Firstfives.org

Fuel injection is different from carbureted ( for bone heads ) in the idea the injectors squirt fuel electronically, with the Air fuel meter and throttle body in the business of adding or subtracting air to the mix. Thus, the adjustment needles on either the throttle body or AFM adjust air, not fuel flow.

Same computer in the glove box, same serial # AFM, (switched to test) same throttle body, timed correctly, vacuum lines checked, grounds clean, two idle switches swapped, adjusted to click off at the last instant. New fuel pumps, fuel pressure regulator...bushings...

Unplug the low idle switch it's less sensitive but I don't like mickey mouse. What causes jerky gas pedal, trailer hitching ?

Push on the pedal in second gear to 2500 rpm. Let off or add pedal and it's not smooth, semi mushy as my '79. It's right now, off / on and if I tap the pedal I can get it to bounce off the guibo, jerky pretty good.

If that's the way it's supposed to be, peppy, and you all just drive it that way, I'll quit asking.

It sounds like you have covered many of the possible issues. Could it be something wrong/slack in the driveline?

Without getting into technical jargon, the AFM (air flow meter) does send a signal to the ECU (in the glovebox) how much and when the injectors should squirt fuel. For a complete understanding of L-jet engineering and performance I encourage a read of the Bosch booklet "Electronic Gasoline Fuel-Injected System with Lambda Closed-Loop Control - L-Jetronic".

I also concur with Blaise's questioning the driveline.

Once long ago, I drove my car for an independent mechanic sitting in the passenger's seat exactly the way you describe. Bouncy, jerky. I asked him what that was and he told me it was the way I drive. He then piloted the car in the smoothest fashion I had ever experienced. I then made it my mission to accomplish driving that way and have done so for the last hunnert years or so. I *can* drive it jerky, but I don't. Having said that, I believe there is slack (wear) in the differential that contributes to this condition. A quarter of a million miles will do that. We should be happy these cars still exist and actually run at all.

What causes jerky gas pedal, trailer hitching ?

That can be caused by either bad bushings for the accelerator pedal in the pedal box creating excess play or too much timing advance. Also check fuel pressure on the original problem. 30 year old distributors could have a different advance curve from each other too.

I pick too much timing advance, or backing it down a dab to see.

The bushings got replaced (*#@!) awhile ago. New regulator, drive line is all up to spec from the rebuild the engine process and of course I'm an ex race car driver, pilot like every other butt in the seat.

The reason I'm obsessed comes from my 635 being nuts a few years ago, to discover the idle switch on this board. Adjusto-presto-fixo. And (again, again) my '79 is smooth, doesn't do what this is doing.

You'd have to drive it to experience it. It can be," Driven," smoothly, and I do to not abuse the machine. I did with the 635, kick the clutch out decelerating. With the throttle switch closing early it was like a sprint car with a baby flywheel.