air intake tube diameter 98-00 1uz

[Brad Bedell]

Can someone with a 98-00 VVT-I engine measure their intake tube where the AFM mounts? My best guess is that it's around the 3.250" range, but I don't have anything to measure against. I want to make sure the velocity is correct for the AFM.

-B

 

[Brad Bedell]

Well, since either noone understands what I'm asking or noone is bothering to modify the late model VVT-I engines, I've taken it upon myself to find the answer.

3.5" is too large. I'm getting 20% fuel trims now. 3.0" tube had 7.8% fuel trims.

I'll track down something like a 3" OD tube and it should be pretty close.

-B

 

[Zuffen]

Brad,

If some one on this Site knew the answer to your question they would have posted.

I'd rather no answer than 10 uninformed guesses!

 

[Brad Bedell]

I tend to agree, as I'll question any answer I get that doesn't 'make sense'. I'm guessing 2.75-2.8" is probabliy pretty close to what is needed. I'll just have to try it out and see where my fuel trims are in the ECU.

Am I the only one on here modifying the VVT-I engine? It's a shame really, one can control the cylinder pressure by adjusting the valve overlap dynamically. I found that I gained 30hp under the curve on my 2zz 4 cyl by adjusting cam timing.

-B

 

[Brad Bedell]

Just updating in case someone needs this info in the future:

I measured a stock intake as best I could without disassembling it too much. it's somewhere around the 2.75" mark (+/- 1/16") However, I found with a sleeve this size on my IS400, I was running air fuel ratios around 11.7:1. Way too rich for a NA engine. 3.0" tube got me around 12.4:1 and 3.5" got 13.5:1

This was done with a computer reset each time to help reduce the adaptive nature of the OBD II computer. Now that long term trims are adjusted, I'm sitting right at 13.0:1, which feels and sounds about right. (nice crisp note with out any surging)

-B