2.7 CRD high 1.500rpm idle when engine warm (only in 4Hi)

[OffroadSpike]

Hello.

I've been having this issue since I bought the car a couple years ago. It doesn't really bother me but it might be an indication of a malfunctioning part.

The car sounds perfectly fine in idle. I have no leaking injector seals or intake leaks.

I have a known issue that I have still not fixed that is the swirl flaps actuator linkage is detached so swirl flaps are not working, I put them in the open position. Will do the swirl flaps delete mod in the near future. Anyway I don't think it is related to this issue.

But if you put the gear in P or N, then press on the accelerator pedal, it jumps to around 1200/1500 rpm and stays there for a while, after some time it goes back to 750rpm which is the normal idle speed. If you switch to R or D gear it will instantly go back to 750rpm. This only happens in 4Hi position, will work fine in 4Lo where it always goes back to 750rpm.

High idle video:

Grand Cherokee 2.7 CRD high idle on P/N and on 4Hi - YouTube

Normal idle when in 4Lo:

Grand Cherokee 2.7 CRD regular idle - YouTube

I have no relevant codes on engine or transmission.

I have no clue on what's happening. Found some people having the same problem on google but there wasn't any confirmed solution for it. You guys know what's happening? Might this indicate bad fuel regulator or fuel pressure sensor?

[5oclock]

Think you will find its not a fault, just a 2.7 crd thing, happens to every 2.7 crd I have driven.

[OffroadSpike]

Originally Posted by 5oclock

Think you will find its not a fault, just a 2.7 crd thing, happens to every 2.7 crd I have driven.

Well, that was easy. Any reason it works like that? The guys at Mercedes with the same engine doesn't look like they are getting this high idle, seems to be 2.7 CRD specific "feature"

[RTB]

Post #5 of https://www.ausjeepoffroad.com/forum...d.php?t=160477 discusses this issue. Known issue. I took most of this fueling out of my maps, and mine just drops back quickly all the time now.

[OffroadSpike]

Originally Posted by RTB

Post #5 of https://www.ausjeepoffroad.com/forum...d.php?t=160477 discusses this issue. Known issue. I took most of this fueling out of my maps, and mine just drops back quickly all the time now.

Cool, saw that thread and got interested on what you guys are doing wanted to fix all the stuff before even thinking about moding the ECU. Might get involved once I fix the last (hopefully) important thing with it.

[RTB]

I still run a value of 5 at 950 RPM, but zero on the rest of the 0% throttle. Doesn't hold the idle up at all, gives me more fuel deceleration cut-off, but still provides a nice little softening to the approach to idle. With all zeros we also found there can sometimes be a little bit of diff slap very occasionally when coming off throtlte as the gearbox changes up, but I have found just keeping this 950 RPM fueling at 5 mg/stroke has stopped that.

[JeanLuke]

I had the same experience as RTB.

OffroadSpike, to prove this issue try giving it a rev in N or P with the transfer case in low range. It should drop to idle quickly. The ECU uses a different fuel map in low range with zeroed injection quantities.