1993 RX7. 81k miles, brand new OEM mazda motor with perfect compression. Car was just fixed from a no-start situation (F'd up wire going to ignition coil.) BONE STOCK

It failed emissions...pretty bad

CO%
Idle limit-1.00 Reading-5.82
2500 RPM Limit-1.00 Reading 3.93

HC PPM
Idle Limit-130 Reading-1127
2500 RPM Limit-130 Reading-232

Can you tell anything from these numbers? Car smells very rich, the guy who emissions tested the car suggested it acted like a car with a bad EGR.

Where should I start?

 

Start by checking the codes.

 

Who did the install and tune?
Good oxygen sensor?
Air pump hooked up and working?
All the intake and exhaust fittings tight, including the downpipe?
Factory cat(s)? I would assume so being bone stock, just thinking out loud...

 

did you get a NOx measurement (even if it's not a regulated emission)?

Sure sounds like an airpump/ACV issue. Something could have happened during installation of the engine. EGR has nothing to do with it.

 

Make sure the airpump is working, I've passed smog in CA numerous times without the EGR.

 

since someone bought this up ... might as well ask here

is it better to pump air the way it is (most of the time port air), or just pump straight into the cat at all time to get better numbers?

I was thinking it should be better to pump it into the cat at all times, but I was looking at the spit air pipe into CAT gasket .... the gasket is just a tiny hole ... will this really help to lower the emission with so little air (if I let the ACV to pump air into cat at all times)

 

I wouldn't rig the pump to always flow to the cat. The air pump uses port air to bias the fuel mixture to the O2 sensor.

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/why-engine-so-damn-complicated-part-2-emissions-controls-841963/#post9236816

That thread is all about the emissions system. Read up.

Matt

 

I read that long ago, and yes I know how the system works inside out

and one of the ways to treat emission is by "always" pumping air into the CAT directly, how wanna know how "much"

I have an gas analyzer, maybe I should plug it in to see how it effects the tailpipe emission

 

Was the car driven to ensure it was hot previous to the test, especially with it being winter might make this difficult. Also there are some rumors are that the evap system opens up during the test and may cause the engine to run rich, I would just disconnect it and plug up the lines for the test. I recently failed my first test in pa with a aftermarket catalytic converter, and no air pump. Disconnected the evap system, reinstalled the air pump, and verified it was working. Then leaned the fuel mixture via a power fc and was able to sneak by the test but was a bit lean according the results.

 

Mazda dealership installed the new OEM motor

No idea on O2, air pump. Exhaust is pretty rough on the car, may be a leaking issue. But I know the car runs rich 100% and it's not just an exhaust issue.

I pulled plugs after 500 miles and they're extremely rich. I'm not sure where to start. Emissions stuff that would cause it to fail wouldn't affect my rich issue (which is really what I care about. I dont care about an emissions sticker, I want the car to run right.) It always smells like fuel, runs rich, and is a little down on power.

 

Think you may have an AFR issue more than an emissions one. The dealer may have upset something with the install. The vacuum hoses are brittle if orginal andd easily did they replace the injectors w/o replacing the o-rings? Did they hook everything back up correct? Although they are Mazdas, dealers arent used to worrking on them. How long ago did you have the work done. It may be under warranty

 

run it in port air. it allows for better oxidation, and it draws fresh air into the combustion process through reversion.

 

First thing that's easiest to check is can you spin the air pump mechanism? With the engine off, the inner housing should be able to be turned by hand. (triangle part below)




Next thing. Even though it's stock has the ACV been blocked off, or has it seized?

ACV
My Rx7 was also running extremely rich (after replacing the airpump) and the whole ACV had seized up inside and jammed shut. There should be free movement of the 2 soleniod things inside this unit. Once this was working fine, it idled smoother, has less exhaust fumes and doesn't smell rich at all.

Thirdly: I would also check the catalytic converter. If your airpump hasnt been working like mine for some time then no doubt your cat is completely chocked full.

 

mmmmmmm

well that make sense, it allows more times for air to blend in.

my damn emission analyzer broke, new one coming in next week to test the diffs.

 

What does it measure and where are you hooking it up? Tailpipe?