XJ 1998 VM 2.5 turbo diesel - limp mode?

[croitoru]

Just FYI...I personally don't care.

[amlav]

Installed the application on one of my old Pendo tablet and it doesn't work . The earphone socket hasn't got an external microphone input function . Sooo...maybe some Android phone tablets or phones should would work .

[layback40]

Originally Posted by croitoru

Just FYI...I personally don't care.

Never loose sight of the fact that these engines predate all this stuff by a long time. Much of it could be discussed in gaming forums.

[croitoru]

True layback40.
Got the jack from Jcar (3.5, 4 legs). So if time as a single full time father permits tomorrow I'll go down amlav's troubleshooting pathway.
Still no injector , first or second hand , anywhere near on sight, on the net.
Bro also ordered a mini-osciloscope kit
So at this stage, no further progress. Still same :
1,2,3 revs over 2000 and boost holds on or above 9-10
4th,5th - not so much.
Under load, even if the lower gears rev, psi is under 10
Flat is ok on 1.2.3.4
I'm starting to think cracked head, thermal sensor, speed sensor (speed and load seem to be a factor)
Again, thankful for all the advice you guys gave me so far.
R

[layback40]

Originally Posted by croitoru

True layback40.
Got the jack from Jcar (3.5, 4 legs). So if time as a single full time father permits tomorrow I'll go down amlav's troubleshooting pathway.
Still no injector , first or second hand , anywhere near on sight, on the net.
Bro also ordered a mini-osciloscope kit
So at this stage, no further progress. Still same :
1,2,3 revs over 2000 and boost holds on or above 9-10
4th,5th - not so much.
Under load, even if the lower gears rev, psi is under 10
Flat is ok on 1.2.3.4
I'm starting to think cracked head, thermal sensor, speed sensor (speed and load seem to be a factor)
Again, thankful for all the advice you guys gave me so far.
R

I am jumping at shadows. May be worth while making sure your turbo waste gate is closing properly. It could have a weak spring. It is good that you have a boost gauge. Where is it connected to? It should be T into the pipe from the air side to the waste gate actuator.

[croitoru]

Originally Posted by layback40

I am jumping at shadows. May be worth while making sure your turbo waste gate is closing properly. It could have a weak spring. It is good that you have a boost gauge. Where is it connected to? It should be T into the pipe from the air side to the waste gate actuator.

Hi
Thanks again for the reply. I got the gauge for ~ 65 from SCP.
I had to fit it on top of the intake manifold, where the turbo hose comes in from the intercooler. It already had been drilled, and had a blank plug screwed in.
As far as I understand, my wastegate is operated directly from a small vacuum pump fitted on the other side of the ECU located in the engine bay. Being vacuum, should I T there...?
I posted some pictures earlier in the thread, but here it is:
Current tap for turbo gauge:


Vacuum waste actuator (as per my understanding):


Would appreciate your guidance...
R
PS: I seldom have any black smoke, even under acceleration. Unless I'm revving in neutral, which can easily do redline. Hence me saying before , it behaves differently under load (hills) as opposed to flat or downhill.
Guess I'm making some progress with your help, but still looks like a long journey... which is fine, it's engineering 🙂 afterall.
And no, unfortunately I don't know any diesel specialists North of brissie unfortunately.

[layback40]

Originally Posted by croitoru

Hi
Thanks again for the reply. I got the gauge for ~ 65 from SCP.
I had to fit it on top of the intake manifold, where the turbo hose comes in from the intercooler. It already had been drilled, and had a blank plug screwed in.
As far as I understand, my wastegate is operated directly from a small vacuum pump fitted on the other side of the ECU located in the engine bay. Being vacuum, should I T there...?
I posted some pictures earlier in the thread, but here it is:
Current tap for turbo gauge:


Vacuum waste actuator (as per my understanding):


Would appreciate your guidance...
R
PS: I seldom have any black smoke, even under acceleration. Unless I'm revving in neutral, which can easily do redline. Hence me saying before , it behaves differently under load (hills) as opposed to flat or downhill.
Guess I'm making some progress with your help, but still looks like a long journey... which is fine, it's engineering 🙂 afterall.
And no, unfortunately I don't know any diesel specialists North of brissie unfortunately.

You are a bit mixed up. What you are talking about is the EGR.
the pressure that you are measuring is the charge pressure not the boost pressure.
If you look at the air side of the turbo you will see a fitting with a small hose that runs to an actuator under the turbo. That is the waste gate actuator. If the boost pressure gets too high it opens the waste gate & that allows exhaust to bypass the turbo & so reduce the boost. If this is not working properly it could cause what you are seeing.