1999 3rd Gen MOT Emissions Failure

[rxangus]

Thanks for that....

I think the fast idle test is above 2500 rpm though so air pump will by default be off at that speed I believe.

Just to recap I\'m thinking of trying to get a 1996 through MOT emissions with a cat and standard ECU.

I\'ll have a look at the air pump power supply today and see what I can do. I\'m thinking along the lines of adding a switched permanent 12V.

Maybe a silly question but why did Mazda not just keep the air pump powered until say 3500rpm and the emissions would have been greatly improved. Might even have stopped the 7 being killed off so soon in the States??

Angus

[rxangus]

Okay I\'ve had a look at the schematics and it seems that the air pump is controlled as follows:

A dc voltage from the ECU is used to energise the air pump relay coil. When the relay coil is energised the contacts are shorted. One of the contacts is always at earth potential so basically the relay is used to provide a switched ground to the air pump ie it will see +12V all the time but only runs when grounded.

Off to look/measure in the car but in principle I don\'t see why it shouldn\'t be possible to make an adapter that replaces the stock relay and operates as follows:

New relay which closes contacts under control of a switched ignition voltage. This would mean that the air pump would run anytime the ignition is on regardless of the ECU output.

Does anyone know if the stock ECU senses coil current flow when it energises a relay or is it just dumb?

The $64000 dollar question is whether anyone thinks I will definitely pass the emissions test with a permanently running air pump and cat??

Angus

[bnaellis]

No There more to it than that.

[ScuttleRX]

Ive got my mot tomorrow afternoon, on a 96 with cat, cat-back exhaust, apexi filters and a downpipe, and a power fc

From searching through threads ive found about 4 recommendations for getting through, can anyone give their opinion on these
1/ make sure engine is v warm (presume warm intake temps will lean out fuelling slightly)
2/ have air con on full whack
3/ or 4/ either put stock ecu back in, or lean out the apexi which im not sure how to do, can anyone describe how to do this?

cheers

Andy

[davefrith]

I would suggest you go to a rex friendly garage, those mods are the same as mine and that what I had to do

[ScuttleRX]

yeah have sent an email off to thames valley to see if they have any slots free, just really trying to avoid having to go as its miiiles away. Wouldn\'t mind normally its just im working every hour under sun and cant be bothered with stuff like this on my weekends off!

Maybe the garage im booked in will be rotor friendly, he does drive a modded up pulsar so he might have some sympathy, jap car allegiance and all that:D