Adjusting on-boost fueling (Lucas)

jonathan_dyane · Post by **jonathan_dyane** » Sun Nov 02, 2008 8:01 pm

Terribly excited to report that I am picking up my 'new' TZD Turbo estate on Friday, which necessitates a train journey to Exeter...

One one of the issues I will have to sort out for the MOT would seem to be a smoking issue; the car has had the pump (and I guess) boost fiddled with, and it would seem to smoke excessively on-boost. Which gizmo on the pump do I twiddle to reduce on-boost fueling? It is a Lucas CAV/rotodiesel pump.

Also, I would appreciate comment on the likelyhood of me getting away with the 'pre-booked MOT ploy' on my drive home, particularly as the distance necessitates booking the test for the next day...

Post by **mat_fenwick** » Sun Nov 02, 2008 8:45 pm

I think that the case regarding the MOT should be OK, I'm not aware of anything stipulating that it has to be a journey to the nearest MOT station. It seem reasonable to want to take it to a local station if case it requires a retest. I would make sure you have your insurance documentation with you though.
I've done it once, but wasn't stopped. I'd try and avoid any known camera areas, as you can't argue your case with a camera...

Jaba · Post by **Jaba** » Sun Nov 02, 2008 9:59 pm

I have spoken to the DVLC in the past on this MOT issue - asking can I drive my car back from France with no MOT. They said, surprisingly, yes, you can drive the car back from abroad to a prebooked MOT.
Its not a criminal offence. Its the DVLC who prosecute you within their rules for no tax or MOT.
So just make sure you take it for that pre booked MOT the next day.

jeremy · Post by **jeremy** » Sun Nov 02, 2008 11:30 pm

The easiest screw to adjust is the throttle stop screw on top of the pump. Its the one the lever strikes when the throttle is opened fully - and if its never been disturbed will have a seal on it. Its actually quite sensitive - so try turning it in a turn initially and see if its any better. If the car is slow but doesn't smoke then after the MOT undo it 1 flat at a time until it just smokes then do it up one flat.

The effect is simply to limit the throttle opening - so if it only smokes when you have your foot right down and doesn't if you lift off a touch then this screw may help.

Debelix · Post by **Debelix** » Mon Nov 03, 2008 7:27 am

What is the color of the smoke? I'm asking because the smoke color on diesels is a very important indication for lot of things. If it's gray then your problem is not with the "boost" - you just have air coming in the fuel, or the fuel filter is VERY dirty. Anyway, the Lucas/CAV pumps doesn't have a "boost" feature on a accessible place - it's under a plastic cap at the front of the pump and it's sealed, because the only people meant to play with it are the people in a diesel garage (or whatever the name

). So - if the problem it's not air in the fuel but overdosed fuel portion, you can't fix it - you need special equipment for that task...

As for the other colors of smoke - blueish smoke means you're screwed (engine needs fixing); black smoke is when the engine doesn't get enough air (or it's getting too much fuel, depends on the point of view

); continuous white is for water/coolant in the combustion chamber (also not good!); and gray is when you've got air in the fuel.

Last option is quite interesting - recently i've got lots of gray smoke from my car when revving over 3k rpms - changing the fuel filter fixed this, but the filter itself wasn't so clogged to cause this. It turned out that somewhere in the fuel system i've got a small crack that don't show itself under low pressure. But when the engine goes over 2,8-3,2k rpms the vacuum that the pump does cause the crack to open and the pump sucks air in the fuel - then comes the gray smoke. When diesel filter is clean and new it doesn't cause so much of a pressure drop to open the crack, but when it clogs up a little - here comes the smoke again!

jonathan_dyane · Post by **jonathan_dyane** » Mon Nov 03, 2008 4:42 pm

We-ell, I have realised that if I disconnect the pipe twixt intercooler and pump compensator the car will recieve no extra boost fueling, so if the car does seem very smoky I will try removing this for the MOT and setting the pump up an my leisure...

Thanks guys.

tom · Post by **tom** » Mon Nov 03, 2008 6:27 pm

no comment

jonathan_dyane · Post by **jonathan_dyane** » Mon Nov 03, 2008 6:39 pm

tom wrote:Leave it alone and drive it hard from Exeter to Liverpool. The terrain around Exeter is most conducive to sooting up a TZD. My old car was followed back from Manchester way and by the time I arrived in Southampton, it was not only smoke free, which it had not been, but a good ten miles per hour quicker! Try this first. You might find that you haven't really got a problem. Good luck.

I shall and will; the desire to fully 'test' the thing will be hard to resist (although I will be somewhat paranoid until I have fitted a temperature gauge...)

Incidentally, my previous BX TZD had a XUD9TE pump, and unless the air filter was either replaced or hoovered every couple of months it was a heavy smoker, but yet always passed the smoke test...