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I’m having problems with my Toyota RAV4. I bought the car 6 months ago with a lambda sensor fault. By time I got it home, had lambda bank 2, sensor 2 and Mass airflow sensor faults. Changed both, okay for 300 miles then had lambda sensor bank 2, sensor 1. Changed this and was fine for 5 miles then back to original lambda sensor fault.

It’s failed MOT by emissions. CO @ 6.81%. should be max 0.3% HC @ 459ppm should be max 200ppm Lambda @ 0.82 should be 0.97-1.03

The CO is x20 what it should be… I’ve had it in 3 garages, electrical specialists. Had wiring harness checked, put as close to OEM lambda sensors in, checked for vacuum leaks. Just going round in circles with the fault codes and changing sensors

What do I do?

LEP
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2 Answers2

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Given the age of the car, check the compression on all cylinders before trying anything else. You don't want to spend money for repairs on a car with a blown engine. While you are at it, be sure to check the spark plugs.

The combination of improper MAF reading and unburned fuel points directly at poor compression (and thus weak intake manifold vacuum).

Carguy
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Following what you have done, the next thing I would check would be the fuel pressure, by adding a fuel pressure gauge to the injector rail supply.

If the fuel pressure is higher than it should be, then the injectors will inject more fuel than the ECU is intending.

You can also use this gauge to check that the injectors are not leaking when closed, which could also cause an issue. After running the engine and shutting it down, the fuel pressure should stay constant for some time. If the fuel pressure drops quickly, it is a sign that an injector is leaking.

HandyHowie
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