Diesel power loss

samcro · Post by **samcro** » 16 Nov 2004, 18:02

Has anyone got any bright ideas why my 106 1.5D occasionally loses the top 1/4 of its power?
Under hard acceleration it can sometimes lack full power. Engine power seems to increase as expected the further I press the accelerator, up until about 75% and then there's no power increase after that even though the pedal travels further.
It's not just a case of poorly adjusted accelerator cable as it doesn't hapen all the time and i've felt it 'click' in and out while driving. ie. Foot flat to the floor and engine developing approx 75% power then suddenly engine power jumps to 100% with no pedal movement.

beezer · Post by **beezer** » 16 Nov 2004, 18:19

Sounds like injector pump problem. No doubt you have thought of this already, hence your previous post.

samcro · Post by **samcro** » 16 Nov 2004, 18:29

Got it in one.
I've checked out the air intake and replaced the filter. Checked out the fuel pickup and replaced the filter with no signs of any problems there and no improvement in the power loss problem.
Maybe a dumb question, but do diesels have some kind of full throttle boost like an extra valve letting in more fuel or something? I seem to remember that petrol engines can supply more fuel under heavy acceleration, like an extra nozzle in the carburettor. Do diesels do this kind of thing, inject additional fuel under heavy acceleration??

beezer · Post by **beezer** » 16 Nov 2004, 19:04

As far as I know the curve is a lot steadier with an injector pump. I would be looking for a good price for a scrap pump. These things are not easy to fix at home! Have you tried an injector cleaner?

Pedrolot · Post by **Pedrolot** » 16 Nov 2004, 20:00

Try Wynns Injector Cleaner, its in a 325ml (i think) purple bottle...works like a treat!

samcro · Post by **samcro** » 16 Nov 2004, 20:33

I tried a bottle of redex in it a while ago (lasted about 3 tankfulls) and it didn't seem to make any noticable difference. I'm quite wary of doing anything much to the injector pump myself and am hoping it's not it. It's the lucas type which doesn't receive much good press so it could well be it.
Cheers

rotodiesel · Post by **rotodiesel** » 17 Nov 2004, 03:52

Check the operation of the exhaust gas recirculation (EGR) valve which is actuated via a microswitch on the fuel control lever cam. This switch operates an electrovalve (mounted on the bulkhead) which admits vaccum to the EGR control valve which is fitted between the exhaust and inlet manifolds.
This fault is very unlikely to be the fuel pump - I would not recommend touching it. A new Bosch fuel filter would also be a wise move if the existing one has been on for more than 25k, or if you have seen any dirty fuel or water in the fuel.
rotodiesel.

beezer · Post by **beezer** » 17 Nov 2004, 04:54

Didn't realise the 106 had an ECU system and EGR. Would this be failing to switch off at high loads?

rotodiesel · Post by **rotodiesel** » 18 Nov 2004, 00:08

There is no ECU - thank god. The EGR is controlled directly using a microswitch on the fuel control lever cam. This admits pilot vaccuum from the brake vac pump to a control valve, which in turn operates the EGR valve. All nice and simple.
rotodiesel.

samcro · Post by **samcro** » 18 Nov 2004, 13:38

Hmmm.. think I know what you mean. Is that the switch on top of the injector pump? One that gets pressed by a plastic cam that moves with the accelerator. Worth checking it out. As far as I know the pump is original and the car's done 67k.
Cheers guys

samcro · Post by **samcro** » 22 Nov 2004, 13:52

It was the EGR switch causing the problem. Unscrewed it and 'carefully' dissected it with a hacksaw. Ithe innards of the microswitch were minced! Contacts were all corroded and arced ant the switch wasn't activating. Wired in a working toggle switch and fed it through to the cabin. Took the car for a spin and flicked the switch a few times. Bingo! Power at higher revs came and went with flicking the switch. Will replace the microswitch and hopefully everythign will be hunky dory.
Thanks heaps, Rotodiesel, for the suggestion

beezer · Post by **beezer** » 22 Nov 2004, 14:11

Glad you got it sorted. The thought of plastic cams etc does make you think 'cheapskates'.

samcro · Post by **samcro** » 22 Nov 2004, 17:02

Now,
Is having the EGR valve open going to increase the engine power or decrease it? I know that in one state it gives a small (but useful) increase in power and in the other state (ie flick switch inside car) it reduces the power a bit. Trouble is it's not obvious whether the valve is open or closed, based on the position of the bodged-in switch.
I'm wondering whether i've accidentally discovered a power boosting trick or not. You could hard wire the microswitch open or closed (whichever gives the increased power) and override the EGR system.
Could of course be that the power 'boost' is meant to be there and just with the EGR NOT working that it reduces the power a bit.