[firehawk618]

I can't speak directly of the VX but can tell you how my HX works.

From what I understand the VX is much faster to go in LB vs the HX.

With my car it's much easier to get it into LB when you meet the following conditions:

RPM's ~2700. It will go in at lower rpm's. I have watched it kick in just under 2000 before but it's much harder to do it below 2700 rpms. It will kick out of LB at 3100 on the dot.

Throttle position must be 20.9% or lower but above 10%. On my car 10% TP is foot off throttle, so you must be on the throttle a touch but never above 20.9% to engage it. Once it is in LB I can roll into the throttle and at that point I watch engine LOAD. Once the load hits just north of 90% it will kick out of LB.

Engine load: It must be pretty low for any hope of LB. I have not figured out the lower / upper threshold that must be met to engage LB yet.


Speed: Mine will engage as low as 28 mph but will kick out at 75 mph. THis is because at 75mph I am at 3100 rpm's. I'm confident if I had taller gears I could go faster.

I am very happy with the gearing in my DX transmission. I don't need to exceed 75mph. 65 mph puts me at the sweet spot to get LB engaged. ~2700 rpm's.


I know if I have engine codes then LB will never engage. I am battling EGR issues right now * to be fixed today* and have a persistent pending P401 code. Low EGR flow. I can still get LB because the code is pending and not a hard code yet.

O2 sensor is another touchy one. If yours has never been replaced I would suggest to pony up the $$$ and just do it. O2's can test fine, look fine on a scope but not be fine. Especially our super sensitive Lean o2 sensor.

Maybe for giggles try cruising the highway in 4th gear for a day and see how LB goes. I bet you have an easier time keeping in LB because 5th is so super tall which puts your engine load higher and throttle position higher.

It sounds like you do not have MPGuino. I highly recommend one if you're serious about really monitoring what's going on.

That bump in power you experience is most likely what you think it is. LB dis engaging. It could also be issues with your EGR system. The only way I can think of to tell for sure is an MPGuino.