Chev/Holden 1.4L Cruze E85 FlexFuel Conversion

[GMPX]

Hi All,

As you may have seen in our latest newsletter, EFILive now has a 2012 1.4L Turbo Cruze, the first R&D project we wanted to do on this car was a conversion to make it a true 'FlexFuel' vehicle, you can't buy one from GM like this so it seemed like a good starting point. Admittedly this wasn't as hard as it might appear because at least in the case of the 2012 Holden Cruze, the E85 Ethanol fuel tables are already set up, it's just a matter of turning the E85 function 'on'.

Traditionally GM have used an ethanol estimation system to detect the ethanol content of the fuel, however, in the last few years they have moved away from this method and started fitting real ethanol percentage sensors. This is the route we've chosen as the sensors are very accurate and they instantly tell the ECM what the ethanol content is without the need to drive the vehicle for a while so the ECM can figure it out. Not only that, the new ones they are using are very cheap, you can find them online for about $70.
There is two E85 sensor part numbers that could be used, we ordered both and it appears the difference is just in the type of fittings on the fuel lines.
The other thing that needs to happen is the injectors must be changed, the standard ones are rated at 23lb/h (or around that), so we chose to use the 42lb/h Bosch 'Green Giant' injectors #0280155968. For us they were 'almost' a direct drop in. The size is fine but on our car the injector clips didn't fit the same, no big deal to get around that though.

It will be interesting to see how this engine runs on E85, they knock pretty bad on low grade fuel, on our local 98 Octane they aren't too bad, still some knock every now and then, especially on the stock tune!

These photo's aren't intended to be a step by step guide on doing this conversion, but it at least will give you an overall feel on what needs to be done.

The Flex Fuel Sensors:
There is two part numbers for these, 13577394 and 13577379. The first one seems to be fitted to V8 cars, the second shows up on some SIDI applications. We chose to use 13577379 (on the right).



Wiring in the Sensor:
The first step was to wire up the Flex Fuel sensor to the ECM. The sensor requires +12V, Ground and then it's signal output.
The +12V for the FlexFuel sensor we obtained from the Powertain Relay switched +12V IGN feed to the ECM, this is the same +12V that supplies other EFI related sensors so it seemed like the best choice. This connection needs to be made in the ECM wiring harness as there is no +12V output on any ECM pins. On our Cruze this +12V feed can be found on two wires in the harness to the 'Black' Connector, (Red with Dark Blue stripe).
The other two connections can be made on some ECM pins. Both are on X3, the 'Grey' Connector.
Pin 20 = GND
Pin 34 = Flex Fuel signal (called 'Out' on the sensor).

X1 = Blue Connector


X2 = Black Connector


X3 = Grey Connector

Below you can see the harness partially pulled apart to run the new wires off to the sensor now the ECM connections have been made.



With the loom all taped up like factory new.


Fitting the FlexFuel Sensor:
GM seem to fit the flex fuel sensors all the way at the back of the vehicle, usually next to the fuel tank, probably for simpler packaging purposes when dealing with the same vehicle where one can be FlexFuel and the other isn't.
We chose to mount the sensor in the engine bay, which thankfully on the Cruze is very simple. However, the fuel line Holden used from the under car fuel line to the injector rail is just standard rubber fuel line (not good with E85), on this day we didn't replace it with the correct ethanol compatible fuel hose, we will revisit that shortly, so for the moment the FlexFuel sensor has just been spliced in to the existing rubber line and held in place with some cable ties (it was one of those 'Git-R-Done' moments)? From what we could see this was the only rubber part in the fuel line.





Swapping the Injectors:
As I mentioned above, we replaced the factory injectors (Bosch #0280158205) with some higher flow 42lb/h Bosch 'Green Giant' injectors #0280155968, due to the additional fuel demands needed to run E85.



Before we fire it up:
Prior to fitting the new parts I had put a significant quantity of E10 fuel in the tank (10% Ethanol), this seemed like a safe way to ensure the ECM was reading the sensor correctly and making any minor adjustments to the fueling with the slight change in Ethanol content. Filling up with E85 was too much of an unknown at this point.
The first thing that needs to happen is we need to tell the ECM that this car is a FlexFuel vehicle. EFILive has grouped these calibrations in one area, of course from factory this is configured for a non FlexFuel vehicle.

Stock:



Modified for FlexFuel:


Calibration B0187 was important for us to change. GM would normally have this set so once the ethanol content change is detected at the sensor (normally back at the fuel tank) the engine will need to consume 'x' amount of fuel before the new enthanol mix reaches the injectors. In our case we put the sensor on the engine so there is minimal fuel useage before it actually gets to the engine.
The value we chose was a guesstimate, but it should ensure the ECM adjusts fueling right away once the new ethanol content is detected.
We also chose to enable the Flex Fuel sensor fault codes P0178 & P0179 (not shown here), we want to know if the sensor goes bad.

We also changed the injector flow table to suit the new 42lb injectors, this was easy as the 6.0L L96 truck (with the E78) uses 42lb injectors, so it was a simple copy/paste effort.

Time to fire it up:
With the V2 plugged in and the WBO2 being monitored it was time to run the engine.
It was good news all round, the Ethanol Sensor was reading perfectly (it said 6.7% ethanol with a sensor frequency of 57Hz) and the ECM had already adjusted it's target Stoich value down to 14.33:1 AFR to compensate for the small ethanol content.

So now that it appears the ECM knows exactly what is going on with the ethanol content we will put a higher E85 blend in to the car, we'll target about 40% to 50% as the final mix, if all continues to go well at that point then a full tank of E85 is next. Of course that might take a while on the Cruze, high fuel consumption isn't something it's known for.




Can't buy one from the factory like this....


Thanks To:
Brian at Vermont Tuning for the tip on the 'Green Giant' injectors.
Guy Tripp at SoCal Diesel for organising all the parts to get over here.
Thanks to Steve down at MKAL Automotive in Melbourne for assisting (actually, doing most of the work) to the Cruze.



Text and Images Copyright EFILive 2012.

IMPORTANT NOTE: This upgrade does NOT work on 2011 Cruze's.