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rusty70f100

2004 Trailblazer conversion?

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Ok, so someone might need me to convert a 2004 Chevy Trailblazer to be able to run on E85.  It's got the 4.2L I6.

 

My question is what would be the best conversion kit out there?  Which one should I pick, why, etc.  My experience has only been in changing out injectors and going all E85.  But they need FFV capability.

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Ok, so someone might need me to convert a 2004 Chevy Trailblazer to be able to run on E85.  It's got the 4.2L I6.

 

My question is what would be the best conversion kit out there?  Which one should I pick, why, etc.  My experience has only been in changing out injectors and going all E85.  But they need FFV capability.

 

Rusty- I am also looking for a kit for a Trailblazer- V6 2006, and have not yet selected one. I am thinking of going to the more basic models w/o tapping the O2 sensor for ease of install since we are going to put it in ourselves. I may just go with Flex-Tech instead of FullFlex--what have you found out there for a good ,easy to install kit?

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Guest colchiro

I can't recommend the autoffv. It probably starts well in the winter, but my gas mileage suffers. Supposedly they have a new model coming out, but after sale support only gets a C-.

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Rusty- I am also looking for a kit for a Trailblazer- V6 2006, and have not yet selected one. I am thinking of going to the more basic models w/o tapping the O2 sensor for ease of install since we are going to put it in ourselves. I may just go with Flex-Tech instead of FullFlex--what have you found out there for a good ,easy to install kit?

 

I haven't.  That's why I'm asking!  ;D

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How adaptable is the ECU on that model?

 

On the late model Subaru's you can get away with upgrading the injector to 15% more fuel flow and letting the ECU adjust using the closed loop fueling. The car runs a bit lean on Open loop with E85 but that helps fuel milage and due to the high fuel octane you can get away with it.

 

If you include an adjustable fuel pressure regulator and tweak the fuel pressure up on E85 and down on gasoline by about 10 psi the car manages quite well as a home made FFV as long as your not running high boost (the Subaru WRX is turbocharged).

 

On turbocharged cars it is a bit too risky unless you also do the tweak to the fuel pressure.

The Subaru has +/- 25% fuel trim authority so by splitting the difference on the fuel flow of the injectors to only 1/2 the required increase for E85 it uses +15% fuel trim on E85, and -15% fuel trim on gasoline.

 

It all depends on how much "user intervention" is acceptable to the owner.

 

Food for thought if anyone wants to experiment.

 

Larry

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Really I dont know how adaptable the ECU is.  Haven't messed with Chevy's before, or anything this new for that matter.

 

How would I keep open-loop fueling from being off with a small injector change?  Or do the new ECU's take care of that too?  I know my Explorer certainly didn't!

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Open loop will be off a bit, some ECU's carry long term fuel trims into open loop as I understand it, but do not actively monitor the O2 sensor in open loop. As a result it will be a little lean but on the Subaru it is not a problem if you stay out of high boost. It essentially is not an issue if you have a means to adjust the fuel pressure as the change in fuel pressure is enough to correct the open loop.

 

To do it right you need to have a wide band or an OBDII logger to watch your mixture or fuel trims.

Then by watching the fuel trims or wideband you figure out what the proper pressure tweak is for full E85 and full gasoline.

On my adjustable fuel pressure regulator it is a single full turn of the pressure adjustment screw to go from E85 to gasoline.

 

Larry

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