snoops

Hello to all, this is my first post so please bear with me. I have a 1990 na with 56k that I bought 3 months ago. I have no prior experience with a rotory and therefore seek help with my idle. I've done some research and am aware that at start-ups, it is normal for the idle to shoots up to +/- 3200 RPM's and then dwindle down to +/- 750 once it has reached it's normal operating temperature. As of late however, at start-ups, I have been experiencing some erratic behavior regarding the idle. Instead of starting at it's normal +/- 3300, the idle would only rise up to +/- 2000 RPM's. in addition, I recently have noticed that when I'm at a light with my foot on the brakes, the RPM's would drop a line or 2, from +/- 750 to 650-600 and fluctuate/struggle within this range. This would also be accompanied, primarily when it bottoms out at 600 and even more so when the headlights are on , by a strong tremble/vibration that has become significantly noticeable and irritating...especially when i rest my hand on the stick shift **** that vibrates strongly when fluctuating and gives the impression that the poor car is struggling....aarrrgggghhhhh!!!!
Anyways, Any explanation as to why this is occurring and a possible solution will be greatly appreciated. I hope it's nothing major like an apex seal cause that would probably idicate a rebuild. This car truly kicks-*** in every aspect and I'm planning to keep it for a while and therefore wanna keep it in superb shape. Once again, thank your patience and time.

Steven W.

1FastT2

iTrader: (1)

Sounds like another TPS prolbem, do a search for "idle prolbems" at the top of the page.

jimmyv13

Poor ground connections, too.

mazdaspeed7

First check your spark plugs/wires and fuel filter. If they havent been replaced lately, now is probably a good time. Same for the air filter.

Then check your timing to make sure its set correctly.

Also, make sure your Throttle Position Sensor is set correctly. To do this, unplug the connector, and check the resistance between the two right-most pins(top and bottom). Just to make sure its the right 2 pins, look at the wires and follow them up to the sensor thats closer to the front of the engine. The resistance should be between 1K ohms and 1.1K ohms.

Is your idle always that low, or just sometimes? If it always it, it might simply be that your idle is set too low. To adjust turn the screw on the top of the throttle body CCW until the idle is higher.