AbeFM

iTrader: (3)

first check for +12v on one pin of the connector when the car is on - if not, perhaps the jumper on the board isn't right.if you have a scope you should see a pulsing pattern...

Also, checking across the pins on the connector, you should see a voltage (expecially if you put a large (<1k) ressitor there), which will vary as you change the duty cycle.

Look for those before you worry about a non-functioning valve.

Marc D

iTrader: (7)

I think I have a more serious problem on my hand rather than getting this damn idle to work.

I just pulled the TB to clean out the IAC with TB cleaner. And when I pulled the coolant lines from the TB, some very brown, dark looking fluid came out..

****.

I think the head gasket is toast. I do have a spare assembled stock short block in my garage ready to go, but i would still need to do some work to the block and the head on my car before i mate it up and drop it in. Funds for this are nonexistant. looks like the miata will be down for a while. I dont want to keep driving it until something really BAD happens, where I couldnt reuse anything on that engine anymore. I think its best to salvage what I can now.

AbeFM

iTrader: (3)

How brown and how dark? SURE it's not rust? They can get pretty nasty and still be ok. Oil would be greasy, milky. Check the oil for water (should be the first thing to come out, or the dip stick will be milky)...

Can you get a leakdown test? Compression test? I have all the tools here but it's probably not worth the drive...

Marc D

iTrader: (7)

It could be rust. Its not milky to be honest, but a few blotches of oil does float. Maybe im just shittin myself. Going to drain the oil jsut to be sure when I get a chance. I did a compression test last time on cold, the numbers werent too good. Ill check again the next time im home. It was pretty brown, I wouldnt even think coolant was in the radiator anymore. If its just rust, i really need to flush the damn system.

Ill let you know the details soon. As far as the IAC, I pulled it off and then I turned the car to "on." I did hear it hum, but it was very faint. Had to literally put it next to my ear to hear it. The resistance readings are within spec though, so I duno whats up. Ill double check the wiring again. When I started up the car, I checked the voltage from both wires and got one with 10-11V, and the other was 0V. Makes sense. Still going to double check again though. When i do increase the duty table, is the idle supposed to increase?

AbeFM

iTrader: (3)

I'm sure the motor isn't 100%, no hot rod motor is. Might as well get it running first.

If the valve hums, it's probably ok - then agian, it SHOULD change the idle pretty drastically with even a few percent change. There is a chance the transistor is getting too hot (doubt it), so you could put a heatsink on there (a little thermal compound and a block of aluminum or copper) see if it makes a difference.... Again, it worked on mine, but I didn't drive it around much either.

A faint hum is about right.

Marc D

iTrader: (7)

Got it.

For the hell of it one time, I changed the duty table to close to 90, and i still didnt get a reaction from the idle. Its REALLY strange. I do hear a hum, and the voltage does check out, but even after I change the settings in tunerstudio, the idle not reacting to any kind of setting change is mind boggling.

WestfieldMX5

FWIW when I change my duty table with like 5%, the idle changes only 50-100 rpm or so. I have it in the 20s @ 80°

Woops, never mind. Did notice you had it up to 90. That's definitely not right. You shure you hooked it up correctly?
IAC on 3O
12V on 3M

Marc D

iTrader: (7)

Well, looking at the traces on the board, 12V was added to the board to pin 3M, per se Abe's instructions using the Positive from the capacitor on the board. I could try to grab this from another 12V reference. The pin on the 3O section is right, Abe did test this as well. I went outside the car and tested the voltage coming on the lines, and it seemed to be getting the correct voltage. I read it at 10-11Vs (while car wasnt running, but on position). If you saw earlier, I tested the IAC whle the car was running.

First, I started the car. The car has a hard time starting on its own, I would have to rev it to keep it alive for the first few seconds. I tried pulling the plug on the IAC, and the car immediately dies. Ok. Means something I guess?

Then I tried starting the car with the IAC unhooked. Same hard start, need to keep revs up. After I keep revs up, it stays running, but it acts if I never unhooked the IAC at all. Same shitty idle that it was earlier. (Keep in mind, these are cold starts. On hot starts, the car somehow keeps its idle afloat without me having to press the accel).

Again, if it helps, (i doubt it would mean anything) I had OBDII code P0507, starting abnormally high idle, but i dont remember anythign about idle circuitry going bad. This has me stumped.

AbeFM

iTrader: (3)

I think you're right, I think the hardware might really be an issue. I don't like to fault it too early, but if you're getting the voltage there, you should be ok.

I assume you don't have another idle valve you can borrow? You could put 12 volts across it with it off the car and see if it moves. When I had mine wrong (no +12 pullup) there was like no voltage across it, so I don't suspect the wiring.

It sounds to me like the gauge might be flakey. I get you could get a salvage one from FM or someone fairly cheap.

My guess is you have some other vacuum leak, or the throttle plate adjuster opened really high to compensate....

FYI my valve is at ~30, idles around 1100 rpm.

Marc D

iTrader: (7)

Ill see if I can go about getting another IAC valve through here, or calling the mazda recyclers around the area.

The idle valve doesnt move at all when i start the car. I had someone turn on the car while I looked at the valve... no movement.

thirdgen

iTrader: (26)

Just my 2 cents here, but I had a similar problem with my idle valve. My car started idling high with MS (I was running MS-1 in parallel at the time) and I was getting code P0507, which is: Idle Control System RPM High. I am running on the stock computer right now as I am still working on the MS stuff for the MS-II and Abe's adapter board, and the car idles ok, which is weird, cause the MS in parallel had NO control over IAC. Anyway...I removed my IAC and hooked it up to a 12v switched tester. When I hit the switch and it got voltage, it clicked back and forth and seemed to work perfectly.

AbeFM

iTrader: (3)

Certainly turning it on and off should have it move. When hooked to the MS, it should move some when you turn the car on, and move to another position after starting (and a second or two depending on settings).

Hey, congrats, 3rdgen, I didn't know your car was running at all. Any issues?

thirdgen

iTrader: (26)

Actually Abe, it is running on the stock ECU right now. I still have to solder a jumper wire in the PNP board. I am thinking Wednesday might be the day of trial for me. I'll keep you posted.

AbeFM

iTrader: (3)

Awww, I was all excited. C'est la vie. Well, good luck, and I should be around - and most of my IM info is in my profile.

Marc D

iTrader: (7)

So a little update.

Been searching around for a damn IAC valve. Most places are charging well over 100 bucks just for one, and they wont separate the IAC from the TB. Ugh.

Comes in next week, so it's a waiting game from this point.

On a side note, I called the mazda dealer cause I might need to replace the IAC valve gasket but since im getting an entire throttle body it doesnt matter. Anyway, I asked them for that specific gasket.



Parts guy: "$46.83"



Me: "Wait. wat."


You've got to be ******* kidding me.
No way did I buy one. If I ever need to fix that damn thing, RTV should work enough for me.

AbeFM

iTrader: (3)

RTV should be fine there. In fact, probably a paper cut-a-gasket would be totally fine as well, the only flow is for the idle, it just needs to seal, not be pretty.

Makes me think I should dig out a spare TB and try to bore it...

Marc D

iTrader: (7)

Hell, i still need to figure out a way to mount the damn thing in my car. Im still thinking a home made bracket might be good, but since its a pain to work on on your back, that bungie cord idea isnt looking so bad anymore.

AbeFM

iTrader: (3)

You always learn so much by doing... Get it running, race around, then figure out where you should have put it. I'm about to redo my third mounting location. :-)

Marc D

iTrader: (7)

so whats your plan this third time around?

On a side note:

A new MS2 Beta/Alpha code has been released, which allows higher frequency to be used. Frequency can now be increased up to 457.5Hz, close enough to a 99's stock 500Hz. Im not sure on the resolution of the duty cycles anymore, but this should clear the "hum" noise on your IACs if you have any humming.

Apparently, they rearranged the code to allow the higher frequency, so resolution may be preserved and the PWM idle multiplier board wont be necessary anymore. It seems they also fixed another code problem with the IAC closed loop control. Once I figure out my current idle problem and get it running right, I might tinker with the PWM IAC Closed loop settings to see If I can get us some good settings that will work for us.

AbeFM

iTrader: (3)

Who knows, I might give it another try - it still bothers me in principle... It doesn't do PID control. You can't just say "I'd sure like it if it responded to the RPM being too low by opening the valve more", you can only put in numbers they say works. Which is how the last set worked, and worked poorly.

Everytime they put out new code it's got *something* worse than the previous. Not to say that overall it isn't worth doing, but you have to keep it in mind. I'll probably upgrade myself in a bit due to "improved AEA settings" (or is it EAE?) which are supposed to run faster. The simple one worked amazingly well but after the "10x change for sensitivity" my tires don't chirp whenever I touch the gas anymore.

Ok, enough MS-II code bashing. :-)

I have a long cable which locates the MS behind the passenger glovebox. I used to strap it to the AC box, which was excellent. Easy to reach, gently suspended, short vacuum lines... Then I took out the AC, and moved the MS to high on the wall of the transmission tunnel, parallel to it, in the passenger footwell. Sometimes people kick out the serial adapter now, and once it rotated down due to a loose screw, the DB-37 came partway out, only enough to disable the fuel pump, and it took me a long time to figure out why - AFTER my tow home (I thought the FP broke on the road).

I do remember checking the MS + board, with no cable, looked like it would fit above the steering column, but never figured out just how I would mount it. I've trimmed the tie downs on the OEM harness so I could reach the plug nearly anywhere and it made a big difference. Perhaps you need to free the beast as well.