1-2 Shift Flutter

RedFX4 · #1 Thu, September 2nd, 2010, 03:42 PM

Ok well I'll maybe give it a go next tank of gas and see. As long as it doesn't start knocking or anything. Thanks for your help.

RedFX4 · #2 Thu, September 2nd, 2010, 03:48 PM

Strangely enough I found a video where my that 1-2 flutter happens.

YouTube - 2008 5.4 F150 Magnaflow 12268 5x8x18 CAI and Edge

It occurs at 2:52 in the video so just advance it to 2:45 or so. Kinda nice when someone video tapes your problem. Makes it easier to explain.

***Jackpine*** · #3 Thu, September 2nd, 2010, 11:49 PM

Sorry, Red - I'm not seeing (hearing?) what you are. To me, it sounds pretty normal, once you get past all the exhaust noise. I personally like "quiet" and that noise would drive me right up a wall.

What you were describing made me think it was a "slip" and and an abrupt "lockup". I was not seeing that on the video. What you have COULD be a small needed adjustment in the WOT upshift RPM and the WOT max RPM.

I would not have the upshifts much higher than 5000, maybe 5100 max and then set the max RPM 400 higher. But, keep the 3-4 upshift quite a bit lower, at around 4500. You are getting a HP and a torque dropoff above 5K, so it doesn't make a lot of sense to go much higher than that. Bill has said to keep the 3-4 upshift lower to minimize stress on the transmission.

Above 5400, your Torque Converter starts to balloon, so that's why you really don't want to set the max RPM too high. I would never put it above 5600 for that reason and I sure would not consistently have it revving in that range.

The max RPM needs to be at least 400 above the shift point to allow the shift to take place. There is a moment when everything is "uncoupled" and the engine is freewheeling and accelerating rapidly. If the max is not set high enough, you'll hit the rev limiter before the shift completes.

- Jack

RedFX4 · #4 Fri, September 3rd, 2010, 11:06 AM

Ok maybe that is the issue then. I believe these canned tunes have the max upshift rpm set at 5200. I don't know what the max rpm is. Maybe what I'm hearing is the engine bouncing off the rev limiter when it shifts.

As for the video you won't see anything, only hear the motor "double peaking" (for lack of a better description) in rpms when its shifting. Not necessarily a quality I want with my truck.

***Jackpine*** · #5 Fri, September 3rd, 2010, 11:30 AM

When I said "seeing", I misspoke.

I really DID mean "hearing". But, I guess I'm not as sensitive to the sound (or what you are probably "feeling") as you.

As I said, I don't think I've ever felt the need to do a WOT 1-2 upshift, but I've certainly done 2-3 and 3-4 WOT upshifts. If the shift point is set too high relative to the max RPM, you have to back off on the throttle to let it complete properly. And, with the "firmer" shifts, you can easily get a serpentine belt squeak during the shift which is kind of scary the first time you hear it.

I'd definitely back off the upshift from 5200. I'd set it to 5000. I think 5200 is way too long to keep it in 1st.

- Jack

RedFX4 · #6 Fri, September 3rd, 2010, 03:31 PM

I just went into the custom programming and it showed that the shift points were set to 5000rpm with max revs set to 5400. I distinctly remember seeing pass this though. Maybe its as you said and I'm just seeing the flywheel freewheeling. Does it usually default to 5000 when you select the customize feature?

Also I was goofing around on the gryphon and noticed it logged my max rpm at 5383. That is a little high for my liking if the TC starts ballooning at 5400.

Long story short, I have the 1-2, 2-3 shifts set to 5000rpm, and the 3-4 set to 4500rpm. I might increase the 3-4 later depending on how it drives. Max revs I have set to 5350.

***Jackpine*** · #7 Fri, September 3rd, 2010, 03:53 PM

Quote:

Originally Posted by RedFX4

I just went into the custom programming and it showed that the shift points were set to 5000rpm with max revs set to 5400. I distinctly remember seeing pass this though. Maybe its as you said and I'm just seeing the flywheel freewheeling. Does it usually default to 5000 when you select the customize feature?

Also I was goofing around on the gryphon and noticed it logged my max rpm at 5383. That is a little high for my liking if the TC starts ballooning at 5400.

Long story short, I have the 1-2, 2-3 shifts set to 5000rpm, and the 3-4 set to 4500rpm. I might increase the 3-4 later depending on how it drives. Max revs I have set to 5350.

IF you do a WOT 1-2 upshift with the shift set at 5000 and the max at 5350, you may not get it to complete unless you back off on the throttle. A brief burst at or even above 5400 will not hurt anything. Personally, I'd either set the max at 5500 or move the shift points down to 4900.

- Jack