Question about 1984 Ford F 250

1 Answer

RS4 performance chip in a 2008 Class A motorhome

Will the RS4 performance chip improve HP, torque and/or fuel economy on a 2008 Class A Coachman Mirada RV running the Triton V-10 in a 2007 Ford motor home Chassis? Specs on the engine are around 360 HP and +420 # torque. Currently averaging around 10 mpg with transmission in overdrive (out of towhaul) @ 62 - 64 mph and fueling with 87 octane. When I push the speed up to around 70 mileage drops to around 9 mpg on flat pull. Obviously highway grade makes a difference and I never operate in cruise control unless grade is relatively zero to 3%. Running Royal Purple synthetic lube in engine and the Dana 110 rear axle.

Posted by on


1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.

    Brigadier General:

    An expert that has over 10,000 points.

  • Ford Master
  • 3,854 Answers

RS4 performance chip is just a $0.50 resistor that fools your IAT (Intake Air Temperature) sensor. All it will do is cause your engine to run leaner or richer depending on what the resistor rating is on the resistor. You can get the same result by disconnecting the wire leads to your IAT, the resistor only keeps your check engine light from coming on.
The higher resistor rating, the leaner the engine will run and the lower the resistance will cause your engine to run richer. But the program to your engine PCM has set perimeters which takes readings from your MAF, MAP, Engine Temperature, and O2 sensors to keep your engine running at 14.7:1 air fuel ratio, so the RS4 Performance chip only works during start up on a open loop with the engine still cold and under 400 RPM. It IAT is only there to determine the amount of fuel needed to start the engine during cold starts.
If you are interested in a true performance and economy for the amount of fuel used. Dyno tune your PCM for the best performance your F250 can provide. is one of the best tuners out in the market that is worth investing.
Thank you for using fixya, and good luck

Posted on May 10, 2010


1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

How do I get decent gas mileage?

To put it as simple as I can --the faster you go the more fuel you use-- Not rocket science really.-- At the recommended speed the vehicle is in the optimal torque range and is returning the best economy for that speed . any thing over and it takes a big nose dive.. At the recommended speed you have maximum control of the vehicle and it will last the longest time . Now you have to improve the economy by paying attention to the following items
Tyre width , size pressure is critical to economy
Loads being carried at speed is critical to economy
Add-ons such as load racks add to fuel usage so take them off.
Fast take offs at lights uses fuel. If you let the engine bog down instead of changing gears will use fuel.
Not using the cruise control uses more fuel as every time you alter the accelerator pedal position that is extra fuel being used.
Using E fuel mixes will lower economy. So economy is a matter of your driving habits and not of the make of vehicle.
If you want better economy at the speed syou travel at then visit a speed shop and have the CPU re-chipped for more power at the higher rpm's but be aware that it may void your warranty on the vehicle.

Aug 14, 2014 | Cars & Trucks

1 Answer

2003 Marquis performance and economy

I don't think you'll ever beat what you're getting for mileage now. Those numbers are really good.Improving performance usually sacrifices economy.

Sep 14, 2017 | Cars & Trucks

1 Answer

Hello, Pat here from Ks, I have a 1994 class A coachman mtr home. The Rv doesnt get any spark or injector pulse, seems a power issue. The underhood fuse panel looks a bit worn. I placed a high...

You need some basics before you get too far off track.... First, your starter does not start your engine. It's only job is to turn the engine so the ignition and fuel system can work. You should test your fuse panel electrically with a test light, or better, a volt meter. All fuses should have power on both ends when the key is on. Having no spark or fuel often happens if an engine sensor such as the crank position or cam sensor fails. There also relays that control some functions.
If you can have someone scan the computer, you may get some valuable information from what you find, I believe your motorhome is on a Ford chassis...for engine work, you can use a manual for the same year Ford truck. Most larger parts stores sell chilton or haynes manuals that outline tests you can make using a digital multimeter. Likely, you can get a meter and manual for less than you paid for the starter!

Jun 11, 2011 | Ford F Cars & Trucks

1 Answer

I just purchased a 2011 T&C. There is no information in the owners info on the Pentastar engine or about the econo mode. What it does how it works and when do you use it or turn it off. Do you have...

You've got a 283 hp pstar engine with a vehicle with all the accessories that you can ask for. Here is an excerpt from an internal chrysler memo regarding your vehicle.

The Town & Country gets a new, simplified powertrain lineup for 2011. The new Pentastar 3.6-liter V-

6 engine that produces a best-in-class 283 horsepower and 260 lb.-ft. of torque, yet delivers excellent

fuel economy, powers the entire lineup. The Pentastar V-6 engine is mated to Chrysler Group LLC's

62TE six-speed automatic transmission. Chrysler Group was the first manufacturer to offer a sixspeed

transmission in a minivan, debuting on the 2008 Chrysler Town & Country. New for 2011 is a

fuel economizer mode switch, a driver-selectable engine economy mode which assists drivers to
maximize fuel efficiency while driving. All the economy mode really does is to take the transmission out of sort mode which means it will have lower shift points and not rev up and produce as much torque as it would otherwise that's all. You should get around 17mpg city and around 24 highway dependant on your driving habits. It is your personal preference whether you choose to use this function or not. Try using it in econo mode for 2 weeks and without for 2 weeks, to notice the difference while driving and fuel economy, then you can decide your preference. Nice vehicle

Mar 03, 2011 | Chrysler Town & Country Cars & Trucks

1 Answer

I got a 97 vision 3.5 and i am havin big fuel economy issues what all can i do to help improve it?

Hi! Try replacing your sparkplugs. It may be full of carbon and causing a reduction in fuel economy. New sparkplugs can perform better fuel burning. Hope this helps

Mar 12, 2010 | 1997 Eagle Vision

3 Answers

1997 jeep grand Cherokee laredo hesitation problem

You should add a rs4 performance chip or the fuel economy chip also made by rs4. there like 70 bucks. If the problem is electrical changing your chip could solve the problem. Even if is doesnt work the chip will make your truck idle more smoothly, have better throttle response, and you will add 3-7 mpg. I bought one for my 1997 jeep grand cherokee straight six, and it felt like i was driving a different truck . It mae that much of a cant loose!!!Like everyone says , it could be a vac leak or a clogged fuel filter , soetimes bad gas...your problem is a needle in haystack. Try the chip...I hope this helps

Oct 27, 2009 | 1997 Jeep Grand Cherokee

2 Answers

Is there a way to improve fueleconomy on 4.7 L 4X4 Durango's

swap in a tcm for 2002 to 2004 jeep grand cherokee with a 4.7 and 545rfe transmission. you have a 45 rfe transmission and it is identical on the inside to a 545rfe. type in 45rfe to 545 rfe conversion on google and follow the dodge threads that come up for more details.

Mar 07, 2009 | 2001 Dodge Durango

2 Answers


It ould be expensive to replace the cam for a higher torque range. Firstly, I would look p the torque curve on your engine and then try to keep the rpms at the peak torque rpms when going up hill. If this isn't enough, I would have someone put a power chip in your engine computer. Find a good reputation company though. The chip will usually advance the timing and deliver more fuel to the injectors. Ask what the chip spcifically does if you can. (Ford frowns on power chips, but if your warranty is uo, no problem.)

A last thing is to install new injectors that have a higher flow rate (lbs/hr) than your exsiting injectors. This will require the power chip though since your existing chip is designed for max fuel economy and not max power.

good luck.

Jan 09, 2009 | 1988 Ford F 250

2 Answers

Performance improvement

Take a look under all of these for your favorite.
Also try ebay. You want a DIRECT ECU wiring chip not a intake resistor. Should increase Horsepower and torque around 20%.

May 16, 2008 | 2008 Infiniti G37

Not finding what you are looking for?
Cars & Trucks Logo

304 people viewed this question

Ask a Question

Usually answered in minutes!

Top Ford Experts


Level 3 Expert

76051 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22156 Answers


Level 3 Expert

5516 Answers

Are you a Ford Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides