p38 4.6 hse emissions

raf499 · Mar 31, 2011

hello to all, i am new to this but i really need some advice. my 1994 p38 4.6 v8 has failed the mot on emissions. i replaced both cats because they were rattling around put it in for a re-test and it failed again on the same thing, is there anything else i can change? please

according to my mechanic the lambda sensors are switching on and off.

juiceyv8 · Mar 31, 2011

check lamda sensors and make sure engine is nice and hot pre-test.

rewmer · Mar 31, 2011

Air filter and O2 sensors

JamesBB · Mar 31, 2011

I have also just replaced the 2 breather hoses from either rocker cover to the plenum chamber. Both in various states of perishing, torn, collapsed and oily.
Not that I had an emission problem, but just that I knew they were likely to be an emissions issue at MOT time in a few months.

What condition are yours in?
Cheers

eightinavee · Mar 31, 2011

You would be far better off finding a decent local independant to check it over and run some live data tests - that way only faulty parts will be replaced.Things like Oxygen sensors are made using precious metals and are expensive to change only to find it needs a couple of plug leads or a manifold gasket.
Do you have a printout of the test results ?

treeman · Mar 31, 2011

What readings are out to fail it ?
If the HC readings are within in limits as-well as CO reading and only the lamda reading is out then the exhaust is sucking in air somewhere throwing out the last reading.
That's what happened with mine my centre box was full of hole's sucking in air so throwing out the lamda reading, replaced centre box reading went back within limits.

p38 4.6 hse emissions

raf499

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juiceyv8

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rewmer

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JamesBB

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eightinavee

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treeman

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