I am working on a $0D application, stock 350 TBI in a pickup.

One of the things I have noticed is that the O2 crosscount speed is MUCH slower than what I am used to - but the only thing I am used to is the $8D TPI setup in my '91 Z28.

I have tried a new O2 sensor and it acts identically.

Is it typical that a wet manifold TBI setup will have slow O2 crosscounts (due to the less precise fuel control, all the fuel hanging out in the manifold, etc.) as compared to a TPI/port injection setup?

What I am seeing is that it can take sometimes 2-3 seconds to generate a crosscount, and several INT steps each direction to generate a crosscount, so it looks like the INT has to slew back and forth more than I'm used to, to generate crosscounts.

Even at steady state, 40+mph speeds, where the sensor should be plenty hot and everything should be functioning well, I only get about one crosscount a second.

Edit: I'm not necessarily trying to solve any problem, it's running fine; I was just surprised to see how slow the crosscounts are.

 

The INT shouldn't be moving to create crosscounts. TBI set ups are typically slower in this department then MPFI set ups. This is due to the capacitor affect of the wet plenum.

It just may be that the calibration has reduced proportional gains. As it is better to have it that way, then to have too much proportional gain.

RBob.

 

I feel it is very normal, having worked with many E6, OD, and OE calibrations on different trucks. Remember too the emissions standards are less strict on trucks and they generally run richer with less timing.

 

Thanks guys. it's helpful to know this is normal.