Piggyback Heaven – Installing a SAFC NEO in a SRT-4


Today we are installing the ever popular SAFC NEO into our Project SRT-4. While piggyback computers aren’t as commonplace today as they were 10 years ago, they are still quite useful for the tuner on a budget.

While I install quite a few AFC NEO’s, I don’t recommend this install for the SRT-4 due to the difference in TPS and MAP sensor voltage. The AFC NEO operates in a range from 0-5 volts, where as the SRT-4 does not.

When you add aftermarket injectors such as the 760cc ( or 76# for those domestic fellows ), you can cause all kinds of problems without a device to lean out the mixture. Using a SAFC, we aren’t truly “leaning out” or “turning down” the fuel, but rather fooling the ECU into seeing less air, thus accomplishing the same result.

OBDII vehicles such as our SRT-4 have 2 values you should keep your eyes on, the STFT ( short term fuel trim ) and LTFT ( long term fuel trim ). When the SRT-4’s ecu sees the overly rich condition created by the larger injectors and upgraded fuel system, it will decrease these values in a vain attempt to restore “normalcy”

The problem is, when the SRT-4’s STFT and LTFT reach a value of -14, the ECU throws the ever popular P0170 Check Engine Light, Fuel Trim Malfunction (Bank 1).

By installing our SAFC NEO, we can lower the airflow value before it reaches the ECU allowing us to adjust the injector pulse width and therefore leaning the vehicle out.

Tools you will need for this install :

  • Soldering iron
  • Solder
  • SAFC NEO
  • 10mm wrench
  • wire cutters

First you must undo the ECM, held to the chassis by 10mm bolts, then unplug the ECM terminals.

FIrst, locate your C1 connector, the fourth plug down on your ECM, it will have an BLACK housing.

Here is a look at front face of a ECM connector, the back of this connector is what you will need to pull off.

You will have to pull back on the mounting tabs ( all four ) and pull the back half of the housing off to expose the wires.

I really really really hate these connectors......

With the back half removed, we’ll start the wiring fun by starting with our ground wires. The two wires in question are brown and black, locate those on your AFC harness and find pin 18 on your C1 module.

Using your wire strippers, expose 2 spots of the wire approximately 2 inches apart. The brown wire needs to be soldered in before the black wire, and closer to the ECM.

With your grounds properly wired in and installed, we now move to the 2 power wires on the SAFC NEO. Locate pin 11 on ECM Connector C1, this pin is a blue wire with a red stripe.

Wire in your red wire and red with white stripe on the NEO harness to pin 11, in the same method as you did the ground wire. Make sure the red wire with white stripe is closest to the ECM.

Now with the power and ground sorted out, move onto the MAP signal wires on the NEO harness. These wires are white and yellow on the NEO harness, we will also be wiring the TPS wire ( gray NEO wire ) in at the same time.

Now locate pin 23 on orange ECM connector C2, pin 23 is a dark green / red wire. This wire should be cut, and the yellow NEO wire must be wired in leading TO the ECM.

The white wire is then wired into the opposite side, make sure to solder for best connection.

Now with the white wire connected to the vehicle’s MAP sensor, take your gray throttle position sensor wire ( gray ) and wire that inline with the white NEO wire. Make sure to wire the gray TPS signal closer inline to the actual MAP sensor found on the intake manifold.

Why wire the gray wire into the MAP sensor? because of the SRT-4’s 3-7 voltage range, the NEO’s normal operating range of 0-5 will cause issues when tuning fuel trims according to throttle position. Using the MAP sensor, we can tune for engine load, as opposed to guessing and hacking our way through different voltage ranges.

Here is an example of this wiring, please note the brown wire depicted is the actual gray TPS wire, and the light green / red wire is the NEO white wire. Sorry I had to extend the wires using another loom and didnt have colors available that were close to gray or white for that matter.

Now find your green RPM wire on the NEO harness, this should be wired into a tach adapter, msd part number 8913.

Connect to the gray Tach adapter wire for a consistent rpm reading based on the vehicle’s spark.

Now with your NEO fully wired up, make sure to pick up some loom and clean up your rat’s nest!!!

Now to setup your AFC NEO, go into the menu and select sensor type as “Pressure” as your SRT-4 operates on a MAP sensor.

Select the “in” value as 10, set the “out” value as 10 as well.

Go into the car setup, and change the cylinder value to 4 and set the “thr” setting to the arrow pointing up and right.

Now go into the “TH-POINT” Menu and set your throttle values to 20% for low settings and 80% for high throttle.

For example if your MAP sensor sees load under 20 percent, then it will use the low-settings on the AFC for adjustment. Anything higher than 80% will run off the high throttle map and anyhing inbetween the two maps the neo will interpolate between the 2.

Now run the NEO Harness inside the cabin, and you are all set!

Happy Boosting!

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3 thoughts on “Piggyback Heaven – Installing a SAFC NEO in a SRT-4

  1. Pingback: Case Studies : Apexi Super AFC Wiring Diagram : How to install a AFC. | StockSpyder

    • Hi Keith.

      That would really depend on what kind of ecu or management you are running now. If you are wiring this into a Karmen type vehicle, there will be left over wires which would have normally be meant for MAP based or hotwire based ecus. You’re very welcome and glad it helped you out.

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