I have an 02 lancer es and i bought it like a year ago. The engine was swapped because the previous owner locked the engine. The odometer read that the car has 160xxx. The engine we swapped it with has about 20,000 to 25,000 miles on it. about 2 weeks ago i felt some hesitation/ jerking. This would happen when i would try to accelerate after leaving it in gear and taking my foot off the gas pedal. It wasnt too bad at first but now its doing it mostly even time i try to accelerate then accelerating. Now ill put it in first gear and it will go into the gear smooth but when i start accelerating faster it will do it around 2000 to 3000 rpms. At idle it was randomly drop to around 500rpms then go back up. also when i was on the highway today i downshifted to get some more speed and it started doing it again. I can tell that there is a lack of power and it seems like there is a problem when i try to accelerate fast. Im getting a misfire code but the spark plugs were changed when we did the swap, and its saying cylinder 4, which has coil on it that connects to cylinder 1.

also ive put about 1200 miles since it started happening

Does it seem like a bad fuel pump?
or a dirty filter/strainer? (which would be in the tank)

 

Could be a bad fuel pump/filter that needs replacing. I kinda had similar issues for a day, and I thought maybe I had a filter, but maybe my fuel sensor got stuck, and I was actually really low on fuel, or maybe it was bad fuel because it went away after the fill up.

Have you tried running some fuel cleaner in the system just to see if anything improves?

Did you ever get the ECU flashed? My car bogged at lower rpm's when transitioning between gears, or on heavy acceleration there were big holes in the power band, but much has improved after having the ECU flashed.

 

I'm going to try a fuel system cleaner as soon as the part store opens. Ive filled the tank a couple of times since it started happening, but it could have been super dirty gas and clogged up the filter. So I'm think about trying the fuel system cleaner, and if that doesn't work I'll see if cleaning the filter would work. I just don't want to buy a new fuel pump assembly for $450 if it isn't that

 

Well I tried a fuel system cleaner and it was still doing it so I changed the fuel pump and strainer and its still doing it? Any other ideas?

 

my car started doing the same thing a few weeks ago. if you figure out what it is let us know so i can try to fix mine.

 

What plugs did you use? You might want to check that the gap on them are within spec. Whenever I start to get hesitation/misfire during acceleration I check my plugs and usually with my case my plugs changed gap and I had to re gap them then all is good. Also just so you know you shouldnt really ever have to replace the whole pump assembly just have to change the pump itself inside which is closer to $100

 

check the spark plug and check the coil boot, after check that swap out the actual coil in case it wasn't that.

 

I removed the plugs and they were at .050 to .055 so I put them to about .040 and turned it back on and it was still doing it so I took off the coils one by one to see if they were giving a spark and all of them were

 

i thought it might have been an injector so i switched the fourth injector to the first one to see if the misfire changed from the fourth to the first one but nothing changed. Im thinking about taking it the dealer and just get it figured out there but i dont want to pay them $107 for one hour of labor, if its just something small.

 

So only cyl 4 is getting the misfire code then correct? So far you have swapped injectors, changed fuel strainer and ran injector cleaner through with no change. You said all four were showing spark. Have you swapped the coils around yet? They are the same and can be swapped, maybe its giving weak spark. If you havent tried you could also swap around the plugs themselves. Also I would run a compression test to see what that shows. I have to run my gap at .020 being turboed.

 

Have you compression tested each cylinder?

Have you checked to make sure the cats are still good? Hesitation on acceleration can be a sign they are bad or going out.

 

Yea the 4th cylinder is the only one that is misfiring, i also changed the fuel pump. Im going to swap the 2nd and 4th coil to see if it comes up as a 2nd cylinder misfire. if it doesnt im going to get a compression tester. Hopefully its not a compression problem!

 

How would i check the cat?

My exhaust fell off on the 2nd of march and I had to drive it a mile with just the flex pipe at 3am. It was so loud!!

Would that be the only way to test it?

 

every cat i seen go out would glow red hot....drive it around at night and then look under the car and at the manifold to see if either one is glowing.

 

It can be bad enough to cause hesitation on loading/acceleration without glowing, but either way, I would not recommend driving around trying to make them glow...not the best for the engine. Usually if they are glowing then you will likely have issues driving over 40 mph or something.

You can unbolt everything and check to make sure there is no sediment or melting or movement of the filter. It you can see through it and nothing falls out and it doesn't move then you are still good. If not, then that could be the issue.