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View Full Version : Can propane users trust their 02 sensor?

NickSJ
02-25-2004, 05:28 PM
I've been running propain for a few months now, and since it was connected have been basically ignoring my 02 counts. Recently installed an EGT gauge as a more accurate tuning tool, but haven't gotten it sorted out yet.

How much does using propain, really affect how trustworthy my 02 readings are?

Thanks
Nick G, San Jose, CA
86 T-Type, TE44, MSD-50s, propain, RJC PP, LS1 MAF/translator, Nitto DRs
JayC
02-25-2004, 06:02 PM
The O2 readings will be generally about the same, possibly slightly leaner.
HairDrier
02-25-2004, 07:38 PM
I dont understand why you would think they would render the O2 sensor useless. As long as you arent drowning the engine in the stuff and the engine is burning it the sensor will be as it always is. The real answer is to go to a wide band to remove the stockers limitations. What kind of EGT's are you getting?
NickSJ
02-25-2004, 11:43 PM
Actually, I just heard from someone, that I can no longer 100% trust the 02 sensor if I'm throwing alternative fuels at it. Not using all that much propane really, KRs stay lower that way.

EGTs are about 1400-1450, but I've been taking it pretty easy. Besides, the POS digital EGT gauge I have has about 2-3 seconds of delay (mfr calls it "filtering") and as such is mostly useless for tuning. If I can't get that to improve, I'm returning it.

Thanks for clearing it up.

Nick G, San Jose, CA
86 T-Type, TE44, MSD-50s, propain, RJC PP, LS1 MAF/translator, Nitto DRs
1badTTA
02-26-2004, 11:28 AM
O2 reading will be as accurate with propane as they are without. The only real problem is leaning out the engine enough so that the propane isn't making it overly rich. I was getting O2 readings higher than .840mv and it was causing KR. Once I got them down to .790-.810mv the KR went away. Propane works great as a 7th injector also. HTH
HairDrier
02-26-2004, 06:06 PM
Nick what kind of EGT gauge are you running?
SMC
02-26-2004, 06:21 PM
Nick what kind of EGT gauge are you running?

Definitely NOT an SMC meter....ours update twice a second! :zahn:
SMC
02-26-2004, 06:29 PM
O2 reading will be as accurate with propane as they are without. The only real problem is leaning out the engine enough so that the propane isn't making it overly rich. I was getting O2 readings higher than .840mv and it was causing KR. Once I got them down to .790-.810mv the KR went away. Propane works great as a 7th injector also. HTH

Rick:
You're close....propane stoichiometric A/F ratio is 15.7, where gasoline's is 14.7. So if I'm right it takes less propane to do the same work.

See: http://www.afdc.doe.gov/pdfs/fueltable.pdf
1badTTA
02-26-2004, 08:22 PM
Rick:
You're close....propane stoichiometric A/F ratio is 15.7, where gasoline's is 14.7. So if I'm right it takes less propane to do the same work.

See: http://www.afdc.doe.gov/pdfs/fueltable.pdf
What I was reffering to was that part about injecting more fuel (propane in this case) into the engine when the injectors are supplying enough gasoline. It causes a rich mixture if you don't pull a little fuel out or throw too much propane into the mix. Also, it has been noticed by myself and others that getting a rich knock is much easier to do with propane than just gasoline.

I must say though that I won't need to upgrade my injectors for quite a while due to the propane, it is actually pretty difficult to keep from getting too much fuel in the mixture. I really need to get a newer chip!!!!! Can we say Commander :fragez: :fragez: :fragez:
NickSJ
02-26-2004, 08:55 PM
Yeah...I've noticed the same thing (rich knock w/propane). Thought I was nuts, because my FP was not even high enough for that.

The EGT I'm using is CruzPro PY30. Nice features, peak hold, alarm, dimmable red backlighting...but with the delay, not real useful other than to recall peak EGT.

Thanks for the info.

Nick G, San Jose, CA
86 T-Type, TE44, MSD-50s, propain, RJC PP, LS1 MAF/translator, Nitto DRs