Chrome Tuning Large Injectors

[Chris@Rvengeperformance]

First of all none of this would be possible without Greg and others who have contributed to the Chrome Ecu project. Please visit chromedecu.org to get started flash tuning your 3/s!

Also, please read the stickies in this form with Greg (Monochrome's) tuning guides. Don't start tuning your ecu until you have read through it several times.

If you use a relatively tame injector setup with known latencies and values then you won't really have to change a ton of tables to the car running basically decent, but the larger your injectors get or the more into uncharted territories you get into then the more tuning that will be required. You also can't necessarily rely on latencies posted ANYWHERE. You can't rely on what I post in here. You can't rely on what EVO guys are running and you can't rely on what injector shops testing results show.

Any of these settings MUST be used as GUIDENCE ONLY. Don't change settings you do not understand and don't expect mine or anyone else's settings to be the silver bullet for your car. EVERY car is different. Even if all components are exactly the same. Your injectors may even be different enough from another of the exact set and type of injectors due to manufacturing tolerances.

Your engine's airflow is not going to be the same as mine. Your alternator may put out a different voltage. Your FPR may not be new like mine, etc and etc.

Do not get discouraged if your settings require quite a bit of trial and error and deviation from accepted or posted values. In fact the numbers aren't nearly as important as the fact that the car runs to your satisfaction. Don't get hung up on scalings or latencies, etc and think your car is broken because your settings do not match someone elses.

Persistence is key. If you run into a troublesome problem keep a journal. Sequentially number and date your Chromedecu rom files. If you don't approach this scientifically then it would be best to let someone experience tune your car.

I wanted to post these settings because it took a long time to arrive at them and the amount of reductions in some of the startup tables are a lot more than I would've expected. Hopefully it will help someone get closer to the ballpark before starting.

I am running the following:

DR750s
ETS FMIC
EVO 399 MAF with huge airfilter
DEJON intake pipes
Tanabe Medallion Touring Catback with concept G catless downpipe and DN precat eliminators
Ported Front exhaust manifold
Ninja Performance Fuel pump Hotware
Walbro 416 E85 Pump
FIC 1050 low impedence injectors
NEW stock FPR

It is important to note that my fuel regulator is likely overrun like crazy, so if you run a regulator that can handle the flow of this large, hotwired fuel pump then your settings may be a lot different than mine.

The car started and drove great with just some minor reductions in Cranking IPW and setting the injector scaling close. What I found was that if the car was stone cold it fired perfectly. If the car was hot (shut off less than 10 minutes ago) then it would start perfectly, but if the car sat for more than 30 minutes, but less than several hours it would tend to fire up right away and die from flooding. I tweaked the settings a incrementally to be sure I was seeing some improvement and not overshooting the values that it really wanted. What is also important to know is my car is a city car daily, so it doesn't get a chance to really get run hard everytime. Slowly over time my plugs were getting fouled. I'm confident that the settings I'm going to post below are what the car wants, but if I wouldn't have ran out the other night and did some full pulls through some gears I think the car would still have some issues.

If you find you have flooded the car a lot, but WOT is running well enough it would be wise to run the car hard periodically while trying different startup settings to be sure you are not just having issues from semi fouled plugs. Below are my settings:



These WILL not be the settings you arrive at, but the important part is the REALLY low cranking IPW pulse width I have to run to keep from fouling the engine. This is going to be necessary once you start running LARGE injectors on gasoline. Most likely you will need 30% more pulse width when changing to E85. I do plan to change to E85 soon, but I wanted to have a solid pump gas tune first.

I think these are pretty good injectors overall, but you may find your closed loop swings will be greater than an injector with better low pulsewidth resolution.

I really expect that if you were not running a Chromedecu then it wouldn't be possible to get the car to start perfectly under all conditions with injectors these large on gasoline. Especially with an overrun FPR like I have. Personally I find it easier to tune around the high fuel pressure at idle than to worry about more hardware. Please note this is by far not all the tuning I've done to this rom, I've over shared what I feel is most pertinent to startup.