P38A Diesel upper timing chain rail

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Lukas018 said:
Ok sorry to be a pain could you explain what timing modulation and the what values represent just so I can learn? Thank you.
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Wammers could give a more detailed explanation than me, but basically the modulation figure represents the position of the servo in the FIP, 50% is mid point which is where it should be at hot idle (+/-5%)
 
Datatek said:
Wammers could give a more detailed explanation than me, but basically the modulation figure represents the position of the servo in the FIP, 50% is mid point which is where it should be at hot idle (+/-5%)
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Thanks @Datatek can I upload videos on here as would like to record my engine running might help?
 
Datatek said:
Wammers could give a more detailed explanation than me, but basically the modulation figure represents the position of the servo in the FIP, 50% is mid point which is where it should be at hot idle (+/-5%)
Click to expand...

I'd need to check to refresh my memory but I think it is the comparison between the start of injection based on the crank position sensor and that measured by the needle in the #4 injector. As Data says, when the load is stable such as at idle then it should be about 50%. Measurements always raken on a warm engine at idle.
 
@Grrrrrr thank you. I mentioned that the CPS bracket was removed and put back in without the tool and this is still the case. Got a 1.5mm shim for gap. Is it worth doing this check or wait till I get modulation results?
 
Lukas018 said:
@Grrrrrr thank you. I mentioned that the CPS bracket was removed and put back in without the tool and this is still the case. Got a 1.5mm shim for gap. Is it worth doing this check or wait till I get modulation results?
Click to expand...

If the CPS was a problem with no signal the engine would be revving over 2000 RPM i have already said that. Modulation is about point of injection adjustment for various injection pump internal pressures. Static is set with engine locked at TDC number one firing. And is set slightly advanced to aid starting. 0.95mm lift new chains 0.90mm lift old chains. When the engine is switched off, when internal fuel pressure in the injection pump bleeds away timing always returns to static setting. At idle warm engine (minimum internal pressure) modulation should be 45% to 55%. Below 50% static is advanced above 50% static is retarded. The ECM receives a signal from number four injector every two revolutions. This tells the ECM the actual point of injection. The ECM then modulates the pressure control to either restrict or increase internal fuel pressure acting on the timing device piston against spring pressure. This causes the timing device cam to rotate changing the point of injection to 1 or 2 degrees BTDC. As internal injection pump pressure increases due to engine RPM to a max of 4.5 bar, more modulation is required to allow more fuel flow away from the timing device piston to adjust point of injection within specified tolerance throughout the rev range. That is why modulation should never be checked at other than idle warm engine.
 
wammers said:
If the CPS was a problem with no signal the engine would be revving over 2000 RPM i have already said that. Modulation is about point of injection adjustment for various injection pump internal pressures. Static is set with engine locked at TDC number one firing. And is set slightly advanced to aid starting. 0.95mm lift new chains 0.90mm lift old chains. When the engine is switched off, when internal fuel pressure in the injection pump bleeds away timing always returns to static setting. At idle warm engine (minimum internal pressure) modulation should be 45% to 55%. Below 50% static is advanced above 50% static is retarded. The ECM receives a signal from number four injector every two revolutions. This tells the ECM the actual point of injection. The ECM then modulates the pressure control to either restrict or increase internal fuel pressure acting on the timing device piston against spring pressure. This causes the timing device cam to rotate changing the point of injection to 1 or 2 degrees BTDC. As internal injection pump pressure increases due to engine RPM to a max of 4.5 bar, more modulation is required to allow more fuel flow away from the timing device piston to adjust point of injection within specified tolerance throughout the rev range. That is why modulation should never be checked at other than idle warm engine.
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Thanks @wammers I need to try and borrow a nanocom then and check modulation otherwise be checking things not worth checking. Just wish someone could lend me one for a day.
 
Lukas018 said:
Thanks @wammers I need to try and borrow a nanocom then and check modulation otherwise be checking things not worth checking. Just wish someone could lend me one for a day.
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How are you going to check for correct modulation when you can't get it to idle? You need to find out why idle control is not working. Think you said you fitted a new injection pump hope it's not one somebody has been buggering about with.
 
wammers said:
How are you going to check for correct modulation when you can't get it to idle? You need to find out why idle control is not working. Think you said you fitted a new injection pump hope it's not one somebody has been buggering about with.
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No sorry just to recap the below is what is happening:

1. Engine starts.
2. It idles but very bad readings on live data between 728 and 750 rpm but fluctuates right down to 628 and smokey.
3. Any load like put in gear at tick over and it stalls but no load rough idles.
4. When starting from cold it doesnt idle higher like should until warm.
3. When at say 1500mm rpm sounds fine no smoke.
4. Live data on 4 runs 2 runs showed idle not active then active on tick over.
5. Lift needle injector 4 comes up as fault and then goes.
Last 2 runs showed no faults but still idling rough.

This is where I am confused on what to do and check?

Hope that makes sense might throw some light.

The pump was removed from another p38 and I saw it running and you remember how many times it took for to time it unless this has been disturbed when tensioner on upper chain may have thrown it out slightly?
 
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Lukas018 said:
No sorry just to recap the below is what is happening:

1. Engine starts.
2. It idles but very bad readings on live data between 728 and 750 rpm but fluctuates right down to 628 and smokey.
3. Any load like put in gear at tick over and it stalls but no load rough idles.
4. When starting from cold it doesnt idle higher like should until warm.
3. When at say 1500mm rpm sounds fine no smoke.
4. Live data on 4 runs 2 runs showed idle not active then active on tick over.
5. Lift needle injector 4 comes up as fault and then goes.
Last 2 runs showed no faults but still idling rough.

This is where I am confused on what to do and check?

Hope that makes sense might throw some light.

The pump was removed from another p38 and I saw it running and you remember how many times it took for to time it unless this has been disturbed when tensor on upper chain may have thrown it out slightly?
Click to expand...

If static was done correctly and locked at TDC fitting upper chain can change nothing. Think you have an electrical problem. But you need to go over everything again to take things out of the equation. Sort CPS, check static. Check wiring to number four injector for damage and connection. If it's running like a bag of bricks and Hawkeye is showing no faults something is rotten in Denmark.
 
wammers said:
If static was done correctly and locked at TDC fitting upper chain can change nothing. Think you have an electrical problem. But you need to go over everything again to take things out of the equation. Sort CPS, check static. Check wiring to number four injector for damage and connection. If it's running like a bag of bricks and Hawkeye is showing no faults something is rotten in Denmark.
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Right ok will go over it all.

What's best method to check static timing same as before or RAVE procedure?
 
Update - CPS is ok and injector cable was damaged re-wired it, it idled a bit better fluctuates between 728 and 750 rpm at idle. Seems to get better every time start it. So next thing to check is FIP static timing as that be next thing.
 
Lukas018 said:
Update - CPS is ok and injector cable was damaged re-wired it, it idled a bit better fluctuates between 728 and 750 rpm at idle. Seems to get better every time start it. So next thing to check is FIP static timing as that be next thing.
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You are getting there. I doubt that the static timing would cause a fluctuation of 22rpm. The aircon is switched off I suppose?
 
Datatek said:
You are getting there. I doubt that the static timing would cause a fluctuation of 22rpm. The aircon is switched off I suppose?
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I removed the compressor and air con rad as they were both bust. Would this affect the weighted balance of the engine having the compressor off?

Sorry forgot to say two faults are now persistent, needle lift sensor, going to get injector checked.

Other fault is engine speed sensor? This wouldn't be the cps would it?
 
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