hello, i've never posted here before. my friends and i are absolutely stumped with this engine issue. it is a OBD2 96' with 140k miles.

the camry hesitates very badly when throttle is opened quickly and it eats a ton of gas. i mean less than 15mpg in the city with no OBD 2 codes at all.

originally i was askedto diagnose a wandering idle problem which was quickly fixed by cleaning the idle valve, but the engine still ran really rough. i started working down the line with,new plugs/wires/cap/rotor, cleaned EGR, checked all vacuum hoses, pulled codes, checked temp gauge, unplug MAP, unplug O2. still no codes. the car is poorly maintained like most toyotas out there, since working as an SA for a toyota dealer, i find that most owners are more worried about oil changes than ripped cv boots.

unplugging the O2 made the car run worse, unplugging the MAP made it run better (hesitation went away), but i tested the car with another used MAP sensor and it still ran rough with hesitations, chances of 2 MAPs being bad is unlikely. now it has a MAP code, figures that is because of me.

i'm completely stumped need in need of advice, since i work on audis more than toyotas, i'm out of ideas.

 

Have you checked for an exhaust leak that would give false readings to the O2 sensor?

Have you inspected the plugs to see if they show you'rerunning rich?

 

the plugs i changed out were very rich and there are no exhaust leaks

 

Did you test Engine Temp Sensor? If the car runs ok when cold and not so good hot that may be a clue.

 

Typcially if the engine runs better with the MAP disconnected then this system is the problem. If a known good replacement does not solve the issue start checking the hose running to the MAP, MAP wiring, etc.

With MAP disconnected the computer should reset to a default mode, with a deffective MAP circuit the computer may be getting bad sensor data.

 

thanks for the replies, my friend took the car to the dealer after my attempts, it's been 4 days and they haven't got a clue yet. it's gotta be something with MAP or coolant sensor.