I have a 92 camaro z28, yesterday I took it up to 105 or 110, and then the rpms quit climbing and almost started to chug. Basically I am wondering if my car has a govern on it....Please help if anyone knows?? thanks

 

Officially, yes, it might. To get an ungoverned top speed required the car to have Z-rated tires on it from the factory. Cars with lesser tires got speed limiters built into the chip that would shut off the injectors at whatever the chip was programmed for (110 sounds about right). The result was kamikaze assaults on the speed limiter in the more powerful cars that could still pull pretty good at 100+ MPH speeds. It's all fun until it hits the limiter and then it's like the car shuts off until the speed drops a few MPH and then it goes again until it once more hits the limiter. Over and over and over.

I owned a 1991 with the V6 and never knew it had a limiter until I layed out on the far reaches of the PA turnpike one day. Around 110-115 (who can tell when the speedo isn't accurate to begin with?) it was "party over". I though I blew then engine. Just about the time I got out the words "what the fu..." it took off again. I knew instantly at that point I had hit the fuel cutoff speed.

It's a lot more annoying in a V8 car that can push past 110 in a lot less real estate that my wheezing V6 could. Just about the time you feel like you're starting to get it really cooking, big brother steps in a shuts down the party.

 

so is it built into the prom or the ecm ? and how would I get rid of it, change computer??? thanks
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and the worst thing is it wasnt even really 110, because the car originally had 2.73s and I just put a 3.42 in, so I was prolly only going 85, I gotta get this fixed

 

It's in the prom. There's a couple of options for dealing with it. You can get an aftermarket prom chip with no speed limiter, or have someone like TPI Parts delete it from your factory chip. They can also disable your EGR, VATS, lower fan turnon temps, etc. You can also do it the "hillbilly" way. Go to the tech articles here on the site, and there's a how-to article on how to bypass the speed limiter by installing a toggle switch between two of the wires running to the ecm. Also, if you get the correct speedo gears for your new rearend gears, you'll at least be able to hit 110 instead of 85 before the speed limiter kicks in.

 

well I went and checked out that tech article, and I am confused it says that it is for only TBI and that TPI's dont have a govern, but my car is a TPI so now what??

 

Or.. You can wire up a switch to your speed sensor in the trans to shut off the speedo, thus the computer doesn't know how fast your going.

 

thats strange because i have a 90 trans am that came with 245-50-zr16 tires and it has a limiter

 

why exactly do you think you need to go faster than that?

 

Yeah, if you're totally sure your car came from the factory with those tires, that is kinda strange that it has the speed limiter. Who knows, maybe it had to come with the 5.7 motor to not have the limiter. Hard to say for sure. Another possiblility is if your car has a California emissions chip. That might play a factor as well. You could find the broadcast code on your PROM chip, and then post a message on the DIY PROM forum. One of the gurus on that forum might be able to tell you why you ended up with the speed limiter.
That's a pretty lame response dude. If the guy wants to find a deserted, straight stretch of road in some remote area and see how fast his car can actually go, who are you to say he shouldn't? I still haven't buried the 145 speedo in my car yet, but I came damn close on a deserted road last summer. I hit about 140, and my motor still had more to go, but I figured 140 was fast enough at the time! In fact, not having the speed limiter in mine made all the difference that day. I was actually racing another guy on the interstate, and we were almost neck and neck until about 120 mph. I think he must've had a limiter on his car because once we hit 120 I just started walking away from him. Lol.

 

If you have the code axxb on the memcal your fuel cut off speed is 108 and it will resume at 106. The rpm has a cut off of 10031rpm crazy they even set it up that high. If your wanting a piggyback chip with modifications pm me.

 

That's a pretty lame response dude. If the guy wants to find a deserted, straight stretch of road in some remote area and see how fast his car can actually go, who are you to say he shouldn't?


https://www.thirdgen.org/forums/theo...-lost-car.html

 

thanks for replying broadcast code is ATNY i asked a while back in the prom section and a couple guys there said that it was a correct code for a '90 so it is definitely weird

 

Sure, you're always gonna see terrible incidents come up such as the one in the link you posted, but that's all part of the risk factor. Believe me, I had enough adrenaline flowing through my system after that 140 mph run, you could've hooked up a power cord to my heart and been able to power a small city for a short period of time!

 

the atny was superseded to the awlt and that was superseded to a axyd. there were a couple service bulletins on these tunes. The most common tune for the 305 , 700r4 for 90-92 is axxb and it is still available but the chip is now a one time burn. The is a minor difference in the tune for rear gear ratio. service bulletin #91-239-6E Low Speed Drivability.

 

Even if you decide to get a brand new performance chip burned for the car, I'd hang onto your original PROM chip if they don't want it for a core. The 90-92 SD PROMs have gone up to crazy prices in the last couple of years.

 

the axxb is just 108 thats not so bad? but it is now made in singapore by delphi with a one time burn eprom. piggy back is the way to retune.

 

If they should want your eprom for a core I wouldn't let it go without a dump to a binary file as part of the agreement. If you should want to go back to it at least you would have the option.
When I modified the speed/rpm limiter I went from an H to Z rated tire.

I use to sell tires & wheels I had customers sign a waiver if they wanted lower speed ratings than what the manufacturer put on the car. But when I see young children in the car I just had to refuse.

Raul.

 

i wasnt trying to be cool and these cars really arent built to go that fast as it is. but hey if he wants to be a moron go ahead.

 

my car was equipped with the 2.73 gears also and i swapped them out with 3.42's just like you did according to gps 105 is when my limiter kicks in

 

I worked at Pontiac back then and ran up cars on the rack. The ones with 16 in tires cut off not much past the speedo max I think was 140. The 15 in tire cars cut off at 105 or 115.

 

I'm a little surprised that a thread from 2011 is still going, and still hasn't been corrected. Anyone who has ever even casually looked into the ECM programming for these vehicles would already know that ALL of the ThirdGens had speed-based fuel cutoffs. They have to, or they would not move. If you have a piggyback PROM card and some spare time (there is no sense in burning a UV PROM since it would be a waste) try burning a PROM without setting the parameter for FCO to a no-value entry, and then see if you don't get a CHECKSUM error when you go back to verify the burn (if it even lets you compile and try to program it).

In short, there MUST be a numeric value in the FCO word, and it must be between 0 and 255 (0000:0000 to 1111:1111). Cars with "H" rated tires got something like 118, Cars with "Z" rated tires got 254 programmed in. While that is for all practical purposes beyond what a stock ThirdGen could achieve, it is still a limit. I believe it was Gale Banks' team that took the stock body Trans Am to 280+ MPH on the salt flats, but they were not likely running a stock ECM so even 254 MPH wasn't a problem.