Originally Posted by
nkautz
Scenario: Customer pays to have their car towed to you from several hours away, you put the car on the dyno, strap it down , do a pull... you see a ton of false knock, unable to work around it. You do a quick inspection , no exhaust is rubbing anything , everything looks right. Most likely valvetrain noise / electrical issue or something else requiring significant diagnosis and correction to eliminate vibration. Do you take the car off the dyno , give it back to the customer and tell them sorry you can't help them? Or do you tune it anyways the old fashioned way so at least they have a good tune and they can sort out the vibration later if they choose?
I suggest looking a little deeper into spark plug reading , it won't give you a precise AFR but you can get very close. It WILL tell you exactly how much heat you have left to work with or if combustion is too hot. It's called reading the heat range on the ground strap and it's more precise than you think. You can see the difference from changing half a degree of spark advance.