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View Full Version : Odd shift at strip. Log photo.


G8V8
10-04-2008, 04:51 AM
This is a data log i took of run # 3 at Cecil Dragway. It was in Normal mode and when I expected it to shift to 4th near the end of the run, it didn't and seemed to go flat.

In the scan you can see it hit 6300 rpm. In first it hit 6250 and seemed OK. Did I nudge the rev limiter in the top of 3rd?

It did this in the 3 runs I made in normal mode. The 1st run I thought it was because I forgot to turn off TC. In the second run it did it but TC was off so I decided to try to log the 3rd run to see what it might show.

What do you think?

http://img.villagephotos.com/p/2002-11/65524/log-Cecil3-Norm.JPG

My time slips are in the 1/4 mile run folder.
http://www.grrrr8.net/showthread.php?t=1117
wreckwriter
10-04-2008, 05:00 AM
Ewwww... that looks a lot like mine. It does appear you hit the limiter in 3rd but I'm more interested in the major sawtoothing at the 1-2 and 2-3 shifts. TM appears to be creaming you.

You must have felt major issues up until you were fully in 3rd, no?
G8V8
10-04-2008, 05:08 AM
Ewwww... that looks a lot like mine. It does appear you hit the limiter in 3rd but I'm more interested in the major sawtoothing at the 1-2 and 2-3 shifts. TM appears to be creaming you.

You must have felt major issues up until you were fully in 3rd, no?

Actually, with the excitement of my first time at the track and so much going on, 1st and 2nd felt pretty normal compared to my "street" acceleration runs. Guys were saying traction was fantastic at the track. My 1-2 shift didn't feel quite as "crisp" as on the street where I now get a little chirp with TC off. On the strip I didn't hear a chirp.


I think it may have hit the rev limiter. I'm no expert and I figure VMS can shed some light but the RPMs bounce after they hit 6300 at the top of 3rd and this is right where power went flat. I could feel it then and really feel the difference when I slapped to sport mode in later runs when I crossed 80 mph and then pulled back to hold third.

What I don't understand is why holding in Manual 3rd worked great but Normal 3rd hit the rev limiter ,if that is what it did.

I expanded the log view. peak at 1-2 was 6281, 2-3 was 6104 and 3-4 was 6300.

http://img.villagephotos.com/p/2002-11/65524/log-Cecil3-Norm-expanded.JPG
g8_795
10-04-2008, 05:17 AM
Ed,
This is exactly what I am seeing. I will post my numbers soon, but this is a big problem. I had to go back to the holding 3rd trick.
-Robert
wreckwriter
10-04-2008, 05:17 AM
Here's snip from a log I did not long ago. Notice the similarities? I could feel this very distinctly, car was falling all over itself at the top of 1st and in 2nd. The yellow line is absolute throttle position.
G8V8
10-04-2008, 05:23 AM
I added an expanded view of the log while you were posting.
g8_795
10-04-2008, 05:27 AM
Do you know where you crossed the line on your charts?
G8V8
10-04-2008, 05:32 AM
Do you know where you crossed the line on your charts?

Right around 57 1/2. You can see the timing spike up as I closed the throttle. It meshes pretty well with the ET for that run.
GTPprix
10-04-2008, 05:55 AM
You tagged the limiter in third, if the car was cold its possible it will do that. Easy fix either way, everything else looks perfect.

Tom his car isnt doing anything like yours, the "sawtooth" in RPM you see is 1st and second gear, you can even see the TM step in at the bottom ;)
G8V8
10-04-2008, 07:13 AM
You tagged the limiter in third, if the car was cold its possible it will do that. Easy fix either way, everything else looks perfect.

Tom his car isnt doing anything like yours, the "sawtooth" in RPM you see is 1st and second gear, you can even see the TM step in at the bottom ;)

OK Thanks.
g8_795
10-04-2008, 07:15 AM
Here's snip from a log I did not long ago. Notice the similarities? I could feel this very distinctly, car was falling all over itself at the top of 1st and in 2nd. The yellow line is absolute throttle position.

Did it do this with and without your stall? Does it do this a lot? Seems like something is very wrong.
wreckwriter
10-04-2008, 08:32 AM
Did it do this with and without your stall? Does it do this a lot? Seems like something is very wrong.

Its only done it since the converter. Yes, something is very much wrong.
locrzn#92
10-05-2008, 05:25 PM
Mine has no tune and it hit the limiter on every pass somewhere around 1100-1200 ft. Mine won't shift out of 3rd in the sport mode. I didn't look at my tach since it was dark, but, it was definetly studdering. I've been on the rev limiter many times when I had my old 9 second Nova, it had a 6.17 gear and turning the motor 8900 rpm and at 1000 ft it was on the limiter every pass also. Then I raced mostly 1/8 mile and just occasionally made some quarter mile runs when big money was being paid out that was never an issue. I've heard that sound too many times. I didn't hit the limiter until I put my stock wheels and tires back on. My aftermarket 19" tires are just a little taller then stock which keeps the R's down at the finish line. How much can the limiter be raised without issues on these motors, maybe 6500 rpm's?
SS Enforcer
10-10-2008, 07:35 AM
Its only done it since the converter. Yes, something is very much wrong.

Mine has some issues with the stallie and shift points . For instance I am having trouble getting the 1-2 shift in with out tagging the limiter. The box is tuned properly so we have raised the limiter to 7200 and still just clip it. 2-3 changes at 6900 but it's commanded much lower. Mines cammed and runs 11.6 . I suspect that there is something else going on in the box that Efi live and HPT can't yet access OR the extra HP is screwing with the shifts.
Maybe it's a case of the A6 not liking the fact that the revs are out of whack with a stall converter and we can't do anything about it atm . I'm just speculating there though.


cheers
SS Enforcer
10-10-2008, 07:39 AM
How much can the limiter be raised without issues on these motors, maybe 6500 rpm's?

6500 shouldn't hurt it just make sure you have plenty of oil in the motor I run an extra 500 mls to be sure. These have pretty strong rods and rod bolts in em so spinning em high should be ok. I have spun mine to over 7300.

cheers
wreckwriter
10-10-2008, 07:40 AM
Mine has some issues with the stallie and shift points . For instance I am having trouble getting the 1-2 shift in with out tagging the limiter. The box is tuned properly so we have raised the limiter to 7200 and still just clip it. 2-3 changes at 6900 but it's commanded much lower. Mines cammed and runs 11.6 . I suspect that there is something else going on in the box that Efi live and HPT can't yet access OR the extra HP is screwing with the shifts.
Maybe it's a case of the A6 not liking the fact that the revs are out of whack with a stall converter and we can't do anything about it atm . I'm just speculating there though.


cheers

It's as good a theory as any I've heard yet. Seems odd though that some cars run perfectly with the same converter, this is why I suspect there is a problem with my converter. Unfortunately it's going to be pricey to prove or disprove.
GeorgeInNePa
10-10-2008, 08:23 AM
6500 shouldn't hurt it just make sure you have plenty of oil in the motor I run an extra 500 mls to be sure. These have pretty strong rods and rod bolts in em so spinning em high should be ok. I have spun mine to over 7300.

cheers

While I wouldn't suggest 7300 with the stock bottom end (man that had to sound cool ;) ), we're more worried about the valve train with the AFM system.