Topic: Catless and readiness codes and 87 octane observations.

[tazz]

After purchasing the Mangaflow catback from a member hear I also installed my solo catless downpipe again.  Playing around with my GMPP tune altered to the same values as a STOCK GXP tune with only 4 parameters of the 3 bar sensor data changed so that the T-map sensors will read correctly just to see if it would run fine.  What do you know it runs fine and all the readiness codes except for the evap code reads ready right now which I did not think would be possible since there is around 15 codes turned off for the cat and 02 sensors but it works.  Also was brave enough to try and run 87 since the stock GXP tune can handle 87 and the ECM should compensate enough even states that in the manual for the stock GXP tune. Again actually really good the stock GXP tune CAN run 87 octane safely and actually has less KR than the GMPP tune on 91 octane for my car. 
Just thought Id pass that along since some have inquired about 87 and it is possible and is safe as long as it is the STOCK GXP TUNE and NO way in HELL would I try it with the GMPP tune on 87 that's just too risky in my book with all the KR even with 91.

[Carbon Sky]

Yah, I don't know what it is about the GMPP tune . . . knocks like mofo.  The stock one does too, just with lots of KR.

I run catless as well, and with the COT stuff turned off, and my running slightly lean under light load conditions and low rpms, I've been getting ridiculous mileage (30mpg ish) the last couple tanks.  But I do run 91 octane . . . not sure how I'd feel about boosting 21psi, spiking to 23, on 87.  And I do make use of the passing power regularly.

[tazz]

Just kinda of playing around and not driving too hard just sensible when Im not logging.  Logging the run iI get on it harder but not crazy and it does seems to be fine with 87 but it could also be the fact that most if not all 87 has some E85 in it and is helping it out.  I have noticed that Phillips 66 87 must have somewhere around 10% ethanol since my Fuel trims are 3 points higher when I run that fuel vs BP Amoco 87 which must not really be mixed with E85 since my Fuel trims drop back down when I run that fuel.  Running 91 BP my fuel trims stay about the same and from what I was told the Premium 91 from BP in my area does NOT CONTAIN E85 so I conclude that the 87 from BP does not have E85 either or very little.