Mathias10 Posted October 22, 2014 Share Posted October 22, 2014 Hello guysI need some helpI have some 4AGZE injectors that i want to put in my glanza, but there are 2.9 low empadence, and the originale are 14.8 High empadenceIs there any one that has experince with installing that on a JAM ecu? Quote Link to post Share on other sites
Stu Posted October 23, 2014 Share Posted October 23, 2014 (edited) Not with a JAM ecu but i've fitted ballast resistors to lots of cars that I've installed aftermarket ecu's into. Ohms law means you can work it all out. First you need to work out the existing current the injector drive is capable of. The stock ecu setup is 1x inj drive supplies 2x injectors, so: Standard injectors are 14.8 ohm from memory so using say 14v / 14.8ohms = 0.95 amps x2 per injector drive = 1.89 amps (with some rounding)4agze injectors at 2.9 ohm so 14v / 2.9ohms = 4.83amps x 2 per injector drive = 9.66 amps (with some rounding) aka way too much Ballast resistors need to be wired into the +ve feed side of the injector wiring and you need one per injector so: To be exact the calculations are:Original resistance per injector less 4agze resistance per injector will give you the required size of the ballast resistors ie 14.8 - 2.9 = 11.9ohms But you don't need to be too exact - as a rule of thumb for aftermarket ecus I use 4.7ohm 50watt ballast resistors which work out fine.Calcs for using 4.7ohm injectors are:4agze injectors at 2.9ohm + 4.7ohm = 7.6ohm so 14v / 7.6ohm = 1.84 amps x2 injectors = 3.68amps which should be fine on the stock injector drive Oh by the way, don't use small 1w/5w resistors that you can buy at a electrical component store - they'll burn out almost instantly. its better to use either 25w or ideally 50w ballasts. If you mount them on a piece of ali and mount them in the engine bay they wont get hot from load. You can see them in this photo: Confused? Edited October 23, 2014 by Stu Quote Link to post Share on other sites
Mathias10 Posted October 23, 2014 Author Share Posted October 23, 2014 Hi StuThank you for the quick reply. So the Way i'm Reading your calculations it's Best if i Got 4x 50 watt 12 ohm resistors. 14/14,9 *2 = 1,879 amps which is as close to stock as possible(2,9+12) Is this correcly understood.?Any other for or Against for choosing smaller ohm resistors ? Quote Link to post Share on other sites
Stu Posted October 23, 2014 Share Posted October 23, 2014 Yeah 12ohm would mean that the ecu is seeing the same current draw as the original injectors. HOWEVER - I'm not sure on how well the JAM ecu will do adjusting for the extra fuel supplied right across the map. Bear in mind that say at idle the ze injectors will be pumping in nearly 24% more fuel. The narrow band oxygen sensor will tell the ecu its running rich but I don't have any idea on how far the JAM ecu will be able to scale that back to normal idle AFR targets. Its likely to run like a dog/foul plugs (and potentially run hot with that much fuel) until the map is adjusted back. Let alone at boost - Im not sure if the narrow band sensor does anything at all in the positive pressure zone. Just something to consider. Quote Link to post Share on other sites
patman Posted November 3, 2014 Share Posted November 3, 2014 Sorry for butting in this thread as I'm curious too about injectors and as I'm in the middle of rebuilding my engine I want to check my injectors are all working, I'm just presuming for stock injectors when testing them with an ohms meter is it all 4 should read about 12ohms is that correct? Thanking you in advance Pat Quote Link to post Share on other sites
Mathias10 Posted November 3, 2014 Author Share Posted November 3, 2014 there are at 14.8 ohms //Mathias Quote Link to post Share on other sites
patman Posted November 3, 2014 Share Posted November 3, 2014 Thankyou so much mate this is the next thing on the check list Pat Quote Link to post Share on other sites
Johnboy GT Posted November 3, 2014 Share Posted November 3, 2014 Suggest Stu's explanation becomes a sticky if there isn't something similar already Admin? Cracking Explanation John Quote Link to post Share on other sites
Stu Posted November 3, 2014 Share Posted November 3, 2014 Did you end up trying the ze injectors on the JAM ecu? Quote Link to post Share on other sites
Mathias10 Posted November 4, 2014 Author Share Posted November 4, 2014 (edited) I didn't end up with the ze injectors on the jam ECU due to the connectors being different than the stock one.was told they would fit, but they definitely dont. so injector project is on hold for now. but thank you very much for your expertise & answer //Mathias Edited November 4, 2014 by Mathias10 Quote Link to post Share on other sites
Stu Posted November 7, 2014 Share Posted November 7, 2014 No worries. Maybe try some 330cc Mazda injectors, should be ok on the stock or JAM ecu. Use a rrfpr if your running out of fuel on boost Quote Link to post Share on other sites
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