Joe, why tweak the AFM? That meters air. The injectors are driven by the code in the DME chip as far as I know.

True. I'm curious how this system would react to intake/exhaust/displacement changes and how it would compare to a Steve Wong solution.

The AFM is more than just an air meter. The DME uses the AFM metered air signal to calculate when and how much fuel delivery and spark timing. That's why all the hubbub over replacing it with a more precise MAF or Map sensor, while the AFM is still mechanical and infinitely adjustable...no code necessary.

Cheers,

Joe

Hi Joe,
Sal's system would cost $600 more on top of the Ford injectors. I can understand the desire to save money. The AFM is indeed very adjustable, and with a good wide band O2 sensor or dyno you may eventually get an acceptable result.
Sal has done this on the fuel and timing side with his chip and DME.
Good luck with your efforts.
Dave

More than saving money, I still need to smog here in Cali. I think I could get away with the injectors but all the rest would be questionable on the visual. These smog techs here in Marin Co are pretty sharp on older 911s and I wouldn't want to push my luck.

My paranoia tells me to avoid any potential problems for myself or future owner...


Joe

Do not attempt to put these 24# injectors in a stock system with a stock DME! Even though flow wise the are close to stock the injector characteristics are way different. These FORD injectors are top notch matched set of modern day 6 hole injectors but the inj offset times are very different as is the low and high slopes. I've totally re-written the fuel model in my chip to match these injectors perfectly.

I'm also very confident that if a car passes California smog with the stock setup it will pass with these injectors as well, most likely even better numbers simply from the much better low flow atomization.

The reason I sell chips with injectors is simply because I have to have at least one thing rock solid, either I need the air model or the injector model solid. Or with my MAF both are solid. With my injectors + Chip working with the stock AFM I know I can trust the fuel model so any deviation in AFR I know is from the AFM out of calibration or Fuel pressure sightly off. But if I have a chip with old injectors, old AFM and unknown Fuel Pressure I just chase my tail trying to figure out what's causing the deviation. These 6 hole injectors can be sourced for a fraction of the cost of OEM ones and are far superior technology, this is why I mated them to my chip.

Hope that helps.

Joe,

You may achieve some level of tune by tweaking the AFM but you will never properly model the fuel doing that. It's not possible, the injectors are very diffrent than the stock ones, not just the flow rate, the bigger issue is the on and off ramp times and the low and high slopes. If you want to really understand this get 2 books from Greg Banish he covers these topics in great detail.

Just to give you and idea of what I'm talking about see this video from Greg:
https://www.youtube.com/watch?v=JZmV10pFsCM
He clearly shows the dangers of not understanding how injectors actually work.

Here is a good primer.

https://eficalibrator.files.wordpress.com/2014/09/fuel-injector-article.pdf

Long story short, even if you adjust your afm for ideal afr's with the new injectors, you could still be way off on your fuel delivery... And this down on power and efficiency. You would just be tuning around a problem. The above two books are great!!! Greg banish works as an oem engine tuner... And does work on aftermarket stuff because it is so easy and relaxing for him.

To get the most out of a modern injector... You need a dme that will talk to them correctly. I also see the benefits of modern injectors... That is why my DME is out of my car to mail to Sal. No more 200-250$ an injector, for solid, but 30 year old tech.

Great article, also written by Greg!
Bottom line, you can't just drop in any injector and expect it to work properly. Sure some may work, or you may think they are OK but if not properly modeled you get injection time deviations. Like they over fuel at low pulse widths (below 2ms) and under fuel at the higher PW (above 6ms), if this happens you just leaned out WOT conditions! And if the inverse happens you can easily over fuel at WOT. You will never get this correct by just adjusting the AFM. You could tune around issues like these by tuning fuel trim maps in the chip but that's also not the correct way to do this. What I did is re-write the entire injector model portion of the software using Greg's principles. My code even has low and high slope modeling ability, the stock 84-89 code does not. Back in the 80s they simply did not fully understand dynamic injector characteristics. Plus the OEM injectors are low-impeadance and are not that diffrent on the low and high slopes but most modern day hi-imp injectors are very different on low and high slopes, you must provide a way to model for this.

If you go with Sal's AFM system, which is the subject of this thread, the purple injectors are the only visual clue to anything non-stock. The AFM is stock and the chip is not visible. For the additional $600 you get a system that will work well and very likely pass any emissions measurement.
Not sure what you mean by "all the rest would be questionable on the visual".
Good luck,
Dave

I'm not to sure the MAF would pass as the stock AFM. Might be a dead giveaway. I'm telling you these smog techs 'round here are pretty sharp.


Joe

There is no MAF in this system. It uses the stock AFM. He does have another system that uses a MAF, but that is not the subject of this thread. Sorry for the confusion.
Dave

Thanks for clearing that out.

Joe

So it is quite obvious these Ford racing injectors would not work at all in my stock system. I would have to match the stock injectors low imp. and flow to have any chance of success and hopefully in the multi hole disc type for improved spray pattern. Not that I am having any issues since my car is running perfect but I'm always looking to make it run cleaner, better and smoother (or more perfect) if that's possible and at the same time, the most cost effective way.


Cheers,

Joe

I've been following this thread with great interest. I am very attracted by the idea of modern injectors and an updated and thoroughly checked out Motronic unit. My engine is apart right now, so I'm not sure going this route right at this time would be smart. I'm thinking I'll send my injectors out for a clean and inspection by Mr. Injector, put the engine back together and running so I have a baseline, and then go with Sal's system. Thoughts?

That couldn't hurt. Changing the injectors is an hour or so's work. Once you know your engine is running well as stock, then you can go with Sal's system. If you went with Sal's outright, you would not know if a problem was your engine build or Sal's system.
He is a pleasure to work with and so far there is a significant increase in smoothness and throttle response. No parking lot jerk, which maybe you did not suffer. It was a great experience to work with Sal, and pick up even a tiny amount of his knowledge.
Good luck,
Dave

I always suggest starting with a stock setup as a baseline. I have a few simple tests I always have someone run before we touch anything. You can't expect a chip to fix mechanical issues or other engine issues. It's very wise to start with the stock setup especially on a fresh build. Few exceptions would be extensive mods like twin plugs, you could never run that on a stock chip anyway.

Joe,

The stock DME can run hi-imp injectors without any issue, what you have to do is build a chip that can properly model them and that's not easy. But the DME it self needs no changes to actually run the injectors. Rule of thumb with EFI systems is that a lo-imp designed system can run hi-imp injectors but not the other way around, you CAN NOT take a hi-imp EFI and put lo-imp injectors in it, you will cook the injection driver circuit!

Sal,

I stumbled into this Jeep forum and am basically trying to duplicate what they are doing. Also, it seems the Jeep 4.0 injectors flow very close to Carrera injectors.

0280155703 injector swap, runs good! - JeepForum.com

Injector upgrade thoughts. - AUSJEEPOFFROAD.COM - AJOR

I already picked up a set of 2.4 4 cyl. Caravan injectors to try out but am waiting for EV6 adapters I ordered. Meanwhile, I'm looking into picking up a set of '96 Neon 2.0 injectors and these will not need the adapters. They have a flow of 238cc (22.6 lb) @ 43psi, Part# 0280155703 (OEM# 5277739) which is virtually identical to the Carrera injectors.

So, off to Pick 'n Pull to see what I can come up with. They charge $7 per injector but this weekend is half price...can't wait.

I'll let you know how it goes.


Cheers,

Joe

Joe,

If they are hi-imp injectors they will not properly work without chip changes, even if the static flow rate is exactly the same they will not work because hi-imp injectors typically have 2 times the on time. Our lo-imp stock injectors have a inj offset time of about 0.3ms (the amount of time it takes for injector to open) but most hi-imp injectors are well above 0.7ms this is a huge difference at low flow rates of about 1.8ms (this is the overall pulse width at idle and low loads for our cars). You are risking some significant compromises using hi-imp injectors without properly modeling them in the software on the chip. It has taken me years to properly understand and code for things like this. I also attempted what you are trying to do, I finally had to re-write the code to get it correct.

What will likely happen is that you may hit the target afr at lo loads but then be way rich at WOT or visa-verse. Without properly modeling the offsets and the lo and hi slopes you will never get fueling 100% correct. And making matters worse is that hi-imp injectors have a lot more deviation in lo and hi slopes.

To just touch the surface of this topic see this video:
https://www.youtube.com/watch?v=JZmV10pFsCM
See the red line in that video, it illustrates just how different low and high slope can be in a hi-imp injector. Lo-imp injectors don't vary this much.