E38 Cranking Issues

[mirage]

I recently had a fuel system installed on my 2010 Camaro. The main difference is the new fuel system has a return and a pressure regulator after the rails. The issue is when I go to start the car sometimes will crank for a long time before starting. When the engine is cold it cranks immediately. After a 10 minute drive, the car will turn over multiple times and eventually start but takes about 1-2 seconds to start. This did not happen with my current tune prior to the fuel system. I'm not sure where to begin. Any help would be appreciated.

[gmh308]

I recently had a fuel system installed on my 2010 Camaro. The main difference is the new fuel system has a return and a pressure regulator after the rails. The issue is when I go to start the car sometimes will crank for a long time before starting. When the engine is cold it cranks immediately. After a 10 minute drive, the car will turn over multiple times and eventually start but takes about 1-2 seconds to start. This did not happen with my current tune prior to the fuel system. I'm not sure where to begin. Any help would be appreciated.

Whats wrong with the stock system?

[mirage]

Whats wrong with the stock system?

Supercharger making 14 lbs of boost doesn't like stock fuel lines.

[swingtan]

Heat soak in the fuel rails? If you prime the fuel system a few times to flush fuel through, does it start easier? You may need to richen up the hot start cells to compensate.

Simon.

[mirage]

Heat soak in the fuel rails? If you prime the fuel system a few times to flush fuel through, does it start easier? You may need to richen up the hot start cells to compensate.

Simon.

Yes if I turn the key on and let the pump run it does start easier. So which cells should I increase?

[mirage]

The one spot that looks interesting is here: (Notice how the EQ Ratio is lower after the ECT's are warmed up. This would typically be the case, but might be the issue in mine)

[joecar]

If you changed from a return-less FPR/rail to a return/referenced FPR/rail did you adjust the IFR table...?

When the FPR is manifold referenced, the IFR table has to be flat.


The table in post #6 has nothing to do with the poblem.

[mirage]

If you changed from a return-less FPR/rail to a return/referenced FPR/rail did you adjust the IFR table...?

When the FPR is manifold referenced, the IFR table has to be flat.


The table in post #6 has nothing to do with the poblem.

Hmm.. No I didn't I adjusted for the fuel changes using the VE tables. Here is my B4001 table as it sits today:

[swingtan]

What's the go with the cranking fuel? I would have thought that the commanded cranking fuel would have been around 12:1 - 14:1 AFR, but your table is indicating 6:1 - 7:1 AFR's. With your description of the hot start, I'd have initially guessed it was a little lean, but not with those AFR's. Unless of course you're running Ethanol or your Stoichiometric setting is set to something other than ULP.

The only other thing I'd look at is that the SC is probably restricting air flow at low RPM's ( cranking ) so you may want to add 10% to the hot start cells in {B1832}. A quick test there would be to give it a little throttle when cranking to see if it fires easier.

Simon.

[mirage]

What's the go with the cranking fuel? I would have thought that the commanded cranking fuel would have been around 12:1 - 14:1 AFR, but your table is indicating 6:1 - 7:1 AFR's. With your description of the hot start, I'd have initially guessed it was a little lean, but not with those AFR's. Unless of course you're running Ethanol or your Stoichiometric setting is set to something other than ULP.

The only other thing I'd look at is that the SC is probably restricting air flow at low RPM's ( cranking ) so you may want to add 10% to the hot start cells in {B1832}. A quick test there would be to give it a little throttle when cranking to see if it fires easier.

Simon.

I will continue testing over the next few days and see how it goes. On the cranking commanded fuel, I initially guessed the same thing that you did in that the engine did not have enough fuel to the rails, but after making the adjustments you indicated and the initial results so far I think I will start to bring the cranking command fuel AFRs back to the stock levels and see if starting improves even further. Thanks for your help!