XJ 1998 VM 2.5 turbo diesel - limp mode?

[croitoru]

Originally Posted by amlav

Just check out my thread about injector 1 needle sensor .

Thank you. This one?

http://www.ausjeepoffroad.com/forum/....php?p=1644473

R

[amlav]

Yes . I can see from your pictures that the number 1 injector sensor wiring is not the original (coming of the injector) and not sure why .

[croitoru]

Originally Posted by amlav

Yes . I can see from your pictures that the number 1 injector sensor wiring is not the original (coming of the injector) and not sure why .

I checked your thread, very interesting. I guess after I confirm boost state at 2000 rpm under load, I might bite the bullet and start hunting for a known good #1, based on what Ive read fron your thread. I'll do the android probing if I can before committing to getting another number one.

Yes, not the original. Looks like previous owners went down the troubleshooting route as intercooler and pedal sensor also seem to have been worked on or checked previously....

Thanks for sharing....
R

[croitoru]

Updates:
Tried resistors - 82, 100 and 120 ohm; no difference.
Managed to rig the turbo gauge (don't ask...)..
Stationary - rev up to 4800 rpm, 10-12 psi boost
Moving - rev up to 2000-3000 rpm, 10-12 psi boost
Climbing - rev up to 1800-1900, 10 psi, then psi drops to about 7-8 and car holds usually speed, rpm and psi.
Boost leak or fuel starvation?

[amlav]

Don't forget that boost is conditioned by exhaust pressure .
Exhaust pressure than is conditioned by rpm .
You saying that when moving in 4-th and 5-th gear the engine revs up to 3000 rpm on flat road ???
Seems like from one of your previous post that engine wouldn't pass 2000 rpm in 4-th or 5-th .
Quote: " I can climb in 4th and 5th but at at steady ~2000 rpm and 60-80 kmph.... if it's to high will slow down then kick power back in and climb steady as long as it stays around 2000 rpm."

[croitoru]

Originally Posted by amlav

Don't forget that boost is conditioned by exhaust pressure .
Exhaust pressure than is conditioned by rpm .
You saying that when moving in 4-th and 5-th gear the engine revs up to 3000 rpm on flat road ???
Seems like from one of your previous post that engine wouldn't pass 2000 rpm in 4-th or 5-th .
Quote: " I can climb in 4th and 5th but at at steady ~2000 rpm and 60-80 kmph.... if it's to high will slow down then kick power back in and climb steady as long as it stays around 2000 rpm."

Thanks for continuing to help with sage advice and critical thinking Amlav.
Yes - flat can rev in 4th and 5th past 3000 rpm...
Problem starts on climb, as per original post... even the slightest....
I'll take it for more runs tomorrow, just managed to rig up the turbo gauge late today...
Had a chat and a beer with my brother who's a physicist, he explained how the pulse signal interposes over the #1 12.5v.
My gut is that I have a boost leak, like a valve - everytime I hit 10 psi or thereabouts, the leak lets pressure out. if it was fuel, or limp, on flat wouldn't rev much past 2000 rpm...but it always seems to be governed by the 10 psi, no matter speed or rpm... I thought was rpm until I got a gauge... the only constant is psi...
I think I'll get a 1m silicone hose and connect in and out bypassing the intercooler.... short 5 k runs at 80k max....
What do you think?
R

[layback40]

Originally Posted by croitoru

Thanks for continuing to help with sage advice and critical thinking Amlav.
Yes - flat can rev in 4th and 5th past 3000 rpm...
Problem starts on climb, as per original post... even the slightest....
I'll take it for more runs tomorrow, just managed to rig up the turbo gauge late today...
Had a chat and a beer with my brother who's a physicist, he explained how the pulse signal interposes over the #1 12.5v.
My gut is that I have a boost leak, like a valve - everytime I hit 10 psi or thereabouts, the leak lets pressure out. if it was fuel, or limp, on flat wouldn't rev much past 2000 rpm...but it always seems to be governed by the 10 psi, no matter speed or rpm... I thought was rpm until I got a gauge... the only constant is psi...
I think I'll get a 1m silicone hose and connect in and out bypassing the intercooler.... short 5 k runs at 80k max....
What do you think?
R

Have you tested the resistance of the #1 injector sensor?
If you disconnect it, is there any change?
When I had a bad sensor I could get to 3,000rpm, just took a long time to get there. everything you are saying suggests a bad sensor.
The resistor in the place of the sensor normally does not work. It only works on a very limited number of very early XJ diesels with the very first type of Bosch computers. Yours is clearly not one of them.
Best you give up on all this BS trying other things & just get a replacement injector with a working sensor. Unless you have tested the sensor in yours & it has a resistance of around 80 to 100 ohms. I can find where you have done the resistance test. Just do it!