Engine misses when taking off.

[regencyred]

Just wondering if anyone might be able to give me
some advice about my engine missing and stumbling when taking off.
Cold start is perfect with a gradual decrease in revs till warm.
It's a 91 Legacy N/A with 169 k miles. automatic.

I've been reading through old threads about the TPS which
I suspected. I have set the idle switch. it shows a closed circuit
no resistance with the throttle closed. as the the throttle opens
it immediately goes to infinite resistance and stays there till the
pedal hits the floor. should this be a gradual change in resistance?

I did the voltage test as described by Haynes.
the closed throttle voltage was 5 volts DC and the wide open
throttle voltage was 1 Volt. I thought it was meant to be the
other way around- 5 volts at wide open.

also, what is the buzzing coming from inside the transmission when
you press the gas pedal with the ignition switched on and not running?
just wondering.

Much appreciate some advice. does anyone know a good place to
buy a TPS if that's the problem?

Cheers, Craig

[H4_Deucer]

First things first, how do the plugs and wires look? I would inspect those first before even testing the TPS.

[jefferson]

I would second plugs and wires. Make sure the wires aren't a cheap set either. Good wires go along way.

Jeff

[regencyred]

Thanks guys,
I'll check those wires and plugs.
Cheers, Craig

[Legacy777]

You mention the idle switch goes infinite resistance when open. This is normal on the idle switch, not the throttle part of the TPS.

The buzzing in the trans that you heard is normal.

[regencyred]

Thanks again.
I have replaced the plugs and wires, crank, knock, MAF sensors and tried another
IAC. still misses when moving from rest.
It's like no accelerator pump with a carburetor car.
No Power to accelerate and shift gear. Cold start is smooth and even. good compression.
The last thing to do is replace the TPS.

The car has been sitting outside in the snow for 5 years with the hood down,
but I think some moisture got into it and maybe the TPS is bad.
The idle switch part of it is working OK, zero ohms at idle, but maybe
the variable part is cactus.
Cheers, Craig

[Legacy777]

So does it run better when cold? If so, you may want to also replace the coolant temp sensor. It plays a big role in the ECU controlling AFR, and may be causing you to run too rich or lean.