Thread: 1997 300tdi Auto Massive Fuel Guzzler

Don't know why I bother arguing with you as you clearly know everything. But if there's a blockage it can not use more fuel its that simple.

Come on 460 that's not fair...I know more than Dougal (only joking)

Dougal, are you saying higher revs to compensate for the blockage? Elaborate please.

First post says fuel lifter output good. If there is a blockage then where on from that point (assuming lift assessment correct) - half open fuel cut of solenoid - blockage or boken something or other in injector - or past the injector to blocked pressure line or an injector noz?

Originally Posted by workingonit

Come on 460 that's not fair...I know more than Dougal (only joking)

Dougal, are you saying higher revs to compensate for the blockage? Elaborate please.

First post says fuel lifter output good. If there is a blockage then where on from that point (assuming lift assessment correct) - half open fuel cut of solenoid - blockage or boken something or other in injector - or past the injector to blocked pressure line or an injector noz?

It's pretty simple.

If you have a choked fuel system which can still provide enough fuel for about 30kw then the driver feels a big reduction in torque due to the reduced flow and retarded injection timing and has to run higher rpm more often to compensate.

This results in more fuel use. I have had exactly this situation on my own work car due to a mostly plugged filter. Cell phone dyno results showed it had lost a third of its power.
Fuel consumption improved with the new filter.

Throwing one in from left field, I can't remember if our 300tdis came with EGRs fitted. If so, and not removed, maybe it's stuck open?

It could also be a very blocked exhaust (muffler) I have recently removed my centre muffler 500mm x 250mm and the improvement in response is noticeable and there is not a lot of noise increase just a little droning,fuel use seems to have dropped a bit too,I was using 10+ per 100klm now down to 9ltrs per 100klm

Also make sure you are filling it as with the newer hi-foam diesel the pump will click off 15 ltrs + short, and the last bit is a slow fill to get it right up the neck.

Thanks Guys,

Sedimenter and exhaust were two of the first things I checked. Sedimenter is clean and I disconnected the rear half of the exhaust pre-muffler and ran it for a couple of tanks. No difference. My last tank was interesting though, 555 kms for 79 liters. 14lt per 100kms! That was with a light foot, and hardly ever doing 100kph. Couldn't get past 90 on the way home this arvo, gonna go check all brakes again.

Regards,
Lane

By all means check the brakes but I think if they were holding on you would know all about

Dougal, correct me if I've misunderstood you on other threads, but I think you have said no wastgate, or wired up waste gate or faulty wastegate can lead to excess boost going into pistons - reducing power? A stuck open wastegate would also lose power? Would that potentially increase fuel consumption somehow, or affect injector advancement?

Lane, you said the actuator moved 'just' - as in only just moved or as in you were only just able to get something on to it to move it ie awkward access?

How freely should the actuator move (I assume this is really how freely will the wastegate move or open, I understand with a spring attached to close it) - is there a torque figure ie attach a fishing scale and pull?

Going from bad to good for a few minutes then back to bad could be a momentary change in the blockage or it could be a faulty wastegate?

In a series 3 petrol, I once had a sand grain size piece of rubber fuel line in the float chamber. Accelerate for some time would suck the rubber into the float needle hole causing reduced fuel flow and a loss of power. Stop for a while and the rubber would drop to the bottom of the float chamber and you could motor normally for a while. Hope its not something obscure like this.