P38A Modulation

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Timing modulation (%): This value is the amount of percentage change that the EDC · ECU applies to the injection timing. It can be checked in conjunction with the Injection set points and actual values. On a fully warm engine this value should steadily remain between 45% and 55%. There should be no erratic fluctuations. Either listen or not it up to you.
 
Last edited:
wammers said:
Timing modulation (%): This value is the amount of percentage change that the EDC · ECU applies to the injection timing. It can be checked in conjunction with the Injection set points and actual values. On a fully warm engine this value should steadily remain between 45% and 55%. There should be no erratic fluctuations. Either listen or not it up to you.
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What constitutes "fully warmed up? 80C when the stat opens, 85C, 90C, or higher, the modulation will be different at each of those temperatures so what is "fully warmed up".
 
Datatek said:
What constitutes "fully warmed up? 80C when the stat opens, 85C, 90C, or higher, the modulation will be different at each of those temperatures so what is "fully warmed up".
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When it is fully warmed up. And the temp is stable at idle. The viscous fan will assist stabilisation by the way. Give BBS a ring and argue with them, that is their instruction. The only thing that will change modulation is injection pump internal pressure. Maybe your diag is a bit dicky.
 
wammers said:
When it is fully warmed up. And the temp is stable at idle. The viscous fan will assist stabilisation by the way. Give BBS a ring and argue with them, that is their instruction. The only thing that will change modulation is injection pump internal pressure. Maybe your diag is a bit dicky.
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You seem to have no idea what the temperature is, when as you put it, "the temperature is stable at idle", it is different with an outside temperature of 10C to what it is with 25C, more so with the viscous fan. You have obviously never looked at the M51 temperature gradient. Modulation varies quite a bit with temperature. If you think a Faultmate is likely to be dicky, you are clutching at straws.
 
Datatek said:
You seem to have no idea what the temperature is, when as you put it, "the temperature is stable at idle", it is different with an outside temperature of 10C to what it is with 25C, more so with the viscous fan. You have obviously never looked at the M51 temperature gradient. Modulation varies quite a bit with temperature. If you think a Faultmate is likely to be dicky, you are clutching at straws.
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Modulation is checked at idle 750 RPM with the engine up to temp. You have removed the viscous fan which helps to stabilise temp. And you wonder why it fluctuates come on get real.
 
wammers said:
Modulation is checked at idle 750 RPM with the engine up to temp. You have removed the viscous fan which helps to stabilise temp. And you wonder why it fluctuates come get real.
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You are really getting stupid, as I said you have never looked at the temperature gradient, the rate of change is very very slow and needs nothing to stabilise it. because you do not know, you keep introducing spurious arguments and ignoring the original point.
 
Datatek said:
You are really getting stupid, as I said you have never looked at the temperature gradient, the rate of change is very very slow and needs nothing to stabilise it. because you do not know, you keep introducing spurious arguments and ignoring the original point.
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You dont have bloody clue do you.
 
iu
 
Who else has a diesel and a Nanocom? Lets get some data and compare. A sample of 2 isn't worth ****.

Next time I do a decent long run I will take a trace of the temperature afterwards and see how stable the temp is.
 
Grrrrrr said:
Who else has a diesel and a Nanocom? Lets get some data and compare. A sample of 2 isn't worth ****.

Next time I do a decent long run I will take a trace of the temperature afterwards and see how stable the temp is.
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What is there about up to temp at idle do you not understand?
 
wammers said:
What is there about up to temp at idle do you not understand?
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I understand that. And I believe mine is stable at 89 degrees centigrade when standing at idle. You claim it should be but Datatek claims otherwise. There are 2 opposing theories so let's do the experiment and see which one the data supports. Maybe my car is odd. Maybe it is Datatek's. But if 9 cars are one way and 1 the other then I think we'll go with the 9.
 
IMHO with a thing the size and mass of an RR engine and moving through air then there will have to be some variation.
Set point has to be constantly hunted for
 
Grrrrrr said:
I understand that. And I believe mine is stable at 89 degrees centigrade when standing at idle. You claim it should be but Datatek claims otherwise. There are 2 opposing theories so let's do the experiment and see which one the data supports. Maybe my car is odd. Maybe it is Datatek's. But if 9 cars are one way and 1 the other then I think we'll go with the 9.
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Keith has removed his viscous fan and shroud, whether he likes it or not that changes the charicteristics at idle. The fan would be drawing air and stabilising the idle temp. He does not seem to understand that.
 
wammers said:
Keith has removed his viscous fan and shroud, whether he likes it or not that changes the charicteristics at idle. The fan would be drawing air and stabilising the idle temp. He does not seem to understand that.
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Yes, you said that a few pages ago. It sounds logical to me but the only way to prove anything is to do the experiment.
 
Grrrrrr said:
Yes, you said that a few pages ago. It sounds logical to me but the only way to prove anything is to do the experiment.
Click to expand...

If you want to that is up to you. But i need to prove nothing it is obvious to me. How Keith can keep arguing the toss defeats me.
 
I may be wrong here, but I think what Keith is trying to say is that the "stable" idle temperature on two different vehicles could easily be different by, let's say, 5 degrees and that could lead to a detectable difference in modulation which has potential to fool some people into thinking they have a problem when maybe they don't.
It would be interesting to see several different vehicles modulation against actual temperature to see just how much difference it really makes.
 
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