Injection Pump Timing Weirdness.

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cjcardummie
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Injection Pump Timing Weirdness.

Post by cjcardummie »

Hi, I have been fixing up a ZX which has been fitted with an engine from a Xsara. Its a 1.9 DHY Turbo type with a mechanical pump and I had metal fragments blocking the injectors so I've cleaned the system out and fitted a new filter. It still happened again after a 30 mile run so I got a pump from the breakers. This pump is a Bosch whereas the old one was a Lucas.

I managed to get the injectors off the donor car as well as the pipes and sprocket for the pump so all's fine.

I moved the studs on the bracket and fitted the pump (you can tell i've been reading alot of message boards for info), Fitted the sprocket correctly and timed up the cam and pump to the crankshaft. Knowing this is THE crutial part I have checked this 3 times to make sure it is right.

I fitted the injectors and pipes and everything else to get the engine running.

Next I got the timing gauge out to do the pump position. Now apparently these pumps are timed at 0.66mm with no 4 piston at TDC.

I've followed the correct proceedure AKA Haynes manual, checking I've got compression on no 4 (the cylinder nearest the timing pulleys) and timed the pump up. I then checked 3 times again to make sure.

Now to the problem, When I started the car it ran like sh*t. Lots of white smoke and hunting and missing al over the place.

I reved it up and left it running for a few minutes to make sure it's got out any air that may have been in the system.

Still the same so I undid the pump nuts and moved the pump towards the engine (advanced). The engine started to run better as I moved it so I moved it some more until the engine ran as sweet as a nut.

Locked off the pump and gave it a run up the road. Great no problem, maybe a little sluggish on acceleration.

I came back and after much head scratching got under the bonnet and checked all the timing again, Cam, pump and flywheel lines up correctly. Check the dial gauge again. I found that the setting at 0.66mm is back where it was when I first did it. Start the engine and it runs like Sh*t so moved the pump back to where the engine was happy.

More head scratching and reading the posts on the forum for any info, I put new leakoff pipes on and checked for any air in the system, all fine.

Now I'm a great believer in Sod's Law so I'm thinking the engines running sweet so the pump timing cant be far off, but where in the 'good' range is it best to leave it set.

If I move it away from the engine (retarded) it gets to a point where the engine starts to miss and hunt. If I move the pump forward (advanced) I get to a point where the engine starts knocking slightly (too advanced)

If I was to set it between this range where best, near the point where it starts to miss or near the point where it starts to knock. I know, I know, you'll say somewhere in the middle. There's quite a way between the 2 points so where should it be or more precisely why does it run like sh*t when I do it properly. Am I missing something.

Any advice welcome.


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Post by wheeler »

has the wooddruff key fell out of the pump sprocket when fitting the pullley making you think the timings lined up ok ?
cjcardummie
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Post by cjcardummie »

Hi, Thanks for replying. I dont think so. When I first attached the sprocket the key hole was slightly turned and as I put the sprocket on the damn key fell out so after retrieving it I made sure the thing was in place as I placed the sprocket on.
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Post by AndersDK »

You should set it closets to the "knocking" point - but avoid knocking of course. Remember the engine must be hot when checking for knocking.

Also check that the coldstart timing advancing is working and shuts off when engine is hot. The coldstart advancing will cause the cold engine to knock with a very distinct diesel "clatter". This should disappear or at least calm down a lot when engine is hot and advancing shuts off.
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Post by CitroJim »

Anders, you are absolute correct to set it to just before the point of knocking. It it easily best done by "ear" on a hot engine. If it sounds sweet it will be as right as it'll ever be.

One thing that needs to be address is the cold-start advance. On a Bosch Mechanical pump this is normally done using an electrovalve. This is down low on the front face of the pump. 12V is applied to this electrovalve when cold to give extra advance and remains on unless the throttle is opened beyond a third or the coolant temperature exceeds 60 degrees C. This is the purpose of the microswitch on the top of these pumps. If you have 12V on the electrovalve constantly it will be over-advaced when the engine is hot.

The cold fast idle does just that. It has no effect on timing whatsoever.

Are you 100% sure you have a mechanical pump and not the very similar looking semi-electronic job? These will sort of work but without any ECU control they will "failsafe" to a fully retarded timing point and you'd have to turn it a long way on the mounting to make them run with reasonable advance. These are unsatisfactory for use as they have no mechanical centrifugal advance like a proper mechanical pump so the engine will run at fixed timing regardless of speed. This may account for why the engine feels a bit sluggish with this pump fitted.
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Post by cjcardummie »

Thanks for your quick response, Well I was in a hurry to get the car sorted for a trip to see the folks for Xmas and set the timing just below the knocking point but I must admit the engine wasn't hot. I then did a trip from Devon to Cumbria and I've just got back. The car was great I averaged about 70ish all the way up and did half a tank of diesel which I guess is about 40 miles a gallon. On the way back I averaged about 80 but as I was against the wind it did about 3/4 tankfull. The power was ok,very smooth and responsive in fact at 70 I was holding the car back all the time. I did notice once we got there and was driving up small hills at about 40mph on load it did have a bit of diesel clatter, I dont know whether this indicates something or just the nature of the beast.

Thanks for all your help and advice.

Regards
John
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Post by Brian UK »

White smoke is normally unburnt fuel, which happens when the timing is retarded.
A specialist once told me, to time a pump, slacken it off slightly, turn it until knocking just starts, then back it off a tad. Then tighten.
If you turn it much, you should also slacken off the high pressure pipes on the end of the pump to allow them to centralise, then retighten.
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Re: Injection Pump Timing Weirdness.

Post by fastandfurryous »

cjcardummie wrote:Next I got the timing gauge out to do the pump position. Now apparently these pumps are timed at 0.66mm with no 4 piston at TDC.
Here's a thought.. Are you measuring the 0.66mm injection pump piston travel by rotating the crankshaft forward from 90degrees BTDC up to TDC when the timing pin drops in? I have seen people try to adjust the injection stroke by setting the engine to TDC and then moving the pump... this simply won't work.

The other thought is that the later injection pumps for late 90's 1.9TD models are not the same as earlier ones. Is the measurement of 0.66 definitely valid for this injection pump? I think it might not be as I know the injection pressure was upped at some point, and so the injector stroke will definitely have changed (to get the injection point the same but at a higher pressure)

Out of interest, with the engine running properly, what measurement of injection pump piston stroke do you get? (from 90 degrees BTDC to TDC)
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