Vectra 2.2SRI remapped backfire problem.

[JohnnyRoberts1]

I dont know if this is the right place to post but iv come across a couple of problems (Prob all the same thing)

I bought my Vectra 2.2 petrol, remapped to 180bhp, with a straight threw exhaust (Dont know if any of this is relevant)

Since iv had the car roughly 3 months the engine management light has come on 3 times, all times a fault with the CAT in exhaust system, but with it being a straight threw exhaust im 80% it wont have a CAT?

Anyway my mate in the garage just keeps turning the light off for me, for it to come on a couple weeks later again..

Now the car is backfiring every gear change? It always did it but not as much as it is now.

Iv googled backfiring and it says its something to do with the oxygen/fuel ratio?

One mate said i should try a K&N to get more air into the engine?

One mate says i need a whole new exhaust?

Anybody point me in the right direction PLEASE?

[anonymous-user]

kn will make f all difference

exhaust will not make difference, the issue will be the timing to do with the remap, i would get the full faults read on the ecu, then get the original ecu file back on to try to solve the problem.

Edited by The Spruce goose on Monday 16th June 21:35

[JohnnyRoberts1]

Okay mate thanks. Could do without buying a whole new exhaust if i'm honest.

[stevesingo]

The ECU is registering a catalyst fault code because it has not got a cat.

[JohnnyRoberts1]

I gathered that Steve, but how is it solved? We talking alot of ££££ or easy-ish to fix.

[anonymous-user]

Google "Lambda sensor spacer"


(basically, you move the rear lambda sensor up and out of the exhaust pipe a bit, effectively putting in a little "lee" out of the exhaust flow, as such it won't see the rapid lambda switching from the upstream perturbations that cause the EMS to flag a cat efficiency fault.........)


The "more backfiring" might suggest you have an exhaust manifold air leak somewhere btw.

[JohnnyRoberts1]

Thanks mate, can't say id be able to do that myself will have to explain it to a garage and ask them to sort it.