SAI Question

[sh!tluck]

so I've noticed my car running a tad sluggish so on my break from school I stopped by Andys(Dubtuner) shop for a quick scan. I was showing 2 codes 1 for SAI and 1 for EVAP. both are understandable since the SAI was deleted by the PO. We got in and took it for a test drive while still VAG'd We noticed we got no readings from the O2 Sensor...After a quick interwebz search it says that you have to have the SAI pump and solenoid connected otherwise the ECU will disable the O2. Just wondering why it's beneficial to delete the SAI? Does this mean the O2 Sensor is useless and would that effect anything else?

mk3 vr6

[grayjet]

you supposedly get better mpg at least with the mk4. just through some resistors on the clips for the sensors and you should be fine.

[OrangeDUB]

Removing it frees up a lot of engine bay space, and simplifies the vacuum tubing.

It should'nt be effecting your pre-cat 2 sensor (main one) though. It is probably just effected by the post-cat o2.

Delete the SAI, delete the evap system.

[Helltime]

I deleted all of mine on my mk4 because it frees up so much space in the engine bay, and on a mk4 (not sure about mk3s) if you resistor them off correctly fuel trims will still adjust like they are supposed to and supposedly helps throttle response (i thought i noticed a difference, but they could be the placebo effect or maybe i have a bad vac line before i deleted it).

[OrangeDUB]

I'm about to delete it on my mk4. I think mk4's actually use it while driving for stuff.

Correct me if I'm wrong....
Mk3's only use SAI for injecting fresh air into the exhaust stream, quickly heating the cat up to a useable temp. After the cat is warmed up to its working temp (by showing less fuel at the post-cat o2 vs the pre-cat one) then its done with its job.

[rubberpenguin]

I'm about to delete it on my mk4. I think mk4's actually use it while driving for stuff.

Correct me if I'm wrong....
Mk3's only use SAI for injecting fresh air into the exhaust stream, quickly heating the cat up to a useable temp. After the cat is warmed up to its working temp (by showing less fuel at the post-cat o2 vs the pre-cat one) then its done with its job.

no to the first statement

yes to the second. SAI is only to pre heat the cat by injecting oxygen to "burn" the excess fuel during open loop

[OrangeDUB]

So there's totally no benefit to having it in a mk4 even? I'm gonna ditch this stupid SAI ASAP.

[Dubtuner]

we have no 02 control movement. Direct from a post from jeff at united if the air pump and solenoid are not connected it will disable 02 control. Not sure if it just goes to open loop using the maf readings or what? With a resistor it tricks it into thinking its there so than you would be fine.