Hi - my scooby just failed the MOT on CO emissions, and it's not running right - won't hold a steady RPM without fluctuating. It's an 06 STi with some mods (sports cat, remap etc.)

With the bank hols it's a bit tricky getting it looked at asap and I'm doing my normal headless chicken panic impression trying to find a loaner

I did try a re-test after driving at high revs for 20 mins or so, but it didn't make any difference (worse if anything) so I don't think it's a matter of a cold cat (plus the revs are fluctuating so something is up).

Is there anything I can do personally before I get it to a garage to try and narrow down the source of the problem (to speed up ordering parts etc.)?

 

Coolant temp sensor.

Plugs.

MAF.

HT leads/coilpacks (not sure what a Hawk has?)

???

 

Add Lambda to that list too.

Do you have the emissions failure print out??

 

LOL, I totally forgot that one....... The obvious one!

Cheers bat.

 

two minds are better than one Joz.

 

 

plugs????

 

Ha ha, under the Subscriptions page I saw that the last post was from 99gw... Ergo, I was already laughing before seeing your post!

 

 

Hiya

Readout:

Fast Idle Test
CO = 0.5 (max 0.2) - FAIL
HC = 30 (max 200) - PASS
Lambda = 0.997 (0.970-1.030) - PASS

Second Fast Idle Test
CO = 0.62 - FAIL
HC = 25 - PASS
Lambda = 0.986 - PASS

When I took it back in the afternoon they kindly rechecked it without restarting the official process and it failed - no printout as it wasn't done "on the system" (they were checking to see if it would pass, before using up my retest opportunity). The readings for CO were higher.

When they asked me to hold it at 2.5krpm it just wouldn't stay there - continually fluctuating.

I'm hoping someone can plug in this afternoon and see what they can see, but my local specialist is mega busy and then going away, and my other garage of choice can't take it til Tuesday at the earliest, and with work being busy I probably can't get it there til Thursday.

ANything I can do to try and diagnose the fault myself and maybe get parts ordered in would be really helpful, because struggling to get to work without it :s

Thanks!

 

PS it is remapped, sports cat, cat-back aftermarket exhaust, uprated fuel pump and had the air intake resonator removed. Most of this was done about 6 months ago.

 

the sports cats dont bloody work,i had the same issue,stick the oe cat downpipe on and im sure it will pass.

 

Had a better look and I'm sure it's not the cat; the emissions readings fluctuate from fine, low and in the green, to really high and well into the red. Then back down into the green again.

Which sounds to me like a sensor. However when I heard the price of a MAF sensor from Subaru I was a bit surprised...... over 300 quid !

Is there a better (or rather cheaper) parts supplier or is that just the going rate?

 

Is this http://cgi.ebay.co.uk/Subaru-Impreza...item43a37a8173 thew same part No. as yours??