Hey RXers I have been troubleshooting a very annoying problem on my FC3S for the last month or so, when I get time.

Car
FC3S Series 5 Turbo II
Single exhaust
Automatic for now

At first I would have a bit of hesitation and very bad fluctuating idle when the car is in park.
This is how I got the car, so I changed out oil, plugs and plug wires.
Same
I changed the ground wire on the top of the intake manifold to the firewall.

Slightly better performance

I ran a new Negative ground from the battery to the shock tower

More consistent and sometimes no hesitation but only when it's warmed up fully.

And yet sometimes when it's warm it's still hesitating.

So I've searched and searched, and it's not the 3800 hesitation because it happens more around 2500

My next thing to do is check the thermotemp sensor.

Then after that I will check the ECU ground under the intake and keep hunting.

If you have any ideas let me know. Thanks


http://www.myrx7story.com

 

1. Any trouble codes?
2. Vacuum leaks?
3. Timing, advance, idle rpm and mixture set per FSM
4. Adjust TPS?
5. Water thermo sensor
6. Check BAC valve per FSM
7. Check proper ops of AWS system
8. Is the O2 sensor voltage constant during the surging, or is it going lean (<.5v)?