I had my my first tuning session done on 11/18 and this was the result.



I went back to smooth out the curve on 12/1 and this was the result.



The only difference between thes two days was I went from stock S02s with little tread left to brand new Dunlop Winter Sport M3s. The guys at Ptuning had a difficult time getting traction with the new tires, so they had to strap it down extremely tight, but they still don't think the tires alone could cause the hp drop. Its not just at the top end either. If you could see the overlay of the two graphs, you would see there is a consistent loss of power throughout the entire curve.

So I took my car to a local dynojet (not like the nice dynamics one above) and this was the result.




The difference with this one is the temp inside was about 70 degrees and the Ptuning temp was about 40 degrees, but it STILL shows a loss of power that I cannot account for at 261hp. I expected to see something closer to 300 on a dynojet and over 280 on the dynamics. I'm running about 9.5lbs of boost up about .5 psi from the 276.2 number. I actually increased the boost and my numbers are lower. Before my car was even tuned and at stock boost it was making 261hp on a dynojet. I don't have that dyno from 2 months ago to show you though. My car stock makes about 170 on a dynamics and 190 on a dynojet for comparison.

Are the winter tires messing with my head? Is there something else I should be focusing on? I'm so fed up with the inconsistency and having my heart broken on the dyno. What kinds of things should I be checking into to get over 280 on the dynamics? My car is a 2000 Ap1 and I just passed 122,000 miles to give you a little background.

 

check that your manifold isn't cracked, unless you have the new cast manifold

 

It was cracked and replaced last month with a cast manifold one day before the first dyno chart was done. I looked at it again this morning and everything looks tight and solid in the engine bay at a glance.

 

your car went flat after 8400rpmish, yeah your down in the mid, but def went flat up top. start checking things, cuase something happened.

is boost holding up top?

leak somewhere in charge pipes?

leak in exhaust mani?

wastegate broken?

did tune change by itself?

did plugs foul ouit?

this is the fun with modifiying a car, good luck

 

so your boost guage is showing 9.5psi to redline still?

ever pressure tested the IC pipes to make sure there are no leaks?

possible clogged cat?

 

Thanks for the replies so far.

The weekend of 11/18 my car was tested for leaks and there were none. I have not run any tests since the bad news dynos this past weekend.

I have in fact been studying my boost gauge all weekend and doing runs on the road and it appears to consistently hold between 8.8 and 9.5 all the way to redline. The Greddy E-01 boost controller detects WOT and flashes the highest boost achieved for 3 seconds or so as soon as you let off the throttle. In addition to the max value being over 9 most of the time, it holds steady as a rock every run. The curve itself is smooth and it feels that way when accelerating. There is no drama and just a solid push in the back until redline. Its just that every point in the curve is lower than it should be. I don't know what to make of the flatline after 8400. Toan raised my VTEC and altered timing to help smooth out the big dip I used to have, and now my vtec transition is 6900 or 6800 I think. Could this cause the flatline after 8400? If not for the flatline, my topend would be a bit better but I was down on power from the moment he got my car on the dyno. This was before he even started to tune out the dip.

I will consider getting the IC pipes checked and the CAT checked. Additionally, the plugs and manifold are on the list. I just need to come up with a coherent list of stuff to concentrate on before jumping into the debugging process.

A bad wastegate was what led to me being on my second Greddy turbo in the first place. I assumed it was either my original installer messing up my install or just a flawed turbo, but I'll consider getting the new turbo looked at too but it's not high on my list of culprits at the moment.

I have an Ultimate Racing High Flow Cat on the car, and a consistent CEL complaining about low CAT efficiency, but I assumed this was common and I had the same CEL when I pulled the 276 too.

 

Put compression and leakdown check on the list.

 

^ yea. I agree. At least you will have a baseline if it isn't the problem.

 

The tension on the tie down straps will effect the HP reading.

 

The CEL is not causing the ECU to override anything, is it? I am assuming you could get rid of it with a test pipe-like CEL fix...

I would think it would be a boost leak, but if you say the pressure is constant.... Only other thing I can think of with your system leak-free would be the ECU pulling timing for something.... My dyno peaked out after a few runs when it got a bit hot and the ECU started to pull timing (6-7 pulls)...

Are you sure the tuner used the proper correction factor (probably not an issue, as Ptuning has a pretty good rep)?

John