Diesel jeep lag help

[Lawson]

Hi all, I am new to this forum. I just bought my first second hand Jeep it is a 1999 Cherokee 2.5 diesel with 200,000kms. I love it so far however I am a bit perplexed as when I put my foot down it takes a long time to pick up sometimes I can't get over 60 and putting my foot down doesn't change it, other times it seems to cruise well part from time to time it feels like the aircon kicks on and it lags (the aircon was not on). Could this be a fuel filter or injector?

[kyphonii]

Yes I have a 2000 XJ diesel with the same issue.
Intermittent lag as If the turbo is not coming on.
It doesn't do it all the time.
I get a hesitation as well.
I suspect fuel but I can't locate any issue. I have replaced the filter assembly with a fuel miser unit.
What to look for ?
Cheers

[layback40]

It could be s fuel blockage in the line. With a near empty tank & the cap off, use compressed air on the fuel line where it joins to the filter ~ blow back to the tank.
Also it could be a failed EGR valve.
If it was me, the first thing I would do is to put a blank plate (piece of tin can) under the EGR valve so it has no effect.
Another possibility is that the waste gate valve is jammed open & needs freeing up.
it doesnt sound like the #1 injector sensor but it never hurts to unplug it & test its resistance with a test meter. If its open circuit, its a problem.

[amlav]

Originally Posted by layback40

It could be s fuel blockage in the line. With a near empty tank & the cap off, use compressed air on the fuel line where it joins to the filter ~ blow back to the tank.
Also it could be a failed EGR valve.
If it was me, the first thing I would do is to put a blank plate (piece of tin can) under the EGR valve so it has no effect.
Another possibility is that the waste gate valve is jammed open & needs freeing up.
it doesnt sound like the #1 injector sensor but it never hurts to unplug it & test its resistance with a test meter. If its open circuit, its a problem.

Pretty much what layback advised . It also could be retarded injection timing or wrong thickness head gasket if heads where reconditioned (shaved).
Does it has the same lag when stationary in neutral ??
What rpm have you got at idle ??

[layback40]

Just a thought on testing #1 injector & limp.
If you unplug the sensor & take it for a drive making sure you try & run it up to 2,500rpm through the gears, you will soon see what limp mode is. If it doesnt change the performance ( have trouble getting over 2,000rpm) with it disconnected then you may have found the problem.

[mud_slut]

Yep agree with removing the egr. I have made up a blank plate as well as a reducer for the egr pipe on the exhaust manifold to run an egt probe. If you want to go down that path I can make up an extra set.


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