High emissions

[Devmeke]

Hi all my 1998 Impreza is struggling on emissions for the NCT. The first time it was tested it just failed on lambda reading dy +0.01. This time it failed on CO and lambda reading 0.90 the spec is 0.95 to 1.04. The CAT was not sealed fully going onto the turbo the first time. The only thing I have noticed is the car is hesitant sometimes on idle and when you rev it to go it nearly bunny hops but then runs OK. Any one have issues like this before? Thanks

 

[scoobysub]

Sounds like your maf sensor

 

[Love that Turbo]

Recall from the VAG world that if MAF was suspect would disconnect to see if it idles and drives better. Not sure if Subaru are the same.

 

[Grahamo spec c]

So two emission tests? Correct?

What have you done on both occasions (tests)

To fix the issues?
I’m assuming you have changed something on the exhaust system? Or did you send it back in again in the same condition?

More info needed please.

 

[Devmeke]

So two emission tests? Correct?

What have you done on both occasions (tests)

To fix the issues?
I’m assuming you have changed something on the exhaust system? Or did you send it back in again in the same condition?

More info needed please.

First test passed on high rev and low rev. Failed on lambda by +0.01% above required value.
Checked exhaust post test and found a gap/leak between the cat/manifold and turbo.
Closed the gap and tightened all bolts holding the cat/manifold to the turbo.
Sent in for second test failed on low emission and lambda now reading 0.90% which is -0.05% below required value. Passed high rev test.
Car now not idling correctly and when you rev it its like its under fueling or not sparking correctly. I've checked all hoses and no issues there. I also changed out the O2 sensor but no difference

 

[scoobysub]

It failed on low and high idle and lamba sensor on that sheet .
You put in a new lamba sensor . But it’s still reading way low which will cause the car to run way too rich .
What lamba sensor did you put in also is it an original cat you installed or got a loan of

 

[Devmeke]

It failed on low and high idle and lamba sensor on that sheet .
You put in a new lamba sensor . But it’s still reading way low which will cause the car to run way too rich .
What lamba sensor did you put in also is it an original cat you installed or got a loan of

It's the original CAT. The lambda sensor I fitted was a spare one I had but has been sitting for a while so I will get a new sensor.

 

[scoobysub]

original cat and a good sensor and you should be good