I would check operation of the airpump, or make sure the little coolant switch at the bottom of the radiator isn't jaked up.. I know that when it goes bad or missing the car likes to run richer.

 

^ what he said! i would definately start at the air pump, your co2 and low hc says that its running very well but your low o2 and little above normal co( which is normal for rotary) suggests that there isn't enough o2 to catylize that co!

 

What's interesting is all his problems has been at the low 15 mhp level. He's always been good at the 25mph level. What is the common denominator for that?

 

when a cars readings get worse with increased speed its usually always electrical and when it gets better with speed its usually something mechanically wrong but has to be out of bounds at idle to tell. bieng that it gets better as speed increases i would say a mechanical problem not related to the primary efficiency of the engine as the co2 is very nice and the hc's are low. ie air pump. a sluggish o2 would become worse at higher engine speeds as it is trying to keep up.(not always the case tho sometimes high o2 with a bad sensor will cause co to rise but not in this case as there is no o2, then can be masked with an efficient enough ign. system) just by seeing wats on paper and not havin the vehicle in front of me the o2 is very low for a vehicle with air injection. i would check the acv

 

although i assumed you had changed everything on the car befor you switched cats. not sayin that it will definately help you but a new o2 certainly wont hurt you! i would look into the low 02 reading first though

 

Sounds good sleeper thanks buddy

 

And yet another vote for the Air Control Valve. If a 2nd Gen's is anything like a GSLSE's, there is a diaphram the size of a dime in it that fails due to getting hard from the heat. Nick at RRR proved that one to me when that simple replacement took my GSLSE from a gross polluter to passing easily.

Replace that diaphram and it's good to go.

 

Try Marco at Industry Hills Mazda. It's official name is a Check Valve, Mazda part #148013730. It goes for under $20 and it's still available.

 

More load at 15mph.
The test is called an ASM 50/15 25/25
50% load at 15mph
25% load at 25mph

 

Passed!!
Replaced the Air check valve diaphram and cleaned the acv.


No additives to fuel,no smog hook ups and no preheating of cat.

 

:

 

Conga-Rats!

 

^^^^^ you just mad because neither one of you made money ! Guess what the FC is running superb and fixed 90% worn parts in the engine for way less than "going rate". Wink wink lol

 

That Mazda part number 1480-13-730 diaphram is magic sometimes.

 

Very Inspirational. I'm currently in the same boat - quick question though, it looks like we've been testing around the same time - but my max HC (ppm) seems to be 83, where yours is listed 99.

Does anyone know why that is? With my numbers, it seems like I could pass at the same test center that you went to?

 

Is that the little diaphragm on the end, or the big diaphragm on top?

Any pictures out there?

 

It's about the size of a dime.

 

Different years have different limits, same with engine size, transmission selection, etc... For more information, you can always look up a specific vehicle make model and year here: Vehicle Test History

 

Probably the one from the end.

I had no idea these were available separately. Wonder if that's true for older models too? ACVs for 80's are scarce. I've got a couple spares, but I've also got a couple with bad diaphragms.

On the SA units, the most common failure is the hole in the internal check valve wears larger and larger, starts bypassing.

 

Makes sense, thanks for the insight!

 

Call Marco at Industry Hills Mazda for answer to that question.