Speed limiter at 134 MPH

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Nov 9, 2022 | 10:03 AM

jcavrules

Thread Starter

Intermediate

Joined: Sep 2022

Posts: 31

Likes: 7

From: Florida

Speed limiter at 134 MPH

I recently got a 2014 stingray 3lt A6 with the z51 package and have been stalking this forum for advice lol. I have done minor mods like an AFE intake, custom exhaust, and I installed the 93 octane with CAI tune from diablo with the i3 programmer. I went in and disabled the speed limiter, along with AFM/DOD and boosting the throttle a bit, but now when I reach 134 mph it cuts power and shows a message saying "speed limited to 134 mph". Before the tune, the car reached 150 easily with no warnings or speed limiters. I made sure to update the tuner with my pc and removed and re-flashed the tune but the problem persists. I could only find one similar thread with an M7 getting limited in4th gear, but not sure how closely that applies to my situation. Any advice would be greatly apricated. Thank you!

Nov 9, 2022 | 01:31 PM

RonC7

Safety Car

Joined: Dec 2012

Posts: 3,858

Likes: 1,863

From: St. Louis Metro East IL

From the 2014 Owner's manual pg 9-30. You are likely approaching red line rpm and the rev limiter is kicking in.

Ron

For vehicles with a 2.73:1 Axle
Ratio (RPO GU2 with Z51)
. Upshifts to 4 (Fourth) gear
require approximately 31 km/h
(19 mph).
. Upshifts to 5 (Fifth) gear require
approximately 39 km/h (24 mph).
. Upshifts to 6 (Sixth) gear require
approximately 57 km/h (35 mph

To prevent damage to the
powertrain, Manual Paddle
downshifts to a lower gear cannot
be done above certain speeds. The
maximum speed allowed for
downshifting of gears 1 (First)
through 4 (Fourth) are:
. Into 4 (Fourth) gear over
234 km/h (145 mph).
. Into 3 (Third) gear over 176 km/h
(109 mph).
. Into 2 (Second) gear over
113 km/h (70 mph).
. Into 1 (First) gear over 64 km/h
(40 mph).
If an upshift is not requested as the
engine speed approaches fuel shut
off rpm, the engine speed will be
limited to protect the engine. See
Tachometer on page 5-11.

Nov 9, 2022 | 01:42 PM

Bill Dearborn

Tech Contributor

Joined: Oct 1999

Posts: 41,058

Likes: 9,820

From: Charlotte, NC (formerly Endicott, NY)

It was fine before the changes and isn't afterward. That means you have to go back and see which change is causing the issue. I would start with changes that directly impact what you are experiencing. Since you thought you changed the speed limiter maybe you didn't change it to what you thought. You may need to go back to the original tune and work forward one change at a time to resolve the issue. But disabling the speed limiter may be what causes the issue. What happens when you shift into 5th gear? Is speed still limited to 134 mph?

You may have fallen victim to the age old problem of making too many changes at one time.

Bill

Nov 9, 2022 | 03:06 PM

jcavrules

Thread Starter

Intermediate

Joined: Sep 2022

Posts: 31

Likes: 7

From: Florida

I have isolated it to the tune itself, as the exhaust and intake were done before hand at different times. The most recent change was the tune, and before the tune even with all of the other mods completed, it had no problem reaching 150, probably more too but that's the fastest I have taken it. I know the issue is isolated to the tune, but I know there are plenty of others who are running the same diablo tune without issue. So I guess I am more so asking if anything else could cause that issue with the tune, or if the preloaded tunes on my programmer were somehow different? Also, I don't believe it is the rev limiter because it happens way before redline, and there are no traction control or any other type of warning lights other that the warning message saying, "speed is limited to 134 mph". I have not tried shifting up to 5th, but it's hard to constantly test a problem that only happens above 130 without getting arrested lol, however it has always been in automatic mode when it happens, and also happens in every drive mode that I've tried.

Nov 9, 2022 | 06:01 PM

gatormark91

Intermediate

Joined: Jul 2022

Posts: 40

Likes: 10

6cyl Camaro is speed limited to 134mph with same message. Maybe some wonky code?

Nov 9, 2022 | 06:04 PM

squirrelchew

Burning Brakes

Joined: Sep 2022

Posts: 1,202

Likes: 569

From: MSP

is this an OTS tune? call the company and ask. maybe your OTS file is the wrong one.

also, insert obligatory "stop doing that **** on public roads" commentary here.

Nov 9, 2022 | 09:06 PM

jcavrules

Thread Starter

Intermediate

Joined: Sep 2022

Posts: 31

Likes: 7

From: Florida

Quote:

Originally Posted by squirrelchew

is this an OTS tune? call the company and ask. maybe your OTS file is the wrong one.

also, insert obligatory "stop doing that **** on public roads" commentary here.

It is an OTS tune and from what I’ve seen a pretty common one at that. I’ll give Diablo a call tomorrow and see if anyone has had any similar issues. I would just test all the variables I can myself, but i can’t be at the track every day and as you mentioned, public roads are not the smartest place to do that kind of test lol. I’ll update if I get any answers