Co2 Reading Sky High After New Maf

[amusingadam 6 1 Cars]

Hi guys looking for some help.
I have had a problem with my maf recently so I replaced it took it down to do the co2 on the emission’s machine and my co2 readings are sky high 10.00 yet the lambda is between 0. 9 and 1.1 the HC is 300 again fine. We have tried using the screw in the MAF but going from extreme to the other i.e. turning it all the way to the right or left only makes 1.0 co2 difference so my question is should this screw make more of a difference as I no on my old mini turning it would make the car cut out. When the MAF first went on the car was spitting flames all the time we have the car running sweet as a nut no popping flames anymore but just can’t get that co2 down anything to replace or check would be great

Thanks and sorry for the essay.

[Vili 17]

Shouldn't CO2 reading be around 14,5 % for engine in good health? 10 % would indicate poor combustion.

 

What car are you driving, with or without catalysator?

[welshpug 1,626]

Shouldn't CO2 reading be around 14,5 % for engine in good health? 10 % would indicate poor combustion.

 

What car are you driving, with or without catalysator?

 

 

NO!

 

MOT limit is 3.5% CO, run best at 1.5%.

 

its an AFM not a MAF Adam, is it a new unit or second hand and are the part numbers correct for the ecu+engine you are using?

 

check the wiring, also check the wiring and the coolant temperature sensor.

[amusingadam 6 1 Cars]

sorry ment co not co2

[Vili 17]

OK, I guess CO 10 % is not good either.

 

 

That would indicate very rich mixture. You could have faulty air or engine temperature sensor.

Edited January 27, 2013 by Vili

[amusingadam 6 1 Cars]

1 second hand unit tested

2 correct part numbers

3 will check temp sensor

4 gararge will not pass it with a co above 1.5

[welshpug 1,626]

is it a cat model?

[amusingadam 6 1 Cars]

no

[welshpug 1,626]

then the limit is 3.5% and it will pass at anything below that.

[johnsimister 10]

HC of 300 ppm is high for an XU. My 1.9 scores about 100 with CO set to 1.5%, and my old 1.6 was down in the 80s. The fact that the lambda is about right is interesting, though. I'm wondering if it's an ignition problem causing a slight misfire. The CO on my car went up a lot when the coil HT lead developed a bad connection. You could try new plugs and leads.

 

John

[Anthony 1,000]

Did you have the same issue with the previous AFM as well?

 

High CO figures are generally because it's running rich, although 10% CO is very high.

 

Lambda 0.9 to 1.1 seems a fairly significant variation as well (that's approximately 13.2 through 16.2 AFR) and certainly I was seeing nothing like that on a Jetronic car when I had a wideband hooked up for monitoring, rather it was floating around mid-14's from memory (and sailed through its MOT). Is it noticeably hunting at idle - ie the revs fluctuating up and down - as that's again often a sign of running excessively rich and I would imagine might show up as significant lambda reading fluctuations?

 

My gut feeling is that the AFM is goosed and/or been played with previously.