How to reduce the lamda reading?

[alex4twenty]

So cars MOT is up on Wednesday so put it in today for its first since I've had it and one of the things it failed on is the lamda reading is too high on the second run. Max is 1.030 and mine was 1.080 so roughly 5% over could this be due to it having a sports cat? or any other suggestions to get it down?

 

[Lee s]

A hard drive before the test is supposed to help, I had this issue.

 

[Ellis]

Common Things that can affect it are
-air leaks
- exhaust leaks
- ignition issues (plugs usualy)

As lee said a good "purge" also sometimes sorts it.

 

[Puggie]

That is an AFR of about 15.9, pretty lean! I'd be looking for air leaks in your exhaust, Duff lambda sensor or possibly a lazy injector if you have one branch of your exhaust manifold running rather hot.

the idle test is closed loop IIRC so your lambda sensor should be correcting the AFR, either its not working (new lambda sensor needed) or air is getting into the system after the lambda sensor (poor seal around the can maybe).

 

[alex4twenty]

I changed the plugs less than a 1000 miles ago so im happy its not that, If it was the lamda sensor would I not be getting a CEL? I take it there's no way to check for an air leak except touch/sight? unfortunately I cant take it for a hard drive due to a problem I've got in another thread ha.

 

[alex4twenty]

Had it up on the ramp earlier there is no lamda sensor, i knew it was remapped so guessing that was deleted at the same time. so going to ask the garage to let me thrash it just before they test it and I'm going to try taking of my whales ***** intake and putting the smaller one on that came with it,

 

[Ellis]

No lambda sensor at all? That cant be right? If it is im fairly sure thats your problem lol.

 

[alex4twenty]

My mates having the lamda sensor deleted from his dc5 so it must be doable. Maybe once it's done you just have to go to a mot station willing to overlook the emissions?

 

[Ellis]

Some input from vtec6000 would be good, hes the man that would know.

Im an MOT tester myself and i just cant see you passing a basic emmissions test without one, as u say mate maybe need to take it somewhere willing to overlook the emmisions ha.