Fellow SMC users: Lets compare O2 numbers

[GNVAIR]

This is to satisfy my own curiosity. I know that O2 numbers should not be used as ultimate numbers to watch when tuning, but mine have been as low as 720's on a sub freezing night. Max KR I have gotten was less than 2° which is usually on the 2-3 shift once into 3rd and 4th gear it stays at 0. My current set up is TE45a (25-27lbs of boost), 55lb injectors, Extender chip (21°/23°) 15 row stock location intercooler, 340 pump, and your other basic modifications.
I am running a single nozzle SMC kit with straight denatured spiked with WD40. I always run 94 Octane Sunoco Ultra. I have h have a VERY well trained ear for detonation. It has been working fine like this for almost a year now.
I am just curious about whether I should worry about the low O2's.

*Please note that I have a completely stock long block (stock cam, unported heads and intake)

 

[Turbo__Tim]

I've heard of a few people running into the low .700's. I've heard .720's mentioned a few times. I believe that one guy even changed the 0-2 sensor and got the same results. I pick up knock around .770 - .780 if that helps...

Come to think of it, at least one of the others was running alchy..

Guess every car is different.

 

[Eric Stage I]

!

Lee,
It really all depends on where you are seeing the low O2's. It is normal to see the O2's drop throughout a run because of the O2 sensor heating up. It is not uncommon for them to drop as much as .100-.120volts. What I have seen that works fairly well is O2's at about .800-.820ish at the start and then they dwindle to .720-.740ish by the end of the run. If you've got some real hot egt, it might even drop into the .680-.690 range. Realize that the mixture may not be getting any leaner! I have seen this time and again on directscan where the O2's drop, but I'm squirting the same amount of fuel through the run.

Now if your running straight pump gas (no alc), you may have to make a chip that progressively gets richer through the run just to ward off knock. In that case you may see "flatter" O2's. But for race gas and alcy users, I would expect to see the O2's drop during the run.

Just my experience.

Regards,
Eric

 

[GNVAIR]

Great answers! Thanks guys!

 

[BLACK6PACK]

My 02s drop through a run too. I see low 800s at the beginning and end up around 770 by the end. I've kinda got out of the habit of watching 02s and watching the egt instead. The 02s are never very consistant on my car, but the egt tells the whole tale. If my egts get above 1650 or below 1500 i need to do some tuning.

 

[blackbuick87]

Not using SMC but my O2's also drop, but I have not been able to record them since my turbolink just arrived 2 weeks ago.

I am usually in the 770-780 range. According to my Gtech I am about .2 faster than when tuned for 820's.

 

[GNVAIR]

It looks like mine is still pretty rich. I pulled my turbo today to do some maintenance on the headers. The turbine wheel and inside the housing are very sooty. Definitely not the whitish color like most of the turbo Buicks I have been working on usually are.
I think this is probably a good time for me to install my SMC EGT.

 

[turbo]

Re: !

Originally posted by Eric Stage I
Lee,
It really all depends on where you are seeing the low O2's. It is normal to see the O2's drop throughout a run because of the O2 sensor heating up. It is not uncommon for them to drop as much as .100-.120volts. What I have seen that works fairly well is O2's at about .800-.820ish at the start and then they dwindle to .720-.740ish by the end of the run.

Yup..same here. Identical!

 

[blackshoebox]

I would..

..compare your EGT temps to the O2's once you have the egt meter in. 720's for 02's sounds lean, but the O2's sensors can begin to foul if they heat up during a WOT pull. I still tune with O2's, but will be moving up to EGT, since exhaust temps don't lie.

HTH,
Alex

 

[blackbuick87]

Tuning today I had O2's in the 650's, but only 2.1*KR

Man I gotta get Tlink on there