4 hole injectors
Champion
Joined: Aug 2009
Posts: 3,015
Likes: 8
From: Western NY,
that is on my list...I have a new distributor to swap out and will have the shop resync it then... Question will they be able to see the peak performance sync point with whatever equipment they use point or will the sync procedure still put them at the old sync point?
Record Breaker
Joined: Mar 2009
Posts: 2,181
Likes: 3
From: Battle Ground WA
stock is plenty big enough and only flow about 80% of capacity.... however they stock injectors are the outdated pencil spray type which shoots a jet of fuel instead of a fine atomized mist so more fuel goes unburnt and combustion can be less efficient.especially during times like warmup when the valves arent all that hot yet... it is a common swap on the jeep forums and many pick up 2 to 3 mpg as a result... I imagine results would very depending on how hard the truck is already working... many here are always standing on the pedal to get from stop light a to b as fast as possible and they wont see much gain ...especially with oversized tires and undersized gearing... the stock gearing / tires are already pushing the limits of the drivetrain..
as far as the resistance thing... some say it does in fact matter and some say it doesnt.... injectors are controlled with pulses from the pcm... different ohm load could totally effect the actual pulse reaction and if the pcm has no way of knowing? I'm just guessing of course since I dont know the details of how much things would be affected.. I can say my idle doesnt seem quite as smooth with these 16ohm injectors even though fuel trims look fine....
as far as the resistance thing... some say it does in fact matter and some say it doesnt.... injectors are controlled with pulses from the pcm... different ohm load could totally effect the actual pulse reaction and if the pcm has no way of knowing? I'm just guessing of course since I dont know the details of how much things would be affected.. I can say my idle doesnt seem quite as smooth with these 16ohm injectors even though fuel trims look fine....
And again the resistance doesn't matter. Dead time does, and changing injectors without having a way to tell the PCM the dead time is silly IMO. I highly doubt it's possible to change the dead time in the factory PCM.
Spending a lot of time and money on something that isn't broke.
Champion
Joined: Aug 2010
Posts: 2,697
Likes: 3
From: Cape Carteret NC
There won't be a detectable peak.. what there will be is a really noticeable response to throttle.. it will ramp a lot quicker..
The amount you retard is going to be specific to your engine.. advance at the timing gear plays a role, the cam plays a role, the rockers play a role.. you'll have to play with it.. you have torque, and you can see the rate the trim fluctuates, which is where the only 'gain' in economy is.. it will be slight, but there..
The notion is, and while using heavier injectors: the duty cycle tightens up, but the volume doesn't.. you 'sposedly catch the intake valve after peak and closing, where it hits it with suitable volume in a better dispersed spray, which has an opportunity to provide a more measured injection for what's needed, and instead of losing some volume as the piston rises..
I saw maybe a mpg gain when retarding it, but the real gain was throttle response.. all told, after injectors, after wideband, after software to monitor trim, and after custom sct tune, I've got a grand or so into the project.. way too much for anything gained..
Auggie, you're almost there, so I rec you finish the project by adjusting sync, for other readers: don't waste your time or money... Put it somewhere else..
That's pretty much all I know about the subject..
The amount you retard is going to be specific to your engine.. advance at the timing gear plays a role, the cam plays a role, the rockers play a role.. you'll have to play with it.. you have torque, and you can see the rate the trim fluctuates, which is where the only 'gain' in economy is.. it will be slight, but there..
The notion is, and while using heavier injectors: the duty cycle tightens up, but the volume doesn't.. you 'sposedly catch the intake valve after peak and closing, where it hits it with suitable volume in a better dispersed spray, which has an opportunity to provide a more measured injection for what's needed, and instead of losing some volume as the piston rises..
I saw maybe a mpg gain when retarding it, but the real gain was throttle response.. all told, after injectors, after wideband, after software to monitor trim, and after custom sct tune, I've got a grand or so into the project.. way too much for anything gained..
Auggie, you're almost there, so I rec you finish the project by adjusting sync, for other readers: don't waste your time or money... Put it somewhere else..
That's pretty much all I know about the subject..
