P38A Mechanics, FIP and timing chain investigation

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brianp38dse said:
BigAd scribe a mark on the pump and the block were the pump mounts loosen the pipes and mounting bolts and tap the pump in towards the engine , we are talking tiny amount mm or less and re check modulation till you get it right , and it will sound like a new motor.
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Would it not be best to get the static timing 750 first and see what the modulation is then.
I’m confused as to why the mechanic would time it out in the first place, because he had to fit the FIP from my original engine onto the new one as it didn’t come with one.
 
BigAd said:
I’ll get it up to about 95 and take another reading. From what I gather from reading up the correct settings are:-
750rpm
fuelling @ 128 on nanocom
5-6 mg/str
modulation 50% (+/- 5%)
Modulation of 95 is the max the electronics can account for chain stretch apparently, I’ll post back when I get new readings.
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Yep. That needle needs to be steady at 12 o'clock and then check modulation. 95% could be chain stretch but they might have set the static to the new chains lift and not the second number so need to check static before naking any assumptions. I believe worn FIP and duff lift pump can also make a small difference to modulation. Others might disagree. If modulation was tgat high I would expect warning lift on dash on lift-off approaching roundabouts.
 
BigAd said:
Re done the readings at 95 and they still seem way out.
Im right in saying this is pointing to a slack chain?
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Check static first. See above. 2 settings, one for new chains and 1 for when run in. Mechanic might have done wrong one - or messed it up. It can drift a bit on tightening up if you're not careful.
 
Grrrrrr said:
Check static first. See above. 2 settings, one for new chains and 1 for when run in. Mechanic might have done wrong one - or messed it up. It can drift a bit on tightening up if you're not careful.
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I vaguely remember him saying he tried setting it at the correct spec and it idled badly. So I assume that’s why it’s ticking over at 820, with him messing about to cover an issue he couldn’t be bothered dealing with. but I’ll check the static and see where it’s at.
 
BigAd said:
I vaguely remember him saying he tried setting it at the correct spec and it idled badly. So I assume that’s why it’s ticking over at 820, with him messing about to cover an issue he couldn’t be bothered dealing with. but I’ll check the static and see where it’s at.
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Yes, unfortunately it is now a case of trying to work put where he went wrong or what he missed as you say, should idle at 750rpm.
 
BigAd said:
I vaguely remember him saying he tried setting it at the correct spec and it idled badly. So I assume that’s why it’s ticking over at 820, with him messing about to cover an issue he couldn’t be bothered dealing with. but I’ll check the static and see where it’s at.
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There used to be a clutch place down the road in Huddersfield, Clutchfix? Might be worth ringing them as they made and supplied racing clutches for people racing BMWs. They made one up for me years ago. They'd know a BMW mechanic who knows the M51 engine back to front.

The other thing that occurs to me is that there are 2 holes in the flywheel quite close together. He might have got the wrong one when looking for TDC.
 
The modulation should be 50% with an engine temperature of 95C. Using my steel rule method, you will need to move the FIP around 3/16" towards the block, maybe more. Idle should be 750 +/- 50 rpm so don't worry about the idle speed for the moment.
I can send you my guide to modulation adjustment if it would help. PM me with an email address if you want it.
 
Datatek said:
The modulation should be 50% with an engine temperature of 95C. Using my steel rule method, you will need to move the FIP around 3/16" towards the block, maybe more. Idle should be 750 +/- 50 rpm so don't worry about the idle speed for the moment.
I can send you my guide to modulation adjustment if it would help. PM me with an email address if you want it.
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Why don't you just post the guide Keith? Then it could be added to the Technical archive.
 
+1 for Data's method. Mine was stalling when put into drive or reverse, lumpy running.
Modulation was 87 iirc, moved the pump around 3/16" and she runs sweet now.
I had to remove the viscose fan to get the temp up which I highly recommend you do as you'll be able to adjust and recheck much quicker but saying that, I couldn't drive mine on the road due to no MOT/tax/insurance. Standard tools needed to do the job but a cranked 12mm ring makes the difficult nut nearest the block on the FIP easier to do. Make sure the very last movement you make with the FIP is TOWARDS the block. Replace the leak off pipes while the inlet manifold is off if they look iffy, same with the map pipe, under the manifold to the fuel filter on my 2001, early models differ I think.
 
Datatek said:
The modulation should be 50% with an engine temperature of 95C. Using my steel rule method, you will need to move the FIP around 3/16" towards the block, maybe more. Idle should be 750 +/- 50 rpm so don't worry about the idle speed for the moment.
I can send you my guide to modulation adjustment if it would help. PM me with an email address if you want it.
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Hold on, his idle isn't 750rpm because someone has bodged something. He needs to get to the bottom of why the bodge was needed before he tries your bodge and by that time he may not need it. :)
 
Grrrrrr said:
Hold on, his idle isn't 750rpm because someone has bodged something. He needs to get to the bottom of why the bodge was needed before he tries your bodge and by that time he may not need it. :)
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When modulation was out on mine idle went up and down 700-750, when I put idle up to 800 on nanocom it stayed smooth. Modulation sorted put idle back to 750 and it's smooth.
Mechanic maybe did the same to mask lumpy running?
 
Grrrrrr said:
Hold on, his idle isn't 750rpm because someone has bodged something. He needs to get to the bottom of why the bodge was needed before he tries your bodge and by that time he may not need it. :)
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Idle should be 750 +/- 50 rpm so not too far out and may be affected by the modulation. Sort the modulation first then if needed look at the idle speed.
If the idle figure has been changed it's easy enough to correct it with Nanocom. By the way it is not always 128.
My method of setting the modulation is not as you put it "a bodge", it's a very accurate way of getting it right which is almost impossible using the DTI method.
 
Grrrrrr said:
Hold on, his idle isn't 750rpm because someone has bodged something. He needs to get to the bottom of why the bodge was needed before he tries your bodge and by that time he may not need it. :)
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Exactly my thinking, i remember him telling me he advanced the timing because it ran lumpy at 750rpm

At this point i'm more thinking its the timing chain not the FIP because it ran fine on the original engine, that and the modulation reading.
 
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BigAd said:
Exactly my thinking, i remember him telling me he advanced the timing because it ran lumpy at 750rpm

At this point i'm more thinking its the timing chain not the FIP because it ran fine on the original engine, that and the modulation reading.
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If the modulation can be brought into spec, I wouldn't worry about the chains.
 
Datatek said:
If the modulation can be brought into spec, I wouldn't worry about the chains.
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Until they part company or jump a tooth.if the chains are stretched you can bet the sprockets are worn,:rolleyes: Your choice of course if it's still making a rattling after you've done the modulation.;) When I was in the trade I wouldn't touch the job unless everything necessary was replaced, they have a habit of coming back to bite you in the arse.:eek::D
 
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