06 G6 GTP M6 tuning/TM question

I have been playing around a bit with my 06 3.9 G6 GTP to get a feel for HPT so I am more confident when I go to tune my TT GTO.

Anyway, I have a couple questions-

1- I was trying to lean it out a touch while cruising for slightly better MPG- should I just change the stoich to a leaner # and let it run from there, or is there something else I should/could change? I have added a couple degrees to it in cruise and such and it seems to be a bit better, but I was wondering if anything else can be played with since we have no "lean cruise" here :(.

2- The car seems to "buck" on a hard WOT shift. I always thought it was TM closing the throttle on an abrupt shift, but I set all the values to max and it still does it. Is there anything else that would do this? It almost feels like it is slamming the throttle shut for a brief second on a hard shift. Not that am going to race this thing, I have the GTO for that, but I do want it running it's best :).

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Originally Posted by kwiktsi

1- I was trying to lean it out a touch while cruising for slightly better MPG- should I just change the stoich to a leaner # and let it run from there, or is there something else I should/could change? I have added a couple degrees to it in cruise and such and it seems to be a bit better, but I was wondering if anything else can be played with since we have no "lean cruise" here :(.

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No, you generally want to leave the stoch value alone. If you want to improve MPG, take a look at the DFCO values and the o2 crossing values. Reducing the 02 crossing values may increase your MPG ever so slightly. And DFCO entry can either help MPG or cause surging as it goes in-out of DFCO too quickly (if set up for faster DFCO entry).

Quote:

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Originally Posted by kwiktsi

2- The car seems to "buck" on a hard WOT shift. I always thought it was TM closing the throttle on an abrupt shift, but I set all the values to max and it still does it. Is there anything else that would do this? It almost feels like it is slamming the throttle shut for a brief second on a hard shift. Not that am going to race this thing, I have the GTO for that, but I do want it running it's best :).

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If you could post your tune & scan we can all get a better idea of what is happening there.

BTW: you can press *M* during the log if you get that surge/buck so we can see where it is happening. Then you can annotate that location with comments when you are done with the log.

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Originally Posted by EC_Tune

No, you generally want to leave the stoch value alone. If you want to improve MPG, take a look at the DFCO values and the o2 crossing values. Reducing the 02 crossing values may increase your MPG ever so slightly. And DFCO entry can either help MPG or cause surging as it goes in-out of DFCO too quickly (if set up for faster DFCO entry).



If you could post your tune & scan we can all get a better idea of what is happening there.

BTW: you can press *M* during the log if you get that surge/buck so we can see where it is happening. Then you can annotate that location with comments when you are done with the log.

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OK, I'll leave the stoich alone. I already dropped the DFCO quite a bit, not surging yet- but I don't think I can go much further before it does. I normally don't care about trying to improve MPG on my cars if they are a toy, but this thing is my DD and gets roughly 24mpg average on me- same as my LS2 GTO before the turbos :(.

I'll have to try to log the buck. It has done it since new- if you shift too fast (especially trying to speed shift it), it will fall on it's face when you let the clutch up, then recover. I used to think it was the throttle closing due TM or something, but apparently not.

OK, here is a quick log of a 1-2 shift and you can see the TPS falls right off, even though I was WOT- I'm assuming this is where the buck is coming from. I tried to mark it, but I guess you have to do it DURING the log run, not after :o . It is between frames 858 and 882. I also attached the tune that was in it on that run.

Also, I tried to play with the DFCO a bit more and I am confused- the stock TPS %'s were ~.04 for enable and .11 for disable- yet, in an entire run- even at idle, my TPS reading never shows below 20%. Am I safe to assume it is never even going into DFCO? Thanks!
Joe

Anybody???

The ETC TPS% shows the actual throttle opening.
Accelerator Pedal Position is more correct for determining requested throttle opening for DFCO etc.
BTW It looks like you are hitting a the accel based rev limiting. Check this table and compare to a V8 cal:
Attachment 5039

OK, didn't realize that- I just saw TPS and assumed it was pedal. That makes sense now. As for the accel based limiting- do I max it out of 0 it out to remove it? Thanks.
Joe

OK, I see where I was mistaking TPS for pedal position- the DFCO settings say "throttle position", not pedal. I am taking the acceleration based limiter settings from my GTO to try. I still think it may be something else though, I short shifted it before to keep it away from the limiter and it bucks pretty good on a WOT shift :(. Thanks for your help so far, it is appreciated!
Joe

You need to log ETC position%, not TPS% SAE. Why are your fuel trims all -100%, the ECT & IAT at -40, and the O2 MV at 0? Make the changes to your tune as shown.

Russ Kemp

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Originally Posted by Russ K

You need to log ETC position%, not TPS% SAE. Why are your fuel trims all -100%, the ECT & IAT at -40, and the O2 MV at 0? Make the changes to your tune as shown.

Russ Kemp

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for some reason, the logger is not picking up those items, I am waiting for an update from Chris- he said Kevin is working on it.

I'll try to log ETC. I know my TPS drops very abruptly if I speed shift this thing- I tried completely disabling the TCS, TM, acceleration limiter or whatever it was, CFCO, even the rev limiter to make sure it wasn't hitting it on the shift and it still does it- you can see the TPS drop abruptly on the shifts.

Thanks for the help, I can't wait to get this thing resolved. Funny, I am in the middle of finishing up a 750ish whp GTO, yet I am so anxious to get this thing right haha.
Joe
PS- I already made those changes you show above- no go :(. Only thing different I have done and not tried yet is having the CFCO disabled along with everything else. Maybe it is a combination of things? Also stinks because I have to do a "write entire" since it won't let me do a "calibration only"- so I am always nervous that something could go wrong..

Not to worry on the Gen IV (E38/E67/E40) PCMs as they have a native boot loader that can't be corrupted (by any normal means anyway!) so a write entire will always work.

That's good to hear! Takes the worry out of that part of it. Now, I just have to figure out this damn buck. I pretty much disabled all the limiters, cuts, CFCO, etc. and it still does it. You can still see the TPS dip when it happens..
Joe

Hmmm. May need to send your stock/modified/vcmlog to support. Wonder if there's something else in that cal tripping up the throttle.

Before you do that: What happens if you move the rev limiters up by 500 RPM more just as a test?

I believe I've turned the limiters off completely and it still did it. Don't remember, I'll play some more later. Not that it is too long, but having to do a full write makes it difficult to make quick changes and experiment. I'll try some more stuff tomorrow.

I've already sent stuff to support about the car not logging all parameters and am waiting for that to be resolved, so I don't know if they'll even be able to deal with this right now. Ken's gotta be busy as hell, I'm sure.
Joe

My TC light pops on whenever I go full throttle through certain gears in both auto and shiftronic. When this happens, my gears feel like they are slipping and the shifts become harsh as if the transmission is failing. I immediately pull over, turn the car off, wait 5-10 seconds, turn it back on and everything is fine. Computer codes show different things such as MAP and MAF failures, but I know this has nothing to do with why my shit is driving like this when at WOT and it happens sometimes, turning off TC helps, but it is not an absolute answer. Most forums don't explain why this is happening, and I believe most people are not being honest about what they are doing for this TC light to pop on at full revs at WOT, it happended to me at launch and happens from 3rd to 4th WOT.