So most of you know I swapped in a new 3.4l motor that I previously 90% rebuilt. Just didnt touch the timing.
The car started right up and is running, only I have one odd issue. Its almost like the throttle is sticking. I dont know how to describe it really.
I will open the throttle to 4k rpms, and instead of coming right back down like normal, it sits there for a couple seconds then very slowly comes down until it boggs at 500rpms. So it has a low idle, and the throttle just sits. I put in a new loaded throttle body, the cruise control is disconnected, and the weirdest part is it isnt throwing any codes. I drained the old gas and put in new gas, I cant find an evap leak, Im at a loss.

 

I'd check voltage at TPS

 

Wouldnt it typically throw a code for an extreme voltage change at the tps?

 

Typically. But I've seen vehicles that misfired to the point an unintelligent person could tell it was doing so by ear and not have it throw a light. Does it do it while driving or just idling?

 

Just at idle, it smooths out if i stay on the throttle.

 

Can you get a video of what it's actually doing?

 

yea, about half way through i pull the throttle, listen to how long it takes to drop.

 

exhaust leak somewhere. egr maybe. sounds like its before the 02 sensor which would mess with air fuel mix

 

exhaust leak would be right on the nose. the exhaust only goes to the downpipe. I had just finished putting the engine back in the day before this video.
I just cant figure out why the idle wont come back down and it doesnt have a code. There are new denso O2 sensors in it. New plugs and wires, but the plugs did get black fairly quickly. It isnt oil, looks like a lot of carbon.
I also have a video of when it was cut at the down pipe when i tried a different exhaust set up before and it was very smooth and idled fine. Luckily I recorded it before I put the exhaust on back then so I could compare it.

I was guessing TPS, IAC, MAP sensor but there wasn't a code so I was confused. Should I just replace the sensors in case the light isnt reacting to it actually being bad?

 

check fuel pressure and level. not running out of gas?