I had my truck tuned on the dyno yesterday and have a few questions about the procedure:

I was under the impression that by tuning specifically for my truck, I could avoid detonation, or at least have very little. What I found was, after making 9 pulls, with 4 of them at 390+ HP, the truck was pinging like crazy! I couldnt hear it when the truck was on the dyno, but when I took it for a drive afterwards, it was terrible. Is there any way that the tuner can determine if there is detonation during the tuning process, other than sending me on a test drive after running the truck at WOT with lots of detonation?

I dont have the data handy, Im out of town for a couple days, but the final pull was substantially higher than the rest. The peak HP was 391.5, only slightly higher than the rest, but the curve up until that point was way higher. And the peak torque was up to 461 from 443. I noticed that on the last run he seemed to step on the gas much quicker, and was just wondering if this could skew the results or if it is normal. I just found it strange that it was so much higher than all the rest.

 

Well, I'm a novice when it comes to dyno pulls. See my sig. for the one and only dyno session I've ever been invovled in. It was not a 'tuning' session, just to find out what 'numbers' the modded eng. would produce. I made 2 pulls at South Georgia Corvettes in Thomasville . GA. Aaron Scott, the owner/tech had me operate the throttle while he monitored the computer/dyno controls. We made 2 pulls in July(90+ degrees-high humidity) with no ice used. The pulls were about 40 mins. apart--the first, after driving 3 hours to his shop. At that time, I had JDM's 'warm weather' chip installed. I post all of 'this' to point out that my L has never 'pinged'(to my knowledge) in pretty 'horrible' conditions. It's also made many 1/4 mile passes in 90+ degrees--some were 'hot laps' too. I use Texaco 93 octane--you have to use 91 octane--?

So, something is wrong.........with your chip/tune--I think .

Btw, I plan to make 2 more dyno pulls this winter--colder air--better numbers.

Dan

 

With these engines and the way they compress the air you will find that the L will Ping (if it is going to) in the cold. This is because the air is denser (more oxygen in cylinders) making the A/F leaner. I have a few thoughts on why you are pinging.

1) Do you have ram air? If so you are going to be forcing colder air in while driving than on the dyno.

2) On the dyno the truck is not under much load and when you are driving it has more load (weight, going up hill) I noticed that if I have my ice cooler filled with ice in the truck or 2 more people and it is cold the L will ping on WOT. I just changed the plugs to the NGK BR7EFs and seems that this problem is fixed for me.

 

Thanks for the responses. I do have to run 91 octane gas, but that is accounted for in the tune. I also have the JL ramair setup, but the scoop is not currently on. I'm sure that it will still get some air, but not quite like if the scoop was on there. As for the cold air = more detonation, I can understand that, and there is definitely more load driving the truck on the street versus on the dyno, but I just wouldnt expect that there would be so much detonation if it was not detonating while on the dyno. I suspect it was detonating while going through all the dyno pulls, maybe not as bad, but I think it probably was. Of course you cant hear anything with all the noise from the supercharger, but is there a way to monitor detonation from a computer?