Fluctuating Idle RPM -Diesel P38

Wams amd N20, awesome bake-off!!
for the crustiest bottom, stay tuned...

If RAVE was a girl she'd be dragging you to a Jewellers

I'm no lad @55. Thanks anyway for the kind words, Wammers.

Yes, I was very lucky to get the setting back on to correct position. Anyway, that was about two yrs ago.
You mean that when we switch off the engine, the spring in the timing unit pushes (mechanical force not any electrical/electronic force or internal fuel pressure) timing back to 'static setting'?
Then same thing should happen when engine is hot, too. So what is this 'hot start' kit trying to achieve by fooling the ECU to think the engine is cold & thereby evoking 'cold start' setting? This is said to be some advanced timing point not the static setting. confusing.

I checked the timing solenoid function yesterday with & without engine running. When engine idling I could not feel /hear any difference. When engine off, I could hear ticking noise. It means that the solenoid is in good order but whether it's getting the job done is doubtful. Shall I remove the diamond shape piece and check the spring inside, whether it's broken or lost springiness?

kapilamuni said:

I'm no lad @55. Thanks anyway for the kind words, Wammers.

Yes, I was very lucky to get the setting back on to correct position. Anyway, that was about two yrs ago.
You mean that when we switch off the engine, the spring in the timing unit pushes (mechanical force not any electrical/electronic force or internal fuel pressure) timing back to 'static setting'?
Then same thing should happen when engine is hot, too. So what is this 'hot start' kit trying to achieve by fooling the ECU to think the engine is cold & thereby evoking 'cold start' setting? This is said to be some advanced timing point not the static setting. confusing.

I checked the timing solenoid function yesterday with & without engine running. When engine idling I could not feel /hear any difference. When engine off, I could hear ticking noise. It means that the solenoid is in good order but whether it's getting the job done is doubtful. Shall I remove the diamond shape piece and check the spring inside, whether it's broken or lost springiness?

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I have explained this a few times. Even with the engine hot the internal pressure will bleed away after a short time when the engine is stopped. Returning the timing to static setting. The only thing the hot start does is tell the ECU the engine is cold and the ECU then sets cold start fuel on quantity control servo, activates glow plugs and runs lift pump. At my age you are a lad to me.

wammers said:

I have explained this a few times. Even with the engine hot the internal pressure will bleed away after a short time when the engine is stopped. Returning the timing to static setting. The only thing the hot start does is tell the ECU the engine is cold and the ECU then sets cold start fuel on quantity control servo, activates glow plugs and runs lift pump. At my age you are a lad to me.

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Just to build on what Wammers has said above. There are maps in the 2 chips in the ECU that take temperature and all the other inputs you see on your EDC module on the Nanocom. From those maps it reads off what it needs to adjust. For when the engine is cold it has more forgiving parameters than when the engine is hot, hence why the fuel quantity is adjusted and so forth and the car is easier to start. On later ECUs BMW changed some of the hot parameters but they also changed some mechanical things too. I think Wammers said the later diesel's lift-pump runs while cranking? All these little things add up and the later cars shouldn't require a hot-fix, as far as I'm aware.

Your car doesn't have a hot-start issue though, does it? That modulation means it is fighting something. So it is either getting a duff reading from a sensor such as number 4 injector or something is stopping the FIP from working as it should. You've done the chains (brave man!) so it must be the FIP or possibly the feed to the FIP which means lift-pump, although with modulation that far out it looks like the FIP.

Grrrrrr said:

Just to build on what Wammers has said above. There are maps in the 2 chips in the ECU that take temperature and all the other inputs you see on your EDC module on the Nanocom. From those maps it reads off what it needs to adjust. For when the engine is cold it has more forgiving parameters than when the engine is hot, hence why the fuel quantity is adjusted and so forth and the car is easier to start. On later ECUs BMW changed some of the hot parameters but they also changed some mechanical things too. I think Wammers said the later diesel's lift-pump runs while cranking? All these little things add up and the later cars shouldn't require a hot-fix, as far as I'm aware.

Your car doesn't have a hot-start issue though, does it? That modulation means it is fighting something. So it is either getting a duff reading from a sensor such as number 4 injector or something is stopping the FIP from working as it should. You've done the chains (brave man!) so it must be the FIP or possibly the feed to the FIP which means lift-pump, although with modulation that far out it looks like the FIP.

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It is easy to check with Nanocom on EDC switches page. Needle sensor RPM should never be more than 40 RPM different than CPS. Stuff like that will tell him what is at fault. IF he has timed the static correctly ( Engine locked at TDC .95 lift on cam) it should not be possible to get 93% modulation. Maybe he timed static hooked up on the CPS pip 20 degrees after TDC and not located in the timing pin hole at TDC. All other things being correct that would give him what he has because the static would be retarded.

Got it. Anyway, let me re do the static timing. I think may be it's the internals of timing unit.

kapilamuni said:

Got it. Anyway, let me re do the static timing. I think may be it's the internals of timing unit.

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The timing device is a pretty simple setup. The static cam has an arm which extends from it and is slotted mid way along a piston. The cylinder for the piston goes across the pump, at either end of it is a diamond shaped plate sealing the cylinder. The one that can be seen on the side of the pump looking over the wing has a spring behind it. This spring pushes the piston head into it's rest position against the opposing diamond shaped plate. This is the position the piston should be in when static timing is set. When the engine starts and internal fuel pressure builds in the pump. Fuel pump internal pressure flows through a feed drilling to the piston head pushing against the spring to change injection timing by rotating the fixed cam with the lever arm. Subject to signals from the number four injector the ECU modulates the timing solenoid to either restrict or allow flow of pressurised fuel out of the piston, to control how much the fixed cam is rotated to maintain point of injection at TDC, Modulation enables the fixed cam to be rotated by adjusting presssure on the piston setting the point of injection to coincide with TDC as read by the CPS signal to the ECU.

Reset the static timing to 0.95mm but the random low RPM fluctuations remain.
May be it's the inj pump.

kapilamuni said:

Reset the static timing to 0.95mm but the random low RPM fluctuations remain.
May be it's the inj pump.

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When the throttle is below 9% the idle switch is engaged. This cuts off throttle pot from control of RPM. RPM is controlled by ECU subject to speed signals from CPS. When the pump is calibrated nominal idle fuel is set by adjusting the position of the quantity servo and therefore quantity sleeve. Which is stored electronically. This nominal position can be adjusted with Nanocom by increasing the idle setting to raise RPM or reducing idle setting to reduce RPM. As load is applied to the engine at idle the CPS detects a speed reduction and the ECU increases fuel by moving the quantity servo and sleeve to maintain 750 RPM. As load is reduced the CPS detects speed increase and the ECU moves the quantity servo and sleeve to reduce fuel and maintain 750 RPM. If the pump mid section is removed it MUST be put back in EXACTLY the same position it came from. This is done by running the engine until up to temp and with mid section fixing bolts just nipped and tapping the top forwards or rearwards until a rock steady 750 RPM with no fluctuations is achieved before bolts are finally tightened. OR having the pump recalibrated. If the quantity servo sleeve is in the wrong position after the pump is put back together giving too much idle fuel, the the ECU will constantly move the quantity servo sleeve to reduce fuel to try and maintain 750 RPM. The converse will apply if idle fuel is too low as set by position of quantity sleeve. This will cause hunting. You have been told what the problem is most likely to be why do you not listen? What is the modulation at hot idle now you have reset static?

I understand what you are telling. Yes, the pump centre section was removed to replace the oil seals as it was leaking.
It was done very carefully by myself with proper markings for aligning. After replacing, the engine started first time and stayed at 750RPM idle without any fluctuations whatsoever( I was extremely lucky). All that was more than two(02) years ago. It ran perfectly until December 2016, when I replaced the HG,Timing chains, Sump gasket etc. But the inj pump was not touched except for removal of sprockets & injector lines.
As you say if it's the centre section, then the bolts should have loosened with usage which I think is unlikely as there should be diesel leaking or else it got to be something like a worn bush in the shaft(don't know the exact name but it goes down in the middle of centre section, which gives accelerator motion).
With all that said, I guess that the pump needs re-calibration of sort. But the local Bosch agent does not appear to understand a VP37 in a BMW.

kapilamuni said:

I understand what you are telling. Yes, the pump centre section was removed to replace the oil seals as it was leaking.
It was done very carefully by myself with proper markings for aligning. After replacing, the engine started first time and stayed at 750RPM idle without any fluctuations whatsoever( I was extremely lucky). All that was more than two(02) years ago. It ran perfectly until December 2016, when I replaced the HG,Timing chains, Sump gasket etc. But the inj pump was not touched except for removal of sprockets & injector lines.
As you say if it's the centre section, then the bolts should have loosened with usage which I think is unlikely as there should be diesel leaking or else it got to be something like a worn bush in the shaft(don't know the exact name but it goes down in the middle of centre section, which gives accelerator motion).
With all that said, I guess that the pump needs re-calibration of sort. But the local Bosch agent does not appear to understand a VP37 in a BMW.

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Possibly because you do not have a VP37 injection pump it is a VE-EDC pump. The pump needs special equipment to calibrate it. If there is a problem with the fuel quantity servo operation you should be getting faults recorded by Nanocom. I will ask again, what is the modulation at idle warm engine now that you have re timed the static? Hopefully with the locking pin in the correct position. The timing out of expected range fault has nothing to do with the quantity servo

They only told me it's VP37, after having a look at the engine. They are surprised to see a BMW engine in a Landrover of this age.
The modulation with hot idling engine ranges from 42 to 94 and most of the time it's@ 94.
With RPM above 1500, it settles to around 55. Anyway, still shows the timing out of expected..........' fault.

kapilamuni said:

They only told me it's VP37, after having a look at the engine. They are surprised to see a BMW engine in a Landrover of this age.
The modulation with hot idling engine ranges from 42 to 94 and most of the time it's@ 94.
With RPM above 1500, it settles to around 55. Anyway, still shows the timing out of expected..........' fault.

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Only thing i can advise you to do is make absolutely sure the number four injector is sound. You should be able to read it's signals on Nanocom. Point of injection at idle warm engine, should be within a couple of degrees of TDC at which time modulation should be within the 45% to 55% range. A malfunction on number four injector will usually cause the Mil lamp to come on with a total fail or flash if it is intermittent. You should also get a fault code as you are getting. Try the number four injector or CPS first, they are the cheapest options. The engine speed reading from the CPS should never be more than 40 RPM different from that shown by the number four injector at any time. If it is you have a malfunction of one or the other. If you check the CPS, DO NOT remove the bracket it sits on. Remove the sensor from the bracket. If you remove the bracket you need a special tool to reset sensor spacing. If all is good pump refurb is on the cards.

kapilamuni said:

They only told me it's VP37, after having a look at the engine. They are surprised to see a BMW engine in a Landrover of this age.
The modulation with hot idling engine ranges from 42 to 94 and most of the time it's@ 94.
With RPM above 1500, it settles to around 55. Anyway, still shows the timing out of expected..........' fault.

Click to expand...

The Rangies have had BMW engines in for a LONG time!

Ordered CPS from rimmers . Will revert once it's fitted.

Guys, it happened again. The engine cut off while parked and idling. Luckily I was in a parking bay near kids school.
Got it started after waiting about two hours. Checked faults with Nanocom after coming home, nothing there except the usual 'timing value out of expected range...'
Also, checked gear box faults assuming it could be the torque converter lockup issue, but nothing.
Noted that 'fuel quantity current' value is floating around 0.00 to 0.50 mg/s @ idle and rarely goes to 2.25 mg/s while 'fuel q/feed back' gives steady 63.25 or 63.00 mg/s.
If I accelerate to 2000 RPM 'fuel quantity current' value moves to about 17 mg/s. Is this a valid set of values for fuel quantity current?
Appreciate your quick responses as this is my daily runner and scared to take it out again.

More info.
Car seems like an old Leyland diesel bus with mechanical governor , RPM fluctuating upto 2000 RPM. The whole car shakes with RPM going up & down. reduced when in gear.

With Nanocom got the following;(warm engine, )
Idle (rpm);low Idle (rpm);Needle (rpm);Crank speed (rpm);Road speed (kmh);Road speed (mph);ELAB;Alarm status (on/off);Primary brake (act./ina.);Secondary brake (act./ina.);Aircon requested (yes/no);Aircon grant (yes/no);Clutch (yes/no)
HIGH;HIGH;455.00;864.50;0;0;HIGH;LOW;LOW;HIGH;LOW;LOW;LOW
HIGH;HIGH;409.50;978.25;0;0;HIGH;HIGH;LOW;HIGH;LOW;LOW;LOW
HIGH;HIGH;409.50;796.25;0;0;HIGH;HIGH;LOW;HIGH;LOW;LOW;LOW
HIGH;HIGH;864.50;728.00;0;0;HIGH;HIGH;LOW;HIGH;LOW;LOW;LOW
Needle RPM & Crank RPM difference is high.

Water temperature (C);Air temperature;Boost pressure (kPa);Ambient pressure (kPa);Throttle potentiometer (%);Throttle potentiometer (V);Battery (V);Low Idle value;Cruise status
76.72;39.31;103.46;102.33;0.00;0.3;13.32;796.25;CRUISE OFF
78.76;38.63;104.60;102.33;0.00;0.4;13.32;796.25;CRUISE OFF
78.76;38.63;110.28;102.33;0.00;0.8;13.32;796.25;CRUISE OFF
78.76;38.63;110.28;102.33;1.55;0.5;13.32;796.25;CRUISE OFF
78.76;38.63;108.01;102.33;0.00;0.3;13.32;796.25;CRUISE OFF
something wrong with the throttle potentio meter. % does not go up even if pressed up to 2000 RPM.

Start fuel(mg/str);Fuel quantity feedback (mg/str);Fuel quantity current (mg/str);Fuel quantity compared (mg/str);SWG set point (mV);SWG actual (mV);Inj. setpoint (deg.);Inj. actual (deg.);Fuel temperature (C);Timing modulation (%)
;;;26.25;3072.00;2740;1.95;0.00;37.95;94.37
32.00;63.00;2.00;26.25;3072.00;2700;2.00;0.15;37.95;51.47
32.00;63.00;0.00;28.50;1945.59;3060;1.85;0.85;37.95;94.37
32.00;63.00;5.00;26.50;972.79;2620;1.85;0.70;37.95;83.06
32.00;63.00;5.25;27.25;3046.40;2660;2.29;0.50;38.63;94.37
32.00;63.00;15.25;27.50;1152.00;1940;2.50;0.00;38.63;90.47
32.00;62.75;2.25;28.25;3072.00;1540;2.50;0.55;38.63;57.71
32.00;63.25;0.00;26.50;3020.80;2640;2.25;0.45;38.63;52.25
32.00;63.50;0.00;26.75;972.79;2680;1.85;0.30;38.63;66.68

SWG set point is not below 1500mV

Your views please.

Would think the CPS is knackered. Change it, don't forget to remove it from the bracket it sits on DO NOT remove the bracket. See what you get.

Weird. Ignore the 1500 set point. It never is!

That injector degrees is way out.

All values should be from warm engine idling. And it should idle at 750rpm.