Am I running lean? Log inside.

[4G63dsmpwr]

Hey guys I'm stumped.

I bought a logger for my car (90 AWD) and when I logged it, the car was running horrible. I was seeing 02 readings around .76-.78V, 20-30 counts of knock, and timing advance around 7/8 degrees

The worst part: The readings above are at stock boost! So I realized that there was a problem, causing me to run lean, I tried the following fixes:

New Fuel Filter
Chevron Techron Fuel Cleaner System
Pressure tested the intake system, replaced SMIC (leaking)
Bought an AFC2, which lead me to...

3RD gear pull:

+30 across the board, 9LBS of boost, 80deg out, 93 oct., 10 deg base timing, 100% mid/high fuel trims.

RPM--O2V-TIMA-KNCK

2781---.83---20---0
3031---.82---20---0
3343---.82---20---0
3562---.83---20---0
3937---.82---20---0
4093---.78---18---0
4562---.78---18---0
4906---.80---18---0
5375---.78---19---0
5593---.76---20---0
6031---.76---21---0
6375---.76---19---0
6531---.76---18---0

Now before I hooked up the AFC, and made these adjustments (+30% on a stock setup!) the O2s were the same!? I don't get that at all, I mean if I'm adding 30% more fuel, how can the O2s not change?

However, before I hooked up the AFC/made an attempt to tune I was getting TONS of knock, and barely any advance timing (sometimes as low as 6-7 degrees).

As far as the knock/tim. advance looks - it looks like my car is running good. But the O2s are WAY too low!

Is my car really running lean (via the O2 reading)? And if it is, why is the ECU advancing timing, and isn't seeing any knock? Also, the mid/high fuel trims are at exactly 100% - so doesn't that mean the ECU isn't adding/attempting to add any fuel at all?

When dealing with total timing your getting, and your running 10deg. base timing - do you add the 5 over the OEM base timing to the timing advance you see with a logger?

I'm totally confused, and not sure what to do. Any suggestions would be really appreciated! Thanks very much for the space!

 

[Liquid Illusion]

If your car was lean it would have a knock sum greater then zero

 

[4G63dsmpwr]

Exactly! So is my car running fine? And the O2 reading just messed up?

Thanks very much for your input Liquid

 

[Liquid Illusion]

The o2 value is not relevant, and I would turn the boost up past 8 psi and lean the car until it knocks just a little. If you want to monitor your air/fuel signal buy a wide band. I suggest not even using readings from a stock 02 sensor for any kind of open loop tuning.

 

[4G63dsmpwr]

Alright thanks alot. I really appreciate all the help. I'm going to hook the boost controller up, and give it a few more pounds.

How does the timing advance look? Is that where I want to be with 10deg. base timing?

Thanks again man, really helped me out!

 

[Liquid Illusion]

it looks good for 8psi as boost goes up timing will go down.

the ecu will show a base value of 8-10*. the only way to check uncorrected timing is with a timing light.

 

[4G63dsmpwr]

Alright, thanks again for the help.

A buddy of mine used a timing light, and set it to 10base. So I dont add anything at all to the timing adavance? When I see 20deg, thats exactly what I'm getting?

Thanks!

 

[Liquid Illusion]

Timing advance is accurately shown by your logger under boost.

 

[CanadianTSi]

Timing should be set to 5 degree's BTDC.

You shouldn't have to be adding 30% fuel on a stock setup, something is wrong. Maybe your fuel pump is bad.

 

[Blk_99gst]

You shouldn't have to be adding 30% fuel on a stock setup, something is wrong. Maybe your fuel pump is bad.

Yeah, I agree. You should not be at +30% on the safc. And you shouldn't use that as a bandade to fix things. Like others have said, you should only be at 5deg not 10deg base timing. You might need a new fuel pump, maybe new o2 sensor. With +30%, your o2 should be 1.0+volts.

And I don't see how your fuel trims are 100% if you have your low safc settings at +30%.

 

[4G63dsmpwr]

Alright, a buddy of mine bumped the timing up to 10 deg. BTDC. I don't have access to a timing light, so I can't change it back right now.

I tried numerous fixes for this problem. I don't want to just cover up the problem, but I didn't know what else it could be causing this problem.

If you guys think its the fuel pump, then I'll pick up a Walbro 255HP, only $110. Do you think that this is definately the problem? Is there any way to test the voltage/fuel pressure or anything?

Do you think clogged injectors might be a problem? Has 170k miles...

I've tried two different O2 sensors as well, same voltage readings.

My high settings are at +30%, the low is closer to +15%...

The med/high fuel trims are exactly at 100% even, and the low is at 115% (this is a 90, so thats almost maxed out).

If you guys that the fuel pump is causing me to run lean, then I'll definately pick one up. Thanks very much for all the input.