XJ 1998 VM 2.5 turbo diesel - limp mode?

[amlav]

That litlle electric motor is the vacum motor for the EGR valve .

[croitoru]

ok, turbo hoses look like swiss cheese.

[croitoru]

alright. so silicon tape and then gaffer taped the hoses . Did 3 test runs around the block. E A C H time turbo out to intercooler clamp blown.Evert single time, at exact the same location! And I've frigging tighten it, seriously...
Boosts to 11 psi now, then comes down to 9 then slowly builds up. I think it's the wastegate.
Oscilloscope on no1 is inconclusive for now unfortunately (long story) but I'll progress with that.

[croitoru]

Hi
Managed to test the signal today . It's about 1/2 the amplitude Amlav's post shows, on the same scale. I think it figures in the light of slightly higher resistance (119 Ohm as opposed to 100)
Amlav, looks like the newer phones need resistance between left and right channels to activate jack...so I soldered them.




So I'm at:
-thinking overboost and fuel cut-off compensation
-injector #1 resistance ( I think the correct terminology is impedance) slightly high and signal amplitude ~50% of amlav's measurements on a good injector

[amlav]

Before reaching a conclusion on the signal amplitude from the injector#1
would be advisable to check amplitude of your scope (phone ) with a calibrated signal .With my scope (350mv) and android phone (300mv) I had 50mV difference on the reading of same injector . Input impedance varies probably with each phone a bit . In your picture with the Weleman scope the pulse signal amplitude seem to exceed the lcd screen.You seem to have 4 x 50mv/div =200mv pulse only vizible than maybe the rest of it just wasn't visible unless you would have adjusted the amplitude settings to 100mv/division or higher . I think your injector#1 sensor would be ok but can't say for sure because of some garbage pulses in between the normal regular pulses visible ....?
If you can post some more images (even of the phone screen) of the pulses could help . On the other hand the amplitude would be conditioned also by the fuel timing and pressure coming of the injection pump.
Higher the pressure more travel of the needle ...less pressure less needle movement (travel) accordingly less or more voltage coming out of the coil inside the injector.
How did you go with the intercoller hoses popping off and with turbo wastegate actuator checks ???

[croitoru]

Ok...
Unplugged the hose that actuates the EGR (behind PCM) - flatspot moved from 1900 to 2100 rpm. Plugged it back in.
Unplugged the short tube that goes from turbo inlet to wastegate... she's a rocket, no flat spot.
I realise I now have a boost leak, but the difference is incredible.Also I can now boost to 15 Psi and it holds the boost, even with the leak. (I think factory is 16?)
I guess my wastegate opens too early, maybe weakened spring?
Probably the turbo needs to come out for reconditioning....
I'm so happy...TBH I thought I'd never work out what's going on...
Thank you guys so much for the ongoing support and suggestions, couldn't have done it without your guidance...
R

[amlav]

Pfiuuu....glad to hear . It sounds that the turbo vanes actuator does not work for some reason as it should and are open (full boost) all the time (when small hose removed).
It must be some permanent constant vacum in that litlle hose that activates the vacum membrane of the actuator and keeps the turbo vanes closed rather than moving acording to load and rpm .
Seen on ytube a guy who plonked a mobile phone in the engine bay facing the actuator and this way he could see what's happening while driving .
Well you getting close...and nearly there . keep as posted . Cheers .