Tdi not tdi?

resto_d1 · Nov 2, 2018

Probably a really stupid question but in my defence any project I've had has been petrol!
Am I correct in saying direct injection didn't come in until td5? So my 300tdi would have a pre combustion chamber?

When someone turns up the fuel pump on a tdi engine, why does the engine not run rich due to a lack of maf?

jamesmartin · Nov 2, 2018

resto_d1 said:
Probably a really stupid question but in my defence any project I've had has been petrol!
Am I correct in saying direct injection didn't come in until td5? So my 300tdi would have a pre combustion chamber?

When someone turns up the fuel pump on a tdi engine, why does the engine not run rich due to a lack of maf?

tdi is direct injection both 200 and 300
if you turn fuel up enough it will black smoke

resto_d1 · Nov 2, 2018

So you can have a tdi without a hpfp then.

jamesmartin · Nov 2, 2018

resto_d1 said:
So you can have a tdi without a hpfp then.

what do you mean by hpfp, tdi injection pump runs at twice that of previous lr diesels

resto_d1 · Nov 2, 2018

jamesmartin said:
what do you mean by hpfp, tdi injection pump runs at twice that of previous lr diesels

All the modern stuff like my daily has expensive high pressure pumps.

As I understand it, the lift/diagram pump pulls from tank then pushes to injection pump. I assume that injection pump then pushes out at a far higher psi to the injectors and from there is the only high pressure part of the fuel delivery. Does the pump know how much to put out by engine speed as there's no ecu present?

jamesmartin · Nov 2, 2018

resto_d1 said:
All the modern stuff like my daily has expensive high pressure pumps.

As I understand it, the lift/diagram pump pulls from tank then pushes to injection pump. I assume that injection pump then pushes out at a far higher psi to the injectors and from there is the only high pressure part of the fuel delivery. Does the pump know how much to put out by engine speed as there's no ecu present?

its only about 10 psi to the injection pump and then injection pump produces high pressure, pre tdi 135 bar was standard om many diesel, tdis about twice that, pump is calibrated to deliver a certain amount of fuel depending on throttle position,you could only put in as much as air engine could take in, hence using turbos to chuck more air in so you could put more fuel in before it black smoked showing you there wasnt enough oxygen, no ecu was needed,ecus are used now and pressures are higher to reach admission targets to match fuel with the air whereas previous an engine at certain times would be running with more air than was needed (as diesels dont have a butterfly valve like petrols which governs the amount of air going in) and so produce nox gases, egr and ecu etc are there to reduce nox and other emissions, you dont need anything but a good high pressure pump and a turbo for power but you need ecu ,egr etc for emissions

resto_d1 · Nov 2, 2018

Thanks for explaining James. Makes sense

SteveSw · Nov 2, 2018

This video explains the basic operation of the tdi pump (except for the aneroid on the top)

jamesmartin · Nov 2, 2018

resto_d1 said:
All the modern stuff like my daily has expensive high pressure pumps.

As I understand it, the lift/diagram pump pulls from tank then pushes to injection pump. I assume that injection pump then pushes out at a far higher psi to the injectors and from there is the only high pressure part of the fuel delivery. Does the pump know how much to put out by engine speed as there's no ecu present?

simply , the amount of fuel injected governs its speed you put a little in it will idle, press the throttle and it increases the amount injected each time revs and power rise, the physical limit on amount is black smoke showing you its over fueling, pumps are set so that doesnt occur unless you adjust it yourself which is why they adjuster screw was wired and sealed so it could be seen if it had been tampered with

dieseldog69 · Nov 3, 2018

resto_d1 said:
Probably a really stupid question but in my defence any project I've had has been petrol!
Am I correct in saying direct injection didn't come in until td5? So my 300tdi would have a pre combustion chamber?

When someone turns up the fuel pump on a tdi engine, why does the engine not run rich due to a lack of maf?

You could always dump the Tdi and slip something in there that might raise a few eyebrows off the traffic lights

resto_d1 · Nov 3, 2018

No way. Would've bought a ps13 Silvia if I wanted that. I wanted a utility vehicle I could manage myself, throw my rods and gear in and disappear from the hustle and bustle or working life

Tdi not tdi?

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