Automatic trans going bad or speed limiter?
Automatic trans going bad or speed limiter? Ok i just picked up a 1995 Firebird Formula with 61,000 miles. It's got several mods done including a JET module that plugs into the PCM. What i noticed is when flooring it it shifts in 1st-2nd-3rd fine but when about to shift to 4th around 115-120mph it hits a limiter. It's like a speedlimiter or a rev limiter and it will bounce off of it as long as you hold down the accelerator. I cannot manually shift it from 3rd and get it to go past 120. Can i get rid of this or is this my tranny about to crap out?
I don't know if the car has a stall converter or what rear gears it has. I just picked it up yesterday. I do know that is has a 10 gallon fuel cell and holley fuel pump so maybe the owner installed a stall converter as well. I doubt it's the rev limiter because it will do it at the same rpm band, only on the 3rd to 4th shift, in performance or standard driving mode, and it doesnt work to shift from 3rd to D manually.
Any ideas? If i just get my PCM reprogrammed will that fix it?
I don't know if the car has a stall converter or what rear gears it has. I just picked it up yesterday. I do know that is has a 10 gallon fuel cell and holley fuel pump so maybe the owner installed a stall converter as well. I doubt it's the rev limiter because it will do it at the same rpm band, only on the 3rd to 4th shift, in performance or standard driving mode, and it doesnt work to shift from 3rd to D manually.
Any ideas? If i just get my PCM reprogrammed will that fix it?
Hmm.. not 100% but it sound to me like OD is getting ready to go bye bye.. i would have the trans serviced and see how the fluid looks. I know my trans builder only charges 50 dollars to diagnose and change the fluid.
I believe OD on the 4L60E is one of the weaker components.
I believe OD on the 4L60E is one of the weaker components.
Launching!
Joined: Jan 2004
Posts: 277
Likes: 0
If the original owner didnt pick the z-rated tire option, GM put in 112 mph limiter and 115mph speedometer. The cars with z-rated tires has the speed limiter set at 255mph (161 for later LS1 cars) and a 150mph(155mph for 97+cars) speedometer for the z-rated tire option. Without the speed limiter a stock car should top out around 157-160mph.
DOH!!! Im a dumbass and didnt read that too closely. Yeah speed limiter. Unless ZR rated tires were ordered RPOs (QZF and QZA I think) You have a speed limiter... Very annoying... Hypertech or any aftermarket tuners can remove it for you.
Wooh i got replys 
i havent been getting email notifications.
It's not a rev limiter because it's not at the point it should shift. I don't think it's OD about to go either. The trans shifts perfect. I also have a 150mph speedometer. I've tested this about 6 times and at the exact place, 115mph, it hits the limiter. Also how do i tell what gears i have?
1st gear - 55mph
2nd gear - 95mph
3rd gear - don't know
What gears would allow me to go that fast? Do i have 2.73? This car pulls extremely hard and sends my rear sideways when shifting into 2nd gear at WOT. I'm running 245 Z rated tires in the rear and 235 Z rated in the front.
Also my rear end makes kind of a rubbing sound when i turn. Is this an LSD or posi rear? I know i have to have one of them becuase when power braking, flooring it, or doing donuts (i've been having alot of fun) it leaves two distinct black marks. Is there any way i can check the codes in the glovebox to see what all i have?
i havent been getting email notifications.It's not a rev limiter because it's not at the point it should shift. I don't think it's OD about to go either. The trans shifts perfect. I also have a 150mph speedometer. I've tested this about 6 times and at the exact place, 115mph, it hits the limiter. Also how do i tell what gears i have?
1st gear - 55mph
2nd gear - 95mph
3rd gear - don't know
What gears would allow me to go that fast? Do i have 2.73? This car pulls extremely hard and sends my rear sideways when shifting into 2nd gear at WOT. I'm running 245 Z rated tires in the rear and 235 Z rated in the front.
Also my rear end makes kind of a rubbing sound when i turn. Is this an LSD or posi rear? I know i have to have one of them becuase when power braking, flooring it, or doing donuts (i've been having alot of fun) it leaves two distinct black marks. Is there any way i can check the codes in the glovebox to see what all i have?
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Teching In
Joined: Oct 2003
Posts: 3
Likes: 0
you cant just use anyones hypertech it is only for one car at a time... if it wont let you go past 115 it is probably your speed limiter... someone may have put z rated tires on the car... what does your speedometer go up to
It goes to 150mph. It says my car was equipped with 235R rated tires so i guess that's why it has a speed limter then. I also have 2.73 rear gears, a posi rear, suspension FE2 (was this the ws6 package?) and painted aluminum wheels.
