Hi,

Every once in a while from idle when I go to hit the gas, it won't rise up immediately like it did before. The RPMS will drop maybe 100-300, and then will go up fast.

This only happens from idle, and it seems the further I push the gas in, the more the RPMS will drop before climbing like normal.

It happened every once in a while before I got my PFC tuned, but seems like it's doing it more now.

Thanks!

Cavell

 

bad engine ground maybe? bad cable?

 

See if you notice it happening when playing with the clutch. Some people on the forum have had their clutch switch go out and it went from the rpms dropping a little to the car almost stalling when pressing the clutch.

 

Dumb question, where is this clutch switch located?

At the pedal? Is the fix just as simple as getting a new switch and replacing the old one?

 

It does it whether the clutch is engaged or not. A couple of times on starting the car the idle will be erratic, goin from 1300 or so down to 500, back and forth. Did it just now after coming back from lunch. The car was started at operating temp.

Then 2 stop lights from where I started it I blipped the throttle, and it almost died. The lights came on, but then the engine caught again. But from then on all the way back to work I couldn't get it to repeat itself.

 

Sounds like you need to adjust your Throttle Position Sensor (TPS). Do a search.

It is located on the throttle body near the fire wall. It is a grey plastic peice below a small coolant hose. You will need to loosen two screws (or bolts) and turn the sensor until the voltage is in the proper range. There is a procedure in the Mazda service manual on how this is done w/o an SST (special service tool). You just need a voltage meter.

Good luck.

Jeff

 

Yes and yes - about $10. Check this switch first very carefully for continuity before you replace it. That switch and the brake pedal switch are know to fail - about $13.00. They frequently are the source of "gremlins" that will drive you crazy trying to diagnose the problem you have as well as cruise control problems.

If that does not work, Jeff's solution is right on the money.

If that does not work - and I know this sounds crazy -
put in some new spark plugs.

 

I had a similar problem with hesitation from idle. It turned out that my (settings 3)INJ ADJUST 1000 rpm was set to 67. I raised it to 80.1 and my hesitation went away. I found that at 1000 rpm only, 100 was just too rich. Just a thought.

 

Steve adjusted some fuel map at idle on my PFC. I never ask him exactly what he did, I wouldn't understand... But that fixed the hesitation completely.

Now just sometimes when I warm start the car the idle will fluctuate like the PFC is learning. But now luckily it only goes from 1000-15000 RPMS.

Doesn't wanna die on me or get below its normal idle range.