Ok, I'd been pretty happy with the tweaks I've made to my tune... been leaning things out here and there. Each individual pull I made was giving me consistent afr's, timing and 0-1 knock counts.

Then I started doing back to back runs from 2000rpm-7500rpm, (what I mean by back to back is flat out to 7500, hitting the brakes and slowing way down, then running flat out again.

I was dismayed to find that my first pull was great, 0-1 knock counts, but on the 2nd pull, I'd get knock from 2500-5500rpm or so, up to 7 counts.

I dropped my boost by 5% and did more back to back runs. Consistently, the first run is fine, but I get knock on the 2nd run. Less knock, with the decrease in boost.

So I guess this means I need to do back to back runs when testing the safety of my changes.

Ultimately, my car is my daily driver and sees track time as well. How many consecutive back to back runs do you guys make when testing your tunes for the track?

 

The best way I have found to get good logs for what you do (open track) is to hit a couple on ramps and do some full throttle runs off and on them. That will simulate track driving a bit better than doing a full WOT run, slowing down, (and getting less airflow over the car), then doing a WOT again.

 

if your getting knock i understand the turning the boost down but why lean things out? I understand that your boosting less so you dont need as much fuel but what do you meen by leaning out, are you saying a point or 2 or are you saying 10ths of a point?

 

sorry - poorly phrased post. After I tweaked the tune and thought it was ok based upon my individual pulls, I started doing back to back pulls and got knock on the 2nd pull each time. I decreased the boost after finding the knock but did not lean things out after finding knock.

 

Your little experiment is basically showing the effects of heat soak. Doing a few runs back to back gets the coolant temp up, and everything under the hood warmer.

It shows the big difference between tuning for drag racing and road course time. How much boost were you running? Gas octane? Any changes to the timing maps?

 

I agree with Spd Racer....I don't know your boost, AFRs, or timing but you may be running too lean or too much timing or a combination of all of the above....Generally a road course tune is more conservative than a drag tune...

Also, you'll want to do tuning in the summer when it gets really hot ...Good luck

 

good info, thx guys. looks like I need to stress the car harder than individual WOT runs here and there.