On page F-79 of my 1994 FWM is one procedure for adjusting the temperature at which the fast idle cam is bypassed, and another for adjusting the separation (something) of the cam. I get how to do the temperature adjustment, but can someone please translate the following for me:

"1. To adjust the first idle cam separates point D turn adjust screw B."

I understand "turn adjust screw B," but what is one trying to do here? I do see point D on the "first" [sic] idle cam, but I don't grok what is supposed to happen when "adjust screw B" is set correctly. Apparently the separation of the throttle butterfly control from the cam is set by this adjustment, but what criteria is supposed to be used to set it?

 

Too easy for you guys?

 

Screw A adjust at what temperature the cam gos from point A,B,C,D. And screw B adjusts what the RPM would be at each point.

What's your goal here? Are trying to lower the fast idle? Or trying to kick it out earlier?

Paul


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Sorry for stealing the thread but how long is the fast idle cam supposed to be on anyways? Mine goes off after about 15-20 min of idle is that normal or should I also be looking at this adjustment? About half way something kicks the rpm up to about 1400 and when it fully warms up it drops to 720rpm.

 

Then Mazda's statement "1. To adjust the first idle cam separates point D turn adjust screw B" means that you are setting the rpm of the fast idle? If so, that's a really bad translation!

My goal is to eliminate random changes in the warm idle from the 720 rpm (where I set it using the TEN/GND jumper) to over 1000 rpm, and back. I was thinking that perhaps opening and closing the throttle sometimes erroneously puts the throttle stop back on the "D" or thereabouts setting of the fast idle cam, even when warm.

 

Ya, and what's your point?


Unlikely, but you could wire the fast idle cam open if you want to eliminate it from the equation. The problem is the idle speed solenoid can't control the idle. Assuming your using the OEM ECU, try removing the idle solenoid and cleaning it. If that doesn't help, lower the idle to around 700 with the TEN/GND jumper in, then remove the jumper and see if that does the trick.

Paul



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Gadd,

Did you read my post #5? I stated that I have already used the TEN/GND jumper to set the warm idle at 720 rpm. Also, I recently had the UIM off and cleaned both the IAC and the AWS solenoid units. The idle does sit at 720 rpm... sometimes. But from stoplight to stoplight, it will sometimes drop back to a 1000 rpm idle and stay there. I have loosened the throttle cable... no effect. Sometimes it will return from 1000 rpm to 720 rpm just by waiting long enough. But sometimes not. And yes, the car is nearly stock, and uses the OEM PCME. Only changes are a Bonez DP replacing the pre-cat, and Viton hoses replacing OEM vacuum hoses.

I will disable the fast idle cam temporarily and see what happens... good idea.

 

You might want to make sure your dashpot is clean and not binding. That could be preventing the throttle from closing completely every now and then.

 

I did, I even quoted it.

What I was suggesting was to lower the idle speed below 720 with the TEN/GND jumper in. The idle solenoid can only control the idle in a very narrow range, and that may help.

Here's an experiment, next time the idle sticks and 1000, turn on the parking lights. If the idle drops to about 800 and then about 750 when you turn them off. You'll know it's the solenoid controlling the idle.

Paul

 

Thanks scotty305 and Gadd for your latest suggestions... will try both. Do not intend to deliberately set the open-loop idle below the optimum point, though... not going there.