Why would a 2001 Mitsubishi Eclipse hesitate and sputter?

Answer 1

There are many possible reasons. This sounds mostly like a fuel-related problem but can also be related to electrical issues (i.e. ignition). I'll list them form the most-likely to least-likey: 1. spark plugs - replace them if needed and verify they are gapped correctly. 2. spark plug wires - these wear out over time. check for signs of cracking and torn boots. You can also *lightly* spray water on them with the car running and look for any arcing or sparks. 3. clogged or drity fuel injector - you should run a full tank of Amoco Ultimate (has the most cleaners in it) every other month or so. Doing this regularly will avoid the needless expense of having to get your injectors cleaned. 4. clogged or dirty fuel filter - replace if necessary. 5. distributor cap & rotor - these also wear over time. Check the cap and rotor points and make sure there isn't carbon buildup. 6. Igniter or ignition coil - if your distributor cap & rotor are bad you should also check the coil and igniter. 7. throttle body - if you regularly use lower quality gas you can get buildups over time leading to a gas pedal that feels "sticky". Clean if necessary. 8. fuel pump going bad? Check your fuel pressure to make sure your pump is not on its way out. 9. EGR valve - exhaust gas recirculation valves can occasionally go bad 10. PCV valve - similar to the throttle body this can cause similar probs. 11. air filter - easy enough to check 12. ignition timing - did this problem begin after a timing belt replacement? If so, I would guess that your ignition timing needs to be adjusted. Usually, this can be done by rotating the distributor housing. If you have reached the max. that the housing will turn and it's still not timed correctly, the timing belt might be "off by a tooth" or so. 13. bad gasoline - is this consistent or did it only begin after you bought the "gas that was on sale"? Has your car been sitting for a LONG period of time? Also, you may want to check the valves, if you have the 2001 eclipse GS, you have the 2.4 L 4g64 engine, which is known for having burnt valves from running it too hard/racing it. I had the exact same problem, and am just about to put the engine back to gether and set the timing on it. I had all 8 of my exhaust valves burned pretty bad, but was able to grind them and re-lap them in.