Can't get fueling right

[smokeshow]

I switched to the Ford LU80 injectors several months ago and have had driveability issues ever since. The injector data is good (as far as I know...), but its difficult to nail down fueling. During high vacuum decel (around 14inhg to 20inhg) the wideband slowly swings rich to settle around 11:1 AFR until I roll back into the throttle again to increase manifold pressure. Also, during tip-in, it goes momentarily lean, 16+ AFR. I have tried adjusting transient fueling by increasing the values a little bit, but it made no change. Another problem worth mentioning...I always have to hold the throttle down a bit on startup and slowly let it out as it idles. Otherwise the engine dies immediately after it fires up. I've tried all the normal tables, base idle airflow, STIT, timing, etc...no change. I think its still injector related.

I haven't been able to put a good tune on this thing because any work I do in the VE is just covering up what ever the error is. Pretty frustrating... Anyone seen/solved a problem like this before? Will upload a tune if necessary, just fishing for someone who has seen this before. Thanks in advance.

[IDRIVEAG8GT]

You scale the cranking VE any?

[smokeshow]

No. What would that change?

Here's a screen shot of the rich decel that happens during very low manifold pressure situations.

[IDRIVEAG8GT]

Cranking VE set to 50 will make the truck start the way it should. Otherwise your data is off, and I know you're running a boost referenced FPR, if anything she should go lean while decelerating, not rich.

Sorry if I seem blunt Jake, I'm tired as shit.

[Nodnarb]

It goes rich because you're at the injectors minimum pulse width.

[Snyper]

Cranking VE set to 50 will make the truck start the way it should. Otherwise your data is off, and I know you're running a boost referenced FPR, if anything she should go lean while decelerating, not rich.

Sorry if I seem blunt Jake, I'm tired as shit.

Explain this a little more...

[IDRIVEAG8GT]

Jake you need to turn your DFCO on as well. That should set most of your problems straight.

Snyper: if the tune is scaled by 50% to accommodate the injectors, the ECM uses the cranking VE to aid in starting no matter wether you have it in pure MAF or not. From the factory it's set to 100 across the board. It needs to be set to 50 to prevent over-fueling on start up.

Jake is a friend of mine, and we run nearly identical fuel system setups, and since total fuel pressure is controlled by manifold vacuum/pressure, this tends to screw with the factory calibration.

[smokeshow]

As I told Robbie over text, I shouldn't need to use DFCO to lean it out. It should maintain stoich with it disabled. I have been tuning VE using my histograms and DFCO messes with my values, so thats why I have it disabled. I'm wondering if with my 1:1 FPR the ECM adds pulse width from the offset table because of a larger pressure delta when its in high vacuum. The IFR table is static because of the FPR...should the offset be static for pressure delta as well since there technically should never be a pressure delta?

[IDRIVEAG8GT]

You can hack it a bit and set the Injector flow rate down a few pounds in the high vacuum situations, and that should allow it to be leaner during deceleration. It's a hack, but works. Stupid Ford injectors. I hate the Ford part.

[Snyper]

Ohh I did not know the tune was scaled. I had to do that when mine was scaled.

[smokeshow]

I shouldn't have to hack it. I know half the guys on this forum would cringe at seeing a tune like that. There is a right way to do it, I just need to get the right info to do it.

[IDRIVEAG8GT]

I shouldn't have to hack it. I know half the guys on this forum would cringe at seeing a tune like that. There is a right way to do it, I just need to get the right info to do it.

Well sure if you actually have the right damned injector data it would be perfect all the time, however that's not the case as it seems.