Strange 02 readings on my scanmaster

[Larry Smith]

I recently upgraded my old combo to a TA60 turbo & 009s.
I also ordered a turbotweak street chip, with the intention of getting the best pump gas setup for the street. The car is running great, but I'm having a strange issue concerning my o2 reading. I sometimes get incorrect readings after a test run, like .05 or some other obviously incorrect number. Other times I'm good to go with 770~800 numbers. No knock and the car is running good. O2 sensor is about 1 year old and I haven't run race gas or anything that would kill the sensor. Again, the car is running great just the strange numbers.
All opinions appreciated. (all of my mods are in my signature)
Larry

 

[TurboDave]

When exactly, and under what circumstances do these "strange" readings occur?

 

[Larry Smith]

Thanks for the reply,
I forgot to mention that these readings are in the recall mode. As much as I can watch the scanmaster during a pull the numbers are moving around a bit, but seem to be within the ballpark of the desired range. I have gotten these numbers both in third gear pulls on the freeway between aprox 60mph till past the 85 mph limit on my speedo. Also from a dead dig until the third gear shift. (leaving with 0 boost) there doesn't seem to be any correlation with shift points etc. It's pretty random.
Larry

 

[TurboDave]

If, when you push and hold the recall button, you push the other button, two new sets of numbers will show up. They are the mph that the O2 and knock figures occured..

I suspect that you may be seeing the results of "MAF dropout". It's very complicated, but when the maf reads it's max of 255 for more than a few seconds (no real actual time, it varies), it's buffer overloads and resets. This then causes a near zero drop of LV8, O2, and boost solenoid signals. Sometimes it's severe enough to feel (not often).

 

[Larry Smith]

Your diagnosis makes sense to me,
I guess the next decision I need to make is....Translator + and LS1 maf, or Trans-pro and no maf at all. Thanks again for your reply,
Larry

 

[Eric Stage I]

Larry,
At WOT, your chip bypasses all MAF input and uses a fixed fuel curve. You may be getting some bad readings from the O2 sensor. I would try a new O2 first.
Regards,
Eric

 

[Larry Smith]

Eric,
Thanks for the input. I guess that would explain why the car is running fine. I will try a new 02 first. By the way, I'm very happy with the chip. I have it set up with about +3 degrees timing in 1st & second gear, and - a bit in 3rd. Also, a little less fuel @ wot. I'm able to run 18 lbs of boost without detonation! I imagine the CAS V4R intercooler may be helping in this area. I'm hoping to get to the track for some real testing in the near future.
Thanks,
Larry

 

[thunderace31]

Larry I am in Dearborn when are you going to the track?? I am having the same problems you are also
Some strange 02 #s and Knock crap would be cool if we can hook up

You may have seen me around I have a white T-type with Silver ROH 17's :biggrin:

 

[Larry Smith]

Thunderace,
I'm hoping to go to Milan on Oct 4th. It's "run what you brung" night. $10.00 entrance fee, all the passes you can make. I'm not 100% certain yet, but it would be a golden opportunity for fine tuning my street combo. I'm pretty easy to spot, Skull & crossbones on the front bumper where the license plate would be, and GNX style wheels. If that falls through, shoot me an e-mail at
myleslong_49@hotmail.com. We'll get together anyway and compare notes.
By the way, I'm in Garden City.
Larry

 

[thunderace31]

Thats a Tuesday ???
I can most likely make it then dosnt look like we will be going tomorrow (Wed the 28th) since they are saying rain Only the 4th time I was planing to go and it rains LMAO What a pain good ol mother nature can be lol.

My # is 313-724-8434 (Home Office line) Give me a call I would love to have someone to compare notes with on things
Derek

 

[suicide six]

check for loose grds on passenger rear head. mine recently was giving odd numbers on o2 yet car ran excellent. hard to get to but easy fix.

 

[Larry Smith]

Derek,
Yep Tuesday night. I'll get in touch and let you know if i'm going.
Suicide,
Thanks for the tip....I'll check it out.
Regards