If you add jcw injectors in a MCS, do you need to do anything to the ECU or do they work natively? Is this an option that would require a Unichip to be reprogrammed? TIA Michael

 

I believe that the stock ECU would still think they are the 330cc injectors and not utilize their capacity. Only with a reflash can the car recognize them as 380cc.

 

When you get a reduction pulley and larger fuel injectors you'll need the right ECU software to take "Full" advantage of air/fuel ratios for max performance (usually at the top rpm range). Without it you may or may not see much difference with larger injectors.

Try calling Eric at Helix13.com and ask what you can do given that you have a 17% helix pulley already. Most times it doesn't really make any difference which injectors you use whether Helix injectors or JCW injectors as it's mostly cost of the parts not what they can do.

If you have Unichip already then you'd need to find out if there is a version for the 17% pulley and if that version is with or without larger fuel injectors.

 

You need "tell" the ECU that you changed the injectors and "teach" it how to use them properly. This can only be done by a flash and maybe (not really sure) a piggyback (Unichip). Unichip does not mention injectors in their application guide but mentions other kits that I know include bigger injectors so I would think it can be done.

If you don't do a flash/piggyback reprogram you will not get much out of the new injectors except a lack of efficiency.

Helix advertises the 19% + injectors + GIAC and the 15% + GIAC but doesn't mention the 17%, while the GIAC site makes reference to the 17% but not the injectors.

Eric @ Helix should be able to clear that up for you.

 

Correct me if I'm misunderstanding, but I don't think its a big deal. . .

the mini has dynamic trim based on the 02 sensor doesn't it? If it does, then it shouldn't be a huge problem to switch to the larger injectors.

For those who don't know, dynamic trim is the feedback control based on the 02 sensor(s) that tells the ECU how much to multiply its base injector times by (theres ususally 2 trims, short term and long term, but they are both just % by which it multiplies the base fuel tables based on the 02 sensor). When you add the larger injectors, it will create a lean condition, which the ECU will then try to correct for. The problems you usually run into which require fuel tuning (adjustment of the base maps) are things that affect the A/F ratio diffrently depending on RPM. Given that changing injectors will likely have the same effect at all rpm (it'll just be richer everywhere I think, assuming that you haven't hit 100% duty cycle on the injectors at any point). Its always best to retune after ANY mod really, but this is one I think you can get away with alright. . .

 

Running the stock ECU with bigger injectors *may* result in a fuel trim OBDII code.

 

An ECU tune would be a good thing with the 380s, but not a requirement.
Rubyred is correct about the trim, however 380s will not degrade fuel mileage by running rich. The ECU doesn't know what injectors are in the car, it adjusts pulse width & injection timing as it sees fit. To take advantage of the larger injector the ECU needs those parameters to fully use the extra flow capability of the 380. I can't say, with this car, there has been any difference in AF or fuel mileage, start up in the cold is way better & the AF is higer only durring warm up.

 

we wouldn't recommend a pulley & 380cc injectors without a tune. There wouldn't be any gain from the injectors alone, you might actually lose performance

 

true, theres only so far an engine is allowed to adjust, you are correct. . .

 

ralphHelix wrote "we wouldn't recommend a pulley & 380cc injectors without a tune. There wouldn't be any gain from the injectors alone, you might actually lose performance"
OK but is that tune from the dealer with the ECU or is it a tune via my Unichip which I have but have not yet installed?

 

Well we are a GIAC dealer so thats what we would use . If you have the unichip then you could use that instead