Another 454 Vortec Build Thread - Documenting, Q&A, Help

[BNielsen]

Looking forward to the progress! You'll love the 0411, I did the swap back in 2019 and aside from a few hiccups I don't regret it.

 

[454C2500Longbed]

Ok update. Drive 10 miles today. Started out driving ok started to get slower and slower and after mile 10 would barely move. Any chance this is fueling? Seems to idle fine. Here’s some codes I pulled gonna get it towed home. Guide me almighty gmt400 gods need to know where to start to get running good.

Well it sure is odd that all the O2 sensors are dead or just not functioning, but it's only the front ones right after the manifolds that the PCM needs to read to calculate correct fueling. Check those two front ones out to see if anything is visually wrong with them.

 

[Bachert24]

Well it sure is odd that all the O2 sensors are dead or just not functioning, but it's only the front ones right after the manifolds that the PCM needs to read to calculate correct fueling. Check those two front ones out to see if anything is visually wrong with them.

will do, do the O2 sensors cause that kind of a driveability issue on these? I have 2 bad sensors on my Equinox and it doesnst seem to affect anything.

 

[BeXtreme]

will do, do the O2 sensors cause that kind of a driveability issue on these? I have 2 bad sensors on my Equinox and it doesnst seem to affect anything.

no, it should still run fairly well without the O2 sensors, just on the default safety program instead of actively adjusting to be stoic. That's assuming you don't have any other issues.. which seems to be a poor assumption in this case. It sounds like you might have a power or ground issue in the harness. As others have said, visually inspect the O2 sensors and the wiring back to the PCM. Make sure all fuses are not blown and are present. The power falling off as you are driving until you basically can't drive anymore almost sounds like a plugged exhaust. since it is already in open loop mode, you could try disconnecting the exhaust after the manifolds and drive it a short distance to see if it no longer loads up. You can also do a backpressure test using a sensor that screws into the O2 sensor bung, or you can monitor the manifold pressure and rev the engine up to ~2k rpm and see if the manifold pressure slowly climbs up over a minute or two.

 

[Bachert24]

no, it should still run fairly well without the O2 sensors, just on the default safety program instead of actively adjusting to be stoic. That's assuming you don't have any other issues.. which seems to be a poor assumption in this case. It sounds like you might have a power or ground issue in the harness. As others have said, visually inspect the O2 sensors and the wiring back to the PCM. Make sure all fuses are not blown and are present. The power falling off as you are driving until you basically can't drive anymore almost sounds like a plugged exhaust. since it is already in open loop mode, you could try disconnecting the exhaust after the manifolds and drive it a short distance to see if it no longer loads up. You can also do a backpressure test using a sensor that screws into the O2 sensor bung, or you can monitor the manifold pressure and rev the engine up to ~2k rpm and see if the manifold pressure slowly climbs up over a minute or two.

Unfortunately there is no exhaust but one of the codes is leading me to a possible FPR issue so I’m going to do that, injectors and oil sending unit while I have the upper intake off.

 

[BeXtreme]

Unfortunately there is no exhaust but one of the codes is leading me to a possible FPR issue so I’m going to do that, injectors and oil sending unit while I have the upper intake off.

No exhaust means no O2 sensors... which would cause all those codes. If they are there and you don't have any exhaust pipe after the sensors, that will also keep them at basically zero voltage because they will read all the oxygen rushing in from the atmosphere. No code is going to lead to FPR.. you need to hook a gauge up and measure your fuel pressure, otherwise you are just chasing your tail while throwing money and parts at it.

 

[Keeper]

Unfortunately there is no exhaust but one of the codes is leading me to a possible FPR issue so I’m going to do that, injectors and oil sending unit while I have the upper intake off.

The lower intake gaskets might be a good idea while you're in there. They are a known service item on those engines.

 

[Spareparts]

Be careful on what FPR you order. Several wrong ones will fit, but only a few have the proper pressure and i can not remember the number of the proper one.

 

[Bachert24]

No exhaust means no O2 sensors... which would cause all those codes. If they are there and you don't have any exhaust pipe after the sensors, that will also keep them at basically zero voltage because they will read all the oxygen rushing in from the atmosphere. No code is going to lead to FPR.. you need to hook a gauge up and measure your fuel pressure, otherwise you are just chasing your tail while throwing money and parts at it.

Has O2 sensors on the manifolds still. P00D9 is coming up as FPR or Fuel pump as likely culprit.

 

[Bachert24]

The lower intake gaskets might be a good idea while you're in there. They are a known service item on those engines.

10-4 will add to my list