i have a 2003 lightling, with a 4# lower pulley & an exhaust system consisting of an x pipe through 2 flowmaster 40 series delta flow mufflers. the exhaust is mild, no cabin resonance but just the nice flowmaster sound.
the main question is will a computer chip enhance the performane or should i just leave it stock. the gains fell great, but i have not run it through the 1/4 or 1/8 mile??? any advice would be appreciated

 

Hi wsa,

This is something you would normally want to ask in the Computer Chips section, but I'll go ahead & respond to it here...........

Not only will a *properly tuned* chip help your power and performance, but anytime you are running *any* size pulley to raise boost on the Lightning or factory supercharged Harleys, you *need* a proper custom tune & here's a very brief & loose explanation of why.........

The MAF (mass airflow meter/sensor) is what "measures" the engine's incoming air volume and sends that signal to the PCM - the MAF is the powertrain's primary load signal, and it needs to function properly and have it's full voltage range available, otherwise the PCM cannot properly respond to load - then you have the potential for blowing the motor.

The full 5.0 volt MAF range (0.0-5.0 volts, based on incoming airflow & load) is not even available in stock factory programs in FoMoCo vehicles - you are limited to just 4.78 volts in the program, even though the physical MAF itself has a 5.0 volt range. Well, the difference in available CFM between 4.78 & 5.0 volts, even though it is less than 1/4 volt difference, is a *sizable* difference in actual CFM flow.

The kicker is, just the installation of a 4 lb. pulley will cause the 5.4 Lightnings to peak the meter **in the program** at anywhere from about 4000 to 4400 rpm in 3rd gear for example, and once that happens the PCM can no longer respond to load properly or control the A/F's, timing, etc. reliably. When you hit *that* point, that's just begging for a blown motor.

Unfortunately, some people try to get by on the cheap (bad idea when modifying any vehicle) in their modifications, or sometimes their vendor doesn't warn them properly about this issue, and thus some people will slap a higher-boost pulley on a Lightning and run on the stock program - bad idea.

So the quick answer on why running a higher boost pulley on the factory program in the Lightnings (and the 2003 & 2004 factory-blower Cobra's) is a very bad thing to do is because of the limited MAF voltage range allowed in the stock Ford program/tune.

The guys who get away with that for the longest are generally those that drive their Lightning the easiest overall - perhaps they aren't towing, or aren't doing significant 1/4 mile drag racing or high-speed driving, etc. - in other words, the more conservatively you drive the vehicle, so that you don't reach the load levels at which you run out of MAF voltage, then the more you can, so to speak, "get away with" running a higher-boost pulley on the stock program - but it's *never* the smart thing to do, as anytime you go to full-throttle thru the gears in any Lightning with any raised-boost pulley you *will* run out of MAF voltage in the stock program - and from that point on the PCM *cannot* protect the motor by responding to increased load. And *then* you've got the potential for serious engine damage.

Load increases anytime you give the engine more throttle, or as rpms rise @ WOT, or when you start going up a grade, or when you put on a higher-boost pulley, etc., etc. - just installing a 4 PSI pulley will increase load over stock @ WOT by 45%-47% on average in the typical Lightning, for example.

Some people do get away with that for what seems like a long time - but in reality, the longer they do it, the bigger chance they are taking unless they *never* got to WOT (wide-open throttle) and run it thru the gears, or for just long enough to hit 4000+ rpm in 3rd gear, for example - and what Lightning owner do you know has never applied full-throttle thru at least the first 3 gears? I don't know any.

I would rather lose a sale than have someone try running any raised-boost pulley on the stock Lightning program.

Please give us a call at our number listed below to go over this in more detail, & to see just exactly what the cost, benefits, performance & power gains will be from having a properly tuned chip in your vehicle - we'll be happy to help.

Best of luck with your truck,