2017 1LE Camaro Flex added issue

[Blue Bee]

Hey guys, so I have heard of this problem and have done many sensor add ons on LT1's but this one is the first I've had an issue with. Sensor reports proper E%, PCM sees it, no DTC's but trims out bad, mainly at idle. Once rolling it seems fine and WOT oddly enough is hitting Lamda target on the Dyno. But at idle it acts like it doesn't want to change Stoich to E%? Eventually gets a lean code. Anyone else run into this?

Tune 9.hpt

idle trims 2.hpl

Thanks

[Jabercrombie]

Hey guys, so I have heard of this problem and have done many sensor add ons on LT1's but this one is the first I've had an issue with. Sensor reports proper E%, PCM sees it, no DTC's but trims out bad, mainly at idle. Once rolling it seems fine and WOT oddly enough is hitting Lamda target on the Dyno. But at idle it acts like it doesn't want to change Stoich to E%? Eventually gets a lean code. Anyone else run into this?

Tune 9.hpt

idle trims 2.hpl

Thanks

Not sure if it will cause it to lean out but the Alcohol base correction table is zero'ed out. Gas table is good

[sevinn]

Under fuel>Oxygen sensors try setting LTFT Idle Cells Thresholds> Enable VSS to 255 and Disable VSS to 256.

Usually only see this on decel in gen 4 cars but give it a shot.


Also add a chart of fuel rail pressure if you don't have one. This car is spiking from reading 3 to reading over 600 MPa at times.

VCM_Scanner_2019-05-01_08-48-01.png

[Blue Bee]

Not sure if it will cause it to lean out but the Alcohol base correction table is zero'ed out. Gas table is good

I guess I'm not sure which table you are referring to?

Under fuel>Oxygen sensors try setting LTFT Idle Cells Thresholds> Enable VSS to 255 and Disable VSS to 256.

Usually only see this on decel in gen 4 cars but give it a shot.


Also add a chart of fuel rail pressure if you don't have one. This car is spiking from reading 3 to reading over 600 MPa at times.

VCM_Scanner_2019-05-01_08-48-01.png

I'll check that out, yea I always log LP and HP pressures, especially in this case making sure it was keeping up with ethanol. Thanks

[LSChev]

I guess I'm not sure which table you are referring to?



I'll check that out, yea I always log LP and HP pressures, especially in this case making sure it was keeping up with ethanol. Thanks

I have seen this on a few different cars. Doesn't seem to affect anything. Not sure what's causing it.

[Blue Bee]

I have seen this on a few different cars. Doesn't seem to affect anything. Not sure what's causing it.

Well this car gets a lean code at idle because the trims move to far, on pump gas it's fine...

[paulsmithsr]

I have a good all motor e85. Tune.

[sevinn]

I have a good all motor e85. Tune.

He didn't ask for one.

[Ben Charles]

Fuel trims aren’t precise if they sway that much and fuel is dialed in on 93...

Could not have the flex fuel tables set accordingly... most don’t on the gen 5, lots of tables to actually change for it to act right

[LSChev]

Well this car gets a lean code at idle because the trims move to far, on pump gas it's fine...

Sorry I meant the random blips in rail pressure.

[Blue Bee]

Sorry I meant the random blips in rail pressure.

I've seen similar in DI logs, I believe it has to do with "idle pulse mode" and part of the low pressure diag, as that changes slightly the LP system so PCM knows the LP side pressure sensor is working correctly. I could be off base but I had to research this all quite a bit dropping a 2017 Silverado engine/trans/FP control module in a 1987 C10. Little tricky getting all that setup and working but it's been good!