Fluctuating Idle RPM -Diesel P38

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RAW111111 said:
My guess would be the fire seal may have seen better days, and therefore the injector is jammed in with carbon maybe? Not got any tricks for dealing with the problem unfortunately though.

Good Luck!

Richard
Click to expand...

This injector was removed not too long ago so should not be a problem if it was properly reassembled. All the injectors were supposedly refurbed, surely new fire rings would have been fitted. And the threads copper slipped.
 
Sorry, as usual fora allow the most benign comments to be misinterpreted. I was not trying to suggest that anything had been done wrong. Fire seals do get damaged sometimes through age, or reuse, and I've even seen new ones fail before. My comment was intended to give an idea of what might be the problem, not to imply that any kind of error was the cause. I figured that if that was the cause, someone might have a tip as to how to deal with it.

Thanks to Mark for being a voice of sense and pointing out the potential to be misunderstood. My apologies.

Rich
 
RAW111111 said:
Sorry, as usual fora allow the most benign comments to be misinterpreted. I was not trying to suggest that anything had been done wrong. Fire seals do get damaged sometimes through age, or reuse, and I've even seen new ones fail before. My comment was intended to give an idea of what might be the problem, not to imply that any kind of error was the cause. I figured that if that was the cause, someone might have a tip as to how to deal with it.

Thanks to Mark for being a voice of sense and pointing out the potential to be misunderstood. My apologies.

Rich
Click to expand...
Mark Piercy said:
this sounds awful but maybe your blokes in the garage are not helping as much as they intend!!
Click to expand...
edit! :(
 
haha oops! I might be inclined to agree with that though - like most home mechanics I should think, I have a distrust for those who do it for a living, as for the most part I don't think that they can often afford to spend the time to do jobs as properly as we might like.
 
agreed, there's always a process to follow. Be it, physical examination or use of diagnostics first..
I hope you get this fixed kapil' your head must be hurting going around in circles. Take step back, recap and maybe start from the beginning....
 
wammers said:
This injector was removed not too long ago so should not be a problem if it was properly reassembled. All the injectors were supposedly refurbed, surely new fire rings would have been fitted. And the threads copper slipped.
Click to expand...

Yes, all the injectors were removed for servicing/pressure setting in December last year while I was doing the head g/cut & timing chains.
The guy who serviced the injectors did not have the proper size copper washers/seals and refitted all with the old copper seals. In doing so he
tightened it so hard saying that old copper washers need that. Did not use copper grease in threads too.

Immediately after that I got the CIL on continuously, but it disappeared after running for about 2-3 days.
May be it's that too much tightening is causing that bind now.
May be, if I use a socket without window ,will have enough power to get it moving but then I have to give up the wire connector.
Anyway, I need to buy that window socket to install the new injector, that will be another two weeks minimum.
 
kapilamuni said:
Yes, all the injectors were removed for servicing/pressure setting in December last year while I was doing the head g/cut & timing chains.
The guy who serviced the injectors did not have the proper size copper washers/seals and refitted all with the old copper seals. In doing so he
tightened it so hard saying that old copper washers need that. Did not use copper grease in threads too.

Immediately after that I got the CIL on continuously, but it disappeared after running for about 2-3 days.
May be it's that too much tightening is causing that bind now.
May be, if I use a socket without window ,will have enough power to get it moving but then I have to give up the wire connector.
Anyway, I need to buy that window socket to install the new injector, that will be another two weeks minimum.
Click to expand...

Then the bloke who fitted them is an idiot. Copper washers can be annealed by heating and quenching. Injectors should be torque loaded to 48 lb ft and no more.
 
Got it removed, at last.
Bought a 27mm long socket (no window) then cut the wire from the injector (as I am to fit the new one anyway)
with the 4ft breaker bar it came out.
Fitted new one torqued to 48 lb ft . Started car, fine. No CEL.
Now, back to my original RPM issue at idle, it seems more prominent now. Checked with NANOCOM, no faults except 'Air temp..' as the intake manifold is out.
As I mentioned earlier, it appears like an old Leyland bus idling and governor controlling RPM.

I can run the car like this but it cuts out suddenly mostly at traffic lights waiting in D. This I never want to happen again..
PLS HELP.
 
kapilamuni said:
Got it removed, at last.
Bought a 27mm long socket (no window) then cut the wire from the injector (as I am to fit the new one anyway)
with the 4ft breaker bar it came out.
Fitted new one torqued to 48 lb ft . Started car, fine. No CEL.
Now, back to my original RPM issue at idle, it seems more prominent now. Checked with NANOCOM, no faults except 'Air temp..' as the intake manifold is out.
As I mentioned earlier, it appears like an old Leyland bus idling and governor controlling RPM.

I can run the car like this but it cuts out suddenly mostly at traffic lights waiting in D. This I never want to happen again..
PLS HELP.
Click to expand...

Back to the pump centre section being in the wrong place then.
 
No i mean what i asked you about in post #7. You are going to have to go back through the line of events. At what stage, after what event did this idle problem start? Go through and list in order what you have done or had done until this started.. What is the timing modulation now?
 
he's correct, you need a recap of all that's been done, so you can re-access and eradicate.
write down from memory everything done, so your not having to go over everything again, unless you feel you need to double check!
without order in practice, there's no result buddy..;)
 
Last edited:
I have /had a serious issue on hot start, (even with hot start kit fitted). At that time the timing modulation was at 93 96 range nothing below that.
Then the advise I got was the t/chains stretched. So changed chains, h/gasket, sump gasket, refurbed injectors etc in early December '16.
I am not sure this idle issue was there before the repairs in December'16 but it was more prominent / appeared in mid January '17. Then reset static timing
but still the modulation 40-93 range.
Now I have replaced;
CPS, 4th Injector, starter solenoid - all genuine, brand new parts. But the idle fluctuations/hunting remains with more prominence.

No faults shown on Nanocom. Timing modulation is at 42 to 94, hot engine idling.
Now, I'm scared to take it out as it cuts out randomly at traffic lights while waiting in D. This happened like once in every two weeks.
As it is I have no other way except suggestion by N2O. Waiting for his instructions to do that
 
there was a comment on here about stalling while in D, wammers suggested raising the fuel quantity input something to stop that happening? Cant be specific exactly..:(
 
kapilamuni said:
I have /had a serious issue on hot start, (even with hot start kit fitted). At that time the timing modulation was at 93 96 range nothing below that.
Then the advise I got was the t/chains stretched. So changed chains, h/gasket, sump gasket, refurbed injectors etc in early December '16.
I am not sure this idle issue was there before the repairs in December'16 but it was more prominent / appeared in mid January '17. Then reset static timing
but still the modulation 40-93 range.
Now I have replaced;
CPS, 4th Injector, starter solenoid - all genuine, brand new parts. But the idle fluctuations/hunting remains with more prominence.

No faults shown on Nanocom. Timing modulation is at 42 to 94, hot engine idling.
Now, I'm scared to take it out as it cuts out randomly at traffic lights while waiting in D. This happened like once in every two weeks.
As it is I have no other way except suggestion by N2O. Waiting for his instructions to do that
Click to expand...

The modulation should be steady at a figure between 45% and 55% at warm idle at a rock steady 750 RPM. Neither reading should fluctuate. It should NOT be jumping between 42 and 94. The engine RPM read from the CPS and the needle lift sensor should not vary more than 40 RPM. I am beginning to think that the injection pump has been damaged or is past it's best. If the injection pump mid section has been removed it is normal to have to very slightly slacken off the holding screws,then with the engine running tap the mid section minutely either forwards of backwards to reset idle fuel, until a rock steady none fluctuating idle of 750 RPM is obtained with the idle fuel set at 128 on Nanocom . Then torque up when this is achieved. The alternative to this is to send the pump away for inspection and recalibration. Not knowing if all the work has been done properly i can give no further advice other than that already given. You need someone who really knows what they are doing to look over it, and check that everything has been done correctly then work from that.
 
wammers said:
The modulation should be steady at a figure between 45% and 55% at warm idle at a rock steady 750 RPM. Neither reading should fluctuate. It should NOT be jumping between 42 and 94. The engine RPM read from the CPS and the needle lift sensor should not vary more than 40 RPM. I am beginning to think that the injection pump has been damaged or is past it's best. If the injection pump mid section has been removed it is normal to have to very slightly slacken off the holding screws,then with the engine running tap the mid section minutely either forwards of backwards to reset idle fuel, until a rock steady none fluctuating idle of 750 RPM is obtained with the idle fuel set at 128 on Nanocom . Then torque up when this is achieved. The alternative to this is to send the pump away for inspection and recalibration. Not knowing if all the work has been done properly i can give no further advice other than that already given. You need someone who really knows what they are doing to look over it, and check that everything has been done correctly then work from that.
Click to expand...

If you try this then make sure you have someone in the driver's seat ready to switch off if you tap too far and it starts revving its b*ll*cks off.
 
Grrrrrr said:
If you try this then make sure you have someone in the driver's seat ready to switch off if you tap too far and it starts revving its b*ll*cks off.
Click to expand...

It should not do that. Too little fuel it will stop, too much fuel it will hunt. The idle fuel is set when the pump is calibrated to give 750 RPM. So the quantity servo is set in a certain position. Move the mid section even by a very small amount and this null setting for idle fuel is lost. All you are doing is sliding the control sleeve back or forth along the piston to regain the idle null fuel point. His bigger problem at the moment is why even with a new number four injector the timing modulation is jumping between 42% and 94% when it should be rock steady. That CANNOT be caused by a misplaced mid section. Mid section position is about idle fuel quantity. Modulation is about timing correction. Two separate functions. Something along the line has not been done correctly that is more than obvious.
 
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