening fully when it should and apparently there doesn't seem to be a problem with the turbo. However, we managed to gain probably 50% more power than before by changing the stock pipe clamps which apparently were "leaking air" with bolt ones. This provided more torque, and so she actually goes to climb a hill without holding revs. There is still that problem where it takes a while to gain revolutions, and i think the engine is more capable then what it is giving, but i am new to XJ's so im not too sure. ALSO: the inter-cooler pipes where checked for holes by the mechanic and although in not so good condition, there was no holes

I still have a feeling the MAF sensor is doing something because, iv been driving with UNPLUGGED for a while now, and there's is no difference to being PLUGGED in. Still trying to order a bosch replacement. Will be checking the continuity of the wires today.

and just wondering, if i were to take it into JEEP to get it scanned with the DRB III to make sure it isnt in that limp mode, are we talking an expensive run?

Originally Posted by layback40

it would still be worth checking the #1 injector sensor ~ What is the resistance of the sensor?
When does this lack of power or RPM build occur?
Do you have good power for a short time & then it gradually dies like 1/2 way up a hill?
Whats your air cleaner like?
Where is the 16 psi being measured?

Will get back to you on the resistance of the no.1 injector sensor, but yes i start of with good power then it gradually dies.

[layback40]

Forget about the MAP ( its not a MAF) for now.
You need to give concise information if you want help.
At what RPM does it start to run out of power?
If you cant get the resistance of #1 injector, try running without it connected & see if it makes a difference. It will be in limp mode then.
Is your "mechanic experienced with VM diesels & Bosch electronic controlled injector pumps?
You need to start answering all the questions you are being asked if you want good help.
What is your location?

[agwhiteb0i]

Originally Posted by layback40

Forget about the MAP ( its not a MAF) for now.
You need to give concise information if you want help.
At what RPM does it start to run out of power?
If you cant get the resistance of #1 injector, try running without it connected & see if it makes a difference. It will be in limp mode then.
Is your "mechanic experienced with VM diesels & Bosch electronic controlled injector pumps?
You need to start answering all the questions you are being asked if you want good help.
What is your location?

Hey layback, sorry error on my part. After its been back from the mechanic, and the intercooler clamps where changed it dosent "run out of power" as such now, it just tends to hold it at around 2250 rpm and then slowly increase

Not sure if i got it correct but got 560Mohms for the resistance of #1 injector sensor. I unplugged it and run without connected, and there was no difference. Also no, the mechanic is not experience with VM diesels.. in fact id say he has little knowledge of them.

And im in brisbane, queensland

[layback40]

Originally Posted by agwhiteb0i

Hey layback, sorry error on my part. After its been back from the mechanic, and the intercooler clamps where changed it dosent "run out of power" as such now, it just tends to hold it at around 2250 rpm and then slowly increase

Not sure if i got it correct but got 560Mohms for the resistance of #1 injector sensor. I unplugged it and run without connected, and there was no difference. Also no, the mechanic is not experience with VM diesels.. in fact id say he has little knowledge of them.

And im in brisbane, queensland

Your problem is the #1 injector sensor is stuffed. Should be ~ 100 ohms.
If you ask MM he can point you to people in Europe who can supply you with a good second hand injector with a good sensor.