I agree with you that the O2 sensor doesn't lie, but it is giving you the average of that cylinder bank. Even on boosted engines its not umcommon for the A/F to vary from cyl to cyl as much as .5. This is why plug checks should be mandatory to verify what the O2 is saying on each cylinder not to mention timing and plug heat range checks. Now if the average O2 was 11.0 there would be more of a cushion to cover the potential lean cylinder. Imagine if the average is 13.5 and one cylinder (#7) is 14.0 under that boost / power level!! Too bad the dyno sheet doesn't have fuel flow or BSFC's listed. A lot of engine shops rely on the fuel being consumed more than the O2's to get the motor dialed in.
Thread: Advise from my gear head friends
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02-18-2012 12:14 PM
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02-20-2012 10:21 AMVery interesting discussion....
Does anyone have a set of headers he can borrow with sensors in every cylinder? On my Haltech engines, that was what we used so we could go cylinder by cylinder to balance.Getting bad advice is unfortunate, taking bad advice is a Serious matter!!
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02-21-2012 01:13 AM
Im with ya Craig. Thats why i was saying 13.8 AFR on that one bank at full pull, is living on the edge in my opinion! IDK why they dont use BSFC numbers there. I know they look at EGT's as being a tuning tool. If the EGT's are good, then the tune should be good. Im not sure if I totally agree with that?
Meaning you can be borderline lean AFR, put some additional timing in it, and the EGT's come down. Or, be on the fat side, but not enough timing, and EGT's will show high.
I am trying to learn new things everyday. My feeble mind tells me get the fuel right first, then add or remove timing to get EGT's to a safe level. However, thats what my brain tells me, and may not be what actually works.
I actually was on the phone tonight with a buddy from Grand Rapids. He had some 460CI N/A engines in his Formula. The first shop dynoed the engine, doing some full pulls. The egt's and fuel numbers looked fine under full throttle load on the dyno. However, once he put them in the boat, it had a awful lean spot while cruising, that ended up burning some pistons and tuliping almost all the valves. Thats no good! This time around they rebuilt the engines, and put it on the dyno again, and did some cruising simulation, they found the lean spot, fixed it, and all good now. Kinda like those sled engines, Burning down while cruising at 55mph! This is why I think im gonna add 02 sensors in my tailpipes this year. I can then monitor whats going on at cruise, and wot.
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02-21-2012 10:16 AMSounds like Dan is ready to become Cruiser Dan! lol
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02-21-2012 09:34 PM
Give me a few more years then I`ll want some twin Diesels
Cummins 450`s get like 28gal per hour.
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02-21-2012 09:44 PM
Funny you mention that I was just a soldering fool tonight extending the harnesses for my AFR gauges. Had em in last year mounted for passengers to see but what good does that do. They gonna be in the dash now.. You know I gotz to I gotta keep an eye on those big beast motors biotch! lol
If I recall I was at 11.7 at idle to 13.0 at wot
I have pictures.
Last edited by ICDEDPPL; 02-22-2012 at 01:37 PM.
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02-22-2012 08:55 PM
Cool Dan!! I thought about adding those to my dash too. Only I heard that moisture kills the sensors fast. I'd like to look into this. I think having them on the dash would be great!
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02-23-2012 06:51 PMWhere do you pick up the A/G for those?
And when you say moisture, in the fuel because of ethanol? Or when it is sitting?Getting bad advice is unfortunate, taking bad advice is a Serious matter!!
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02-23-2012 07:38 PM
I just remember hearing that any moisture contaminates the O2 senser itself. Maybe from condensation, reversion, etc. My exhaust is totally dry, so I think i'd be fine to run them. The cool thing about them, is say you plug up a needle and seat on a carb setup. A fuel PSI gauge would still show good fuel psi, but the engine is actually going lean. Having the 02, is really nice!