You have to be kidding....the VAF measures AIR flow...not fuel.
Changing injectors changes fuel delivery...not air volume injested by the engine at a given RPM and load...thats what the VAF...MAF...or MAP sensor does.
Dude...read a few books on engine management

 

Don't be a hater bro!

 

I'm not...just trying to lead you 'into the light'

 

Jimbo, best of luck in your project. I think AWilson gave a very solid advice!
I will no longer respond to this thread, I no longer see it as productive...

 

The DME's interpretation of the input signal does not change because you put bigger injectors in the car. The DME still believes it has the stock afm and stock injectors connected. This is the game the Ford Mustang guys play with putting larger injectors along with a MAF scaled for the injectors. It works great to a point. I have a friend who did that with his Ford 5L V8, worked fine with 24lb injectors and a 24lb MAF. As soon as he went to 42lb injectors and 42lb MAF, it went to hell. I talked him into getting the Tweecer which allows one to implement the approach I take and his car runs perfectly now. He can now pick and choose any MAF/injector combination.

Again I will reiterate: You can put larger injectors in and effectively scale back the afm input, but you SHOULD remap the 3D fuel/ignition maps in the chip. The other approach is to reprogram the chip to calculate the correct air flow and required fuel for the specific afm and injectors. EACH approach can work, both require a reprogrammed chip. As to which I prefer, since the DME load value (which is derived from air flow and rpm) is spread out and used in so many places in the code and maps, it is easier to just change the air flow calculation than hunt down and change all the affected load values. Good luck finding someone to do that for you.

 

Everyone answered that your original question contains an incorrect assumption therefore they can't answer the question.

They are basically telling you that scaling is how you adjust the DME when moving to larger injectors. This is assuming two things. First, your chips are currently adequate for your setup. Secondly, the injectors are the only change.

If you are changing the injectors AND using a larger turbo, you will need remapped chips. These chips will have a map that can be scaled to multiple injector sizes.

At some point, the AFM (or MAF that is calibrated to emulate the AFM) will not be able to measure the load present. Basically, it has an upper limit on its ability to measure CFM of air.

So I guess we should go back and see what you are trying to achieve in whole. Are you just swapping injectors into a setup that shouldn't flow any more CFM? OR are you trying to accomodate a setup that will require more fuel for a given load?

 

I'm glad you agree with me TT. Your correct that I will be hard press to find someone to program a chip for me in this manner except for you or danno maybe. I guess I just will have to bail his *** out of jail. You sound like a stand up guy thats not one sided. On a side note. We all know how critical timing is on a 8 valve head right.

 

Please no side notes. Stick to the original confusing thread....

 

Now that some of you agree with me lets address timing. In theory I could scale back timing with the fqs. All I have to do is scale it back 37% and both fuel and timing maps will meet at the correct spot. What do you think about that TT? Pretty clever.

 

In theory all things are possible.

Now to get you from point A to point B.

• Go buy and install a DTA, SDS, TEC II/III, or Link, etc. aftermarket engine management system, take your pick.
• Learn everything about the system you selected and how it will work in your car.
• Bug the sh$t out of the manufacturer to help you with any problem areas (you paid for it).
• Go to a dyno and spend the day/week/month/year tuning the fuel and ignition maps, some people here will share their maps with you to get you started.
• Keep a detailed log of everything you do during this project (good and bad) and post it back here to help those who might want to follow your lead.
• Go enjoy the car.

This should get your car working with the 55lb injectors and MAF.

 

nice! hee hee

 

Danno if your out there and think that my idea would work please pm me. If you could give me a chip that will work as I discribed. Send me a mock up. I have a very close friend that happens to own the largest elevator manufacturing plant in the u.s.a. I could burn you an infinate number of chip in a clean room enviroment. Your chip will never again be faulty. And will be maf spicific.

 

Now you're talking.
Buy a chip from Danno. Thats your best idea yet.
See...I told you guys he was jerkin your chain

 

John and tt. It just came to me how your maf works. I will not post it here because I really don't what to hurt anybody's business by doing so. It's so simple it's not funny. But dam does it work.

 

Good for you, then all you have to do is to reverse engineer the Motronic program code and make the required changes.