XJ 1998 VM 2.5 turbo diesel - limp mode?

[croitoru]

Ok...
Tested socket to loom to ECM with #1 disconnected
1. key off, engine off - 0V
2. key on, engine off - 11. 5v
3. engine on - 12.5v
TBH I thought I'd find no voltage and an open circuit.
Measured resistance as well varying from 7.5kOhm to 17MOhm, not sure what it means.
I need to figure out and understand how the no 1 injector signal works, varies (if) and feeds the ECM.

I think there are only a few possibilities
1. As above, even if measuring resistance ok "at rest", maybe at run-time, signal doesn't match ECM expectations - ie, faulty #1 injector
2. Above values on harness are unexpected and show a fault with wiring or ECM port
3. All is actually well, ECM is in limp mode and might need a specialised DRBIII tool/procedure to erase.
4. 117Ohm might be too high (understand 90 to 100 is expected value)
5. ECM is f-cooked.
6. It's already in limp mode for unrelated reason/ongoing fault therefore the above is all good but irrelevant and getting overriden by current state.

I intend to get a handfull of resistors varying from 70 to 150 Ohm from jcar and see if anything changes.
And I'll do more research, including fsm on what are expected values on the circuit.
Lastly, once I go through the above, I might run paralel wiring directly from #1 to ECM.
I'll also try to understand how the ECM interacts with PCM (if at all)

BTW, I've amassed a bit of PDFs if anyone needs anything ...

R

[croitoru]

OK.

"NEEDLE MOVEMENT OR INSTRUMENTED
FIRST INJECTOR—ECM INPUT
This in put fr om t h e ECM su pplies a con st a nt 30
mA elect rical cu r r ent sou r ce for t h e fir st inject or sen -
sor. It will va r y t h e volt a ge t o t his sen sor wh en it
sen ses a m ech a nical m ovem ent wit hin t h e inject or
n eedle (pintle) of t h e n um ber –1 cylin der fu el inject or.
Wh en t his volt a ge h a s been det ermin ed by t h e ECM,
it will t h en cont r ol a n out put t o t h e fu el timin g sole-
n oid (t h e fu el timin g solen oid is locat ed on t h e fu el
injection pum p). Also r efer t o F u el Injection P um p for
a ddition al in form ation.
Th e fir st inject or sen sor is a m a gn etic (in du ctive)
type.
Th e fir st inject or sen sor is u sed only on t h e fu el
inject or for t h e n um ber –1 cylin der (Fig. 4). It is n ot
u sed on t h e inject or s for cylin der s n um ber 2, 3, or 4.
FUEL INJECTOR SENSOR—GROUND
P r ovides a low n oise gr ou n d for t h e fu el inject or
sen sor only."

[croitoru]

[croitoru]

Originally Posted by amlav

I've heard about the acetone being pored in diesel ...Myself never tried it .
But I do pour 200ml of 2 stroke oil in the fuel tank at every fill up.
It could be many things with your car but sounds like fuel related .
As Layback sugested check or change fuel filter (start with the easy ones),
Make sure there is no air /air leak or water in the fuel system.
Next would be to check the crank shaft sensor on the bell housing above the flywheel if not loose or faulty (unlikely but never know) .
Have a look at wirring if not rubbing against each other or chasie .
Check and clean the MAF sensor .
Pull the tank fuel supply hose of the fuel filter and blow in it to see if not blocked , should hear the air bubles in the tank .
It sounds like engine is starving for fuel . In the same time have a look at the sensor on the accelerator pedal and check for damage or wirring fault .
Worst ...it would be the IP but unlikely (quite robust).
A bit hard to pin point your problem . Hope you'll manage to find the problem and let us know .

Amlav, I'm with you now...very hard to pinpoint. I will check the Crank next, as Ive exhausted everything else but a turbo boost leak now...thank you.

[croitoru]

Ok... plot thickens.
I'm leaning towards this now:
6. It's already in limp mode for unrelated reason/ongoing fault therefore the above is all good but irrelevant and getting overriden by current state.
Specifically, fly-all boost pressure in intake (turbo works though)
Reason ( correct my potentially biased thinking please):
I went and bought a SaaS 30 psi boost gauge.
While examinining where to fit it I found this tap on top of the intake mainfold:

Not a fit, but as I did with disconnecting inj #1, I loosened the bolt creating an artificial leak... (blew and lost the bolt in the process though, thus far). Principle of either fuel, air, or spark missing ( last obviously not applicable to this!)
No change in behaviour with or without that in place!

So I think the turbo hoses, intercooler and possibly turbocharger comming off next... As little as I know about diesels and turbo, that's definitely consistent with a leak
R

[croitoru]

This! as I said, keeps climbing fine at 2000 rpm or slightly below...
Intake/turbo definitely coming off...
Fished from another forum:
"ive got the intercooler prob also. its got a leak and does what youre saying at around 3000rpm (where it hits about 0.5bar). before it would be at 0.9bar at 3000rpm, but not it gets there and just dies, constant 0.5bar reading, and no power at all. with all the windows open i can hear the leaking of air, and the bov also sounds slightly different in a funny kinda way. but yeh, im got boost leak, which if i were to describe would sound very similar to what you are saying..

something that could help, if i dont have the accelerator down quite as much, it will tend to act 'normal' again, and continue to rev through the range until it is creating too much boost, then i ease of the accel a bit more and it will continue to rev another 500rpm til doing the same thing.

as long as i dont create too much boost (in which case air would be leaking while too much fuel is being put in.. im guessing..) and keep it around 0.3bar by lifting off the accel when it gets too much, it will keep on reving. easy to do between 2000 and 3500rpm, but the higher the rpm's, the easier it is to create boost and more precise i need to be with the accel pedal as to not give it too much exhaust gases to spin the turbo thus create boost.

i hope this dribble helps somehow just sharing my expreience..

shaun."

[amlav]

Just check out my thread about injector 1 needle sensor .