My car doesn't reach top speed anymore?

Question

I have a '97 Mercury Grand Marquis and i've recently noticed that it doesn't go above 84mph. Why do you think that is? i used to be able to go up to 115mph and now wen i try to go fast, it seems as though something in my car shuts off and doesn't let me pass 84mph and it slows down to 80mph and then i can accelerate again to 84 but doesn't let me go faster. Any help would be greatly appreciated

Answer 1

Sounds like your car has more sense, when it comes to speed, than you do. LOL

Answer 2

I would go buy Engine Restore,because after time the rings around the pistons scratch the walls and you loose some compression,,It might help

Answer 3

I will give you mechanics 101 class lesson. the parts that limit top speeds are

#1 final gear ratio lower gears give quicker responce but less top end speed

#2 fuel supply, your fuel pump must supply enough fuel presure to reach the desired need of the engine idle requires 1lb 5 grand required 10lbs (example numbers)

#3 air supply the faster the engine revs the more air it needs to continue climbing

#4 cam shaft and valves at a cetain rpm valves float and are not functioning correctly to continue higher rpm

almost always the problem is fuel based in this situation for street driven vehicles. ps

I agree you dont need 115 anyway but the issue could be costing you fuel milage

also the smog system may need replaced and your loosing power through a plugged cat converter.

Answer 4

It might need a tuneup. New plugs, wires, and filters would help.  

Answer 5

does it have a rev limiter

Answer 6

In a car that is 11 years old with I'm guessing plenty of miles.  You will not get the same performance out of the engine as it ages.  Especially, when stupid kids are driving it at 115mph when there is no real reason to go that fast.  Also when stupid kids rag on a old car too hard it will degrade the engine very very fast.

This is your own fault.  Chill out and go slower your car will last longer.  Not to mention you WON'T KILL INNOCENT PEOPLE!!!

Answer 7

Well if it is an automatic which I'm figuring it is it could mean your tranny clutches could be burning up and not staying locked together. Do you feel any "less" accelleration during normal driving(other than the highway), if yes then you prob have a tranny problem either the clutches or your stator in your tourqe converter is locked up(which means you cant achieve top speed and you get bad gas mileage). If it only happens when trying to go 115mph then it might just be that its a tired engine, sad to say but that might be it, SORRY.

Answer 8

those cars are smart they wont let any 1 abuse them!