09RedPony

I'm an old guy getting enjoy a muscle car for the first time in 40 years. I bought a beautiful 09 GT that has been garaged since new with only 5,000 miles on it. I finally worked my way up to really winding it out, and right before I was ready to hit 2nd gear it shutoff momentarily. When I hit second, it wound up just fine. Since it had been sitting so long, I thought it might be a fuel system issue. I decided to check the tach next time it happened so I could discuss it with a technician and it shuts-off repeatedly at 6,000 RPM. Is this built-in protection in the stock engine control program?

algregory

I have an '05 GT and pretty sure you are correct.

First time I found out about that thing I on a real slow twisty on the North California coast behind a car that wanted to go really slow. Finally on a SHORT straight I hammered it in second gear, and right beside that car, with limited space, the damn engine quit!

Now I have a CAI with a "tune" and the spot is further up the scale. I also do the motorcycle thing so knew about that sort of thing. My "2 cents" is Ford decided to just KILL the engine for you, other places they still give you power, but, put a lid on the tachometer. I think just a "KILL" is the wrong way to go.

09RedPony

I thought it might be a programmed feature. At first I thought I had tore something up, but it was consistently at 6,000 RPM. Soon, I hope to add the Cool Air Intake, some Magnflo pipes and an appropriate tune. I'm just glad it's not a mechanical issue. I love the way the 4.6 winds-up (until I hit 6k).

Lem-06

Mine never just shut off, gf's brother said his would shut off at the speed limiter, which i found to be ultra retarded, taking away power at speed

Derf00

If by 'shutting off repeatedly' you mean the RPM needle bounces off the red area of your tach and the engine seems to stutter...that's normal. It's the factory rev limiter. It's called protecting you from spinning a rod or floating a valve. It's cuts the fuel momentarily to maintain the engine under/near the red area.

That can be removed with a hand held tuner but it's not recommended to really move the redline up on an unmodified motor, we don't make any more power above the factory limit.

You may also notice if you're at a light and you decide to rev it up in nuetral, around 3500 or 4000 RPM the same thing happens. This is the free rev limiter to keep people from floating a valve because they want to sit there and rev their engines.

Derf00

You're also modified so you continue to make power above the factory limit. For an unmodded motor, moving the limiter is pointless. If someone puts cams (like you) and or headers then sure, it's probably worth it moving it a couple hundred RPM. Beyond that, if your bottom end isn't built to handle higher RPM's you're just asking to grenade your motor.

Lem-06

before i modified mine never shut off at red-line, just hit the fuel based rev limiter.

Yea i ran cams and longtubes up to 7k often, mostly just because.

SC'd it and stopped at 6k until my new motor and still working on getting it back together 100%

danzcool

Yeah, the default for mine was de-fueling at 6250, and it feels like the fuel is off for about 1/2 to 1 second and then if you atill have your foot on the pedal it will start cycling on and off. Quite a weird feeling the first time it happens. Keeping it under 6K on the stock block and you can throw all kinds of boost at it as long as you have enough fuel pump.

09RedPony

I understand floating a valve or spinning a bearing, but the clip is way early on the power curve of the engine. I drove stock muscle cars back in the 60s and 70s that red-lined at 7,000, and manufacturing technology has to be better today. The natural shift point seems to be closer to 6.5k, but 6k probably makes good sense if your Ford and have to warranty the engine. I'm hitting my shift point in 1st at 5.5k, but that certainly not wringing the engine out. It feels awkward shifting that early, but I do like the power band in 2nd. When I add the cool air intake and the larger pipes, hopefully the custom tune will move the limit up a bit. If not, 1st gear is REALLY going to be useless.

You guys have got some awesome looking vehicles!

Dino Dino Bambino

My car has some simple bolt-ons and with the custom tune, I had the rev limiter set at 6500rpm (same as 2008 Bullitt & 2010 GT). That's high enough anyway since my engine's peak HP levels off at 5300-6100rpm and I hardly ever go above that.