Vehicle speed limited.
 

I took the truck to Mardi Gras and it did great. Stupid traffic added a couple hours to the trip, but I made great time coming back.

Interesting thing though.

On a wide open part of the highway, I had a chance to make some time. At 85 it maxxed out and would bounce between 84 and 85 with the pedal nailed. I made a pit stop and got something to drink and when I got back on the road, it went to 98 as I would expect since my old truck was the same. 98 and that was it.

I asked OnStar for a diagnostic to see if any codes were popping up and there were none. I have not checked it with my own reader yet.

I have no idea why it limited to 85 and the internet offers nothing.

The entire trip there and back I averaged 59mph and 16.9mpg.

98 mph ? :issues:

What kind of truck?

My 2018 F150 will hit 100 pretty easily with the 5.0. I know it does have a speed limiter somewhere above that speed.

2015 GMC.

I rarely have any space or occasion to go that fast, but all big trucks had to stay right and I was left :D so I took advantage.Posted 75 so it wasn't that big a deal.

There had to be some reason it was 85 but then reset or whatever to actually go above that after a restart.

That is odd. :confused5: No DIC events?

If he had a DIC event we don't need to know about it. :slap:

Jackazz you know what I meant. :rofl:

:funnier::funnier::funnier:

I'm going to check with my own code reader tonight. I'm not sure what OnStar actually can access. I took advantage of having it for free for 30 days so I pushed the button. :D

He would be Mr Jackass to you :lol:

All my fuel injected Chevy Trucks have been speed governed at 100.....the fuel pump cuts off until you the truck slows down a bit. That used to be a problem long ago, but these days, there just aren't any places you can inadvertently go 100 anymore, due to traffic. That's supposedly because the OEM truck tires are rated for 100. Any aftermarket tuner can fix that, but I never thought it was worth the expense.

Never heard of speed governed at 85. That's strange.

The 85mph seems to be due to some issue that is unknown. Once I stopped and restarted, it was normal. I thought it may have been related to the same voltage regulator crap, but it didn't seem to have any correlation to the charging condition. It has a speed alarm that I can set, but it wasn't that either. :island14:

Did the fuel pump stop and not restart? You had to coast to a stop then restart? Some. Ting. Wong. When my trucks cut off, the fuel pumps restarted at about 97mph, and you just had to keep it there, or less, and no more problems.

OnStar is great. It gives them a way to telemarket you while you are driving.:leaving:

No. I was driving and there was a line of 18 wheelers. I put the pedal to the floor and it climbed to 85 but would not go faster. It was bouncing between 84 and 85. I got around the trucks and now was just trying it to see what the deal was. Several times it climbed to 85 and that was it.

Further down the road I exited for a bathroom break and something to drink. I got back in it, and on it, and it went to 98 like nothing was wrong. I did it a couple more times just to test and it was fine. I haven't had occasion to try again and there's no chance on my drive to and from work so it will have to wait until the weekend.

Was your cruise control activated at the time?

No. I rarely use cruise. It's like bright lights. As soon as you activate, you end up disengaging.

I was normal temps (200ish)
Oil pressure about 40-45
Charging 12.5 - 14v
No cruise
AC on or off made no difference
Outside temp was about 70
No dash warning lights

I get a suspension needs servicing warning at each start up, but I just cancel it and move on. It is because the mag ride has been removed and one of the shock simulator resistors is bad. This condition exists always so it shouldn't be related.

This might seem too obvious, but have you checked the owner's manual to see if there's anything in there about this?

I've been searching truck forums mostly. The owner's manual leaves much to be desired. I learned more about the truck from YouTube than the OM. Truth !