O2 sensor readings & tuning.

[Jaan]

Hi you Guys:

I have MSed 2 cars & have the same conclusions on both:

When I try to tune them to.5 volt on a narrowband sensor they always seem too lean.

Preamble:
Both motors are flat air cooled 4 cylinder 1220cc. ( Citroen)
One has throttle body & MS1
One has multiport & MSII 2.89
Both have heated O2 sensors, although different brands.

If I use autotune, or datalog & then VE analyzer, the cars hesitate at steady state conditions & feel way too lean. The plugs look & smell lean, & there are hesitations on acceleration also

As I gradually richen the things up they actually start to feel & run like modern cars, & they also get good mileage. The plugs still look leaner than a good running factory carburettor setup.

Datalogging ,I see that if I have an average O2 voltage around .9 to .98 The cars both seem like they are totally happy.

What's up ?

I'm not hot rodding around, these are commuter vehicles that are driven 1/2 in town & 1/2 freeway to get to work.

Is it that a dinky 1220 cc engine needs all the power it can get all the time ?

As an addendum I also noticed that if I datalog with a stock carburettor, the O2 sensor is almost always pegged at 1.0 volt.

Any thoughts ?

Here's a webpage of the last conversion:

http://www.eddinsmoto.com/id131.htm

Cheers!

Jaan.

[Matt Cramer]

Air cooled engines often use additional fuel for cooling, and most engines make more power if run slightly rich.

[Jaan]

Thanks Matt.