Hey I just got back from the Dyno Shop. I had them run my 2000 Camaro SS, to get a base reading and see if in fact it was detonation I was hearing. The guy confirmed that at high RPM's he could hear audible detonation.

Here are links to my run...


Page 1 of the run

Page 2 of the run

Page 2 of the run


I see a reduction in power after 5400 RPM, plus the guy said the air fuel mix was a little on the lean side. The only mods I've done are a SLP air box with Holly Filter and SLP Y-pipe and Loudmouth exhaust.

The only thing I can think of is , I took it to the dealer about a year ago and one of the things they did was update the PCM to fix the knock sensor from being so sensitive. I don't know what to do. Its out of warranty, but the guy at the dyno shop has LS1 edit and said they could do a full diagonostic check and adjust the computer to fix it. He said it would run about $230 dollars. Any sugggestions? Thanks Will

 

It's that damn CA 91 octane . I got detonation too when I dynoed. That pull was 5.5 rwhp and 5.1 rwtq below the max pull (3rd pull). The dyno guy said he'd seen it before on CA LS1's they really should get 93.

 

It looks like your Air/Fuel ratio is right on to me. I believe 13.1 is what you want to shoot for.

I also have a 2000 SS and I noticed a weird dip in the power around 5500 - 5600. I changed the spark plugs and wires and that took care of the problem, for me anyway.

Also, how many runs did you do? My first run is typically the worst. I have dynoed my car 4 times and on average the second run is usually around 7-11HP better.

 

Hmm.. I am starting to see a pattern here.. I have some power loss right around 5400 too. Seems to be KR to me since it takes away then starts trying to add it back, but I have not got it on a scanner to verify that yet. I didnt pay to much attention to it on my first dyno, but when I got my LTs on and dynoed again it appeared to be more obvious, then I looked at the old charts and saw it there too. I didnt realize there was a TSB on the knock sensors for these cars (2000 models).. anyone have a link or something to it??

 

You can buy LS1 Edit for $500 but you need a laptop and I think its difficult to use. but its a great tool for tuning. better than spending the $230 for one adjustment, when you can make unlimited adjustment for 500.

 

Looking at your numbers its hard to say. I'd like to see you get someone with Autotap to see what your timing and KR is actually. Definitely you are lean for being mostly stock. I would expect you to be closer to 12.0 to 12.6 with factory programming (which is what I am and most cars). Some I see are in the 11's.

I can't see why the dealer would lean you out (if they did) when they flashed your pcm, but it is possible it is related to your problem.

I definitely ATAP your car and get more readings.

 

I've been really thinking about buying auto tap, I already have a laptop. I should buy it and get some more readings. Then I could run LS1 edit, but I have no idea how hard it would be to tune. I would hate to screw it up. Well at least I know where I can take it and get it fixed.

Another thing, I've also tryed adding an octane boost to my gas because I live in California and the highest I can get is 91. It didn't seem to help, the detonation was still there.

This was my 2nd pull, the first the didn't record anything, they just ran it up. Also it was done in 4th gear.

I think I'm going to take it back to the dealer first and tell them that they were the ones who reprogramed the computer, wich is what I belive is casing the detonation. Its gonna be a little tough beacuse its out of warrenty, but the work was done while it was still under warrenty. We'll see what I can get them to do. I just don't want to have problems later on.

Thank for the help,
Will