I have installed new Accel #24 injectors in my Iroc, and I am going to need to adapt my chip for the new injectors.

What is a good starting point to begin tuning from?

Is it as simple as I think, just set it at 24 and then watch the INT/BLM data?

(Just changed the plugs, and don't want to foul them by going to rich first thing I do....).

 

I actually just found out that the injectors are rated at 39 or 39.5 psi or whatever rather than GM's 43.5 psi standard. I burned a chip with the injector constant at 24.xx but my fuel pressure is really low 34#. Sorry I don't have an answer for you yet. I probably will tomorrow.

 

I run 46 psi fuel pressure....

I know that the original GM #22's are set to 22.36 in the stock chip, so probably the #24's should be somewhere around 24.36 or so, but that's just what I think.....

 

Start at 24# and adjust it according to what your overall BLM needs are.

 

It's all in the math...

(sq root of (new pressure / old pressure)) X Old flow rate = new flow rate

Use the manufacturer's injector rating flow rate for the "old pressure" and what you have for pressure on your car for the "new pressure", then you can set your constant and know it's right by using the "new flow rate" for the value. Once the constant is set, the you can properly tune the entire RPM range with the proper tables. Here's an online flow calulator I found with a quick webcrawler.com search...

http://www.csgnetwork.com/fiflowcalc.html

 

its very setup-dependent, but i can tell you that my accel 24#'ers require the IC somewhere around 23.10 (whatever the closest possible value to that is) to get the proper trim settings.

 

I'll just bring a couple of test chips to the garage since i have unlimited blank eproms....

 

Mine are set to 24.3 and are still a little rich.

I'll burn a 24.5 chip today and see if that helps.

 

I haven't gotten into burning my own chip yet but I was wondering if I could change my 19# injectors to 21# or 22# without changing the constant. I know it will cause it to run rich. Could I compensate for that by lowering the fuel pressure? Would it even be worth it to go to a larger injector? See my sig for current mods.

 

No, just bump your fuel pressure up about 3psi from stock and you should be good.

 

Well, I think I need to replace my injectors. I think they are leaking. Pressure drops from 44 PSI pretty quick and a couple of them tick. I checked the resistance and they are all at 16.4-16.5 ohms. I was just wondering if I should put a larger injector in or stay with 19#.

 

The injectors should tick, that is the sound of them actuating. Have you checked the pump and regulator to see if they are causing the pressure to drop?

 

I only have 3 that are ticking. I have always heard that a loud ticking from the injectors meant they are going bad.

 

The ticking they should make sounds about like someone tapping on a glass window with a pencil point. If it is loud, as you can hear it 5 feet from the car with the hood closed it may be a collapsed/stuck lifter or exhaust leak. I don't think there is enough area inside the injector for the pintle to make a loud noise when it opens and closes.

 

I don't know about you guys but i've had some major issues with accel injectors. I know that accel knows about the problem and has refunded the cost of the injectors to a few people already.

personally I'd stick with the stock injectors as long as you can.. from there make small steps up

If the car is lean at wide open then tune it first see if you can get fuel back into it

 

I installed a set of Ford Racing 24# injectors in my Z last weekend and noticed the fuel pressure dropped from 46 psi to 38 psi. Is this to be expected? I'm kind of wondering if the f/p is right or if I have a weak fuel pump. I plan to burn a chip for them to cover the injector change.

 

What problem would that be? A problem just showed up with my Accels.

 

Im about to order up a set of accels, I have 22 would you go with the 21 or 23?? Also what kind of problems are they having, and do you recommend any other injector unstead of the accels

 

I've got 24's. Never had a problem.

 

Burned a chip last week based on BLM's being at 108 (minimum BLM constant) with 24# injectors. Now BLM's are for the most part around 124 - 128 and, sometimes under moderate to heavy acceleration 132 - 134 - 136. When decelerating it drops to ~124 then stabilizes at 128. Haven't tried any VE stuff yet. I am interested in trying some of Trax's procedures in his sticky on working with VE. I am still new to this stuff but, it is kind of neat to make changes and watch your results on the scanner.
This past weekend installed a set of SLP headers and still on jacks working on exhaust system, waiting on my Mufflex system so no research on tuning.