2000 Jeep Cherokee XJ 2.5 TD VM engine

[BrokenJeep]

Update:
MAF appears to hold a steady voltage and not fluctuating on multimeter abruptly.

Only other things it could be is:
Crank angle sensor
Ecu
PCM
Fuel pump?
Wiring fault
Injector #1 was replaced (with second hand one) and reads 90 ohms but won't rule it out


There are no fault codes stored when checking thru multiple different obd2 scanners and it's on board fault code reader also doesn't show anything either.

Is there anything else it could be?

[layback40]

Originally Posted by BrokenJeep

Update:
MAF appears to hold a steady voltage and not fluctuating on multimeter abruptly.

Only other things it could be is:
Crank angle sensor
Ecu
PCM
Fuel pump?
Wiring fault
Injector #1 was replaced (with second hand one) and reads 90 ohms but won't rule it out


There are no fault codes stored when checking thru multiple different obd2 scanners and it's on board fault code reader also doesn't show anything either.

Is there anything else it could be?

If Crank angle sensor, it would not run.
Cant comment on ECU or PCM.
Fuel pump normally causes idle issues first. If you have a faucet type external electric pump, you could place it on the feed line to the filter.
If it was a limp issue it would have good pull up to just under 2,000rpm (1750). When you accelerate, it goes good up to 1750 & then flatlines. It also has more boost pressure, measured by mechanical gauge, at the pipe to the wg solenoid. Your wg could be stuck partly open.

[layback40]

Originally Posted by BrokenJeep

Thanks for the quick reply.
Can confirm wg actuator is moving when 20psi is applied
Turbo does spin, i removed the small hose to diaphragm and blocked off the turbo side. Took it for a blat and got 3psi at 2000 RPM.
Gut feeling is that turbo and wg are OK.
Could this just be an effect of limp mode? Injector #1 is reading correct ohms.
I might also look into how to diagnose the MAF.

How are you measuring the 3psi? A tube & gauge?

[BrokenJeep]

I do have a petrol in line fuel pump that moves 300 litres per hour.
But I don't think it will resolve the issue, injectors we're recently bled and they spray diesel when the nut is cracked.
I feel that limp mode is active as it pulls well up to approx 2000rpm and goes flat above 2000rpm.
I'm measuring it through a saas boost gauge with boost pressure sensor.
What boost pressure would you normally expect to see with limp mode active?

[BrokenJeep]

After much research, process of elimination and further head scratching; I believe (gut feeling) it can only be one or 2 remaining components as everything else has been tested:
-ECM wiring fault between injector #1 and ECM.
-Faulty ecm.

To test the ECM wires is proving difficult (like most things on this vehicle)
Have you got any tips for unplugging the ECM. The plug is 60 pins and very hard to get to (close to clutch pedal) RHD. Hard to know if I'm prying the right areas.

Thanks again for all your input Layback40.

[layback40]

Originally Posted by BrokenJeep

I do have a petrol in line fuel pump that moves 300 litres per hour.
But I don't think it will resolve the issue, injectors we're recently bled and they spray diesel when the nut is cracked.
I feel that limp mode is active as it pulls well up to approx 2000rpm and goes flat above 2000rpm.
I'm measuring it through a saas boost gauge with boost pressure sensor.
What boost pressure would you normally expect to see with limp mode active?

I did a bit of playing around for you.
Disconnect #1 injector sensor. The limp point on mine is 1750rpm.
In 5th WOT at just under limp point I get about 8psi boost. Once it hits 1750, it drops to about 4psi & wont go over that. I have my wg set at about 10psi. With no limp, injector sensor connected, I get 10psi just below 2000rpm.
My jeep has done about 400,000km.
Hope all this helps

[BrokenJeep]

I'm truly grateful for your support Layback40.
Once I get mine going if there's anything I can help you with then do let me know.
Thats quite the milestone, have you had to replace any major components?
Mine has done 332000 kms. Hoping to get to 1million.

I'll put mine back together and take it for a blat and see what it does.

Many thanks
Tom