Todays 2.4D discoveries - pump timing. |
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Baxter
Admin Group Scruff Daddy Joined: 29 May 04 Location: Huddersfield Status: Offline Points: 8060 |
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Posted: 27 May 08 at 21:34 |
Now, until now, this was speculation but until today I have been unable to check it.
2.4D's are slow, we all know that.
You can set them up like Mr VW says, or like Mr Autodata says and they never seem "right"
I've done loads of these cambelts and never really had any trouble, it's one of those things, it's booked in, you change the cambelts, set the pump timing up afterwards and off it goes, they always seem slow, but they get set to what the book says, so that must be right, well, seemingly not.
i've long had the suspicion that all it not well with the 2.4D injection pump and today I managed to prove it.
Story, I'll start from the beginning.
I have recently had a reasonably high mileage T4 Westy High top in for a belt change, belt was done, van ran like a bag of shit.
Timing was checked, and found to be a mile out, so timing was reset in the time honoured fashion with a dial gauge in the end of the pump.
van now runs loads better, goes up hills, but blue smokes from cold and even when warm it's a bit lumpy and a blue haze from exhaust.
Engine will not strt from ciold without the coldstart lever (telling me the pump timing is retarded)
So, timing is bob on according to VW, bob on to Autodata but runs okay but not as well as it could.
This moring I took delivery of a "Diesel pulse adapter" it's a small box containing a 9v battery, it has a small piezo electric clamp that goes around an injector line, an eart lead and a loop of wire.
What the box does is sense the pulses in the injector pipe and converts it into a signal that any petrol timing light can use as a trigger for the strobe.
So, this afternoon i managed to test out my worn pump but timed up right theory for real.
Pump timing according to Autodata is .55mm lift@TDC.
I set the pump a little advanced at .60mm lift at TDC.
According to Autodata, to set pump timing dynamically (with pulse adapter) then the timing should be between 12 degrees BTDC and 16 degrees BTDC depending on the equipment used.
So, piezo electric thingy is a bit finiky, and it didn't work at first so the injector line was cleaned with a scotch pad, not pulse adapter springs into life!
I have a Snap On timing light with digital advance and retard.
I set it to the 12 degrees and the timing marks where nowhere to be seen!
I kept dropping back until I could see the marks, which I occasionally saw at 0 degrees BTDC telling me although according to the dial gauge I though the timing was advanced the timing was over 12 degrees retarded! That explains the poor starting and blue smoke then!
After a bit of faffing around I managed to get the timing with the pulse adapter set to about 12 degrees BTDC and all seemed well, started better, reduced smoke and according to test pilot power was as it was pre belt.
So, moral of story, when setting injection pump timing with a dial, be careful, although the dial is telling you what you want to know all may not be as it seems.
I can only presume that this effect is caused by a worn pumping element, taking longer for the pumping element to reach such a pressure that it will open the nozzles, the more wear, the lower the pressure the more the timing will become retarded.
Other things that could effect this are injector nozzle opening pressures set too high.
I have learnt my lesson the hard way today, but as the proverb says
"The only true mistake is the one where you do not learn from it"
or something.
In future, all my timing will be double checked with the strobe.
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monsho
Admin Group Joined: 08 Oct 04 Location: Newcastle Status: Offline Points: 3510 |
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good write up fella...
so you're timing piezo thing - can you use this to measure the revs? need to reset my rev counter, be a good way to do it if it can |
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Baxter
Admin Group Scruff Daddy Joined: 29 May 04 Location: Huddersfield Status: Offline Points: 8060 |
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Yes, it measures revs, or should I say my timing light does.
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Sven
Groupie Joined: 04 Feb 05 Location: United Kingdom Status: Offline Points: 43 |
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Interesting find
Sven
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svenlivesey@hotmail.com
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jc_geddes
Yardie Joined: 26 Jun 06 Location: United Kingdom Status: Offline Points: 452 |
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So out of interest what should the pump timing be for standard Jx and AAZ engines??
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andaru8
Not Quite Newbie Joined: 17 May 10 Location: inverkip Status: Offline Points: 12 |
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Forgive my ignorance,but i resealed my injector pump on my 1994 2.4d aab,refitted pump,belts etc,primed pump and it fired up, but after 2-3 minutes running the idle seems to drop and engine cuts out.I then turned idle screw in a bit to compensate and everything seemed ok .Next morning- idle will not sit still,and engine will not start unless throttle pedal is depressed.
Any tips or ideas to cure this.Much obliged.
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lochy
Newbie Joined: 14 Jun 10 Status: Offline Points: 5 |
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I've reseal a few pumps. I think you'll find that the small spring that goes to the idle regulater
has been stretch a little. so you need to adjust the screw that point upward at the engine side
turn it in untill the problem stops. with out the correct test equipment you'll just have to turn it say a half turn and then start the engine. until the problem is resolved. it will act different when cold.
it also can incress the idle so dont adjust it to much.
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andaru8
Not Quite Newbie Joined: 17 May 10 Location: inverkip Status: Offline Points: 12 |
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yes that would make sense as the idle is not "regular".I did stretch the spring a bit on removal of pump head.Surely the idle should run the same hot or cold?i wonder if the spring has come off when i replaced the pump head?I will have a go at adjusting the screw you mention before performing further surgery.thanks for your comments.
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Brookster16v
Not Quite Newbie Joined: 12 Mar 11 Location: Dewsbury Status: Offline Points: 35 |
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Great Thread
Just purchased a Gunson Diesel Pulse Adaptor to set up my Injection pump Timing
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Brookster16v
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Brookster16v
Not Quite Newbie Joined: 12 Mar 11 Location: Dewsbury Status: Offline Points: 35 |
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Recieved the Diesel Pulse Adaptor today Connected it all up and the LED is flashing, connected the Timing light to the Pick up loop but nothing :* Connected the Timing light to my other petrol cars and its working fine :confused: any ideas anybody ? could the pick up loop be faulty cheers |
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Brookster16v
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max and caddy
Vanorak Joined: 12 Dec 09 Location: Lancaster..uk Status: Offline Points: 4866 |
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tryed it both ways round? worth a shot.
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Brookster16v
Not Quite Newbie Joined: 12 Mar 11 Location: Dewsbury Status: Offline Points: 35 |
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Yeah tried it both ways and every way.
Its picking up the Pulse the LED is flashing , so it must be the pick up loop that you clamp the Timing inductive pick up onto.
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Brookster16v
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Brookster16v
Not Quite Newbie Joined: 12 Mar 11 Location: Dewsbury Status: Offline Points: 35 |
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The Gunson Pulse adaptor will only work if i put the Inductive pick up on the Black cable on the fuel pipe.
the inductive loop pick up on top of the unit doesn't work
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Brookster16v
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