New EFI conversion issues

[mfoster80]

Hi, I just converted to EFI (fox-body set-up). It is idling fine and seems to be driving well at lower speeds but is lacking power at WOT and on the highway. The Bronco has several upgrades (bigger TB, slightly bigger injectors, aluminum heads, long tube headers) not to mention the transmission and rear end are not mustang.
I've got the WH efi harness and am running an automatic computer but my transmission is a NV3550 (I haven't thought this should matter as they don't communicate).
Anyone else experienced this? Thinking I may need a tune/chip but have no experience in this. Thanks in advance.

 

[oldiron]

Gear and tire size?

 

[Sporto]

A tune is probably a good idea. When you change out injector and TB size, you can inhibit the computer's ability to make the correct fuel/air/timing corrections. I would research "EFI Guy" online, he is really good at the Explorer EFI, and probably just as good at the Mustang computer tuning as well.

Just my .02

Rich

 

[Timmy390]

X2 on both posts above. I assume 302?

Tim

 

[904Bronco]

X3 on both above posts as well.

You need a tune to compensate for the changes you made... Auto trans ECU's are a little more forgiving with a manual trans. The other way around can have some issues.

Garry, EFI Guy, can get you squared away... Good luck with your project.

Doug

 

[EricLar80]

(bigger TB, slightly bigger injectors, aluminum heads, long tube headers) .

Every one of these could individually warrant a tune, let alone all of them together.

The biggest issue is that your computer has no idea how much fuel is actually going into the engine because it cannot compensate for more than like 5% off. So if you went more than (19*1.05) 20lb/hr injectors, which I am sure you did, then your fueling is definitely off. Especially at wide open throttle when it is dumping fuel into the motor.

The longer headers cause the timing of fuel corrections expected to be seen by the O2 sensor to be incorrect. The change in heads and bigger TB change the dynamics of airflow through the intake so manifold volume values could change depending on how it and revs after fuel is adjusted. Spark will be off due to the new heads. Full load scaling will also have to change due to more efficient heads and TB.

 

[mfoster80]

33" tires and 4.11 rear end.
Thanks for the feed back. Besides Garry the EFI guy, any other recommendations on a tune/chip?

 

[oldiron]

To my knowledge there won't be an "off the shelf" tune available for all the variables involved. To ever run right, that collection of parts will HAVE to be professionally tuned. Properly tuned it should be awesome to drive. Good luck.
Greg

 

[BroncoChicken]

33" tires and 4.11 rear end.
Thanks for the feed back. Besides Garry the EFI guy, any other recommendations on a tune/chip?

Garry is the best you will find to help you with this. He’s a magician with tuning.

 

[MeyerzBronco]

Hi, I just converted to EFI (fox-body set-up). It is idling fine and seems to be driving well at lower speeds but is lacking power at WOT and on the highway. The Bronco has several upgrades (bigger TB, slightly bigger injectors, aluminum heads, long tube headers) not to mention the transmission and rear end are not mustang.
I've got the WH efi harness and am running an automatic computer but my transmission is a NV3550 (I haven't thought this should matter as they don't communicate).
Anyone else experienced this? Thinking I may need a tune/chip but have no experience in this. Thanks in advance.

Needs a tune. You can’t expect to throw a bunch of parts together and think a stock tune will work. I used Dynamic Powertrain in Huntington Beach. Steve. 714-373-0068

 

[nvrstuk]

Difference between a tune and what Garry can do -especially if you have a wide band O2 sensor is he can dial it in perfect. I mean perfect.

A chip is a "best guess" tune. You give some tuner your specs and he throws all those factors into a big box, shakes it up a couple dozen times and sends you a chip which is pretty close. Close enough that it runs good and you will never know how much better a real tune can/will be.

Garry is the go to guy for several reasons.

 

[Eoth]

As everyone is encouraging, Garry is the "go-to" person for this type of issue. Your other option is to look up a local "Dyno Tune" shop in your area (quick Google search shows several in your area). They would certainly be able to get you dialed in but expect to pay a decent amount of money for their services (dyno time is not cheap).

 

[garberz]

If you put the stock throttle body and injectors back on, it’ll probably run perfect.

Mark