Piggyback Heaven – How To Install SAFC NEO in a SRT4

As many of you know, we here at Pro Street love the 4G63 and the many vehicles it came standard in. After all you are talking about a 2.0L motor that was robust enough to support 400whp on stock internals, it’s not something that was commonplace back in the mid 90s.

Which leads us to our SRT-4, one of our personal favorite vehicles despite it’s sluggish sales and limited production run by Dodge. A stout motor with plenty of grunt to spin a big turbo, and a relatively cheap price tag in the high teens make this 4 door coupe a bang for the buck buy.

We take a look in today’s chapter of Piggyback Heaven at installing a SAFC NEO into a 2005 Dodge SRT-4. We’ll be showing you how to install SAFC NEO in a SRT4 turbo.

The age of piggyback computers has definitely passed us, but for cheap reliable tuning the SAFC NEO works fairly well with the SRT-4, especially given it’s Manifold Absolute Pressure (MAP) setup. We do install several AFC NEO’s and while it works fine on this vehicle, there are some limitations you need to be aware of.

SENSOR VOLTAGE DIFFERENCES

While many of the imports and vehicles we install this NEO unit into operate in the 0-5 volt ranage the SRT-4 does not, instead opting for the 3.5-7 volt range. This can cause a multitude of problems if you do not know what you are doing.

The key to operating and tuning this vehicle using a piggyback such as this lies in the OBDII Short Term Fuel Trim (STFT) and Long Term Fuel Trim (LTFT). When the PCM in the SRT-4 sees an overly rich condition created by a bigger fuel pump or fuel injectors it wil decrease the trims in these tables. A lower trim value means the PCM is trying it’s best to restore the operating AFM that the manufacturer dictated.

We now have a solution to this sensor voltage difference, for this AFC Hack for Super AFC NEO’s click here.

But because the MAP voltage and TPS voltage are out of range, you are talking about only reading the upper half of the NEO’s 0-5 volt range. This isn’t acceptable when you are tuning on load dependent parameters, or part throttle for that matter. As the PCM will not know what throttle position you are using for lower throttle usage, it will be difficult to determine a good cruising speed and tune based on the traditional throttle position sensor.

This often leads to SRT-4 owners being left high and dry after their Long Term Fuel Trim ( LTFT ) reaches a value of -14 or below, triggering the P0170 Check Engine Light, Fuel Trim Malfunction. This issue becomes worse when you add larger injectors like a 660cc injector or higher (66lb or higher).

Because the AFC NEO isn’t truly adjusting the fuel trims, the PCM can only operate on values manipulated by the AFC NEO, tricking the ECU into thinking there is less air entering the engine and therefore adjusting the fuel trim as we need.

The solution? Use your MAP sensor as the throttle position sensor for this install therefore making your NEO a boost dependant fuel controller. We’ll show you how in the last segments of this How To Install SAFC NEO in a SRT4 writeup.

Tools you will need for this install :

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

The PCM is located in the engine bay, to the right of your radiator. Free the PCM by undoing the 10mm bolts holding the PCM to the chassis and unplug all the PCM terminals, starting with the C1 connector first. The C1 connector is the fourth plug down on your ECU harness and will be lined with a BLACK plastic housing, this housing must be removed to access the terminal pins and wires.

It can be difficult to open up this connector, as you must depress all four mounting tabs and pull the cover off to expose the wiring and pinouts.

Now we move onto the power connectors after your grounds are done, locate the C1 ECM Connector and the pin 11 on it. This wire is a blue wire with red stripe, and we’ll be teeing the red wire with white stripe and red wire from your AFC harness.

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 we’ll be tackling the voltage issues you read about earlier in the How To Install SAFC NEO in a SRT4 writeup, starting with the Manifold Absolute Pressure (MAP) sensor. The wires for the MAP input on the NEO harness are white and yellow. This connection is also the only connection you will have to cut for this How To Install SAFC NEO in a SRT4 install.

We’ll be installing the MAP sensor as well as the (throttle position sensor ) TPS sensor (gray wire) at this step. The wire to cut is pin 23 on the ORANGE PCM connector C2.

The Manifold Absolute Pressure sensor wire is a dark green / red wire and should be cut with enough length on either end to solder an additional lead. The yellow AFC wire must be soldered into the wire leading INTO the PCM. The white wire is then wired into the harness side of pin 23, make sure these connections are solid and soldered as the vehicle will not start if there is a disconnect.

Now, to resolve the TPS voltage issue we spoke of earlier we will NOT be teeing the throttle position sensor into the throttle input going to the PCM. Rather, we’ll be using the vehicle’s MAP sensor as a throttle position sensor, therefore making the AFC NEO a high throttle / boost tuning solution.

Now with the white wire and yellow wire soldered in, take your gray AFC wire ( throttle position sensor ) and wire that with the white NEO wire. Make sure that the gray TPS wire is wired in CLOSER to the actual MAP sensor that is located on your intake manifold.

What will this do?

By using the MAP sensor as a Throttle position point, we are utilizing the AFC NEO as a tuner based on engine load as opposed to guessing and hacking our way through different voltage ranges.

What drawbacks will this have?

As your AFC NEO will not know the true throttle position of your vehicle, it’s imperative to have your fuel pressure and injector pulse width as close to factory specs as possible. You will not be able to fine tune the part throttle map without getting into boost. This may seem troublesome to many, and we agree there has to be a better solution.

Pro Street’s 5V 3BAR MAP Solution

Here is another picture of the wiring and how it’s supposed to be connected, please reference the brown wire shown is actually the gray TPS wire and the light green with red stripe wire is the NEO white wire. Now it’s time to tee the RPM signal into your NEO harness, this wire should be green and you may require a tach adapter for usage of your tach. We are using MSD part number 8913

Connect to the gray Tach adapter wire to the output for the tach driver 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!!!

How 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.

What is the blue wire mod?

The “blue wire mod” is a common term thrown around for the optional input that the AFC NEO has. You can use this wire to tee into your narrowband 02 sensor and give you real time on the fly measurements of your vehicle’s a/f ratio as seen by your PCM.

To find out how to perform this mod, check here. For our 0-5 voltage range throttle position sensor AFC hack for the SRT-4, click here.

Happy Boosting!

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