jerking issue with U7191

supachim · Post by **supachim** » Sun Jul 08, 2007 4:03 pm

Hello

I am fairly new at modding and tuning cars, so please excuse the lack of expertise on my end. I have a 2006 Pontiac Grand Prix GXP with the LS4 5.3L V8 engine. I recently had a shop order and install the Predator U7191 for the LS4 engine. They added the performance tune and right away I noticed an improvement while accelerating. I am extremely happy with that. However, after driving it for a while, I have noticed that every once in a while, if I'm cruising, that it will kind of jerk like it had wanted to accelerate and then it had decided not to. I was wondering if there is anything I could do to fix that.

Some other information about my car - I always use premium gasoline, but I'm not certain of the octane (91 or 92). It has the K&N Aircharger and the Magnaflow Performance Exhaust kit on it.

Any help would be greatly appreciated. Thanks!

Post by **06MonteSS** » Sun Jul 08, 2007 7:41 pm

this is a known issue with the Diablo Tune - this tune leaves the DOD enabled, and the jerking you feel is when the car is switching between 8 and 4 cyl. modes... to eliminate this, install the Diablo Tune No DOD. This disables the DOD altogether so that you're always in V8 mode, and thus the jerking is gone since it's not switching to 4 cyl. mode anymore.

I have a feeling that they won't be able to totally fix that jerking issue until they have tranny support for our vehicles and can access the parameters on the tranny side of things.

supachim · Post by **supachim** » Sun Jul 08, 2007 7:50 pm

=(

That's a shame. I like the DOD. I don't want to imagine my gas mileage with it off. =P

There must be a way to fix it through the manual settings (I just don't want to mess with it too much because I'm not exactly sure what I'm doing) because without the performance tune, it doesn't jerk.

Thank you for the info, though!

Post by **06MonteSS** » Sun Jul 08, 2007 7:56 pm

well, I run the No DOD tune and am always in V8 mode... and once I got my fueling dialed in (via injector slope and PE adjustments), my mileage actually went UP compared to when I was running with DOD still on.

I run 50/50 city/highway driving - and don't baby it, believe me - and I get a solid 20mpg everytime I fill up and check... and like I said, that's with the No DOD tune so I'm always on all 8 cyl.

no, there is no way for us to get into those types of settings that would allow you to adjust any part of that. And that's exactly why they don't allow people to get into it that deep, because most people aren't sure what they are doing/adjusting/changing - and would totally hose their engine/tranny.

supachim · Post by **supachim** » Sun Jul 08, 2007 8:30 pm

Wow, that's pretty good. So, what exactly do you do to get that? Sorry, I'm not exactly sure what getting your "fueling dialed in" means... heh, or injector slope and PE adjustments either.

I really appreciate the info, though! =)

Post by **06MonteSS** » Sun Jul 08, 2007 8:38 pm

here's some tutorials I wrote up for Diablo's forums here...

Logging and adjusting injector slope and PE... http://diablosport.com/index.php?name=P ... opic&t=917

Excel macros I made for filtering/analyzing log data: http://diablosport.com/index.php?name=P ... pic&t=1145

Post by **mikel** » Mon Jul 09, 2007 11:18 am

Thanks Monte....

supachim · Post by **supachim** » Thu Jul 12, 2007 9:55 pm

Hey MonteSS, I've been following your tutorial (so far, all I've done is install the diablo without dod tune and i've been driving it for 65 miles or so - tomorrow I'll be starting the log process and what not). Anyway, after I installed the tune with no DOD, my cruise control stopped working. It starts to engage, but immediately turns off. Just wondering if you knew about this - maybe it was just a corruption when I installed the non-dod tune. I figured, I'd go ahead and get the modifications done with the tune and see if it works after that. I was also going to figure out what modifications I need to do and try it with the DOD turned on to see if it still jerks. Anyway, thanks again for all the info!

ooh! Also, I'm finding it hard pressed to get 93 octane fuel around here. If I am constantly getting 91 octane, should I use the 91 octane no dod tune? And if I do that, should I stay away from 93 octane? Or should I only use 93 octane if I've got the Diablo No DOD Tune?

Post by **06MonteSS** » Thu Jul 12, 2007 11:46 pm

the cruise control thing is news to me... NEVER heard of that happening... restore the original backup and see if the cruise control works again...

jerking issue with U7191

jerking issue with U7191

RE: jerking issue with U7191