Running lean after hitting the rev limiter

[Zinc03svt]

Lol. If you have ever played with your sport mode you will eventually hit the limiter.

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[TheLion]

Lol. If you have ever played with your sport mode you will eventually hit the limiter.

Or if you have a manual. I've hit the rev limiter so many times in 2nd I can't count! Holding 2nd gear and just bouncing off the rev limiter (for those with a non-factory tune) is pretty common in Auto X because it's faster to not have to shift into 3rd then back down to 2nd quite frequently.

I was on the stock ECU calibration until 17k miles (now just shy of 20k). I hated how the stock rev limiter cut power for several seconds instead of just bouncing off of it. That's no good for performance driving, but they do it to make the car "safer". I prefer it to just bounce off the rev limiter and more or less hold the RPM like with the Ford Power Pack's.

Did you know during their torture testing of the 5.0 they run it for 3,000 hours straight at maximum power which is at 6,500 RPM (just 300 RPM shy of the rev limit)? Then they do thermal shock cycles for days by running it WOT, shutting it off, pouring ice water down the intake, starting it back up and doing it again and again and again...that's just part of the torture testing. When it's done, the engine has to be 100% read and capable of doing it again, it can't be any where near it's last leg. These 5.0's are pretty well built and most issues are related to manufacturing errors and maybe an occasional software condition over sight which if fixable with an ECU re-flash.

Sounds to me like first year software bug which they fixed with an updated ECU program. I will say that one thing I do like about the Ford Performance Power Pack 2 is that you CAN bounce off the rev limiter, it doesn't cut fuel and power completely, just bounces off the wall repeatedly which is great for those Auto X type of applications or if you want to run up 3rd all the way out then slow down but stay in 3rd.

There should be absolutely no abnormal behavior after hitting the rev limiter no matter how many times you do it. The rotating assembly is designed to rev out to 7,500 RPM (the 2nd gen 5.0 uses Boss 302 rods, a new re-balanced crank, 302 valve springs and guides, new high flow cast head that flows as well as the CNC ported head on the 302, 13mm valve lift etc. it's all designed for 7,500 RPM operation reliably). The Power Pack 3's GT350 intake manifold and ECU calibration allows you to do just that, you don't build in those capabilities by accident....even Power Pack 2 gives you 7,150 rev limit instead of the horrendous 6,800 RPM stock limit (which made the 3.73's always feel too short in my PP GT), but no it won't rev out as high as Power Pack 3 and make good power because of the flow restrictions of the stock intake manifold which are tuned for more mid-range Power than high RPM top end.

Glad the OP got it fixed, but there's no reason you can't run right into that rev limiter every day if you want. The ECU just cuts fuel to keep it within the mechanical limits and there shouldn't be an adverse effects, especially given the mechanical limits are so far above where the rev limit is actually set on the stock calibration.

Now Mechanical over-rev is another story. Mechanical over rev is where you shift down to a lower gear than you should of at high speed and the transmission forces the engine to rev higher than it's limits, like shifting into 2nd while traveling at 80 mph on the highway, assuming you don't crash into a wall first as the back tires lock up... Ask the AP1 Honda S2000 guys about that, many have sheared valve stop plates on the first gen's in Auto X by mechanical over-rev. ECU can't control that one (well not in a manual).

 

[Zinc03svt]

My rev limiter is 7900. ;).

 

[Lonmon]

Or if you have a manual. I've hit the rev limiter so many times in 2nd I can't count! Holding 2nd gear and just bouncing off the rev limiter (for those with a non-factory tune) is pretty common in Auto X because it's faster to not have to shift into 3rd then back down to 2nd quite frequently.

I was on the stock ECU calibration until 17k miles (now just shy of 20k). I hated how the stock rev limiter cut power for several seconds instead of just bouncing off of it. That's no good for performance driving, but they do it to make the car "safer". I prefer it to just bounce off the rev limiter and more or less hold the RPM like with the Ford Power Pack's.

Did you know during their torture testing of the 5.0 they run it for 3,000 hours straight at maximum power which is at 6,500 RPM (just 300 RPM shy of the rev limit)? Then they do thermal shock cycles for days by running it WOT, shutting it off, pouring ice water down the intake, starting it back up and doing it again and again and again...that's just part of the torture testing. When it's done, the engine has to be 100% read and capable of doing it again, it can't be any where near it's last leg. These 5.0's are pretty well built and most issues are related to manufacturing errors and maybe an occasional software condition over sight which if fixable with an ECU re-flash.

Sounds to me like first year software bug which they fixed with an updated ECU program. I will say that one thing I do like about the Ford Performance Power Pack 2 is that you CAN bounce off the rev limiter, it doesn't cut fuel and power completely, just bounces off the wall repeatedly which is great for those Auto X type of applications or if you want to run up 3rd all the way out then slow down but stay in 3rd.

There should be absolutely no abnormal behavior after hitting the rev limiter no matter how many times you do it. The rotating assembly is designed to rev out to 7,500 RPM (the 2nd gen 5.0 uses Boss 302 rods, a new re-balanced crank, 302 valve springs and guides, new high flow cast head that flows as well as the CNC ported head on the 302, 13mm valve lift etc. it's all designed for 7,500 RPM operation reliably). The Power Pack 3's GT350 intake manifold and ECU calibration allows you to do just that, you don't build in those capabilities by accident....even Power Pack 2 gives you 7,150 rev limit instead of the horrendous 6,800 RPM stock limit (which made the 3.73's always feel too short in my PP GT), but no it won't rev out as high as Power Pack 3 and make good power because of the flow restrictions of the stock intake manifold which are tuned for more mid-range Power than high RPM top end.

Glad the OP got it fixed, but there's no reason you can't run right into that rev limiter every day if you want. The ECU just cuts fuel to keep it within the mechanical limits and there shouldn't be an adverse effects, especially given the mechanical limits are so far above where the rev limit is actually set on the stock calibration.

Now Mechanical over-rev is another story. Mechanical over rev is where you shift down to a lower gear than you should of at high speed and the transmission forces the engine to rev higher than it's limits, like shifting into 2nd while traveling at 80 mph on the highway, assuming you don't crash into a wall first as the back tires lock up... Ask the AP1 Honda S2000 guys about that, many have sheared valve stop plates on the first gen's in Auto X by mechanical over-rev. ECU can't control that one (well not in a manual).

I don't think the oil pump likes you repeatedly hitting the rev limiter. Other then that, I am with you on the strength and design of this engine. Occasional taps of the rev limiter should be ok.

 

[Silver Bullitt]

What is the stock rev limiter on the 18+ gen3? I've seen about 7700 and it didn't cut power yet.

 

[Ace21]

Stock there is no rev limiter per say, the scheme is to close the throttle to limit flow, thus limiting the engines ability to rev any higher. There are maps to cut fuel or spark IF given parameters are met, which is very unlikely on stock tune.

That schemes purpose is to help combat vibration shock to the oil pump and oil pump gears, as mentioned above, due to a phenomena that causes vibration to accelerate thermal transitions of materials, thus shifting the atomic structures and weakening their bonds. This is also the effect that causes the stock oil pump gears exploding in higher HP applications.

If you are on a custom tune I personally would have the tuner fine tune the "soft" rev limit instead of a traditional one because the constant use of a traditional rev limit will inevitably cause fatigue to the above mentioned parts. You literally are rolling the dice on when it will fail if you are hitting the materials engineered thresholds, which in the case of the stock oil pump gears is not very high.

 

[Silver Bullitt]

Stock there is no rev limiter per say, the scheme is to close the throttle to limit flow, thus limiting the engines ability to rev any higher. There are maps to cut fuel or spark IF given parameters are met, which is very unlikely on stock tune.

That schemes purpose is to help combat vibration shock to the oil pump and oil pump gears, as mentioned above, due to a phenomena that causes vibration to accelerate thermal transitions of materials, thus shifting the atomic structures and weakening their bonds. This is also the effect that causes the stock oil pump gears exploding in higher HP applications.

If you are on a custom tune I personally would have the tuner fine tune the "soft" rev limit instead of a traditional one because the constant use of a traditional rev limit will inevitably cause fatigue to the above mentioned parts. You literally are rolling the dice on when it will fail if you are hitting the materials engineered thresholds, which in the case of the stock oil pump gears is not very high.

Thanks. No plans to tune yet. Need to figure out if the "rattle" and "tick" are just characteristics of this engine or something more serious. This thing just doesn't seem to stop making power though. My LS2 had a Texas Speed cam and was tuned at 1,100 miles. But, even with the cam, it would lay down about 6600. Rev limiter was set to 6800, but you could feel it start to give out before it got there. This coyote just keeps going. I'll just have to watch it closer and shift by 7400.

 

[Leigh_bullitt]

Hi everyone, I’ve been experiencing some weirdness with my Mustang GT after hitting the rev limiter last week.

Immediately after that the fuel got cut off and the car lost power for a brief second. After the power came back, the engine immediately felt a bit weird.

I took the car in for service but they couldn’t find any problems with it. It definitely feels different so I was wondering if anyone had any idea about how to diagnose the issue.

Here are the symptoms:
- It feels like it’s running lean as it’s not developing the same power as it used to and it doesn’t respond well to throttle at low RPMs
- Both the engine and exhaust sound different, not as deep as before
- It feels flat around 3k RPM
- No check engine light
- No OBD error codes

Any help would be appreciated.

Sorry this is an old thread.
It’s strange my mustang has just started to do this and it’s intermittent too.
Just like you said
Feels a bit jerky at low rpm
Less power and exhaust sounds different and not deep.

I have thought of everything and to have narrowed it down to the throttle body.
Did the symptoms come back ?.

is their a calibration that the dealer can do that we can’t ?.

please let me know thanks

 

[junits15]

Sorry this is an old thread.
It’s strange my mustang has just started to do this and it’s intermittent too.
Just like you said
Feels a bit jerky at low rpm
Less power and exhaust sounds different and not deep.

I have thought of everything and to have narrowed it down to the throttle body.
Did the symptoms come back ?.

is their a calibration that the dealer can do that we can’t ?.

please let me know thanks

Can you describe what you’re feeling in more detail? The car likely isn’t running lean like OP thought, but that doesn’t mean something else isn’t wrong.

 

[Leigh_bullitt]

Can you describe what you’re feeling in more detail? The car likely isn’t running lean like OP thought, but that doesn’t mean something else isn’t wrong.

Thanks for coming back to me.

it’s like OP said. You can feel straight from the start up that it is running better.
Mine is intermittent it runs ok, poorly most of the time but every so often I will start it and it feels great.

For the when it’s running poorly it has less torque under 3k rpm’s. It slightly surges when decelerating foot of gas say at 50mph. At WOT it doesn’t have the pull that it normally has.

and the exhaust note is different. Almost like a weaker sound.
When it’s running well you can tell.
Loads of torque loads of pull and the exhaust is very deep and burbles lovely.

I would say 1 in every 10 times it will run perfectly.

forgot to mention I have the 2020 Bullitt.
it has a tune but this happens when it’s tuned and in Stock tune.

thanks

 

[Leigh_bullitt]

Thanks for coming back to me.

it’s like OP said. You can feel straight from the start up that it is running better.
Mine is intermittent it runs ok, poorly most of the time but every so often I will start it and it feels great.

For the when it’s running poorly it has less torque under 3k rpm’s. It slightly surges when decelerating foot of gas say at 50mph. At WOT it doesn’t have the pull that it normally has.

and the exhaust note is different. Almost like a weaker sound.
When it’s running well you can tell.
Loads of torque loads of pull and the exhaust is very deep and burbles lovely.

I would say 1 in every 10 times it will run perfectly.

forgot to mention I have the 2020 Bullitt.
it has a tune but this happens when it’s tuned and in Stock tune.

thanks

Can you describe what you’re feeling in more detail? The car likely isn’t running lean like OP thought, but that doesn’t mean something else isn’t wrong.

I mean it seems to me that it’s definitely something to do with the throttle body like OP said. Maybe it’s not calibrated correctly.
can the Ford dealers only calibrate the throttle body with software ?.
I’ve tried other ways like pressing the pedal down etc but doesn’t work

 

[Goterr0r]

Just un hook your battery for a few hours. Plug it back in and things will likely magically reset them for you. You'd be surprised what a simple battery reset can do.....

 

[Leigh_bullitt]

Just un hook your battery for a few hours. Plug it back in and things will likely magically reset them for you. You'd be surprised what a simple battery reset can do.....

Isn’t that the same as a KAM reset though?.

 

[Goterr0r]

Isn’t that the same as a KAM reset though?.

For the most part, but doesn't hurt to try.

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