Engine Idle Question

[Delbwoy]

Hi all,

It's a '96 1.9GTD Ibiza. An AAZ engine.

I have spent days reading and searching, but I'm still not sure as I don't know if other peoples cars are relevant to mine.

Main concern is idle speed. With A/C off it is at around 600rpm and is very uneven. When A/C is on it raises to just over 1,000. I'd like to sort this out properly but don't know how. Taking it to a garage is a no no as I've run out of money!! I've played with some nut locked screws on the pump to raise the revs, but it is not right as it takes ages to go back down to idle, so I put it back how it was.

I've got new fuel and air filters, and did an oil service.

When it is idling the aux belt tensioner is jumping around like the clappers and I am worried it will throw the belt or some such mishap. A new tensioner here is 90 Euros and that's not from SEAT!! I don't want to spend that if I don't have to. I think it would be better to get it running smoother.

Air flow meter? VAG.com? I thought the car is too old. I can't see an air flow meter. The air intake goes straight to the turbo with no air flow meter.

Your help would be greatly appreciated as I would like to get it running better so I know what to expect when I play with WVO for fuel! It's running on DERV at the moment as it runs so bad on proper fuel I can't imagine it running at all on WVO.

Thanks in advance.

Del

 

[Viking]

Tickover speed should be about 850rpm, so something is wrong. There is an idle speed adjustment on the injection pump, and it looks as though it's just a matter of adjusting the accelerator cable where it connects on to the injection pump. So you can adjust the idle by (in effect) shortening the inner cable to pull the injection actuator slightly, as if you had your foot slightly on the accelerator. In reality you're not shortening the inner cable but lengthening the outer sheath which has the same effect.

 

[Muttley]

AAZ is an indirect-injection, tubocharged, 75BHP engine, with no electronic management. The fact that there is an accelerator cable from the pedal to the injection pump should be a clue to this. I'm looking at Haynes manual 3571 which covers it in the Ibiza (covers the AHU engine too, which is what my old Mk 2 TDI Ibiza had).

According to Haynes, AAZ should idle between 890 and 950 rpm. The injection pump has an idle speed adjustment screw and stop screws for minimum and maximum idle speed, shown in the Haynes manual.

 

[Viking]

Yeah, you're more right than I am. I was looking at the VW AAZ engine which has a different set up to the Seat one.

 

[Delbwoy]

Perfect. Thank you.

I was adjusting the screw that is between 2 & 3 which is not marked, also adjusted screw 3.

I'll have a play tomorrow and see what happens.