HHR (E37) 2010 FFV v. 2007 injector flow rates

[MisterBill]

2007 HHR 2.2L running on a 2010 HHR FFV ECM (E37 with VVT disabled). Drove vehicle for several hundred highway miles over the weekend on both E85 and E10 and in both cases the DIC mileage reported is considerably lower than actual mileage measured. On E85 the DIC reported 18MPG, I measured 24. On E10 the DIC reported 20MPG, I measured 27.

It is also throwing a DTC P0171 Fuel Trim System Lean code on both E85 and E10. (commanded AFR looks normal)

Both of these "clues" would point me to look at a difference in injector flow rates...but both tune files have the same value (3.51 g/S if memory serves).

I'm really more concerned about the mileage reading being so far off...is there some other parameter in the tune files that would effect this?

It also seems to take an unusually long amount of cranking to start...if that is also a clue.


Bill

[MisterBill]

Ok apparently I have forgotten how to read! The 2010 tune file does indeed show a higher injector flow rate (B4001 Injector Flow Base) of 5.074 g/S as opposed to 3.51 g/S for the 2007.

Guess it makes sense that a higher flow rate is needed to maintain RPM range for ethanol fuel.

Bill

[gmh308]

2007 HHR 2.2L running on a 2010 HHR FFV ECM (E37 with VVT disabled). Drove vehicle for several hundred highway miles over the weekend on both E85 and E10 and in both cases the DIC mileage reported is considerably lower than actual mileage measured. On E85 the DIC reported 18MPG, I measured 24. On E10 the DIC reported 20MPG, I measured 27.

It is also throwing a DTC P0171 Fuel Trim System Lean code on both E85 and E10. (commanded AFR looks normal)

Both of these "clues" would point me to look at a difference in injector flow rates...but both tune files have the same value (3.51 g/S if memory serves).

I'm really more concerned about the mileage reading being so far off...is there some other parameter in the tune files that would effect this?

It also seems to take an unusually long amount of cranking to start...if that is also a clue.


Bill

Fuel trim system lean means that the trims are topping out and it is still lean. Which is also a symptom of FF VFS not functioning quite right. Have you checked what ethanol content is being reported? GM did change the injector curves that were displayed in the later OS's once they moved to 16g/s injector limits for 09.

[ScarabEpic22]

Sounds like you need to Auto VVE it to get the VVE tables correct. If commanded AFR looks normal, whats the wideband say?

You need to match the IFR table with the injectors, so if you're running stock 07 injectors then use the data from the 07 tune in the 10 ECM.

[MisterBill]

Changing the injector flow rate to 3.51 g/S fixed these two problems.

[GMPX]

Thanks for letting us know.