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rao

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might want to add a WBO2 trace to the log. The stock sensor trace is saturated so there's no telling exactly how rich the car is running

 

You are so right, I will have access to a wideband this weekend, so I hope to get some traces done with that, but this is interesting:

 

I modified the primary fuel tables to add less and less fuel, the idea being if I made small changes and logged it each time at lower rpm's, I could tell when the AFR started to lean out above the 11:1. But I've gone all the way to 12.22:1 in the map, and the logs still say 11:1, so something is WAY out of whack. I'm getting more fuel in the engine than the ECU is asking for.

 

Me thinks it is my injectors. I have the DW 650cc's. I set the fuel injector scale using the process from COBB, watching the fuel trims at idle, but this only really scales the lower ranges of the injectors, what if they do not follow the same scale up through the duty cycle range....

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You are so right, I will have access to a wideband this weekend, so I hope to get some traces done with that, but this is interesting:

 

I modified the primary fuel tables to add less and less fuel, the idea being if I made small changes and logged it each time at lower rpm's, I could tell when the AFR started to lean out above the 11:1. But I've gone all the way to 12.22:1 in the map, and the logs still say 11:1, so something is WAY out of whack. I'm getting more fuel in the engine than the ECU is asking for.

 

Me thinks it is my injectors. I have the DW 650cc's. I set the fuel injector scale using the process from COBB, watching the fuel trims at idle, but this only really scales the lower ranges of the injectors, what if they do not follow the same scale up through the duty cycle range....

 

the stock O2 is reacts to the partial pressure of CO in the exhaust to get an AFR estimate. Because it is placed before the turbo, it will also react to exhaust gas pressure. for a given (rich) AFR, it will read richer if the pressure is higher. you need to becareful if you are using its reading as a leaner mix will show up richer than it really is if the exhaust manifold pressure is high.

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the stock O2 is reacts to the partial pressure of CO in the exhaust to get an AFR estimate. Because it is placed before the turbo, it will also react to exhaust gas pressure. for a given (rich) AFR, it will read richer if the pressure is higher. you need to becareful if you are using its reading as a leaner mix will show up richer than it really is if the exhaust manifold pressure is high.

 

Sounds plausible, wow I bet I was running really lean. Good thing I kept the RPM's low.

 

So, why do we log AFR's off the factory O2 anyway if it is useless under boost?

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its good as a reference point. if you start getting odd readings with the WB then take a look at the factory O2. it will show you if the sensor is way off or if the car is way off.

 

i used the factory O2 to help figure out if my wb sensor was messed up.

Work hard. Play even harder.

 

My Garage

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:confused: As long as its powered there is no issue running it all the time.

Agreed, the stock 1O2 sensor is a WBO2 that is run all of the time (most production cars are similar). Just make sure that you install your WBO2 sensor properly (MoTeC has a good write-up on this in their PLM Manual) and you should be able to run it all of the time. You can extend your sensor life if you remove it after the tuning is complete. Leaving the sensor in or removing it after tuning is complete comes down to personal preference IMO.

 

Christian.

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I got the wideband put in last night (Thanks Bayley!) and after some fiddling, here is my 4th gear pull (at 16psi). I was getting some knock on the early runs, so I backed off the timing a few degrees.

 

Comments are welcome. I left it slightly rich as I need to tune the timing curve next.

6-14_4th_gear.pdf

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What is with you folks :lol: The sensor used in the widebands is OEM in a bunch of cars and it is not replaced every week. It is fine to leave it in so long as the heater is powered.

 

the specs that came with my WB kit (bosch sensor) even state clearly that worst case, located in front of a turbo and exposed to all the high temps and pressures that it shouldn't be, it will still be reliable and accurate for 500 hours of use. Put it behind the turbo, and I agree it isn't worth worrying about, especially when its only $79 for a new one anyway.

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What is with you folks :lol: The sensor used in the widebands is OEM in a bunch of cars and it is not replaced every week. It is fine to leave it in so long as the heater is powered.

 

 

If we are going to be picky about the details, both the heater and pump cell need to be closed loop regulated, not just on ;).

I agree that the sensor is OEM in a bunch of other cars. That doesn’t mean it is appropriate to run it full time in our application. When the sensor was designed into a bunch of OEM applications, the engineers went about measuring the operating temperature of the sensor tip under quite a few conditions. They also made sure the sensor was not installed aft of any large dips in the piping. Our application is probably ok but may have issues in the winter because of the large amount of piping hung below the sensor. I’ve already lost one sensor to cracking of the ceramic element. I’m guessing water pooled in the headers. When I started the car, I didn’t fire it up immediately so the sensor tip had a chance to heat before it was nailed by a slug of water.

Based on your location, I assume you don’t have MMT laden fuel (has been banned for use in the US for years now…. but not for production and export). We get a lot of O2 sensor failures north of the border because of MMT deposits. WBs are particularly sensitive due to the little metering hole on the ceramic substrate. It only takes me 2 mins to yank the sensor so I’m not averse to doing so.

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Forgive me, but when I said that the heater needs to be powered I meant that the sensor has to be functioning; you will damage it in a few hours if you leave it in place and not "hooked up"

 

If you mount your sensor in an improper location you will have problems; that applies to almost every part on the car.

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Forgive me, but when I said that the heater needs to be powered I meant that the sensor has to be functioning; you will damage it in a few hours if you leave it in place and not "hooked up"

 

If you mount your sensor in an improper location you will have problems; that applies to almost every part on the car.

 

that's the funny thing. I thought I had picked a good spot (top of bellmouth). I think it was just bad luck combined with my attempt to log the startup transient. I figured the water couldn't make it up the up pipe on startup but I was wrong. I think it is safer to simply start the vehicle without letting the sensor heat up.

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