Looking for some input, this my first car messing with e85. The car is v2 ctsv with a 60 shot on it, br7ef plugs gapped at .030. This is a 3rd gear pull with immediate shut down and pull plug. On this pull the flex fuel sensor was reading 78% alcohol.

The way I read this plug is its a bit lean as the fuel ring only appears halfway around the base ring. Timing appears to be spot on. Wideband read .85ish lambda, timing is running 19.5*.

 

Imo, positive electrode looks burnt, over heated. Can't tell for sure if the ground strap above it has been slightly eaten away or not from the pic. Possibly add alittle fuel or take out some timing. Line on the bend maybe slightly aggressive. Did you adjust your stochy on the wideband for e85, or adjust it for e78 as indicated to get the correct lambda? What cylinder did the plug come from?

 

Thanks for the reply. I was planning on stepping up the fuel jet one size. As for the timing I thought it looked ok but on the side of safety il pull a degree. This is out of cylinder 1 so I'm sure the back ones are hotter. As for the wb it is reading gas but I have a conversion on hpt to display lambda. What do you think about the fuel on the base ring, am I seeing that right as only some fuel on half the ring?

 

Looks a little hot to me too, and the timing mark looks a little far up the strap.

-Garrett

 

The lighting is making it a little hard to see the fuel ring. Timing looks alright. How long after you made the run, did you pull the plugs? Here is an example of a conservative tune up on E85:







Half turn of color on the base and a conservative timing mark.

 

Where is the timing mark you are talking of

 

On the ground strap. Heat generated from the tip where the electrode is sending the spark to. As the heat goes into the strap, the timing mark moves around the bend. A timing mark past the bend is typically over timed.

 

I shut the car off right as I let off the gas and then pulled over to pull the plug. The flash from the camera messed with the light, the plug was about half turn of gray but just looked hot. I'll make another pull tonight with a lil more fuel to it and get better pictures.

 

How long after you pulled the plug, did you take the picture?

 

Immediately after I pulled them out

 

Yeah. I wouldn't add any timing, I would want it alittle more conservative as you work your way on getting it dailed in. If you worked your way to where your at right now, then I'd say your close to where you need to be. Still alittle too agressive for me on the strap. Try some fuel and pull a rear plug. The conversion to lambda is no big deal, but do you have the right equation for the voltage output from the wideband and the correct stoichy for ethanol programmed in the wb? Unless hpt has some correction factor, idk. On some widebands, the stoich is fixed for gas at 14.7 and can not be changed. So the correction would need to be in the equation. E85 is about 9.8. Straight ethanol is about 9.0. So at e78: (9.0 x .78) + (14.7 x .22) = 10.3 stoich. If the 10.3 stoich is not used, the lambda will be off. Unless it accounted for in the conversion with hpt. ??

 

The wideband displays afr for gas on hpt, then I set up a pid to divide the afr by 14.7 which is basically coverting it to lambda. Im logging that against the commanded eq ratio.

 

I thought lambda was lambda no matter what fuel or mixture of fuels being used..?

 

Exactly right

 

Yes lambda is lambda. That's why it's easier than reading different afr's for different fuels.

But for some tuning dataloggers, you need to know what fuel so that you can enter the correct stoichmetric value. Lambda = measured afr/fuel stoich
For instance, the SCT is to display afr with the equation you program. It uses the voltage output from the wideband. Problem is, the SCT afr function does not work. It only logs the raw voltage. So, I have to manually calculate the afr which requires a simple equation and the stoichiometric value of the fuel. Then I can convert to lambda if needed. Just wanted to be certain the OP was getting an accurate lambda.