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JECS does not offer 740cc injectors as a JECS part.
The JECS being offered as 740cc are drilled injectors from a smaller size injector and my guess is they started as 270cc based on the color. They could start out as new injectors before they are drilled, but they are anything but precision in my experience.
Many people are thinking they are saving money and getting the same quality part as Nismo, but in my experience and opinion that simply is not true.
Some think they can play with the L and K value, and the simple adjustment will make them work fine, you might think it is fine, but is it really?
The problem with these drilled injectors is they do not flow the same through the complete operating range. You can get the overall air/fuel ratio correct by making adjustments to the tune, but the injectors are not offering the same amount of fuel to each of the cyl's.
The biggest issue is you do not know how rich or lean each cyl is, you are only reading the overall A/F.
Just last weekend Seb and I tuned 9 cars in St. Louis and of those cars, one of them had JECS. this set of JECS was the worst I have seen so far.
The car missed like crazy and after checking everything, installing a new set of spark plugs, coil packs, PTU, CAS, MAS, ECT....the engine still missed like crazy and acted like an ignition problem. The air/fuel ratio was solid at 11.5 under boost, but all the cyl's would not fire.
We know the air/fuel ratio needs to be in a reasonable range in every cyl to fire correctly under load, so we decided to try making drastic changes to see if we could get the engine to run on all 6 by changing the overall air/fuel above and below what is really correct for a test to prove it was the injectors..
We tested making the engine a full point richer and the engine ran worse and the power dropped. We then leaned out a full point the other way to 12.5 under 10 PSI boost with the 93 octane and the power came up and the engine fired fairly clean.
For the air fuel to need to be 12.5 overall to fire all the cyl's, some of the cyl's have to be extremely rich and leaning the overall to 12.5 is most likely allowing the rich cyl's to be in the 10's or 9's instead of the 9's or 8's where they did not want to fire.
We made this car drivable and told the owner to keep the boost low and to change out the injectors ASAP, we also offered to provide a chip on us when he changes the injectors and informed him the chip we made would not be safe with any other injectors.
What happens when you bore out the injectors as crude as is being done, is the injector does not flow the same through the whole range, also as the fuel pressure raises they tend to squirt, rather than spray.
Some might think they are OK if they get the engine to feel OK with these injectors, but you simply do not know how rich or lean some of the cyl's might be and this is not safe or optimal
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