wideband O2 says 11.4AFR at 10 psi = good?

[acannell]

90 daytona es 2.5 turbo I
rebuilt engine with 2500 miles
giant front mount intercooler
hybrid T3/T4
stock fuel system
stock exhaust system
grainger set to 10psi
no charge air temp sensor
stage 3 computer (fwdperformance)

just installed the LC-1 with the XD16 wideband O2 system from fwdperformance. replaced existing O2 sensor with new wideband O2 sensor and connected analog output to ECU to emulate old O2 sensor. (literally screwed the new one into the same place as the old one)

at WOT on the freeway from 3000 to 4000 rpm in 4th gear starting at 60mph wideband O2 says about 11.4 AFR.

OTC 2000 says there is double digit (seems like up to 14 degrees) knock retard on multiple cylinders during the above test.

QUESTIONS:

is the above AFR good or bad?

what AFR should I be shooting for at what boost pressures?

if you lug the engine (high throttle in a too-high gear) wont there always be detonation? lets say the answer is YES cause i think it is. so is the above test in this category?

[NoDestiny]

Careful! Wide bands are not as tolerable to heat as narrow bands! Make sure to put that sensor something like 16" away from the turbo minimum if you want it to last!

But 11.4:1 is starting to approach power levels that may not be safe. Figure, 10.5:1-11:1 is a "safe zone" and 12:1 is "not so safe" (At least, that is what I have studied up to over the years and seems to have kept my engine alive thus far)

[Reaper1]

The A/F that the WB returns can be affected by the ambient heat surrounding the sensor. As also stated above WB's don't like a lot of heat. I am also running a LC-1 and I have my sensor installed about 4" before the cat. The instructions for your LC-1 *should* tell you not to install the sensor very close to the turbo...I think they state a minimum of 6" away IIRC...

I think that your A/F(if accurate) is fine...If you are getting knock retard it could be becuase of th grade of fuel. Also the calibration may have an aggresive timing advance curve under part throttle to help spool the turbo and to improve part throttle response. It may also cause the above condition. You may want to retard the base timing to 10* and see if it helps. The other option is to run a progressive type water/meth injection system. You could also ask about having the cal *tuned* slightly less aggressive for your application...

[NoDestiny]

According to my wideband, says 16" minimum from turbo...
http://www.zeitronix.com/installatio...structions.pdf

Course, anything is gonna be better than where the stock O2 is at. Make sure to get that moved and take your measurements again.

[speeduphoria]

Quote:

Originally Posted by acannell if you lug the engine (high throttle in a too-high gear) wont there always be detonation? lets say the answer is YES cause i think it is. so is the above test in this category?

The factory knock sensor is very developed you should not see knock, try better gas!

Quote:

Originally Posted by NoDestiny But 11.4:1 is starting to approach power levels that may not be safe. Figure, 10.5:1-11:1 is a "safe zone" and 12:1 is "not so safe" (At least, that is what I have studied up to over the years and seems to have kept my engine alive thus far)

10.5:1-11:1 is RICH!

11.5:1 is safe!
Some people go in the 12:1-12.5:1 A/F area on lower boosted applications(15psi or so), but many variables decide if thats safe or not(On an 8valve TD I dont think so, possibly with some alky).

In low boost(like 5psi) you can have higher A/F's in the 12's as it will help spool the turbo fast. Everything is a compromise.

[acannell]

let me rephrase that: there will be detonation but the computer will sense it and retard timing

[speeduphoria]

Quote:

Originally Posted by acannell let me rephrase that: there will be detonation but the computer will sense it and retard timing

put it this way if the computer was made knowing it would see knock(being false) at higher rpms or certain conditions, dont you think it WOULD NOT! pull timing if that was acceptable? Then again wouldn't they just tune the ecu to be less sensitive under those conditions so it wouldn't see the knock?

Fact is they have already done this

If your motor isn't exactly stock like using Forged pistons and other mods it can change the sound of the of the motor and make it more likely to show false knock. But seeing as many people running these motors with Forged pistons and other mods and seeing them still using the factory knock sensor I dont think this is a huge deal.

i'll say it again for you, please just buy some octane booster or better gas and try it again to see if its real or fake, please

[NoDestiny]

Quote:

Originally Posted by speeduphoria The factory knock sensor is very developed you should not see knock, try better gas! 10.5:1-11:1 is RICH! 11.5:1 is safe! Some people go in the 12:1-12.5:1 A/F area on lower boosted applications(15psi or so), but many variables decide if thats safe or not(On an 8valve TD I dont think so, possibly with some alky). In low boost(like 5psi) you can have higher A/F's in the 12's as it will help spool the turbo fast. Everything is a compromise.

Factory turbo cars have often been noted to run 11-10.5:1 stock. I have widebanded a few SRT's for instance that have all show similar results. This is where my information came from.

[87turbodance]

Factory turbo car run really rich to be as safe as possible and to ensure that they motor will last the warranty period. My Volvo practically belches lack smoke at wot at 15psi. I have twice the power at part throttle when the engine is running closer to 13:1 compared to WOT when it must be close to 10:1

[NoDestiny]

Good info! Never knew Still merging into the boosted world from an N/A one.

[sleeper_1]

Becareful about the A/R readings. They are probably off due to the high heat and the higher backpressure. The WB sensor's more affected by it. Innovate WB's are good, but only if mounted as recommended. (Far after the turbo). The WB sensor will NOT last as long at that location. You will need to re-locate sooner or later.

Move the WB sensor further away, then test again. It's much more work rebuilding an engine!

11.4 AFR's OK, I touch 13-13.5 AFR for ~2 seconds on 2.2 VNT motor 21 PSI. Stock IC. This is only OK for short - SHORT periods (~1 to 2 seconds). I have the aux-box to log the boost, TPS, rpm etc. You will want to richen up or have water injection for longer WOT. It needs the extra internal cooling.

After a few seconds of WOT, the combustion chamber, sparkplug electrodes, pistons, valves etc. heats up and may cause detonation/pre-ignition at the same (Previously safe AFR).

[87turbodance]

Factory cars add extra fuel to cool the insides of the motor. Water injection is much better then adding so much fuel IMO

[SUPER60omni]

11.4 is fine. If it jumps up into the high 11's or 12's cast pistons are gonna die. I run into the 12.4's but on 116. It would die on pump gas.

[acannell]

okay i will run the octane booster and see what happens (i dont have access to actual better gas)

I moved the wideband O2 about 13" away from the swingvalve/donut (beginning of downpipe)

i turned up the boost to 14 psi

at wot I get readings from 10.1 to 11.1 AFR

thats the latest....

my engine is bone stock except for oversized cast mahle pistons (.030 over)

yes..i know how much work it takes to rebuild this engine. i rebuilt it TWICE in 3 months because the first one had a crack in the block which i didnt find until i started it up (MAGNAFLUX IS NOT YOUR SAVIOR)


AND ANOTHER THING

the engine sounds great and has TONS of power at 14psi...its not like its lugging around or running bad at WOT

[SUPER60omni]

Perfect! 10.1-11.1 is great.