2000 I30 feels sluggish/underpowered

[eyethirty]

My 2000 I30 feels noticeably underpowered. It seems like the engine is working hard but it's just not pulling like it should be. It feels especially weak getting up to freeway speeds (once I hit 40mph it feels like it just doesn't want to accelerate any more and I have to coax it slowly up to 60+.....it's pretty pathetic for a car that is supposed to have 227 horsepower). No overheating problems, no SES light, although it did come on giving an O2 sensor code, but then went off by itself a few days later before I had the money to replace the sensor. Car starts fine every time and never dies on me, but it does seem to hesitate sometimes. Gas mileage also seems to be suffering slightly.



Anyone have ideas as to what might be wrong? I've read that it could be my TPS or MAF but I'm no mechanic so I have no way of being sure.






Car: 2000 I30/65k miles/no mods

[MTZI30]

Wow that is some super low miles. Has the car been serviced? Filters? Oil changes? Spark plugs? (Then again plugs arent do until 100k miles) Just because the CE light goes off doesnt mean the 02 sensor is working. I had an 02 sensor code for high voltage. The CE light would go on and off, and a few months i finally had some money (I was in college) the code now was no communication from the 02 and i replaced it.

[eyethirty]

Just had the oil and oil filter changed, had the transmission filter replaced about 1k ago. Did you have similar symptoms before you replaced the O2 sensor?

[MTZI30]

Nope not at all car ran fine. On my ford however the car ran pretty rough when the 02 sensor was bad. Check your air filter, i totally forgot about mine for a while and it was filthy. Replaced it and was amazed LOL. But ya just check the parts that need to be serviced. In your manual there should be a maintainance schedule, make sure everythings been taken care of.

[loystock]

Just had the oil and oil filter changed, had the transmission filter replaced about 1k ago. Did you have similar symptoms before you replaced the O2 sensor?

Is there any reason why the transmission filter was changed? Have you checked the level and condition of the transmission fluid?

It's never a good idea to ignore the CEL as it could lead to more problems. Usually, a failing O2 sensor causes the ECM to provide a richer than normal fuel-air mixture. This result into poor mileage. But the rich mixture can also adversely affect the catalytic converter and remaining O2 sensors. However, from experience, a failing O2 sensor will not cause the engine to lose that much power. It can contribute but is not the main source.

The Knock Sensor, if defective will result into lousy acceleration due to ignition timing retard by the ECM (to avoid knocking). However, a failing KS will not turn on the CEL but will trigger a fault code, P0325. So have a free scan from Autozone and the likes to find if you have 'ghost' codes.

Your problem may have to do with ignition, ignition timing, fuel delivery or emission components. So start with the basic. Check for any intake/exhaust leak. Then check the entire air intake - replace air filter if dirty; clean the MAF sensor (with Contact Cleaner or CRC MAF Sensor Cleaner) and connector; clean the throttle body (never spray directly into the TB and plate, use rag to clean).

Let us know the result of the above actions. We can continue with the diagnostic if the problem persisted.

[MTZI30]

We can continue with the diagnostic if the problem persisted.

We charge $25 per post for diag then $100 if we solve your problem....which means i owe loystock about $3200.