kenkaru

My fuel trims are maxed out at 25+% to get my A/F at 14.7 while idling.

If I reset the FT's with BIDI, the I get these reading for a second until the FT's kick in again.

WBO2 showed 19:1
O211 showed .100v
O221 showed .060v

If I give it any amount of throttle, the LTFT's go to the normal range of badness like 10%.

Would leaking headers cause my O2's to only read lean (by that much) at idle?

BTW, I only have one WBO2 on the driver's side. Hmm I think I should install a bung in the passenger side this weekend and see if both sides behave the same.

When I reset the FT's, the stock sensors go .0X volts for a few seconds

If there's any other info that can help here, I logged quite a few parameters so I can post more or email a scan.

TAQuickness

iTrader: (28)

Yes, leaking headers can cause lean O2 readings. Likewise, unmetered air entering the intake manifold can cause a similar effect.

we_todd_did

iTrader: (97)

Most cars will run lean on idle due to a rich condition is hard to idle.

RedHardSupra

iTrader: (1)

well, most cammed cars SEEM to idle lean because of overlap letting fresh air into the exhaust and making O2's think it's lean. the real problem with it is that they dump lots of fuel and make it rich, so the car's surging and spewing fuel out the tailpipe, but the WB shows lean. that confuses a lot of people cause they see lean and keep dumping more fuel at it and it's only getting worse not better.

The best way to spot leaky headers is to go WOT. You will see the two O2s lock up ~900mV, and if there's a leak, one of them is going to drop off toward lean territory.

TAQuickness

iTrader: (28)

actually, a safer way to spot exhaust leaks is to do a seafoam treatment. If there's a leak, smoke will find its way out of it

kenkaru

Should have posted my sig.
Advertised Duration Int. : 279°
Advertised Duration Exh. : 287°
Camshaft Duration @ 0.050" I/E : 219°/228°
Camshaft Lift I/E : 0.525"/0.525"
Lobe Seperation Angle : 112°
RPM Range : 2200 - 6500

Does this look like a cam that would have the overlap to trick the O2's into reading lean?

I'm going to "seafoam" with some ATF and see if it's leaking too.

Thanks!

Tommy Tucker

FWIW. That looks like the Hotcam.
I have the Hotcam and although I'm running a very different set-up and in SD I sorted my idle using the STFT and smelling for gas. It worked really well and I have a smooth idle at 750 rpm (1050 down to 750 from cold to hot).
I was surprised at the comparitively small VE values I ended up with at idle MAP in the 800 and 1000 rpm columns.
Tom.

kenkaru

Would you mind posting a pic of you VE table?
I have EFI-L.

Tommy Tucker

Yep will do but it will have to be tomorrow as I'm now at work and my files are at home. As long as you understand that it's a 'tune in progress' and that I'm in SD.
My idle map is about 50KPa by the way.
The hotcam has enough overlap to generally fail idle emissions (hydrocarbons). So that means that a significant amount of the unburnt charge passes into the exhaust at idle.

kenkaru

Thanks a bunch. I'm looking forward to seeing this to get an idea.
Ah so then the overlap is going to make it look lean right? What do your idle fuel trims look like?

Tommy Tucker

That's what I inferred from what RedHardSupra was saying...and it makes sense. Because of the overlap you actually have less air in the cylinder at idle as some is being lost to the exhaust. So although the VE table will require enhancement off idle and in the mid and upper RPM areas, at idle range the VE will be lower than a similar cam with less lobe overlap.
My idle was very rich when I put the hotcam in on stock settings. Definitely had a strong gas smell.

kenkaru

Does SD use fuel trims?
It seems to me that no matter what I do, the O2's are always going to read lean at idle and add fuel.

This is good. I'm actually understanding everything in this conversation so far and your hotcam experience sounds similar to mine. I checked my MAP at idle and I'm right at 50 kpa's too.

I'll post up a pic of my VE when I get home just for whatever.

Tommy Tucker

Sorry Ken. I will try to remember for tomorrow. Got side tracked with an oil leak.
Tom.

kenkaru

No prob, here's mine.

I put my desired airflow in there too.
Could I see what you have in that table also?
Thanks!

kenkaru

I adjusted my IAC steps to 60 today. Yay! It helped out a bit to make the car idle a little smoother and it doesn't surge as much. It's slowly getting there.

Bringing the steps from 30 to 60 also brought my desired and actual airflows within .2 Before, I was trying to get them closer but they would never get closer than about .8


Thanks! any luck on the image of your VE table? or if you'd rather email me an excell sheet, I can pm you my email.