Running Lean?

[DeTomato]

Checked out my VVTL-I with my computer diagnostics today. There were NO error codes, but the fuel/air mixture indicated was it was running "Lean".

It's had a new engine air filter already and 5W/30 oil change. I've checked air hose leaks and cleaned the MAF sensor and all ok.

- I put some injector cleaner into the petrol tank so does this make it run lean?

- Is it worth cleaning the PCV? Will this alter it to "less lean"?

Any ideas please to make my engine run less Lean otherwise?

With Thanks.

[DeTomato]

So I've done some diagnostics on my VVTL-I to see what may be causing it to run lean:Fuel System. A malfunctioning fuel system can reduce the amount of fuel coming into the engine, causing a run lean condition:

1. Oxygen Sensor(s) are working... There are output Volts to both O2 sensors, but the first O2 sensor shows output but the second one does not - I suspect this may be a software limitation until I buy the software. Does this sound right?
2. Air Mass Flow Sensor is working ok - checked and tested.
3. The dreaded Air Leaks - need to investigate further to see if there are really any or not, which means taking off the old air hose. I'm reluctant to do this because it may actually cause more problems; it's been sitting and deteriorating for 5 years of standing. Visual looking at it shows no cracks or holes anywhere. And it has had a new air filter.
4. Fuel Injectors - I suspect this may be the real cause; I'm continuing to use some basic Injector Cleaner because 5 years standing may have meant the injectors may be clogged with 60,000 on the clock and no one having cleared of them before.

Q: Can anyone recommend a Good Petrol Injector Cleaner please?

[Lorc88]

Stp boost restorer and fuel injection cleaner, can be found in Halfords as a twin pack for roughly €15-€20 sometimes as tri pack too as the 3rd will clean the cat out too, it does cause the car to run a little lean for about 1 or 2 tanks of petrol, but the results on a MOT or NCT are worth it, diptane will also clean the engine out but I don't think it's as good as STP 

I left my Corolla sitting for one year and had the same problem, drive the car daily for about 20+ miles and occasionally let her out in 2nd or 3rd to red line. This sorted out my car. 

[Dave W.]

Seems like an old Corolla. It could be fatigue of the electricus. There's nothing that you can do but replace plugs, ignition coils, o2 sensors, maf sensors, throttle positioning sensors, or even the main ganglion. Try to get lucky. One time I got lucky because the guy at Monroe knew that my regular injector cleaner wasn't enough and that the can of ether fuel injector cleaner that they do would be better. Sure enough everything got better with just a professional fuel injector cleaning.

[Dave W.]

I don't know if in 2003 they had used a kickdown cable. This makes the transmission shift to a lower gear when the throttle is pressed hard. This metal cable can tend to become elongated and you may need to adjust it if you are pressing on the gas and it is not shifting down.