1z power issue

[ross b]

Got a 80 avant tdi, which from day one of picking it up was lame and underpowered. Checked usual sensors, maf and n75. checked for any holes in intercooler pipes or loose fits. gave her a service which improved responsiveness marginally. managed to pin it down to porous vacuum hoses which i replaced all of. Now the car picks up well low down to about 3000rpm then when held in the gear for any longer, kind of surges. it feels to pull then die back a little pull then die back a little. difficult to explain and im probably not wording it as well as i possibly could but never come across this before with 1z's. any sggestions appreciated.

[TBone]

check the crankshaft pulley for slack, it's an 1z issue ... prepare for buying new crankshaft ...

[ross b]

cheers for reply. if this was the problem, would the surging not be felt throughout the rev range, not just with high revs?

[Skull]

could be the air mass sensor. it has a potentiometer inside which wears out, as there is a needle that is travelling up and down.

you should open the box, and move the sliding plate just little bit so the needle travels on fresh ground.

[TBone]

1z has a mechanic quantity sensor? not a hotwire mass sensor?

[Skull]

only the very latest have the hotwire, that is from middle 1994 ->

it is easy to know which one it is as the old one is a square box, the new one is in a tube.

[ross b]

could be the air mass sensor. it has a potentiometer inside which wears out, as there is a needle that is travelling up and down.

you should open the box, and move the sliding plate just little bit so the needle travels on fresh ground.

always presumed it was a sealed unit, does it just prise apart? Do the air mass sensor's differ from country to country i notice your from outside the uk.

[TBone]

k, full ack, but i prefer the idea with the loose crank pulley ...

[ross b]

mine is 95 so tubular.

[Skull]

always presumed it was a sealed unit, does it just prise apart? Do the air mass sensor's differ from country to country i notice your from outside the uk.

yes it is sealed, but it is just a plastic cap glued on the aluminium box.

[Skull]

mine is 95 so tubular.

ok, so it makes it also much cheaper to replace it, go for it.

the other advice i have is that you should remove the intake manifold and clean all the soot out of it, and then seal off the EGR valve.

[Skull]

just to give you an idea what will you find in it:

[Max M4X WW]

How easy is it to remove the inlet? Will you need new gaskets?

[Skull]

it is not hard in terms of mechanical knowledge, but it is a bit time consuming. i dont remember exactly if you have remove the turbo (i think not).
new seals are a must, as there must be no leaks.

this is the only pic i have from when i did it...

[Max M4X WW]

I did the manifold, it probably had 20% of what is shown in the photo above