Hi all,
My car, an 07 997.1 Turbo with Tiptronic S and 88K miles, is stock overall as far as performance mods are concerned. I live in the Denver Colorado area, so I am at a higher altitude and pump gas octane is 91. I recently had ECU/TCU tuning done through Markski tuning with the goal being to make the car more responsive and quicker than stock. TCU tuning was done to quicken up shifting and additionally the redline was raised to 6900 RPM. The transmission is more responsive as I expected so I have no issues there (I also did a paddle shift conversion to the wheel, but that does not factor into performance really). For the ECU tuning I am now on my 4th tune and so far the car has only gotten slower from its stock form.

Drag racing is not my primary use for the car, but I have been using it to determine how well a new tune works in relation to stock as it is easily repeatable, cheaper than a dyno, and I live close to Bandimere raceway.

I did initial testing with the car while fully stock last year on pump gas (91 octane). It was 70 degrees that day. Across 6 runs with conservative launches (no overboost) I averaged 117.5 MPH in the quarter (times in the high 12s/low 13s, not doing a hard launch) with a high of 118.2.

After initial tuning I re-visited the drag strip and the best I was able to achieve was a 113 mph with a hard launch, launching the way I did the year before I was only able to get to 109 - it was 81 degrees that day. I brought my car to my mechanic and validated that there were no mechanical issues with the car (boost hoses, DVs, VTGs, all pressure tested and operated to ensure they were good) that they could find. It is worth mentioning I had all new plugs and coil packs done last year and they have less than 3000 miles on them. When the car was in for that maintained it was thoroughly checked over and prepped for tuning as this was always my goal for the car.

After verifying no mechanical issues I ran some logs on the car and it was determined the tune was too aggressive and the turbos could not keep up at my altitude. I worked with Marksi who provided me with 2 new tunes. Tune 2 is the stock profile but with the RPM raised to match the TCU, and tune 3 another is a more conservative tune than the initial tune but should be better than stock. I tested both tunes 2 and 3 at Bandimere today with the following results:

It was 85 degrees at the track today.

Tune 2 (stock tune, rev limit @ 6900): Average across 3 runs 112.4
Tune 3 (higher than stock but conservative tune) Average across 3 runs 113.2

All launches were performed the same as the day of initial testing, meaning no overboost hard launch.

Times for both tunes were similar, high 12s and low 13s. I don't go by times as I am not a great drag racer by any means.

While the car feels better than the initial tune on either of the more recent tunes, it is still slower than stock which does not make sense to me, especially considering tune 2 is a stock tune with a higher RPM. I do understand that the stock turbos run out of steam right around 6300 rpm, but even with manually shifting prior to redline to keep in the power band more I am still not able to get close to what I was able to get while on stock tuning (which shifted at 6700 rpm). While it was warmer on each of the following track days after my initial stock runs, I would not think 16 degrees would account for a 5 mph drop in performance, but as I don't do much drag racing typically I may be wrong about that. I have spoken with others that have had their cars tuned and they think my car is not performing as it should as well.

I let Markski know how the car was running and he agreed that something else must not be right as the car is performing almost identically on the two tunes I have now and on Tune 3 it should still be significantly better than Tune 2 according to him. He said that was something he had not seen before.

That is why I am reaching out to the group to see if anyone else has had this issue and may have an idea as to what might be wrong. I noted in prior thread that after tuning the car initially felt faster with tune 1 but later on felt slower which I attributed to getting used to the new power level. The car has no engine codes active as well.

Any advice or anything you else you can think of that should be checked out please let me know.

Will

 

I’d be really curious to know if you’ve figured anything out on this. I’ve got a (new to me) ‘07 turbo tip that I’ve done some testing on (with my dragy) and am getting a consistent 114 1/4 mile with no hard launch in sport mode. All the research I’ve done shows more like 118 on a stock tune. Pretty significant HP difference. I just chalked it up to an altitude issue being at 4500 msl (lower than you). But when I sent my file off to vr tuned to get a new flash for some more power, they sent it to me with the attached info that I already had a tune in the car. I had no idea cause the car was used but new to me. So now I’m thinking that that tune is too aggressive and pulling timing and actually making the car slower than even a stock tune or something. I wish I could see logs to see what’s happening but haven’t got the proper equipment yet. I’ve tuned some turbo cars before but this is my first P-car. Would love to know if you’ve gained any insight on this.