Upgraded pumps on stock tune

03yllwguy

Daily driven since 2003
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03 cobra specific question in regards to Cali and emissions:

Can one upgrade their returnless system with GT pumps & upsized stock injectors (with a Whipple) on a stock tune for the purposes of passing emissions?

Obviously this is ONLY pertaining to passing emissions without having to yank the blower or hat every two years (just a pulley, maf and tune).

Search resulted in not much and tons of mixed opinions elsewhere. Thanks in advance.


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Black02GT

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Pumps MAYBE but I doubt your going to get the ECU to set and or run well enough to pass emissions with a stock tune with any injector not flowing to stock flow rates.
 

01yellercobra

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Thanks did not know that. If the stock injectors, albeit upsized, require a tune, what’s the point of vendors like Dyno Bob offering them?


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I haven't seen those. My guess would be to have a cheaper alternative to buying a set of larger injectors.

Edit: I found the paragraph they posted. While they are correct that some aftermarket injectors have different resistance values that isn't the reason they require "expensive remapping". There are aftermarket injectors that work with the stock ECU just fine. The remapping is because of the different flow capabilities. If their upsized injectors don't need the tune tweaked I'd guess they're not really increasing the flow. Or if they are it isn't by much. And there are quite a few people on here running large injectors with stock driveability.
 
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03 DSG Snake

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I haven't seen those. My guess would be to have a cheaper alternative to buying a set of larger injectors.

+1

I have the Walbro GT improved pumps on stock tune, injectors will likely make it run like crap though.

Kudos to KB and Whipple for making their inlets bolt on from the rear. Dying for VMP to drop their CARB TVS..
 

03yllwguy

Daily driven since 2003
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I haven't seen those. My guess would be to have a cheaper alternative to buying a set of larger injectors.

Edit: I found the paragraph they posted. While they are correct that some aftermarket injectors have different resistance values that isn't the reason they require "expensive remapping". There are aftermarket injectors that work with the stock ECU just fine. The remapping is because of the different flow capabilities. If their upsized injectors don't need the tune tweaked I'd guess they're not really increasing the flow. Or if they are it isn't by much. And there are quite a few people on here running large injectors with stock driveability.

Great info and feedback. Thank you!


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