Hi Guys

My old 92 4.3L 2wd automatic has 135,00 miles on it and was running okay till it started acting up lately. It starts good, runs good for about a couple miles then it just starts jerking and putting and loses power real bad. The ses light comes on and when i check it Code 45 comes up. If you hold the pedal still and cruise along it jerks bad. Let up a little or mash down a little and it settles down. When it acts up, it won't change gears normally and when it does it changes hard. Any ideas would be appreciated.

Thanks

 

clogged cat?

 

So when you hit the accelerator hard, it will stop bucking and accelerate fine? If so, you could have a problem with the TPS (throttle position sensor). The sensor should give an output of ~0.5V at closed throttle and ~4.5V at wide open throttle. The voltage should increase/decrease in a smooth manner as you slowly open/close the throttle.

When was the last time a tune up was performed?

 

I replaced the intake gaskets not long ago due to a coolant leak at the rear and it's been sluggish since then. Checked timing (disconnected the wire first) used light to set it. Changed plugs, cap, and rotor.

 

Have you checked for vacuum leaks?

 

Hummm.... I put a Cat Back system with dual pipes on it that sounded good, but lately it is quieter than it used to be. Cat stopped up? The tail pipes are pretty Black.

Haven,t found any vacuum leaks, it idles perfectly and revs up okay in park.

 

Hmm. having a really black tailpipe could mean a rich mixture. Im pulling this out of my rear but i wanna say your regulator is bad causing it to run super rich,fouling out plugs and when its below full throttle its running too rich which is causing the bucking. When you floor it, it usually helps a rich situation since its needing more fuel since its turning at 5k thus helping the bucking.


Make sense? Maybe im wrong.

 

Found the problem, evidently mice had filled the air intake hose right where it starts beside the radiator with leaves and nuts. It's narrow and flat there and I had to poke it out with a stick. I'm going to recheck the timing too. Now it runs better.

One more question. Is it common for this engine to take 7 or 8 seconds to gradually return to idle after you poke the gas pedal. Seems kinda slow.

 

Glad you got it worked out, keep them rodents away lol