X pipe Tune Adjustments Required

[decipha]

Its come to my attention that many are unaware of the effects an X-pipe has on o2 readings

An X pipe is a tricky setup for the fact that at very low loads idle and such, you will get reversion in the crossover and an o2 sensor will sample some of the burn on the opposing bank, however whats tricky is that as rpms and thus exhaust flow is increased, the reversion is reduced and the o2 will then read a greater majority of its specific bank

It poses a unique conundrum that can only be mitigated in one of the following manners

1> disable one hego - my most common approach

2> disable closed loop at idle and low loads - takes some finesse

My preferred method is option 1, just makes life easy and I like easy (excluding women)

[lsperformance]

move the X pipe back more will alter torque band some, but will keep reversion to minimum. There is other non reversion fabrication that can be done, but is timely..

[fox bodies rule]

I just ran across this and it could explain my grief with idle and low rpm issues. is there a viable third option-remove the X pipe and put in an H or is reversion still going to be a problem at low exhaust flow rates?

[decipha]

h pipe is fine no reversion issues there

you can just force open loop at low loads or just disable one hego, no issues with either of the two

[Shaker666]

I've definitely run into this when I installed a 3" exhaust with X-pipe behind 1-3/4" long tube headers on my stroked Ford 408 Windsor. The O2 on one bank was just going crazy, ended up pulling and plugging the bung and using the opposite bank's O2 instead. Runs great now.

[leadfootdriver]

Does an X or H have any scavenging effect on a Twin Turbo motor?

[decipha]

minimally, the turbos will be the restriction

if using an x youll have to disable hego 2 regardless

[89mustangcoupe]

I using a bbk 2.5 in x pipe also which side would be hego1 passenger side? I think I'm gonna try this again so what exaxtly has to be changed so 1 o2 reads for 2 banks

[decipha]

yes hego1 is the passenger side

set numego to 1 and fn1327 injector output port bank assignment so cyls 5 through 8 use the same bank as cyls 1 - 4

http://www.efidynotuning.com/tips.htm