So after my engine swap, i have this pesky CEL that I can't seem to figure out.




Here is a snippet of a 3/4 throttle run captured by AE.

https://www.dropbox.com/s/n76tg3a2kb...02017.csv?dl=0

Seems to be working correctly to me?? Once I clear the code, it doesn't com back until I restart the truck. Known good sensor, brand new tube from Riffraff. I still need to check the fittings to see if they are clear but from the AE readings, the sensor seems to be working correctly so I doubt that is the problem.... Anyone have any suggestions?

 

After reading that, I realize that is talking about the butterfly valve.... what the heck??!? How is it throwing a hard code on a 49 state PCM???

 

Mine will do that once in awhile, I just ignore it.

 

Might be a 97 thing? Glenn's is also a 97.

 

It's been this way for two weeks straight... Always comes back.

 

Just clutching at straws. What if the EBPV is sticky? The computer tells it to close upon cold starting, it doesn't close, the backpressure doesn't go up like the computer expects it to, so it throws a code?

 

I think, THINK, he has a gutted outlet. Dangit, I was under the hood, I just can't remember 100%.

 

That's correct. I have no valve.

I'm thinking maybe some crap got into the old plug and is giving the pcm weird feedback.

I'll check today when I get home

 

The code is a combination of the EBPV and the sensor. Here is the definition ...

0476 = Indicates that EPR pressure of 22 in.Hg. (75 kPa) commanded during EBP engine running test was not obtained (Plugged line or exhaust back pressure device failure.)

The 75 kPa converts to approximately 10.8 PSI. The code is indicating the PCM is seeing a value below that during startup. Guess the only way to tell is monitor the sensor during the first 10 seconds of startup as during that period is when the PCM determines functionality.

My 97, build date December 1997 does not throw that hard code, ever, with or without the EBPV plugged in or unplugged. And I now have the EBP pedestal delete when I did e-fuel, still no hard codes.

I believe Cali PCM's will hard code though. Are you running your chip with the new engine?

Just some thoughts ...

 

Yes, same chip, same pcm, same wiring harness. All I did was replace the ebp sensor tube.

I don't think I'll be able to use ae to see the first 10 seconds of key on... It won't connect that fast.

 

The first 10 seconds of key on, the engine isn't running. At least you better not be starting it that fast. With my AE, I can turn key on, get connected, and even if I turn the key off and back on again, it stays connected, just shows zeros in all the live data values. I turn the key on again, and the values come back almost immediately.

 

Same here. My '97 has had the EBPV unplugged since before I bought it in '09 and it's now deleted. Never had a CEL for this.

 

I was just saying that the CEL comes on every time I turn the key to ON, as soon as I do. I can clear the code out, turn the truck off, turn the key to on and the CEL is illuminated.

Basically, I won't be able to see what the PCM sees the second the CEL pops up, I will be able to read data only 10 seconds after the code is set.

I will play with it today when I get in the truck to go home.

 

Still, I would think you'll want to see exhaust back pressure with key-on engine-off vs. key-on engine-running.

 

I'll look at it. If I'm remembering correctly, it was reading 14.7 psi like it should.