Shift Points, Rev Limiters and Knock. Oh my!!

[tatasta]

Hello,

Just like when I started to understand enough about computers to become dangerous to their life, I am there now with EFI Live.

1st - I seem to be able to get the 1 > 2 shift to work ok but the 2 > 3 is running past the commanded shift points, I think, since it keeps blowing past 6400 rpm. Could someone please check my logs and tune to see where I am going wrong?

2nd - There are a couple of instances of knock, both N/A and on spray. Problem is, even the knock is not consistent. I dropped back my timing from 29.5 to 28. Can too little timing create knock as well?

Please take a look and any help would be greatly appreciated.

The April 24 09 WOT is the log previous to todays tuning changes.

tatastaV2 tune is currently in the car.

The other two logs are most recent. The 1stNA_2and3on100WET is a crappy name to describe that the first wot is N/A and the other two are on a 900 psi wet shot.

Thank you for your time.

[N0DIH]

I can't open the logs right now, but you have to have rpm limit exceeded and mpg limit exceeded to have a shift, if you have your rpm limit at redline, you will exceed redline before the shift occurs.

Lets say you need shift before your 6400 rpm redline, so you might need rpm limit at 5800 rpm and the shift point to say 48 mph, where 48 mph is not the redline shift, but yet might be a couple mph lower than it. Think of how fast the engine is accelerating and you have to jump the gun a tad to get it to happen before it bounces off the rev limiter or exceeds your max rpm limit.

Look at where the stock tune was and see what GM did, do the math on your shifts and see what GM did for the redline the car had at the time.

If that helps any. Might be off as I can't look at the logs right now.

Also, there are WOT and non WOT shift tables. Once you are in WOT mode, then there is another table at work. TCC and Shift both.

[joecar]

I can't look right now (non-Windows PC)...

+1 what Tom said: reduce WOT upshift MPH and WOT upshift RPM until it shifts (early), then incrementally raise one or the other until it shifts at the MPH or RPM you want.

Remember to keep the WOT downshift MPH below the WOT upshift MPH (at least 5 mph difference).

[N0DIH]

I found my 3.42 geared LT1 Fleetwood (factory gearing) would really sail up the rpm fast at WOT in first so I had to be cautious on the 1-2 shift point else it would easily overrev and bounce off the rev limiter.

[tatasta]

Thank you guys. I will see what is happening.

[waterbug1999]

Hey joecar... Why cant he just set the shift points at whatever RPM he wants to shift at, and set the VSS (up shift parameters) at a slow speed so its certain to exceed that... Thats one less variable that has to be met. I did that and it works like a charm.

[tatasta]

Yeah, that certainly would be handy. So, you are running that way with no trouble? Cool. Would you mind posting up a tune and log of it?

Thank you

[waterbug1999]

I don't have any troubles at all... Alls I did is under the VSS > upshit > parameters are all set in the single digits... So, then just use your RPM's for shift points only.

So now, the speed has nothing to do with the shifts because it has been met (the reason why you set it low) so its just looking for RPM's now. It just takes out one less variable.

Only thing I have ran into was while logging the N20 run, I had the PID "gear" selected and that was all whacked.. It showed I was shifting from 2nd-3rd at 50mph then into 4th at 55mph.. But, I know it did not and it shifted perfectly/ran perfectly.

Try it, if it doesn't work right just throw the other tune back in.

[joecar]

Set D0930-2 lower than D0915-6
Set D0935-7 lower than D0920-1

[tatasta]

joecar and waterbug,

Thank you for the responses. I see the simple errors that you guys pointed out. I adjusted those shift points/parameters and took the car out today and had much better results. Is it common to see an increase of 400-600 rpm during a shift? I am learning that some parts of tuning are not black and white. Rather, you have to use a certain amount of skill and estimation.

Also, on the TCC settings, third is working pretty well but fourth seems to lock up ok at speeds of 35-45 but at freeway speeds (60-80mph) it seems I have to increase TPS% slightly and gradually (10-15%) to get a lockup. At ~ 75 mph the TPS% is at about 14%. If I fiddle with increasing the the throttle, I can usually get a lock but generally will lose it when I go back to a steady % and mph.

Is there a direct relation to engine load in TCC lockup? If so, how would it be adjusted.

I attached my current tune and a Shift point/TCC spreadsheet to see if anyone can spot a problem.

Are there any other glaring errors in the tune that must be fixed? I am trying to get the tune dialed and safe on N/A so I can finish up the N2O calibration. I plan to trailer the car to a track a few times this summer. I am stoked to get it on a track to see how it does. I missed last year because of a trashed third member.

Thank you very much, again!

Bob

[waterbug1999]

Well, Id like to ask what tranny you have? I have an FLT Stage V, which has no electronic shifting, just vacuum and thats why I do it the way I do.

What I was suggesting just makes it pretty simple. If you tranny takes that long to shift then adjust for it. I dont think giving it a speed to shift on top of the RPM's will make it shift any faster. Also, data logging wont be accurate from what I found out, so use your ears/seat of the pants.

[tatasta]

I am running the stock 1999 4L60E. Other than taking care of it with frequent maintenance and adding a big cooler to it, there has been nothing done to it. I am currently in the market for a new/upgraded trans. I am a bit torn between building another 4L60E with all the good stuff or going to an 80E.

Either way, I will be sure to do it right. After the heads, cam, 9", N20, suspension etc, it may be a while until I get the funds together. My wife told me that I'm about one mod away from being single. lol

I am getting closer, I think. Just alot to learn.

Any thoughts on the TCC issues for 4th gear lock-up?

Thank you

[joecar]

Try setting the first 3 cells in D1003 to 40 mph.

[joecar]

With a stall converter the rpms usually tend spin up higher before the shift is commanded and/or completed...

so you "anticipate" by setting slightly lower values.

[joecar]

Money isn't the problem (she can spend easily)... the real problem is you're spending more time with the car than with her... ;) ...but that's just what guys do... ;)

Would it be better if you were buying a new car every 3-5 years [rhetorical question]...? No, that would be way more costly.

[tatasta]

Money isn't the problem (she can spend easily)... the real problem is you're spending more time with the car than with her... ;) ...but that's just what guys do... ;)

Would it be better if you were buying a new car every 3-5 years [rhetorical question]...? No, that would be way more costly.

Very true. The nice thing about my Trans Am is that I have always wanted one, I got one and there's nothing else out there I like as much as the last T/A's. Having no payments sure makes modding alot easier.

Anyway, I will make the suggested changes and see how it works.

Thanks!