Emission test. Need advice from members who this has happened to.

Grahamo spec c

Grahamo spec c

Well-known member
ISDC Club Member
Anybody here who is qualified tech…or has knowledge of using the same equipment the NCT uses or has anyone else had this issue when doing an emissions test does your Impreza go mad on the high idle test?

Mine is very difficult to hold the rev at anything over 2k RPM.

Normally have to feather it to 3600rpm and come off throttle and try to get it back to the tolerance rev for the 3 minute hold test!

Any ideas why the revs can’t be held properly?

All opinions welcome please.

Pain in my hole now with it!
 
Post the sheet . Is it failing on high idle or failing cos it can’t hold high idle
 
scoobysub said:
Post the sheet . Is it failing on high idle or failing cos it can’t hold high idle
Click to expand...
Failing on co but I know the problem, part on the way to sort it.

It’s just near impossible to hold it on high idle as the revs just shoot up, never done it before in all the years I’ve owned it.
 
Idle control valve can affect it holding steady but would usually be more of a low down if idle issue unless throttle cable was adjusted
 
What exhaust are u running
Standard ,aftermarket,decat ?

HATE NCT .

Going wed for fourth test on wed with golf gtd .new different problem on first 3 tests . Fucking scam .

Ballpoint

Then decat

Then out of focus bulb .

Cunts .
 
scoobysub said:
Idle control valve can affect it holding steady but would usually be more of a low down if idle issue unless throttle cable was adjusted
Click to expand...
Idle is fine Joe and cable wasn’t touched.
new exhaust manifold on order as I’m convinced the weld job I had done is not sealed.
Time will tell when fitted!

Was just looking for other known issues that may cause the issue 👍🏻
 
mac mac said:
What exhaust are u running
Standard ,aftermarket,decat ?

HATE NCT .

Going wed for fourth test on wed with golf gtd .new different problem on first 3 tests . Fucking scam .

Ballpoint

Then decat

Then out of focus bulb .

Cunts .
Click to expand...
HKS full system with sport cat.

It’s a lottery every year with them sure!
Lots of very unqualified looking lads testing the last two years….

Had to show them how to open all the doors last year and where the chassis number was…. 🙄
 
Have you a oe Subaru cat ? Some people are gonna hate this comment but I don't have faith in a sports cat as I've said here before. All the years going through NCT with Subaru I never had any issue when put in the factory one
 
GORDON GT SERIES II said:
Have you a oe Subaru cat ? Some people are gonna hate this comment but I don't have faith in a sports cat as I've said here before. All the years going through NCT with Subaru I never had any issue when put in the factory one
Click to expand...
i agree with this oem cat is the only ive figured for any car really, sports cats can be a hit & miss
 
I've heard this a few times...is it the brand of cat or the CEL count? I've heard 100 cel doesn't pass bit 200 cel should.. but would a 200 cell HKS have a better chance of passing compared to a 200 cel japspeed or something?
 
Passed last year with no changes and done about 3kms since.
Lambda sh1t the bed as it does every few years, as Nf kills them.

New lambda in and reading perfect.
HKS cat is new etc.

Let me know if anyone needs one for jdm twin scroll (air/fuel)
Needs a bit of wiring, swap plug over etc
But works 👍🏻
I’ll report back when I have a new equal manifold fitted.
 
Eoinmack said:
I've heard this a few times...is it the brand of cat or the CEL count? I've heard 100 cel doesn't pass bit 200 cel should.. but would a 200 cell HKS have a better chance of passing compared to a 200 cel japspeed or something?
Click to expand...
Brands has to be a factor too but as said I still thinks factory would be best way
 
Sorry to hear man but NCT testing equipment is also partly to blame in this equation as they just don't calibrate/look after it. I had so many issues over the years with NCT testers just failing the car just coz the machine said so, me then arguing with them to put it on a different machine and lo and behold, it passes without issues!

Check a few things just in case:
1. IACV rubber gasket. If not changed recently, get a new one (have it at hand) then open it up to change
2. Check if the car has a throttle cable whether all of it is tight and no play in it
3. Run the car for a while to get the cat etc roasting and just basically make sure all is up to temp etc. These days with them car sitting around for a while before being driven doesn't help with emissions etc.

I am sure others that would be way more knowledgeable than me will add in more info and the above is what I did on mine (which I will probably need to do again soon for the nct).
 
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