webinar #10, individual cylinder trim

just have a quick question about the position of the sensor in relation to the exhaust port on a N/A v8 motor, how far down the tube should it be placed?

It's not specifically important how far you mount the sensor from the port and normally convenience or where you can physically fit the sensors is the driving factor in deciding. The more important aspect is that the sensors are all mounted the same distance from the exhaust valve. If they differ significantly, this will affect the EGT on its own.

These are my correction

tables that i adjusted but only done in driveway not on dyno so Obviously not

all loads were done.

also a pic of my plugs after the corrections

Hey Ben, no pics attached?

just added the pics to previous post,

these plugs pics are from before cylinder correction

Sorry Ben, I had assumed you were referring to EGT rather than Lambda - I just actually checked the webinar. The info above still is relevant though as the location for the sensor is often driven by where we can actually fit the sensor. It's not critical that lambda sensors are the same distance from the exhaust valve though - This applies to EGT sensors. What you do want to be careful of is not fitting the sensors too close to the collector or you may get your reading being influenced by the exhaust flow from other runners.

Getting solid data into your cylinder trim tables is going to require careful steady state tuning on a dyno, or alternatively a reasonable amount of data is going to need to be collected and analysed from road or track use. I'm a little suspicious of your trims for #7, #8 and #1 though - It's worrying when you see trims that are so larger and this could point to other issues. I'd suggest getting onto a dyno and see what these trims end up needing to be in steady state conditions.

The plug reading is useful to a point, however unless you're doing a proper cut at the point in the map you're interested in, the reading is going to be affected by whatever is happening at idle just before you shut the engine off.

yeah i was a little worried about the trims that i have applied, the car does run a lot smoother then it did before i applied the trim changes, i thought it may have been an injector flow issue, so i had them removed and serviced then put back in the same place and had the same results, i did swap the injectors around to see if it the problems followed the injectors but it didn't, so i have ruled out injectors being the cause for such radical fuel trims. the only thing i can come up with is the extra length of intake manifold runner.

could the injector trigger angle be a contributing factor as it is running in end of injection and the angle in the table is 440deg btdc