Pre MOT failed emissions V6 Camaro any ideas?

[kellys hero]

Hi Folks

Just had my 3.4 V6 Camaro fail on hydro carbons, apparentley they are off the scale (deep joy) everything under the boonet is electronic so no adjustment seems possible, since i have owned it ( 1 year) i have fitted 3 new coil packs, leads, plugs and an air filter so it runs better than ever.

It has a cat so I suppose it could be that. As usual the thing is fitted with a 101 American emmision control devices that seem to do nothing except require more fuel to run them.

Has anyone come across this and am i missing a trick somewhere? I cant believe that in a year of careful ownership its become as bad as they say at the mot center.

[balls-out]

kellys hero said:

Hi Folks

Just had my 3.4 V6 Camaro fail on hydro carbons, apparentley they are off the scale (deep joy) everything under the boonet is electronic so no adjustment seems possible, since i have owned it ( 1 year) i have fitted 3 new coil packs, leads, plugs and an air filter so it runs better than ever.

It has a cat so I suppose it could be that. As usual the thing is fitted with a 101 American emmision control devices that seem to do nothing except require more fuel to run them.

Has anyone come across this and am i missing a trick somewhere? I cant believe that in a year of careful ownership its become as bad as they say at the mot center.

I'm not sure how relevant my experience is, but my v8 camaro failed the emissions test. the bloke asked me if I did a lot of short journeys, which I did.

He then held the engine revs at about 3500 to 4000 rmp for five minutes plus. ***** noisy in the workshop - the windows in the office were rattling and by the end there was heavy smell of oil and hot engine.
A nice hot cat and all was well. After that I always drove the MOT station in 3rd.. It pass a further 2 MOTs without comment (I then sold it).

[jeff m]

Very high HCs often signify a lean miss.

Has somebody leaned it out to save fuel ?

[ringram]

Have you got any codes in the ECU?

Could be bad o2 sensors, exhaust leak (makes it look lean to the sensors) etc.

Some diagnosis needed..

[kellys hero]

Hi Cahps thanks for the input. This is the story so far...

We plugged the lap top into the camaros com port and looked at a screen saying "trying to communicate with host" for 15 minutes.

After talking it over with a friend we decided that rather than spend hours picking through the various sensor tests that the cat is probably well past its sell by date, as well as the lambda sensors (manual says 30k miles is their lot) . I have ordered cat and sensors from the states which should be here soon


So fingers crossed......

[Matt Harper]

Also check MAF sensor burn-off relay. If it's faulty, the MAF sensor gets sooted-up and gives erronious readings to the ECU - which then leans-out the fuel/air mix.
If it's an oxygen sensor, you will definitely have the 'check-engine' light on

[ringram]

Yeah check/clean the maf, oily filters can do that.

[kellys hero]

Reckon this is it, took the old cat off on Sunday guess what, it's a hollow box, the cat has already been removed so little wonder the emissions were high. So new cat fitted, plus 2 oxygen sensors i have a much quieter and cleaner car booked in for the mot this Thursday


Whats a Maf sensor?

[chevy-stu]

kellys hero said:

Whats a Maf sensor?

Mass Air Flow sensor, sits between the air filter and the inlet plenum/manifold. Senses how much (the mass) of air going into the engine and tells the ECU how much fuel to add accordingly.