Large Injector issues
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What ecu mate? What cams? Fuel pressure?
Have you set inj dead time? Inj timing? Do you have idle control?
I can tell you all about good/bad idle with big injectors. First of all, rochesters ate not the best. I had a set of 780cc inj on a wolf 4 and 272 which idled rich. It had idle rich otherwise it wouldnt idle. I changed the inj to Denso power enterprise 1000cc and idle improved significantly. Duty cycle decreased yet we could lean it out to 14:1 and still retain good idle. We put this down to inj spray pattern at low duty and low fuel pressure. Some inj require a certain fuel pressure to provide a decent spray pattern. Think of a cheap garden hose nozzle with low water pressure, it just dribbles out water but once it has full pressure it is fine. If you were to buy a good garden hose, at low pressures it would probably provide you with a much cleaner and more even spray pattern. So consider fuel pressure.
Duty, my experience has found that most of our 4g big inj setups idle with about a 1% inj duty. This is not good but can still allow for decent afrs at idle. You can try and reduce fuel pressure to increase duty, but this contradicts the fuel pressure statment above so you have to find the right balance. If your running closed loop, some ecus will not.close loop below a certain percentage duty cycle so look into that also.
Ecu, depending on ecu, make sure you have defined all your base settings precisely. Most ecus need inj timing and dead time values. This is important for your whole tune not just idle so get it right the first time.
Have you bypassed your resistor pack? Do you need to bypass it? measure your impedance and wire accordingly. This affects how much current your injectors draw which affects physical performance. Plus you could damage your ecu if done incorrectly.
Idle control, I have found that without aircon, powersteering and eng temp comp set correctly, it would stall constantly when these items were being used. Ps and ac when in use takes load off the crank hence drops idle. Voltage changes ie headlights, sub woofer, windows etc cause fluctuating voltages to the ecu/injectors. This changes your afr. Look at your afr and turn your lights on, if it goes leaner, play with your settings.
There is ALOT to idle tuning but the above is the basic.
You can look into using ignition to control idle once you've set the above correctly. I can explain this after if you get stuck. Typing on a phone is alot very fun.
Good luck.
Have you set inj dead time? Inj timing? Do you have idle control?
I can tell you all about good/bad idle with big injectors. First of all, rochesters ate not the best. I had a set of 780cc inj on a wolf 4 and 272 which idled rich. It had idle rich otherwise it wouldnt idle. I changed the inj to Denso power enterprise 1000cc and idle improved significantly. Duty cycle decreased yet we could lean it out to 14:1 and still retain good idle. We put this down to inj spray pattern at low duty and low fuel pressure. Some inj require a certain fuel pressure to provide a decent spray pattern. Think of a cheap garden hose nozzle with low water pressure, it just dribbles out water but once it has full pressure it is fine. If you were to buy a good garden hose, at low pressures it would probably provide you with a much cleaner and more even spray pattern. So consider fuel pressure.
Duty, my experience has found that most of our 4g big inj setups idle with about a 1% inj duty. This is not good but can still allow for decent afrs at idle. You can try and reduce fuel pressure to increase duty, but this contradicts the fuel pressure statment above so you have to find the right balance. If your running closed loop, some ecus will not.close loop below a certain percentage duty cycle so look into that also.
Ecu, depending on ecu, make sure you have defined all your base settings precisely. Most ecus need inj timing and dead time values. This is important for your whole tune not just idle so get it right the first time.
Have you bypassed your resistor pack? Do you need to bypass it? measure your impedance and wire accordingly. This affects how much current your injectors draw which affects physical performance. Plus you could damage your ecu if done incorrectly.
Idle control, I have found that without aircon, powersteering and eng temp comp set correctly, it would stall constantly when these items were being used. Ps and ac when in use takes load off the crank hence drops idle. Voltage changes ie headlights, sub woofer, windows etc cause fluctuating voltages to the ecu/injectors. This changes your afr. Look at your afr and turn your lights on, if it goes leaner, play with your settings.
There is ALOT to idle tuning but the above is the basic.
You can look into using ignition to control idle once you've set the above correctly. I can explain this after if you get stuck. Typing on a phone is alot very fun.
Good luck.
Am running an Autronic SMC, COP set-up and comp 272 cams. Have checked all the basics: compression, spark, timing. They are all fine. Tried playing around with the fuel pressure but it didn't seem to help the issues. It runs reasonably well when the plugs are cleaned but then goes downhill and the plugs get dirty and the backfiring start. Going to try some smaller injectors and see if that solves the problem. It also doesn't help when the last "so-called wiring guru" chopped off the temp sensor wire, fuel gauge wire, tacho feed and couldn't figure out how to get the thermostat fan going. Thanx for the help.
The injectors are listed and my tuner has heaps of experience with autronics. It will idle but it won't do it under 1000rpm and it hunts between around 1000 to 1600rpm. Are you using low or high impedance injectors?
Very interesting topic from toymods: http://www.toymods.org.au/forums/tech-conversions/49972-larger-injector-characteristic.html
Very interesting topic from toymods: http://www.toymods.org.au/forums/tech-conversions/49972-larger-injector-characteristic.html
JETGSR
CAPTAIN BURRITO!
dont panic had sard800 and haltech and 272's couldnt get to idle below 1000
and af were 13's at best any lower and hunt like crazy it is to do with dead time, your injectors and some other shit i cant remember.
it the words of the haltech techs "i've seen worse"
try getting your ign map better 750 - 1600 to stop your hunt start rich and go from there.
it is a bitch to get right and as soon as you think you have it - blip the throttle and it starts again
and af were 13's at best any lower and hunt like crazy it is to do with dead time, your injectors and some other shit i cant remember.
it the words of the haltech techs "i've seen worse"
try getting your ign map better 750 - 1600 to stop your hunt start rich and go from there.
it is a bitch to get right and as soon as you think you have it - blip the throttle and it starts again
My bc 272's idle fine around 900rpm and i have sard 800 low impedance running ecmlink. Nice an lumpy though and i love it. Not as big as yours though.
High impedance injectors appear more controllable when going the larger injectors over 1400cc from the reading i was doing when deciding if i should go bit anyway for future e85 use, you just have to do a simple rewire to run hiZ injectors, the new FIC hi-Z ones are based on the same series of injectors as the ID units.
That's said im running sard 800 low impedance ones and they are not noticeably different to my 560's once they were idled in right, using the data available online for them it was way off and they were not happy at all, don't expect the values available on the web or in the box will just work after punching them in. I just used it as a start and went from there to dial them in and them they are fine.
Rochester injectors and other based on them aren't know to be great in controlling low pulse widths form the reading i did before buying.
High impedance injectors appear more controllable when going the larger injectors over 1400cc from the reading i was doing when deciding if i should go bit anyway for future e85 use, you just have to do a simple rewire to run hiZ injectors, the new FIC hi-Z ones are based on the same series of injectors as the ID units.
That's said im running sard 800 low impedance ones and they are not noticeably different to my 560's once they were idled in right, using the data available online for them it was way off and they were not happy at all, don't expect the values available on the web or in the box will just work after punching them in. I just used it as a start and went from there to dial them in and them they are fine.
Rochester injectors and other based on them aren't know to be great in controlling low pulse widths form the reading i did before buying.
