CWA

Had MOT re-test today, everything was fine except for emissions again! Failed on CO and LAMBDA..

I changed the Lambda Sensor and Cat in an effort to lower the emissions first time round.
Also got rid of all the exhaust blows

All I saw was a slight reduction in lambda (it only just failed), CO didn't change but if anything it increased.

I know there is a chance that the different Cat and Lambda probe may be dud aswell so I need to check them, can anyone give any advice on what might have gone wrong?

When fixing the downpipe to manifold, I didn't use a new gasket (used one which was only 10k miles old). Could this cause an air leak which would mess up the Lambda reading, even if though it is past the sensor?

Also, is it likely to be my temp sender, or anything on the air intake side?

I can post up figures if it will help, really need some guidance on this though please guys.

**caz**

have ya replaced ya air filter recently?

x

CWA

urmm.. about 10,000 miles ago haha

how will new air filter help? :S

CWA

Screw it I will post emissions anyway.. lol

FIRST MOT - Fast Idle 1

CO - 0.543% (0.300% limit)
HC - 71ppm (<=200ppm limit) FINE
Lambda - 1.053 (0.970-1.030 limit)

Fast Idle 2

CO - 0.526%
HC - 73 FINE
Lambda - 1.208

Changed Cat (may have been dud) and Lambda Sensor (may have also been dud) and got rid of loads of exhaust blows..

SECOND MOT - Fast Idle 1

CO - 0.559% (0.300% limit) < Got WORSE?
HC - 73ppm (<=200ppm limit) Same, Fine
Lambda - 1.053 (1.030 limit) < Improved

Fast Idle 2

CO - 0.625 < Still WORSE?
HC - 96
Lambda - 1.036 (1.030 limit) < SO CLOSE!


How come my lambda improved, do you think it was the sensor change? Or just getting rid of all the exhaust blows / air leaks made it improve?

And why is my CO soooo high! Just CAT?

Please HELP!

carlos1395

put some new spark plugs in and if you have a standard air filter box take the air filter out for test

CWA

OK cool, what emissions would this reduce.. the CO or Lambda? Or both?

Why do you reckon I'm getting such high figures.. especially CO?

CWA

this is for a fuel injection car (Polo), not my bug.. surely its something more than just plugs or a filter?

xr2wishy

iTrader: (2)

could be air temp sensor gone guff, discovered the fuel mix needs to enrichen as the air temp increases to maintain afr when tuning my megasquirt, so if the air sensor is shorted internally it'll be reading very hot and richening up the fuel mix.

natehall

iTrader: (2)

removing the air filter will allow more oxygen to get in, which will reduce the CO2, and a new set of plugs will allow the fuel to burn better - again improving CO

There was some stuff I put in a tank of fuel I got from a friend in the trade - my god it lowered my emissions no end! they were 7% (3.5% limit) on test one - took the long route to the test station after filling the tank with fuel and adding this additive - emmissions dropped to 2.9%

CWA

ah sounds good chaps, cheers

not sure about removing the air filter though, cos if i have more oxygen going through then even if it lowers CO, won't that raise my lambda? I need that to go down.. do you think it's been caused by an air leak somewhere?

i will defo get some new plugs in, also will get a multimeter to check the coolant temp sender, although i replaced that about 10k miles ago :S
if the thermostat was broken, would that make the car carry on running rich? or is the ecu only told the heat of the engine by the temp sender?

finally, i think that stuff is redex.. i will give it a go, it clears out the injectors or something don't it? how much of it do you need to use for it to take effect?

natehall

iTrader: (2)

redex is one such item, however this was something stronger - I think it was by millers but i cant be sure as it was a couple years back now

Brian ST-2

iTrader: (1)

What size Polo is it and how is it normally driven.?
Usually choked up ones pass the test after a fookin good thrash up a local bit of dual carriageway in third or maximum fourth gear. Get the exhaust ( internals ) all hot and given a good dusting off like....

btw where'd you get the avatar pic.? got any more

CWA

urmm when i drove it I sometimes ragged it although it's been off the road for two months

and the last month I drove it before I took it off the road I did loads of mtorway miles but economy style lol so didn't go past 60/70 in fifth.. you reckon it could be coked up due to that?

It's a 99 POLO 1.4 8V aswell btw

Cheers nate, might try some redex if i cant find what you are on about.. give it a good old italian tune up lol

Brian, umm do you mean my avatar or sig? Got loads of pics of my sig, but only one of the avatar lol that pic aint me!