SAI-related question....

[911_fan]

This is something that I've been noticing lately, and was wondering if this is just....weird or not.

When the outside temps reach a certain (cold) temperature, my SAI doesn't kick on. Something like below 40*-45*, on cold-starts, it doesn't come on. Just in warmer weather.

Is that odd, or just normal? I was under the impression that the SAI kicks on every cold start, regardless of outside air temp., until the O2 heats up. I removed my SAI system on my old MKIII Golf, so I never really dealt with it.

(this is on my 2000 B5 ATW 1.8t.)
THX

[cri-cri]

Something like below 40*-45*, on cold-starts, it doesn't come on. Just in warmer weather.

I wondered the same thing (mine behaves identically). Turns out that's the expected behavior as per Bentley... Check page 26-23:

Secondary Air Injection operation approximate temperature and time on initial start-up:
1.8L.............................................. ................5-33 C (41-91 F), 100 seconds

[l88m22vette]

SAI uses fresh air to bring up combustion heat initially which helps light the catalytic converter to reduce emissions. In very cold weather it will actually hurt engine heat-up time by blasting it with even more cold air; this also happens to increase cold-start emissions. Those emissions constitute something like 90% of the pollution vehicles emit, anything OEMs can do to reduce those emissions are crucial, which is why you see SAI, EVAP, PCV, cats, all that stuff on engines to begin with...

[911_fan]

Roger that.

Thanks for the replies gentlemen.

The whole reason why I noticed this in the first place is because my pump sounds like a Boeing 747 taxiing because the pump is messed up. It works fine....just LOUD. I just want to unplug it.

Now....to search for which resistor to plug into the SAI connector so I can unplug it and it wont throw a code.

[l88m22vette]

It will throw a code regardless, even with the right plug resistance because you still are missing the increased flow the engine will be expecting. Only a tune lets you truly get rid of the SAI system

[911_fan]

Ah, ok. I don't have a tune for this engine yet, so I guess I'll have to go with whichever company has this delete option as part of the tuning package.

[dliu]

Hi,

I have the same problem with sai, just want to make sure when you say tune is = tune up? I see a 3 step tune up kit that allows you DIY, is that a good idea?

d

[DustyVW337]

He means software. I think Unitronic has a program that will eliminate the CEL after a SAI delete. Not sure about others.