My car is stuttering on heavy acceleration?

#1

I have a 2005 Mitsu Galant GTS with 41k miles on it. I just bought this car in the past two weeks, I have begun to notice an interesting trait. When accelerating from a stop at full gas the car will stutter up to about 50 miles per hr. The rpm needle will jump during this and the acceleration is veryyyy jerky like if the car would be changing gears every second. It does not do this on light or moderate acceleration in the least. It also will not do it when accelerating from 40 up even with the gas fully depressed. Any ideas as to what is going on?



Additional info: the car will do this with the engine warm or cold. Air temp in CNY: currently 30f. Yes premium gasoline is in the vehicle.

#2

Full power demands a constant supply of fuel,sounds like a fuel starvation situation,you don’t mention a check engine light I conclude there is none,do you have maintiance history on vehicle? is it up to date? filters?

#3

A nasty mis-fire like that should cause the CEL to illuminate. Does your check engine light come on when you turn on the key then go out after a few seconds when the engine starts?

#4

Don’t pay too much attention to the idea of the Check Engine light being on or off. Many people who sell cars can have a dishonest mechanic turn the light off so they can get the car sold. But, and this is a big but (No pun intented), error codes which turn the engine light on can not be erased from the computer’s memory. They just give the command to the diagnostic computer to turn the light off because they trick the system into thinking it is an old fault code. Do yourself a favor and have a trusted shop, which you can find through the BBB or your district attorney’s office, diagnose the problem with their proffesional equipment. DIAGNOSE ONLY, and have them give you the paper report that the professional computer spits out. The print out will tell you which sensor is malfunctioning or which part of the ignition process is failing (I.E. Low fuel pressure, spark malfunction, etc.). Sometimes you can be lucky enough to find a competent convenience parts store clerk who will diagnose the proplem with a handheld computer.
Murphy’s law of buying a used car is that the car had a major, expensive problem and the seller made a temporary fix to unload the car. Good luck.

#5

The District Attorney is recommending auto repair facilites? The Better For Business is the place to go,current and history codes cannot be erased? A paper report is generated by a code scan,this scan will tell you what part to replace,a parts clerk will interpet a code scan…where do I start?

#6

Don’t make it complicated before you make it simple. Change the air filter, spark plugs, and (if not located inside the gas tank) the fuel filter.
If it still misfires under full acceleration, change the spark plug wires, and check the fuel pressure at 2000 rpm, under load.
Have the engine computer scanned for trouble codes. Bring those here for cussin’ and discussin’.

#7

The rpm’s jump up? It could be a slipping transmission.