Weird RPM flux when driving.. - Pontiac G8 Forum: G8 Forums - G8Board.com
 
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post #1 of 5 (permalink) Old 03-09-2013, 02:02 PM Thread Starter
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Exclamation Weird RPM flux when driving..

So I just got done with my 2.5 Cam Kit Install from VMS. Everything that the car has on it right now is 2.5 kit, 3600 stall, full exhaust (kooks lt to borla), heads ported and polished no milling done, rotofab. So all was good at start-up besides a P0106 which is a MAP sensor.
The issue is only a little thing that i just find weird. The car preforms perfect in all aspects, the only thing that weird is that when driving and getting up to around 50ish and up, and going from either anything more then 30% throttle (at those speeds), to taking my foot completely off the gas peddal, the car drops rpm's by like a 1000 and more and comes back up and then drops again and comes back up before settleing to a consistant decent.

...SEE VIDEO I POSTED WITH THE ISSUE...
https://www.youtube.com/watch?v=Q4otVNoojr8

The car is remote tuned by Steve at VMS. Both ECM and TCM.
I dont konw if this is supposed to be like this because i have never driven a stalled car. but it just seams really weird too me and i dont know if the CEL issues can cause this or what the deal is... IF any tuner could help that would be awsome. thanks.

2009 G8 GT

RCR 223/232 - Head's P&P-by Joe J. - Yank 3600 - Kooks Lt's w/ Borla catback - Roto Fab - HSRK - Trunion bearing upgrade - FE3's W/ Eibach's - BMR Trailing arms, Toe rods, and Subframe connectors - HID's and LED interior.

12.17 - 1.81 : Old Setup - Vms 2.5, Heads PP'd, 3600 stall, and 20" Hankooks.
11.80 - 1.70 : New Setup - RCR 223/232-PP'd & milled heads - 3600 yank - 17"Gto rims with MT et streets - ls7 maf


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post #2 of 5 (permalink) Old 03-09-2013, 06:15 PM
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Yes, as far as I understand, with a "higher stall" than stock, the RPM's will raise a bit before the car starts to move, so in your case, the RPM's before you "flash it" (tromp the gas pedal to the floor) will raise much higher before she "hooks" than you had before.

It gets the heavy cam into it's ideal powerband faster, and is designed that way.

If you had the stock stall on the 2.5 cam, it would idle so tight that it would be fighting you (and PUSHING through the brakes) at near idle speeds.

I don't know much about stalls, but perhaps you should have studied up a bit more before dropping the coin on such a full combo? Just kidding, but if in doubt, ask VMS, they sold you it!!


Only other idea I have is possibly you're experiencing the converter "locking and unlocking" at that moment.

--zep


2009.1 ZEPCOM MGM G8 GT
Kooks LT's, SOLO HFC & Mach Unbalanced with J-pipes, SLP Tips.
Livernois tune, VCM, FE3's, full Holden blue gauges conversion, iphone on display. Daily Driver FTW
The ZEPCOM G8 was SOLO's test mule
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Bought 3/30/2009, retired 7/18/2017 at 136k miles, still strong. Been a great ride, she will be missed!
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post #3 of 5 (permalink) Old 03-09-2013, 06:46 PM
Yep, that just happened..
 
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That is the basics with a stall. Good explanation zep...


2008 Liquid Red G8, Thunder Racing Custom Camshaft
219/230, 607/610, 114 LSA, DOD Delete
Kooks LTH, kooks catted x-pipe, kooks axle back, Roto-fab CAI and 25% udp, DMH electric exhaust cutouts, little shot(alright, maybe not so little) of happy juice courtesy of HSW and tune by Tony G at HP Performance. Oh yeah, and 08 Super Bee as well!
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post #4 of 5 (permalink) Old 03-09-2013, 07:16 PM
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Re: Weird RPM flux when driving..

Yep, that just seems to be the verter locking (rpm drop plus you should feel the verter clutch when it locks, Its a jerky feel) and unlocking. I have mine locking in 6th gear only part throttle, normal and sport, and 5th and 6th when in manual. It helps with the locking clutch longevity plus the locking feel can be a biatch if you are not use to it. Locking 6th only is all we need for daily driving unless you drive around long hills, in which case you can use manual and ask to lock 4th,5th and 6th depending on how hot things are getting in the trans.

Have fun.

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post #5 of 5 (permalink) Old 03-09-2013, 09:42 PM Thread Starter
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Quote:
Originally Posted by bluegoat06 View Post
Yep, that just seems to be the verter locking (rpm drop plus you should feel the verter clutch when it locks, Its a jerky feel) and unlocking. I have mine locking in 6th gear only part throttle, normal and sport, and 5th and 6th when in manual. It helps with the locking clutch longevity plus the locking feel can be a biatch if you are not use to it. Locking 6th only is all we need for daily driving unless you drive around long hills, in which case you can use manual and ask to lock 4th,5th and 6th depending on how hot things are getting in the trans.

Have fun.

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How long should/will it last with mine locking the normal way as compared to the way you have tuned yours?

----------------------------------------------------------------------

Okay, yeah I have done my studying it's just a weird feeling!.. I do however love the the fact that my rpm's stay exactly the same when i go thru gears normal driving.. I just like to worry, lol.. Thank you guys for setting my over thinking and under educated brain straight. Appreciate it.

2009 G8 GT

RCR 223/232 - Head's P&P-by Joe J. - Yank 3600 - Kooks Lt's w/ Borla catback - Roto Fab - HSRK - Trunion bearing upgrade - FE3's W/ Eibach's - BMR Trailing arms, Toe rods, and Subframe connectors - HID's and LED interior.

12.17 - 1.81 : Old Setup - Vms 2.5, Heads PP'd, 3600 stall, and 20" Hankooks.
11.80 - 1.70 : New Setup - RCR 223/232-PP'd & milled heads - 3600 yank - 17"Gto rims with MT et streets - ls7 maf


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