grad_e

My 94 had a low idle, around 700 or so and it would afterburn at idle making a popping noise. Curiously enough, when I turned on the headlights the idle would go up, but the popping would increase. I tried adjusting the idle, using the usual ten-gnd connection. I have heard that you set the idle to 725 with ten-gnd connected and when you pull it, it should go back up to 850. Oddly, when I pulled ten-gnd the idle went down from 725 back to 700-675. Also, when you step on the brakes the idle gets really rough and the gas milage/power really sucks. I have changed the o2 sensor, looked for loose vacuum hoses, regrounded the battery, and new spark plugs and wires, still no luck. Looking for air leaks right now. Any suggestions would be much appreciated.

RX7SpiritR

iTrader: (1)

check vacuum leaks! check map sensor hose.

grad_e

Already done it baby. Checked the vaccuum hoses, replaced some of the ratty looking ones with silicone. Hoses looked good. Used the carb cleaner trick to check for leaks after the sensor with no luck. Checked the throttle cable to see if it was pulled too tight and the ISC was trying to compensate, but it looks OK.

Mahjik

iTrader: (1)

Well, most of the time I've seen "rough idle" problems here on the forum, it's usually one of two problems (after doing the normal checks like you have already done):

a) alternator problem
b) bad clutch switch

Do you notice the idle fluctuate when you put the car in gear?

nickg

I have almost exactly the same problem at the moment, grad e.
Low idle, which gets lower if you apply brakes. Also, if i put my steering wheel at full lock, it brings the idle right down to about 600rpm as well.
Im getting my alternator belt replaced tomorrow hopefully, so ill let you know if this cures it.

grad_e

Would appreciate it nickg

Trexthe3rd

The trouble shooting guide lists quite a few things that could affect the idle.
Among those are:
TPS
ICS
Ignition system (plugs, wires, coils)
Sensor inputs (Water thermal sensor, fuel temp, etc.)

If you don't have a manual, do a search for online manual and go through the checkout proceedure.
Have you always had this problem or did it start recently after aome changes?

grad_e

It's one of those problems that just kind of crept up on me, although lately it seems to have gotten worse. I have tried a lot of things, and I'm not really sure if some of those things may have messed up various settings. I may just have to play around with it to get it right. I played around for the last few days and found out to my surprise that my throttle cable was pulled too tight, which explains the idle going back down when ten-gnd was pulled. I guess with the ISC disabled, the throttle cable was raising the rpm, and when it was enabled, the ISC tried to reduce the rpm, and was probably acting out of its range. The way I have it set now is with the throttle cable play increased, and with the TAS intirely of the armature, so that way I am adjusting the idle using the AAS only. This seems to work OK, the rpm is a bit low as before but the popping in the exhuast has been reduced. I may try to change the spark plugs again, since a while ago it looks like my EGR valve went bad, and that may have fouled the spark plugs enough to account for the other symptoms. Should be coming in from Mazdatrix sometime this week. While thats going on I'll test the ISC and the TAS again to see if I missed something.