rich when under boost

[chiel]

When under boost my narrowband a/f gauge is directly on the rich. normally it goes from lean to rich up and down.

 

After driving i got dtc:

P0101 - Mass Air Flow (MAF) Sensor Performance (SES) (OLD) (History) (Immature)

P0131 - HO2S Circuit Low Voltage Bank 1 Sensor 1 (OLD) (Immature)

P0137 - HO2S Circuit Low Voltage Bank 1 Sensor 2 (OLD) (Immature)

P0157 - HO2S Circuit Low Voltage Bank 2 Sensor 2 (OLD) (Immature)

 

It still pulls very strong, but looks like at almost wot i have more power than at wot.

 

Looking at the dtc's i will check tomorrow the wires from the ho2s sensors.

 

You guys any idea's?

Edited April 15, 2005 by chiel (see edit history)

[TurbochargedBerserker]

When under WOT, your computer switches from closed loop operation to open loop. In closed loop, the o2 sensors are used to keep your AFR switching around the stoichiometric point of gasoline (14.7 AFR, 1.0 lambda) for gas milage and emissions. When you go wide open throttle, open loop commands one AFR to target and does not switch, so the behavior you describe with the narrow band gauge is exactly what you want to see.

 

The target AFR is determined from the PE table in the computer (which is a lambda value), but isn't exactly accurate because of the narrow band o2s.

 

It sounds like you are a little rich at WOT, but better a little rich than a little lean!! Get that thing on a wide band or a dyno and nail your AFR for max power. You might also log your commanded AFR and your o2 voltages and then adjust the PE leaner (in very small steps).

 

A good, safe AFR for the street is 11.5 for boost.

 

Oh -- I believe the P0101 has a table in engine->diagnostics->general. Multiply the values in the table to raise them up until the code stops setting at boost.

Edited April 19, 2005 by TurbochargedBerserker (see edit history)

[chiel]

Oh -- I believe the P0101 has a table in engine->diagnostics->general. Multiply the values in the table to raise them up until the code stops setting at boost.

<{POST_SNAPBACK}>

 

Thank you for all the advise, i try to understand what you mean, the p0101 table multiply by howmuch? The code acured only once, after resetting it didn't came back (yet)

i now gonne look up and search what th PE-table is/does.

[chiel]

Ok looked in hptuners and stoich AFR is 14.681

 

Looked at PE(power enrichment): PE-fuel multiplier vs rpm is set between 1.140 at low rpm up to 1,230 at high rpm.

There is also a part about: "PE enable %TPS treshold vs RPM" ?

 

Am i looking at the wright table? I now gonne try to log comanded AFR and 02 voltages.

[TurbochargedBerserker]

I think I used 1.5 on the p0101 table.

[chiel]

Ok looked in hptuners and stoich AFR is 14.681

 

Looked at PE(power enrichment): PE-fuel multiplier vs rpm is set between 1.140 at low rpm up to 1,230 at high rpm.

There is also a part about: "PE enable %TPS treshold vs RPM" ?

 

Am i looking at the wright table? I now gonne try to log comanded AFR and 02 voltages.

<{POST_SNAPBACK}>

 

i am running 10psi

[TurbochargedBerserker]

Ok looked in hptuners and stoich AFR is 14.681

 

Looked at PE(power enrichment): PE-fuel multiplier vs rpm is set between 1.140 at low rpm up to 1,230 at high rpm.

There is also a part about: "PE enable %TPS treshold vs RPM" ?

 

Am i looking at the wright table? I now gonne try to log comanded AFR and 02 voltages.

<{POST_SNAPBACK}>

 

 

Yep. Set the threshold to 40% to begin with. You might end up playing with that a little, but 40% always seems to work so that you have enough fuel by the time you spool up.

 

In the PE multiplier table, that's where you set the WOT target. you can figure out the AFR by:

 

14.68/pe value

 

So:

 

14.68 / 1.14 = 12.87 AFR

 

14.68 / 1.23 = 11.9 AFR

 

So far so good. What you need now is to "guess" what AFR these commanded values get you to. Since you are not running lean, you can tweak these values for best seat of the pants performance until you can get on the dyno or hook up a wideband.

 

I would try figure out where in the RPM band it starts to feel sluggish and then lean out everything from that point up (closer to 1.0 = more lean, so if you are 1.23 at 4400 rpm and it seems sluggish there, I would try 1.2 which is 98% of 1.23)

 

You can also do this by watching the o2 voltages and finding the "sweet spot", which for me was between 890 and 920v. Then try to adjust the PE values to keep your o2s in that range throughout the rpm band.

[chiel]

Eric, thanks for the help , now find some time to make the log and read the numbers. i will post here how the tuning went. 15-5-05 there is an 1/8 mile race so i can look for the result too.