THSCC Forums

It actually is not just at redline. It is intermittent at full throttle high in rev range 4500+. Sometimes it happens sometimes not but often enough to be repeatable. I can move the brackets around a bit. I first had it mounted where I used a bunch of the stock holes from the unmounting, but that made it rub on the brakeline, (probably not good) and covered the shock adjuster. (Definitely a PITA) hmmmm...... 3 shocks set a stiff, one at soft that should handle well So I moved it around and rerigged the cruise control actuator. I could probably play with it a bit, but if I move it any more to the left to ease the strain on the cable, I cover the shocks.

My next step is to disassemble (sigh) and put the stock airbox in and see if the stumble persists. If not, drawing board. If so, MAS bad.

Either way, I am going to try to switch to the RX7 one. Any Gen 2 work?

Am I missing anything?

No, read Randy Stocker's site that I posted, it has all the info you need. If you get it before Feb 4th and are coming to the tech day at CAM I can help you get it adjusted, its a bit of a PITA.

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02 Focus SVT
STF 9

Read it and it now registers '86-87. The other thing that registered was not to remove the screwed in plug. I did not read this (know to read it) prior and removed the screwed in plug to make it easier to change. although I have to remove/replace it if/when I change AFMs. I'll see if I can make the 4th.

What mods have to be made to get the RX7 unit to fit? Is it just a matter of adjusting the bracket or is it tubing/hoses and stuff?

Everytime I try to diagnose my full-throttle stumble I get more confused Yesterday, I messed around with it and then test drove and while I can't get it to hesitate on full throttle, it still acts like a kill switch at redline - every time.

Oh well, back to put the stock airbox back on to see if I can locate the problem

OK, Stock airbox back on same problem, dammit. 6500 rpm at redline it cuts out. I am confused. still.

Why at 6500. What in the AFM senses that and says "no more power for you" It sounds more electrical to me. I also recently changed plugs and wires, but if one was bad shouldn't it run poorly at all rpms, idle poorly etc.

Any ideas. This sucks

Rob,

In regard to plug wires, it MIGHT be possible that a high rpm arcing could be confusing the tach or the rev limiter. As I recall you said the tach drops to zero which sounds like an ignition cutoff. Were the new plug wires suppression type? (since if I go back to read past threads I'll probably lose all these words of wisdom )

Are you absolutely sure that "something" else hasn't changed since the last time you ran the engine past an "indicated" 6500 RPM? Such as, tach (or tach signal source) that might be causing the tach to read low? Or something related to the rev limiter or its signal source that might be causing the rev limiter to cut in early?

I agree that with a "clean cut" as opposed to a gradually "flattening" something is telling either the ignition or the fuel to stop. Since I know nothing about Miata systems that is the best I can do in regard to kibutzing.

One additional thought, is there any chance the computer system in your car has some sort of "detonation related protection" that might be detecting a lean condition and shutting things down?

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Dick Rasmussen

FS 50 2018 Mustang GT

OK good news and bad news. I am not confused any more, I have managed to figure out what makes the AFM tick - by taking it apart. I also figured out how to unplug it. (Wish I had figured it out before I tried to remove it the first time. )

The good news is that the soldiered connections in the AFM were broken. I am going to guess that one of them signals the engine to cut out. The bad news is that unless my neighbor holds the sensor in the AFM open the car won't run. I think the 200lbs of excess weight, not to mention the aerodynamic inefficiency will more than offset any gain from the intake Soldiered the connections back, without luck.

Oh well, I was going to replace it anyway. And now I know how it works. I always have to take something apart to figure it out.

So my last question is am I right in thinking that the broken connector was potentially causing my problems?

Ahh. . . yes. I gutted mine like a fish the first time I worked on it. Lucky you your's started.

If can't find the appropriate RX7 AFM, any AFM from a Mazda 1.6er will work. I picked up my replacement from Shi. . . City Auto Salvage for. . . around $30 I think.

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Not spectacular just decent.
I'm not sure what I'm driving.
Maybe an ITR in DS.
Or half-assed STX prepped 330.

Rob:

1.) Call Neal Harrington. He has the right RX7 AFM.
2.) You must modify the clockspring setting in the RX7 AFM to make the door open fully. Mine is set at minus 8 clicks, and is fully open at about 5,000 rpm.
3.) Get rid of the cruise. It's in the way and besides, it weighs 3 lbs.

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Brad

Screwing up a Miata AFM must be a right of passage. I had mine buggered up in less than a month of ownership.

I have a stock 1.6 AFM, $25 and its yours.

I would recomend the RX7 AFM, its a good purchase.

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02 Focus SVT
STF 9

I can't be the only one who recognizes that the proper solution is a set of ITBs and a DPFI system, can I?

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Rich
http://www.v8mongrel.com/

Paging Neil Harrington.

What other mods do I need to do to make the pipes mate? (adapters etc)

I was thinking of that too. I like jigsaw puzzles and found a place to mount it but I was thinking of just ditching it. I only use it on trips and not always then.

Thanks
rob

Rob:

Check mine out at the house in Fuquay-Varina anytime you want. Or...
Take a look at it at VIR.

There is precious little room for a cone-type filter under the hood. I opted for a HKS Mega-flow. It's only about 3-1/2" high and 6" in diameter.

You need to fabricate a couple of brackets to hold the AFM/Air Cleaner assembly in place, as it will need to be "bent" outwards to keep it away from the header heat shield.

With the RX7 AFM, you will also need to get a little creative on the intake plumbing. I actually ended up using a "no-hub" waste line adapter between the AFM and the stock cross-over tube. Fits perfectly with no intrusion on the airflow.

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Brad