Flat spot

Short history, 01 pre runner, purchased about a month ago. The air cleaner box was damaged from a previous crash so I replaced it and also put new coil packs, plugs and wires since I had no idea of any tune up maintenance. All of the plugs had been swimming in fuel. Anyway, the truck runs great now except for a flat spot right at hard acceleration.
Thoughts?

 

Plugs swimming in fuel?

 

Meaning the engine was very running rich.

 

Running rich can be a few things but that description and the flat spot... flat spot at wide open throttle or on quick opening of the throttle or ? My first gut reaction is the check the fuel pressure regulator, D/S fuel rail towards the fire wall, pull the vacuum line and see if the there is fuel present at the vacuum port, if there is the diaphram is ruptured.

The next free thing is if you do not have a scan tool, take it to an oreilly and they will scan it for free. They wont do a diagnosis but you can look at the data. Check for pending codes and look at fuel trims. There is just so much to explain when diagnosing modern cars and OBDII and that cant be done in a paragraph or 2 without data.

 

Thanks for the reply and suggestions. It happens on the quick opening of the throttle. I forgot to mention that I did replace the fuel filter as well. I will check the fuel pressure reg. Thanks again.

 

Any codes tossed?

 

A rich mixture won't leave the plugs wet, it will leave them black and sooty.

A misfire will leave a plug wet.

Are you sure the intake hose between the air cleaner and throttle body is connected correctly?

 

Haven’t had the reader put on it yet. After the tune up, the engine light went off.

 

The plugs were black and sooty and smelled of heavy gasoline.

The air cleaner box had a big ass hole in it plus the connection point between the box and hose was broken so I replaced the box. No vacuum leaking now.

I did check the fuel pressure hose and it was dry.

 

Sounds like a fix to me.

 

Thanks! This truck has a few more issues but I’ll make a new post for those.