way too rich

[Motorsports-X]

My truck, at idle, is ******* both the fuel trims. Bank 1 a bit more than bank 2. The engine is built and i expect Some demand for more fuel but not 75% at idle. Removed the bank 1 exhaust pipe after the collector to replace the trans cooler line and the pipe was very white. It looks very lean to me. I'm leaning towards the fuel pump being a problem but it wouldn't surprise me if i need new intake and header gaskets to.

I also think at the top end, the engine might be out of injector. It goes lean up there.

Does anyone here with a built engine know what kind of fuel trims i "should" be expecting at idle. And also what the factory injector actual rate is?

Lots of bugs. Trying to work them out. 411 swap is a significant upgrade in terms of visability to whats going on. And right now things arent adding up.

 

[Nad_Yvalhosert]

I doubt many of are psychic here, so adding the year, make, model, engine size would be helpful.

 

[Motorsports-X]

I doubt many of are psychic here, so adding the year, make, model, engine size would be helpful.

Lol. My bad . Its a 96 k1500. has a built 5.7 engine from a 98 in it and 411 swapped. 4l60 trans.

 

[Nad_Yvalhosert]

Did you replace the upstream O2 sensors? If the PCM is trying to run an engine with:
different pistons,
or a different cam,
or different compression,
with worn out, carbon covered, possibly fouled O2 sensors would cause all kinds of problems.

Lean conditions are generally caused by low fuel pressure, too high engine temp, or vacuum leak, but if the PCM is getting misinfo from the sensors, all bets are off.

Did you check fuel pressure?

 

[Supercharged111]

So you're running a "built" motor on a stock tune and are surprised it runs like crap?

 

[Motorsports-X]

So you're running a "built" motor on a stock tune and are surprised it runs like crap?

Typical forum poster.

Number one im not surprised about anything except fuel trims being maxed out at idle... number two I'm telling you there is a mechanical issue I'm trying to work out so i CAN tune it. Didn't realize asking for a couple of specs asked for a smart ass response.




Anyways... Nad. Yes both up stream O2 sensors are new. It appears they are doing what they are asked to do. But i think they are getting false data from a leak or trying to compensate for very low fuel pressure. Headed to get a fuel preesure gauge tomorrow to check that. is it possible for an exhaust leak at the header to draw in air and cause the o2 sensor to show lean? I can see the smallest bit of soot forming on one of the spark plug boots on bank 1 so i know its got at least a very small leak. But you can't hear it so it's not bad.


Also..we set the cam/distributor timing last weekend. Was dead on 0 at 1000rpm. Any idea what that value might show up as in the 411? All I'm seeing is a "cam offset" variable and it's jumping all over. Even at steady rpm

 

[Supercharged111]

Typical forum poster.

Number one im not surprised about anything except fuel trims being maxed out at idle... number two I'm telling you there is a mechanical issue I'm trying to work out so i CAN tune it. Didn't realize asking for a couple of specs asked for a smart ass response.




Anyways... Nad. Yes both up stream O2 sensors are new. It appears they are doing what they are asked to do. But i think they are getting false data from a leak or low fuel pressure. Headed to get a fuel preesure gauge tomorrow to check that. is it possible for an exhaust leak at the header to draw in air and cause the o2 sensor to show lean? I can see the smallest bit of soot forming on one of the spark plug boots on bank 1 so i know its got at least a very small leak. But you can't hear it so it's not bad

I'm anything but typical. Your post reads like the typical guy who spends thousands on a "built" motor then never tunes it. How big is the cam? That can really mess with how your O2 reads at an idle. It's possible you're chasing a problem that doesn't exist. What's your fuel pressure doing?