Cleo has become an MPG project

[Philip1]

I picked up a programable ecu for my BMW. The plan is lean her down at part throttle as much as I can get away with and see what happens.

[pgfpro]

Originally Posted by philip1

I picked up a programable ecu for my BMW. The plan is lean her down at part throttle as much as I can get away with and see what happens.

What kind of BMW?

[DRW]

Excellent! Is there a commented disassembly for that ecu?
I've enjoyed the mods I put into mine. I had some good results from lowering cold idle and leaning out cold enrichments.

[Philip1]

The car is an old 1988 535i with 256k miles on the clock. I've lowered her with Bilstein shocks on Spax springs. This weekend I will be adding an airdam and sway bars as well as the ecu. All told I should be able to reduce the drag from .4cd to probably .36cd and fuel milage should climb above (not much but above) 35 on the highway.

[Philip1]

Photo of Cleo the 535i




This is how she looks right now.

[pgfpro]

Originally Posted by philip1

Photo of Cleo the 535i




This is how she looks right now.

Nice!!! I always like the looks of those cars.

[Philip1]

I won't be doing any mods that detract from those looks. I am sure the air dam will improve looks as well as reducing drag.

[Philip1]

Finally got a base tune for the computer so she'll at least run. Next begins project lean out.

This is a paint can pistoned brute so I don't know how lean I can make her. I'll do it slow till she starts bucking then add a tiny bit to keep her smooth. Any thoughts pgfro?

I will have some rudimentary feedback systems, AFM readout, narrow o2 and my decades of feeling out carb tunes.

[theholycow]

I'm not familiar with the phrase "paint can piston"; does that mean that the pistons are not very strong, or that the bore is wide?

[pgfpro]

Originally Posted by philip1

Finally got a base tune for the computer so she'll at least run. Next begins project lean out.

This is a paint can pistoned brute so I don't know how lean I can make her. I'll do it slow till she starts bucking then add a tiny bit to keep her smooth. Any thoughts pgfro?

I will have some rudimentary feedback systems, AFM readout, narrow o2 and my decades of feeling out carb tunes.

Sounds like a good plan. Can you change the emulsion tubes and air bleeds?

If you can I would go for the highest amount of atomization you can with these to parts of the circuit then start reducing the main jets. Then start adding some more ignition timing advance.

Do your carbs have a dual power valve circuit? I would keep a careful eye on the vacuum gauge and to dial in the power valve if so. You can also usually run a restrictor wire in the power enrichment channel (the one that feeds the main jet wells) to lean down the lower vacuum areas.

Also you can always come up with ways to add more heat to the heat cross-over in the intake manifold to help with atomization and lean down.