stprasinz Posted July 25, 2010 Share Posted July 25, 2010 Ok I just swap the 300zx ecu per the afshin write up, well actually 280z turbo's write up, with it being an 81...well I'm haveing a problem with horrible rough seems like only 3 cylinder when below 2700-3000?? seems like it may be related to batch firign mode? But heres something to make it weirder. When I first did the swap, I left the resistor pack in place. It ran perfecty fine with them in place. I haven't tried to reinstall them, because thats a pain of wiring that back up, and seems like that since they aren't supposed to be there.... (84 ecu, 280zx turbo inectors) and the ecu also seems to be relatively hot, well MUCH hotter than normal.... I hope someone can help.. Quote Link to comment Share on other sites More sharing options...
Geking Posted July 25, 2010 Share Posted July 25, 2010 Ok I just swap the 300zx ecu per the afshin write up, well actually 280z turbo's write up, with it being an 81...well I'm haveing a problem with horrible rough seems like only 3 cylinder when below 2700-3000?? seems like it may be related to batch firign mode? But heres something to make it weirder. When I first did the swap, I left the resistor pack in place. It ran perfecty fine with them in place. I haven't tried to reinstall them, because thats a pain of wiring that back up, and seems like that since they aren't supposed to be there.... (84 ecu, 280zx turbo inectors) and the ecu also seems to be relatively hot, well MUCH hotter than normal.... I hope someone can help.. The 280zx turbo injectors have about 20% less resistance than the z31 injectors. The answer seems a little obvious, and it is my guess that if your ECU is only firing 1/2 of the injectors it is doing that because the other bank may have slightly less resistance and it is shutting that bank down to protect itself from burning out. Using these injectors with out resisters can pull as many as 18 amps per bank. (2.3 ohm as minimum resistance per injector, 1/((1/2.3)*3) = .77, 14volts/.77 =18.2amps It is only 12 wires, try reinstalling the resistors. Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 25, 2010 Share Posted July 25, 2010 Batch fire is over 3500 on that ECU, not below. Quote Link to comment Share on other sites More sharing options...
stprasinz Posted July 25, 2010 Author Share Posted July 25, 2010 (edited) well, its only 7 wires, I haven't checked to see if the ecu is hot, since I pulled the resistor pack out.... . what ohm are they supposed to be for the z31 ecu. I don't remember which injectors I used.. as I have 3 comlete spare sets... I may have used z31... It just seems that if there are a few others doing the same swap, then more people would have the same issue also... I did not swap injectors 2+5 but people say they don't and still have good results, and that you don't notice on idle quality and such. Kinda bumming. just had the 280zx ecu do crazt things, of course after selling my other z31 harness ecu ect... now this I was thinking I would run this ecu(the 280zx ) fired off the crank and would be safer to run methanol and higher boost since it would be crank fired well that wasn't cooperating..... oh, and its 3500 rpm for batch fire mode.. I thought it was like around 2700... hmm, thats wierd so what does the ecu do at 2700? all my 300 zx's seem to go from only about 2,3 psi to spike and full spool; at around 2700, and a large spike in power there too... Not as noticable in a complete stock, but larger turbo free'd intake(filter) and a upgraded exhaust and its a large feeling.. is tha just me lol... heck my stock 300 with a k&n filter, and straight exhaust does it and its like a huge torque thrust in that.... but now I'm babbleing, I just think if I knew what the ecu was doing A( thats why I mentioned the batch fir thought thats when that happened) I would think it would be easier to diagnose... Edited July 25, 2010 by stprasinz Quote Link to comment Share on other sites More sharing options...
stprasinz Posted July 25, 2010 Author Share Posted July 25, 2010 (edited) misfire is a gross understatement here... I have switched injectors 2+5 as per the recomendation. And I hooked up the burn off cycle wire, and burned it off once..... no luck, I tried a 2nd ecu it was worse, like that the whole way through the rpms.... ... When I first started the car it was barely noticable... heres something else when it goes into the i don't wanna run mode it also goes super lean(16.00) not enough to have the af monitor say air.. but still!!!!! Boy if i could work on it in my driveway, I'd try alot more (ie are the inj. getting signal at the lower rpms? and that sorta thing... also If I disconnect the chts it idles up pretty high, and is still really rough, just idles up... Air flow meter also has pipe before and after both 3" so its a smooth signal...oh yeah, ecu still hot... plugs all look equal and good...(proper burning) Edited July 25, 2010 by stprasinz Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 25, 2010 Share Posted July 25, 2010 Is your tachometer accurate? How do you know your 2700 rpms is correct? Do you realize the injectors go from double-pulse per cycle batch-fire to a single massive pulse above 5000 as well? Can cause fuel delivery issues as well...5225 or some bizzare number. Quote Link to comment Share on other sites More sharing options...
stprasinz Posted July 26, 2010 Author Share Posted July 26, 2010 No tony I didn't know that... hmmmm. but its soi bad, that if I don't run above 3000 it is gonna stall... Like sometimkes I can get it to jump back up in r's but usually if I can't gear it don to make the r's go above 3 it stalls... and as close to 3 no I don't have a digital display tach, but close to 3000..... also when I let it sit and idle, its not simple vrrrrbmrrrrrrbmrrrrrrbmrrrrrrrmrrrrrr its more like blumpblumpblump and the motor is rocking..... its really sucking, cause it runs like a rapped ape, and I can't even be happy with driving it.... slap it back to na... lol right. maybe if I sprayed a 150 shot I could live with it for a week till I realize man I spent 100$ on nitrous this week lol... tommorow Ill use my timing light and verify that the encoder disc is in right(go to plug opposite side of dizzy and make sure its timed the same..... anyway.. I thinkits something in the injection pulses... but what? what could caues this!!!!! Quote Link to comment Share on other sites More sharing options...
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