Just picked up a 2004 2.3 Hatch auto with 92k miles. It seemed to run good on the test drive a few days later the CEL came on with a coolant operating temp code. Replaced the thermostat, coolant temp sensor, spark plugs, O2 sensor (NTK) ran seafoam through the gas and intake. Car runs ok, little slower than I remember them being but overall seems pretty smooth, at 40-60 MPH at light cruise it feels to surge/buck. I've been driving it around town for the past few days trying to make sure it's going to be reliable and have already gone through a 1/8 tank in 35 mile from filling it up the other day. I'm hoping to hook up a scanner and check out the coolant temp, O2 functionality, MAF and MAP but hoping maybe this was a normal one that has been seen before I start spending hours driving and logging.

 

I used the torque app and ran to get breakfast this morning. I can see the coolant temp rise up gradually like it should, throttle Pedal numbers seemed linear alont with throttle plate %, I could see the O2 voltage numbers fluctuating between .3-.7, Intake temp was running 66* this cool morning with timing in the 42-45* range. Only number I don't have any history on is the MAF at 11-14 g/s but nothing was fluctuating it was staying pretty consistent. I maybe run out in a little bit and unplug the O2 just to verify that does/doesn't do anything.

 

Another test I took it to get lunch and unplugged the O2 sensor, didn't drive any different and got the two O2 sensor codes I expected. Plugged it back in and reset codes for the drive back but its still driving the same. I did notice that the Air temp while sitting in the drive through had gotten up to 120*, unfortunately I forgot to check this going down the road but assuming it was just heat soak from sitting idle for a few minutes.

 

? turbo or naturally aspirated ..

92kmiles - timing chain, anything in suspension, sticky brakes etc.

I picked my one, 160k km ~ 100k miles, wheel bearings and brakes was bad ... don't leave focus on OBD related only.

 

NA 2.3 for the most all stock and original except for the pieces I've been replacing. Surprisingly the wheel bearings started making noise right after getting it. Both fronts replaced, rotors and pads were already newer. I had a chance to pull the injectors and test spray with cleaner. They looked ok for 2 stream injectors, not a fan but it worked. Replaced the injector O rings. If I downshift it from 4th to 3rd it doesn't do it. so it doesn't seem to be speed specific more like either gear, load and/or rpm specific. I'm wondering about the tumbler flaps as it seems to not be noticeable about 3k RPM and up. I've only driven it on the interstate at speed once for a short distance but my GF says its fine on the highway. Timing chain is quiet but there's a few lifters that will need swapped at some point as they are ticking a little.

 

It's lot of ..

VVT after 100k miles shoud work, but ... worn, sticky locking pin etc. (see pic), works randomly as no-no-go at aprox. 3k RPM.

shifting - I had issue with quick shifting (manual 6 gang), change oil (castrol syntrans 75w/90), replace brake fluid in clutch, check clutch pedal piston, dismount shifting console and oil bowdens with penetrating oil. It is much better.

bearings etc: do'nt forget adjust geometry, it is under 0.5l/100km inefficiency, but noise and handing.

 

big issue was "sticky" brakes for me. Former mechanic used torch to loose screws, lines and didn't replace brake hoses after it (replaced ABS unit).
Under warm-up condition it was braking a bit. On highway rattling with steering wheel... nice ..

 

I did see VVT as an optional thing to look at but couldn't figure out if 2004 had it or not. Also I guess I should note that the fuel mileage isn't as bad as I thought, or well not as bad but as far off from specs. I thought the 2004 2.3 Auto was rated for 29 but that was the 2006 and before that only rated for 26 with the 4A, either way this thing is seeing about 23-24.