MAFless and Rear O2's

[Steeler]

So some background first and then a scenario.

I have a supercharged 3.0 from VF with a VF modified ECU.The tune has been revised twice and is as much as VF is willing to do, it is the same tune that Pokeybritches has on his 3 litre.
I installed a header without cats and left the stock exhaust from the header back in place. It sounds very meaty with a deep bass sound and nice pops and crackles that may be producing flames not too sure.
I got the inevitable SES because of the rear O2's not being used after about 75 km's.
I was also getting power surging and hesitation around 3500-4000 rpm which I think is a bad MAF.
I disconnected the plug from the MAF and have been running without it for about 1000 km's. I am very aware of the AFR when driving and with repeated accelerations to redline has shown AFR's of around 13.5 at WOT. Oil temps are around 220f all day long once warm.
The surging and stumbling has disappeared as well as the SES for the O2 sensors, I am only getting SES for the MAF being disconnected.

So I tried an experiment tonight, when I returned home I did not shut the engine down I put the connector plug back into the MAF and shut the motor down. Before when I would restart after shutting down with the MAF disconnected I would get an SES upon start up, this time I did not of course.

Seems to me if my AFR's are good running MAFless and I can effectively turn the MAF on and off before shutdown and after start up I can run cat less and not get SES.

All feedback is welcomed including possible detrimental effects to the engine.

[gmd2003]

Originally Posted by dbarton62

So some background first and then a scenario.

I have a supercharged 3.0 from VF with a VF modified ECU.The tune has been revised twice and is as much as VF is willing to do, it is the same tune that Pokeybritches has on his 3 litre.
I installed a header without cats and left the stock exhaust from the header back in place. It sounds very meaty with a deep bass sound and nice pops and crackles that may be producing flames not too sure.
I got the inevitable SES because of the rear O2's not being used after about 75 km's.
I was also getting power surging and hesitation around 3500-4000 rpm which I think is a bad MAF.
I disconnected the plug from the MAF and have been running without it for about 1000 km's. I am very aware of the AFR when driving and with repeated accelerations to redline has shown AFR's of around 13.5 at WOT. Oil temps are around 220f all day long once warm.
The surging and stumbling has disappeared as well as the SES for the O2 sensors, I am only getting SES for the MAF being disconnected.

So I tried an experiment tonight, when I returned home I did not shut the engine down I put the connector plug back into the MAF and shut the motor down. Before when I would restart after shutting down with the MAF disconnected I would get an SES upon start up, this time I did not of course.

Seems to me if my AFR's are good running MAFless and I can effectively turn the MAF on and off before shutdown and after start up I can run cat less and not get SES.

All feedback is welcomed including possible detrimental effects to the engine.

13.5 at redline ? That's lean as hell on this motor .

[Beedub]

Originally Posted by gmd2003

13.5 at redline ? That's lean as hell on this motor .

yeah we want to be seeing more like mid 11s!!