Aight when am at a shop and i shift to first gear everything fine but when i get to 2nd / 3rd gear i feel lack of power. Like if am hitting the gas but its not accelerating at all. any clue what i should check?
I feel like my fuel runs faster now but haven't checked since i hardly ever fill up my tank >.< student here and never have enough money to fill up. how would i go on and check how much my fuel economy is? and nope no check engine light.
Without knowing what your fuel economy was before, knowing what it is now won't help as much. But at least we can tell if it's drastically off by checking it on the next full tank.
Go fill up your gas tank, all the way until it can't take any more, and then reset your trip odometer to zero before you leave the gas station.
The next time the tank gets low and you fill up, divide the number of gallons it took to fill up again into the total number of miles you drove on that tank to calculate your mpg. To make the mpg calculation as accurate as possible, put as many miles as possible on the tank before refilling it.
How's your air filter? Is it clogged with dirt, even partially? How many miles (years?) has it been since it was changed?
I bought this jeep around six months ago and I haven't changed it at all. I don't know if he changed it but when i opened it up 1 month ago it didn't seem that dirty inside. soo... I didn't buy a new one, should i replace it before i check my mpg?
Whether or not it needs a new air filter is a judgement call. Take it out, bang it flat-side on a table to shake the loose dirt out of it and then see if you can still see much light passing through it when you hold it up to the light. If the light is being blocked by dirt in the filter, you can bet the air is being blocked too.
When dealing with a loss of HP, I always target the main culprits. Fuel, Spark, and Air. Ensure you have adequate fuel pressure, ensure your getting GOOD spark, and make sure your motor is breathing freely.
Fuel and spark are easy to check, that leaves air.
Check the intake and exhaust, ensure the air is flowing freely. It's not uncommon for catylitic converters to fail in higher mileage vehicles. Check your O2s, ensure you don't have a vacuum leak or exhaust leak.
These quick checks will usually turn up the culprit.
I second Knightfires suggestion on checking the exhaust. It sounds like what happened to my 2nd jeep, the cat was plugged and it drove fine on in town but wouldnt go above 50. An exhaust shop can check the backpressure easily and quickly to tell you if that is the problem.