Metal Gen 5 (2015-2017) Throttle Bodies on a Gen 4 (2008-2010)

Steve M

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DISCLAIMERS

This is NOT a performance upgrade. I did this modification for three reasons:

1. Cosmetics - I think the metal throttle bodies look better, especially if you already have a Gen 5 intake manifold
2. Durability - the plastic throttle bodies never really let me down, but I've never liked them. They just look and feel cheap. I also had an incident a couple years ago where one of the blades stuck open briefly while coming to a stop, sending the car into limp mode. The only thing I could come up with was that it was caused by over tightening the hose clamp that holds the intake tube to the throttle body. I loosened the clamp a bit, and never had it happen again.
3. Just to say that I did - it was a fun challenge

This also requires a few specialty tools that most will likely not have easy access to:

1. (Mandatory) A good crimper that makes the proper crimps for the harness (not hard to source though)
2. (Mandatory) The ability to do a throttle relearn (covered with HPTuners software for me)
3. (Optional) The ability to flash the updated throttle body calibration that goes along with these (also covered by HPTuners)

Thankfully, I had all of this stuff covered, so I could do everything from the comfort of my own garage; no trip to the dealership required. For most, the throttle relearn can only be done at a dealership with a competent Viper tech. An updated calibration without HPTuners could likely only be handled by Arrow/Prefix, but I ultimately found this to be unnecessary.

Enough of that...if you are still interested in how to do this, read on.

First, the finished product:

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Compared to what was there (old pic, but you get the idea):

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I hate those oil snail trails soooooo much.
 
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Steve M

Steve M

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Background

I've been wanting to do this for years. It took a long time, but I was finally able to piece together all the information thanks to a little digging around. Most everything is publicly available if you know where to look. And now, you shouldn't have to.

The 2008-2010 Gen 4 and 2013-2014 Gen 5 cars all used the same basic, plastic throttle bodies (Mopar part number 53032837AA). These are made by Bosch, and have a 74mm diameter opening. They can be swapped between the Gen 4 and Gen 5 intake manifolds with no problems, as you'd expect.

The 2015-2017 Gen 5 cars switched to metal throttle bodies (Mopar part number 5184349AC). It is unclear as to why, but I suspect it had to do with eliminating the number of different parts used across the FCA lineup. Either way, these throttle bodies are also made by Bosch right here in the good ol' US of A, and are the same ones used on the Pentastar V-6 engines. They have a 76mm diameter opening, so they are slightly larger than the plastic throttle bodies. Bigger is usually better, but in this case, even the smaller twin 74mm throttle bodies will flow more air than our V-10s can ingest.

The mounting holes are the exact same, so they will bolt right up to any Gen 4 or Gen 5 intake manifold without issue.

Unfortunately, though, they use a different wiring connector. This is where things get a bit sticky. Here's a pic showing the differences:

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As you can see, not even close. Yes, they both use 6 wires, but the similarities end there. To make matters worse, they also reordered the pins. But fear not, for that information is out there too. I don't remember who tipped me off to this (probably Jack B), but there's a wonderful website where you can look up pretty much all of the different connectors for Mopar vehicles by year and model:


The website isn't perfect, but for what I was doing, the information was 100% accurate.

From that site, here are the pin-outs for throttle body connectors on my 2008:

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Cross reference that to the 2015+ cars, and you'll see the differences. I used that information to generate this picture (Note: the color scheme has nothing to do with any of the existing wire colors):

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As you can see, the 6 basic functions are the same, but they've been reordered. It's not a huge deal, but you need to keep track of what you are doing to make sure you get it right.

You have two basic options for how to deal with this:

1. Make an adapter harness (what I'm using currently)
2. Re-terminate the existing wiring harness so you can use the correct connector (I might do this in the future, but only if I start having issues with the adapter harnesses)

These throttle bodies also use a slightly different calibration. In HPTuners, this is handled by the Desired Throttle table (Engine > Airflow > Electronic Throttle), which is set up by commanded throttle vs. throttle area. Basically, you command the PCM to give you some amount of engine torque output with the gas pedal (i.e. commanded throttle); the PCM then references the Desired Throttle table and determines how far to open the throttle bodies to give you enough open cross-sectional area (i.e. throttle area) that will allow the correct amount of airflow to meet that demand. The PCM is torque-based, and as such is constantly gonkulating and performing table look-ups to figure out how much airflow, timing, and fuel are required to meet driver demands (e.g. I want to turn my tires into liquid rubber, like right now) on top of all the other demands that keep the engine running (e.g. the torque needed to spin the alternator, run the A/C, etc.).

Over the past few years, I've managed to collect calibrations from 2008, 2013, and 2017 Vipers, each of which are slightly different. This graph illustrates that:

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The recalibration isn’t 100% necessary, but I had the information, so I figured I'd use it. A quick reflash, and I was about ready to start it up.

When messing with the throttle bodies, it is always a good idea to do a throttle relearn. This would normally require a trip to the dealership. Thankfully, the fine folks at HPTuners built this function into their scanning software a few years back, so all I needed was my laptop and my HPTuners interface. If you can follow on-screen prompts, you can do it in about a minute.

Once that was all said and done, I decided to let 'er rip. It started up and idled just like it normally does, and responded to my gas pedal inputs just fine. I took it for a nice long shake down drive to make sure it wasn't going to go into limp mode, and it behaved just like it should. You better believe I hauled along some tools, my laptop, and the old throttle bodies just in case something went awry. Thankfully, it did not.

So that's pretty much it. I'll get into how I made the adapter harnesses in my next post.
 
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Steve M

Steve M

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Adapter Harness

Wanna make an adapter harness?

Although it is potentially another connection that could fail, this is the way to go if you want to be able to go back to stock in a matter of minutes. There's plenty of room under and around the throttle bodies for an adapter harness, and once everything is together, you can't even really tell unless you really know what you are looking for.

The finished harness (you'll need two):

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First, a word of caution courtesy of Dan Lesser (Viper Specialty Performance):

Originally Posted by Viper Specialty

The contact used in Throttle applications are Au/Ag. They are NEVER Tin/Sn. Mixing these materials will cause eventual failures. This is absolutely critical in the long term... and you would be amazed how many connector shops ignore this little tidbit.

If you are assembling these yourself, you'll need the following parts:

2 x https://www.bmotorsports.com/shop/pr...oducts_id/4587 (those will plug in to the existing plug on the vehicle's wiring harness)
2 x https://www.bmotorsports.com/shop/pr...oducts_id/4503 (those will plug in to the new throttle bodies)

Those will come with crimp on terminals, which are likely to be made out of tin (they don't specify on their website). Toss them, and order the correct ones (Silver/Gold plating) below. You'll also need some 20 AWG automotive TXL wire. Plenty of sources online for that.

There's pretty much one source I could find for the connectors and terminals:

https://www.te.com/usa-en/home.html

If I had to guess, the OEMs get their stuff from them. I'm not in the automotive industry, so I don't know for sure.

The plugs for the plastic throttle bodies are based on what appears to be an older design - the TE Connectivity MQS series of connectors. The metal throttle bodies use a newer TE Connectivity MCON connector, part number 1-1718646-1.

For the connector that plugs in to the old throttle body connector (MQS), you'll need at least 12 of these (gold - silver doesn't appear to be available, but you might check around): https://www.te.com/usa-en/product-5-963716-2.html
For the connector that plugs in to the new throttle bodies (MCON), you'll need at least 12 of these (silver): https://www.te.com/usa-en/product-7-1452656-3.html
You can also opt for gold with the MCON connectors: https://www.te.com/usa-en/product-1670146-2.html

DigiKey seems to have a good stock of these terminals, and you don’t have to order in quantities of thousands to get what you need (which is great for a DIY-er like me). The MQS stuff is getting harder to source (not surprising since it is an outdated connector), but the MCON stuff seems to be reasonably well stocked.

Yes, this isn't exactly an easy DIY project, but don't let that scare you away.
 
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Steve M

Steve M

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Securing the Adapter Harnesses

When Dan mentioned using the correct contact plating surfaces (Gold/Silver instead of Tin) for the throttle body connectors, it made me realize how little I knew about automotive connectors. I still know very little about them, but I at least learned a couple of things. I have a point to all of this, so bear with me.

First of all, the issue we are trying to prevent here is fretting corrosion. What is that? I had no idea, but a quick Google search will give you a pretty good idea. Here's an excerpt from nace.org:

Fretting corrosion refers to corrosion damage at the asperities of contact surfaces. This damage is induced under load and in the presence of repeated relative surface motion, as induced for example by vibration. ... Contact surfaces exposed to vibration during transportation are exposed to the risk of fretting corrosion.

Asperities are rough edges on a surface...I had to look it up.

You know what vibrates? Throttle bodies attached to a big honkin' V-10.

With a little more searching, I came across this from Electrical Contacts: Principles and Applications, Second Edition:

Modern internal combustion engines use a variety of sensors mounted directly on the engine to supply the information needed for optimum engine performance. Throttle position sensors, temperature sensors, knock sensors...are mounted on all kinds of engines. The key to good performance of a connector subject to high vibration is to eliminate relative movement at the contact interfaces so fretting corrosion does not occur. Effective relief of the strain in the wiring harness is one of the most important factors to minimize relative movement at the contact interfaces. Even small movements of the wiring can be transmitted to the terminal contacts. In addition, minimizing the motion in the connector housing and using appropriate contact plating and lubricant for the vibration environment is very important.

Well then...if only the engineers at Dodge had thought of this. Oh wait, they had:

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Those little guys circled in red are the factory strain reliefs, and were installed here on the old throttle bodies:

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The problem is that my new throttle bodies were not drilled to accept them. Out came the drill, and the throttle bodies went into my bench vise. A few minutes later, each of the tabs on the metal throttle bodies now had 1/4" holes in them. The old zip ties weren't in the right spot, and they certainly aren't reusable once you cut them off. They are commonly referred to as "fir tree zip ties", and you can find them many places online once you know what they are called. Most call for a 1/4" hole, hence my decision to drill the holes that size. If you prefer to use a genuine Mopar part, you can find plenty of part numbers on the same website I referenced in my original post where I found the wiring info:

http://connectors.dcctools.com/parts_list.htm

Just scroll down, and you'll find many different part numbers (like 68197784AA) for the different zip ties and clips used throughout the Mopar lineup. I didn't feel like paying Mopar prices, so I just went with what looked reasonable on Amazon and came up with this:

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I figured if they were included from the factory, it was probably worth trying to figure out how to incorporate them with the new throttle bodies. Does it matter? Not sure, but the book referenced above sure thought it was important, and I'm guessing there were a few engineers at Dodge that felt similarly.

And how about one more useful diagram?

The Mopar connector website lists the wire color codes for all of the different connectors. They colors are all two letter abbreviations, but not all of them are intuitive. This diagram, however is:

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Steve M

Steve M

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Cross Compatibility

The metal throttle bodies easily swap between either the aluminum Gen 4 or the composite Gen 5 intake manifold. The bolt patterns are identical. You can use either the plastic or metal throttle bodies on the Gen 4 intake manifold, and the same goes for the Gen 5 intake manifold. The 2008-2010 and 2013-2014 Vipers all used the plastic throttle bodies; the 2015-2017 Vipers used the metal throttle bodies.

The only difference that matters between the two throttle bodies (plastic vs. metal) is the connector - it is the same number of pins, but a different shape, and the pin functionality has been reordered. A throttle body adapter harness will work regardless of which intake manifold you attach it to.

If you don't want to DIY the harness, I'm sure Dan Lesser could whip you something up pretty easily. Looking at the Mopar Connector Repair Kit website, it appears that the Gen 4 (2008-2010) and early Gen 5 (2013-2014) Vipers use the same wiring scheme (pin order, function, and wiring colors) for the plastic throttle bodies, so the set of throttle body wiring harness adapters I built for my Gen 4 would also work for any 2013-2014 Gen 5s that wanted to swap to the metal throttle bodies.
 
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Steve M

Steve M

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Bonus: Throttle Body Airflow & PCM Control

This is a question that comes up from time to time: when logging pedal position (driver demand) vs. throttle blade position (airflow delivered) vs. RPM, why does it only show 86-87% at WOT?

Basically, when you mash the gas pedal to the floor, the throttle blades on the Gen 4/5 Vipers don't open fully until pretty high up in the RPMs. Even then, they never truly open 90°. There are a couple of reasons for that:

1. The twin 74mm plastic (2008-2010, 2013-2014) or twin 76mm metal (2015-2017) Viper throttle bodies found on the Gen 4 and 5 cars flow massive amounts of air...way more than what's needed to feed these engines. Ever notice how even guys that run big honking 9L displacement variants don't touch the throttle bodies? They don't have to open up all the way for a good portion of the RPM range to feed the amount of air required to meet the driver demand, even with a larger than OEM displacement.

2. The reason they don't open fully is best illustrated by some cheesy graphics, so please bear with me.

At idle, the blades on a drive by wire car are always cracked...that's why there's no need for the typical idle air control valve like you'd see on a cable driven throttle body.

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At part throttle, the driver presses down the gas pedal; the PCM sees that demand and determines the amount of torque required to deliver it, along with all of the other demands (A/C, alternator, water pump, etc.); for a given amount of torque, the PCM knows how much airflow (and fuel + timing) needs to be delivered, and opens the throttle blades a set amount to achieve the desired airflow:

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The relationship between the % the throttle blade is open vs. the cross-sectional area of the opening is most definitely not linear.

At wide open throttle, the blades eventually open all the way, but not to 90° as seen here (not drawn to scale to illustrate the point):

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The reason why should hopefully be obvious in this next diagram:

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The shafts upon which the throttle blades rotate are significantly thicker than the blades themselves. I've not measured them, but it isn't trivial. You can see them here:

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That's why you'll only see WOT values of around 86-87% on these cars. Opening them more than that would be a waste. It would also take extra time to shut the blades like when you let off the throttle, or heaven forbid, during a runaway throttle situation where the PCM has to step in and shut everything down as quickly as possible. Every millisecond counts when it comes to safety, so the throttle blades essentially always have a head start on the way to closing.
 
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