I own an 88 GTU. It idles at 800 solid when the lights are off, the heater fan is off, and my foot not on the brakes. When I add load like the heater on full, and my lights on the idle drops by about a 100 rpms. Now this is not a bad drop in idle and I understand that if will drop some due to load at idle, but once I put pressure on the brake the lights dim and it drops another 100 rpm. I had my charging system checked and they stated that it was good, although they may not be correct. So at night with the heater, lights on and my foot on the brake the car comes close to stalling, runs real lumpy. Is this a weak battery, bad charging system (alternator) or could it be bad grounds. Also as a side note, every time I get out of the car I get a small zap from the chassis when I touch it. Any ideas/comments??? I would like it if I didn't have to adjust my idle.

 

poor grounds, and/or a weak alt.

it is normal to have a static electrical shock when using tires that have a low carbon content in the rubber on most cars.

 

What Icemark says.

A weak battery could also cause the alt to overwork and have problem keeping up when under heavy electrical load

Also,
you may want to check the BAC valve since it controls the idle speed when loads are applied (it's a quick check ... see FSM at www.fc3s.org under how-to's->manual)

Hugues -

 

Also I sign of a BAC malfunctioning. Its supposed to compensate your idle speed for loads.

Jarrett

*edit* and the TPS is suspect too.

 

Rotaries have little low end torque, so they don't idle well under switching loads. Mazda designed in several controls to compensate for switching loads. The result is all those extra vacuum circuits all over the intake.

I am chasing an intermittant stall at present. Every time I start to troubleshoot - it works perfect.