I have been having a problem with my car stumbling and pinging at low RPM. The car will miss or ping once, then chug along for a second or so. Then, it will run normally and pull just fine. It's almost like someone throws a switch, and it runs correctly. The car runs absolutely great when it's cold. Once it goes into closed loop, then things seem to get bad.

I also have an off-idle hesitation. If you hit the throttle at idle, the car hesitates a bit and then revs. This also doesn't happen when it's cold.

Basically, the car is a dream to drive for the first few minutes, then gets progressively worse.

Any ideas on what to look for in sorting this out? Please see the list of mods in the sig.

I ran the car over the weekend at LACR in Palmdale, CA. Conditions: around 2600 feet elevation, and a temperature of about 40 degrees with a crosswind of 30-40 mph (It was @#@#$@$ COLD!). I managed a very traction limited 14.3 at 102. I know something has to be off, since I should be trapping a lot higher than that.

 

I've been chasing a similar problem. Remember this:

Keep
It
Simple
Stupid.

Start with checking you wires/coil for arcing, plugs, ect. If you can put it on a scanner, do so. Oxygen sensors are another biggie, especially if the problem appears only after the system moves into closed loop.

There's such a myriad of things that can cause the prescribed problem that it's not even humorous.