Problems solved!!
After preplacing the AFM, i still had a 09 code from the check engine light, it was a thermosensor, basicaly a sensor that looked at the engine temp and because it was failing, was dumping too much fuel into the injectors, that is the sensor that is underneith the spark plug wire connections (coils) on the rear manifold. replacing that sensor, i still was running rough and emmisions were too high to pass the test, but the check engine codes were elimanted, unfortuinatly, the rpm's were still about 1500 to 1750. Now I cleaned the throtle by removing it (lots of built up junk) and had the TPS properley adjusted, and bought new spark plugs and wires, properly gapping them (.044) and replacing sparks and plugs (also had to replace the cat) a mirical occured, the RPM's came into spec's and the car passed emmisions with more than flying colors!!

this fourm is great and thanks to every one for their input and help in solving my issues!!

John


update - i have elimanted the internial codes, so far ;-) I did check out the afm by pulling the connector. the previous owner, or someone had gone into the top cover and had sodered the connections to the circuit board, a couple had broken off. The car is running better, but still has some check engine lights comming on while driving. i will be taking the car back to the shop to a full scan and more cleaning and possible repairs, i will update later today

thanks for every one's help!!


i just inhearited a 1992 mazda miata 5 speed, the poor car FAILED emmisions horibley, the cat passed, oxygen sensor passed, but the check engin light comes on and off, the HC failed BAD, (8.0677) normal is 1.5, the CO was 62.0963 normal is 15.000, my mechanic says it is running too rich as i just replaced the sparks a week ago and they already have black foul around the base of the plugs, i am wondering if the MAF can be adjusted? any idea's oh where to start and in what order

 

The "MAS" (I assume you mean the MAF sensor) cannot be adjusted.
How much oil are you using? What color is your exhaust? Blue is oil, black is gas.
I suggest starting with a cylinder compression test (both static and dynamic).
After that, check your air filter is clean, then clean the MAF and test it. Your vintage indicates it's a vane type, and they're notorious for "hanging up". Check that your PCV rattles. Clean the injectors. Check the fuel pressure on the rail, then see what happens.
Don't expect a '92 vintage to meet OBD-II standards. That also means that any diagnostics testing has to be done with a code reader compatible with OBD-I (Mazda version), and any state inspections also have to the old OBD-I criteria, not OBD-II.

 

It uses an AFM not an MAF. The seal from the AFM to the throttlebody must be perfect,no cracks. It is not OBD at all. Find the diagnostic connector under the hood and jump ground and ten with a jumper wire. Turn the ignition on and count the flashs of the check engine light. 1 short flash =1, 1 long flash =10. Check the fuel pressure regulator as it could be sticking causing a rich condition.

 

oldeng,

thanks for the assistance with the miata, i do have a few questions for you,

you said

The "MAS" (I assume you mean the MAF sensor) cannot be adjusted.
i have a afm, ( you can tell i am new to this car LOL)

How much oil are you using? What color is your exhaust? Blue is oil, black is gas. i have not noticed any smoke, but i will take a close look at it tomorrow
I suggest starting with a cylinder compression test (both static and dynamic).
After that, check your air filter is clean, Air filter is new
then clean the MAF and test it. If i have a AFM, can it be cleaned? how would your recomend and with what?
Your vintage indicates it's a vane VANE TYPE?

type, and they're notorious for "hanging up". ???Check that your PCV rattles. Clean the injectors. Check the fuel pressure on the rail, then see what happens.
Don't expect a '92 vintage to meet OBD-II standards. That also means that any diagnostics testing has to be done with a code reader compatible with OBD-I (Mazda version), and any state inspections also have to the old OBD-I I live in colorado, do you think they have a different test other than the one i have failled?

criteria, not OBD-II.

thanks for your time and help!!

johnnymac

 

hixx,

thanks for the info, i do have a AFM, it is mounted above the air filter. in your message you said

It uses an AFM not an MAF. The seal from the AFM to the throttlebody must be perfect,no cracks. IF IT IS MOUNTED ON TOP OF THE AIR FILTER HOUSING (I KNOW I SOUND DUMB) WHERE IS THE CONNECTION TO THE THROTTLEBODY?

It is not OBD at all. Find the diagnostic connector under the hood and jump ground and ten with a jumper wire. Turn the ignition on and count the flashs of the check engine light. 1 short flash =1, 1 long flash =10. WHAT DOES THIS TEST TELL ME, SHORT MEANS? LONG MEANS? WHAT IS THE END RESULT OF THE TEST AND WHAT AM I TESTING FOR? 1=Check the fuel pressure regulator as it could be sticking causing a rich condition.

THANKS FOR THE HELP!!

JOHNNYMAC

 

OK so it's the AFM (airflow meter) on top of the air filter assembly or ducting just downstream of it. I'm pretty certain it's the vane or paddle type, and its spindle is coupled to a potentiometer which "tells" the ECU how much air is headed for the intake. The seal is not important from a vacuum point of view, but it sure is from the point of view of dirt exclusion; these sensors are real S.O.B.s.
To clear this up with certainty, could you locate a part number on it?
If it's what I have in mind, it will be a metal housing bolted to the outlet flange of the air filter box at one side, and clamped to the intake duct at the downstream side. It's part number will be something like B6S7 13 210A 1971-4090 (This was used on Mazda 1.6L DOHC engines from 1990 to 1995.)
You can check the sensor quite easily. connect a 9V smoke detector battery across the two outer terminals with the +ve on the pin the red stripe wire was connected to and the -ve where the black stripe wire went. With a voltmeter whose -ve is on the -ve terminal, measure the voltage on the center pin (the one the green stripe wire went). Now with a hair dryer on cold, blow air into the filter flange end. If it's OK, the voltage will vary smoothly up and down with the airflow intensity. If it does not, spray the throat of the unit with contact cleaner and retest. If it still misbehaves, you can try opening it up and spraying the potentiometer and spring assembly, but this is an extreme measure, so be very, very careful.
If the voltmeter reading is pegged at either near 0 or at a high +ve value, or if it jumps erratically between the two extremes, the potentiometer is shot and you'll have to replace the sensor. (junkyard and remanufactured units are still available at prices ranging from $20 to $150).

As for the matter of the codes, (now I'm working from memory), they cycle from a
sequence start of ten flashes of alternating long and short flashes, then go in sequence where each sequence tells a story. a short flash means 0, and long one means 1.
You'll need to find a code interpreter somewhere to make a diagnosis of what's up.
I remember on my '87 Camry, this info was in the owner's maanual. You might get lucky with a web search, otherwise it's Mazda, the owner's manual, or the library maybe.

 

B6s7 13 210A
197100-4090

 

The AFM has to have a perfect seal as it uses a flap that opens as air flows through it and reports its position to the ECU. If the tube from the AFM to the throttlebody leaks it reports the wrong info. The fuel pump shutoff switch is also housed within the AFM. It does have an adjustment covered by an alluminum plug but unless it has been tampered with i would not adjust it.
Jumping grd and ten in the diagnostic connector will give you the code via the check engine light flashs. if it flashs 9 short flashs that would be a code 9. If it flashs 1 long then 6 short flashs in succession that would be a code 16.
Earlier Miatas also had a problem with the crankshaft keyway wallering out due to the A/C compressor mounting bracket bolts vibrating loose. It could be out of time severly if so. If the crank damper wobbles you will need to remove the crank gear to inspect it but i would pull the codes first.

 

I had some emmision problems with my Miata and found this thread... hope the response could help me with the problems with my car...
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