This is a one owner car that has been serviced by toyota it's whole life practically.

3.0 V6 XLE Automatic


I bought it from my neighbor after it had been sitting for quite some time, but when purchased it ran pretty smooth other than a dead battery.


I've tried to isolate from doing research. Here's what i've done so far.

Replaced the Coolant Temp Sensor.
Replaced the Distributor cap & rotor.

Sprayed down all vacuum lines that and checked for idle variance. (none)

Pulled injector wires one and by one and noticed that the front bank opposite the timing belt side injector wasn't having any effect on the running condition. Replaced that injector but the same condition still exists. When pulling that injector wire there in no change with the running condition.

I popped off the o2 sensor as well to make sure the catalytic converter wasn't clogged. This had no effect.

The condition starts when the car starts at idle then when in park revving the engine the problem seems to get less severe after hitting about 3700 Rpms, i'm sure it's still happening then, it's just less noticeable.


The exhaust seems to be running really rich and may have some fuel exiting the pipe. Gas mileage is down ton's, and the car can barely make it up the hill with the loss of power.

I replaced the coolant temp sensor that sit's under the EGR/under the side of the air intake, the green plug.

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How many miles? 160k
Has the timing belt ever been changed? Yea, 30k miles ago from the dealer.

I'm thinking it's not an issue with spark. Pull the sparkplug wire while running and it's got spark consistently and strong...(i didn't shock myself I swear) and replaced all spark plugs.

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And yeah the spark plug wire's are on the cap perfectly... i almost transposed the 2 top but fixed em as the car wouldn't start. When i pulled off the wires i taped them and numbered them and it was an OEM cap with the numbers printed on it also

Hopefully this forum can help me out, i've noticed a few threads with similar problem's but it seemed difficult to find resolution after sifting through them.

 

You state disconnecting 1 injector wire plug (only 1 injector appears to have an issue) results in no change in engine operation? If so find out if that injector is being powered.

Each injector plug has 2 wires. One wire receives 12V DC when the ign key is on (black/orange colored). The other wire (another color) goes to the engine computer. When the engine is running the computer grounds this other colored wire to complete the circuit.

Check for 12V at the black/orange wire when ign switch on. If no power find out why.

If power at this wire connect an analog volt meter (has a needle not digital) between the two wires on the plug and start engine. The voltage should vary in sync with engine RPM as the computer grounds and ungrounds the wire. A digital meter may be too slow to respond to the changing voltage.

See link below:
How to Test a Fuel Injector With a Voltmeter | eHow

The injectors make a clicking noise when powered (turning on and off). Use a section of hose as a stethoscope to listen for the clicking noise when running. Or remove fuel pump fuse and listen when then the engine is cranking over.

If no noise or voltage variation the injector may not be getting power thus find out why.

A bad injector is possible, however bad wiring or a computer issue is rare.

If you have an ohm meter, you can compare resistance of the problem injector with the other injectors.

If the injector seems to be working and there is spark might be an issue with the cylinder. Check compression.

How long did the car sit? If the neighbor is still around ask how the car ran before parking it. If OK then the problem could be bad gas, mice getting into the engine air intake system or chewing on the wiring (both have happened). The odds of a sensor failing due to lack of use is rare. If a mechanic part it may have stuck closed or open due to lack of use.

If the car ran bad when parked then this opens up issues with parts sensors.

If the car is running rich, it is more a sign of a stuck open injector.

Check MAF.

You state the engine has lots of spark, should be able easily gap 1/2 inch of are. A bad coil can cause this symptoms.

A very bad plugged fuel filter will cause lack of power but you state the engine is running rich thus suspect the engine is getting too much fuel not less if a fuel issue.