2007 silverado LTZ problems

Vintagemud · March 1, 2007

I have the new 2007 silverado LTZ I ordered it with the 5.3L flex fuel, fuel management system as well as the locker rearend and a 373 gear . The problem that I am having is that my Engine loses power at highway speed without warning twice it did it at 80 MPH while passing a truck on the tollway the engine just would not go any faster its like it loses power to the wheels or something .So I contacted my dealer thinking mabe it has a governer that was malfuctioning They said it does not have a governer on it and to bring it in so they could check it .Upon arriving is the service Dept The tech informed me that they had seen 2 other trucks with this problem but there was no fix for it its the way it was designed and agreed with me that it was very dangerous he then hooked up the tech2 computer to it to prove to me that nothing was malfuctioning and it did show 0 codes but I still think something is wrong. My salemans agreed with me and even reported the defect to chevy as well as talked to a tech at GM he was informed that there was a fuel shutoff on the truck that would shut it to prevent the the engine from reaching 6000 rpm and causing damage to the engine and I understand that however the engine was only about 3000 RPMs. I would think that with it showing 120 mph on the speedo with a V8 engine it sould go more than 80MPH and that if it is going to shut down it would give you some kind of warning Does anyone know what the top speed of this truck should be and whatI can do to get this problem fixed.

HawkeyeOC · March 1, 2007

I have the same truck in crew cab configuration, same engine w/o flexfuel, and same rear end gearing. Top speed is about the 96-97mph range. GM trucks unless they are performance oriented models seem to rarely go over 99mph top speeds these days. There is a governor on this truck. Most newer vehicles have some sort of governor on them.

80mph is way too low so I am sure something is wrong. When it hits the governor on mine, it feels like the the truck is slowing down. I am not sure if it's retarding timing or starving fuel to the engine. You get no warning.

You can bypass the governor and I am sure there are people in this forum that can tell you how if you get nowhere with Chevy.

Vintagemud · March 2, 2007

I have the same truck in crew cab configuration, same engine w/o flexfuel, and same rear end gearing. Top speed is about the 96-97mph range. GM trucks unless they are performance oriented models seem to rarely go over 99mph top speeds these days. There is a governor on this truck. Most newer vehicles have some sort of governor on them.

80mph is way too low so I am sure something is wrong. When it hits the governor on mine, it feels like the the truck is slowing down. I am not sure if it's retarding timing or starving fuel to the engine. You get no warning.

You can bypass the governor and I am sure there are people in this forum that can tell you how if you get nowhere with Chevy.

I would be very happy with that speed at least I could go faster than My wifes ford escort

asepgrad98 · March 2, 2007

just because there are no code doesn't mean there are no problems. keep taking it back until they fix it or buy it back

Ape0r · March 2, 2007

I have the same truck in crew cab configuration, same engine w/o flexfuel, and same rear end gearing. Top speed is about the 96-97mph range. GM trucks unless they are performance oriented models seem to rarely go over 99mph top speeds these days. There is a governor on this truck. Most newer vehicles have some sort of governor on them.

80mph is way too low so I am sure something is wrong. When it hits the governor on mine, it feels like the the truck is slowing down. I am not sure if it's retarding timing or starving fuel to the engine. You get no warning.

You can bypass the governor and I am sure there are people in this forum that can tell you how if you get nowhere with Chevy.

Changed mine to 128 with Hypertech. Haven't had it faster than 106 yet, though. Was just over 4100 RPM in 3rd with plenty of go left. As others are saying, something is most definitely screwy. Trying another dealer couldn't hurt, but you may be stuck waiting for a fix from corporate.

GeoHawk · March 2, 2007

Huh, sounds like some kind of software glitch. Like Hawkeye said, there is a speed limiter on GM trucks somewhere in the mid 90s, but 80 isn't right. That could be dangerous if you are trying to pass someone on a 2-lane highway. Keep pounding on the dealer to fix this. See if they can reflash the ECM to see if that is the problem. Other than that, I don't know.

Big Tool · March 2, 2007

Speed limiter on the 07's is 99 or 100mph, mine hits it pretty often on the interstate without me noticing. You definitely have something wrong. Can you go out and just run it to 80 and it does it every time or is it infrequent. If the stealer can't fix it you'll definitely be getting a new one. either way something is wrong. and whatever you do don't accept "that's just the way it is bull crap"

redvett · March 2, 2007

Speed limiter is set for the speed rating on the tires. Look at the sidewall and see what the rating is probably a "Q" speed rating of 100 mph.

Arctic Cat F7 · March 2, 2007

Thats odd? My engine has been running fine at HWY speeds. I have the 5.3 Flex fuel engine as well and the performace is great. Try taking it to another dealer??

Good luck.

Vintagemud · March 3, 2007

well I filled up with e-85 yesterday and it performes better seems to have alittle more power and the top speed is now 86 to 87 instead of 80 like before it still is not where it should be according to car and driver review it should be upper 90s .Chevy is still blowing me off saying thats its a gray area and refusing to fix it .I gave my 02 silverado to my son when I bought this truck this truck is not half the truck that the 02 is as far as performance goes. The 02 has the 5.3 with the 373 gear as well however it does not have a locker rear end and it is a LS sportside and it is very quick . My new truck reminds me of a saying my grandfather used to say about ford trucks witch he hated and that is it wouldnt pull a greasy string out of a cats ass going down hill . My chevy dealer still agrees with me that somthing is wrong but they cant fix it untill GM gets off there high horse admits something is wrong and comes up with a fix. My son being a teenage genuis that he is has offered to trade back if I keep the payments on the 07 he is so nice

redvett · March 3, 2007

Did you by chance change tire sizes. If so that will be the problem.

Vintagemud · March 3, 2007

Did you by chance change tire sizes. If so that will be the problem.

no it has the tires that came on it

redvett · March 3, 2007

Then i would check with a GPS if your going the speed the speedo says. If wrong see the dealer for a correction.

Vintagemud · March 3, 2007

Then i would check with a GPS if your going the speed the speedo says. If wrong see the dealer for a correction.

no the speedo is right

98 Z71 SLT · March 3, 2007

Is there a way you can turn OFF the Active Fuel Management?? If you can turn it off, turn it off and go for a ride. If your throttle response is better-well, you found your culprit.

If you cannot turn it off manually, I bet that a Tech 2 could turn it off. I would suggest a Tech 2 and a ride with a mechanic.

Your running into a very GRAY area with this problem of yours---speed limits. It's just a matter of time that you will be confronted on speeds you might be traveling with your truck. I don't know what your speed limits are in your state; but here in WI top speed limit anywhere is 65mph.

I am a GMC dealer tech...and we have not seen 1 complaint like yours. BUT, I'll keep my eyes open.