Are the 7.3s rev limited by the PCM? If so, what is max?

I recently installed a PHP 6 position chip and in the 80dd selection the shifts are odd under WOT. It seems to hang in gear to long and stumble a little bit before it shifts under WOT conditions.

I only did it twice out of fear of something bad happening. I'm not sure what my RPMs even were. I just reminded me of hitting a rev limiter. I was focusing on my scan gauge and did see the ICP bounce off 3400 briefly. That cannot be too good either, can it?

 

It could be that to much fuel has been pulled out at a giving RPM and WOT shift points are set to high. Shift points are set by the MPH so for example if your chip starts pulling fuel out at 3Krpm and WOT shift point is set at 31mph there is the stumble you are feeling. The fix would be to change your WOT shift point to a slower speed just 2mph may fix the issue.
Or worst case when mine was doing that and it was the tranny slipping so I just keep doing it until I blew the tranny up! That away I would have a reason to build one more bullet proof.

 

Yes, the PCM has rpm limits set in the programming. Here in Arizona, we get to test the rev limiter once a year at our local emissions testing stations. We have to fully depress the throttle and demonstrate a rev limiter is in place. Then we hold it there for 5 consecutive seconds.....6 different times.

Gotta love the emissions testing methods here in Phoenix.

 

wow, who was the rocket surgon that thought that up?

 

Seriously...
I'd tell the idiot to get out of my truck. No way would I allow it. I never hit the rev limiter and I would expect the emissions guys to be realistic about abusing my engine like that.
A crappy Honda I can see. But my diesel... No way.

Have you directly contacted php about this issue, I would have started there before even posting here. They know their stuff, use their experience (along with ours)

I had a bullydog programmer that would shift weird on the 120hp setting and the engine would flutter some. It also would quiet down and sound like a gasser, then start clattering louder than heck, then sound normal. All at different rpm. Made the trans slip also it felt like.

Call php.

 

They call it a 'snap throttle test' and the owner sits behind the wheel for that one. They guide me into the service bay and ask me to roll down the driver's side window....then they ask if I have ever done the test before (to which my answer is always 'yes'). They then instruct me to hold the throttle to the floor and verify the engine has a rev limiter. Then I have to shut down the engine while they inspect the truck. They look at the right side valve cover to see if the vehicle requires a cat, if so then they look for it. They then check to make sure the CCV is in place. They use a snare to measure the exhaust pipe diameter (must be 5" or less I think...)

If all that passes, then they break out the opacity meter which emits a beam of light across the path of the exhaust towards a reflector. There is a sensor that measures how much light makes it to the other side. The owner starts the engine and performs the snap throttle test three times to clear soot from the system then the machine is turned on and the throttle is pegged three more times to measure opacity.

It doesn't matter if I am in stock or modified tune...the opacity measures somewhere between 2-5% every time. Standard is 40%. So, this means that my state doesn't actually care how clean the air is.....all they care about is collecting their $28 once a year.

 

sounds like someone dose not know a thing about engines.

 

Who is that comment for...

 

That test sounds insane!!

Back to topic for a bit: What is the Rev limiter set for on a 7.3?

 

the goof that made the test, rev limit has nothing to do with how the engine runs.

 

Hmm, that's just crazy. Here in Tucson it's just the opacity test at road speed on the dyno. Maybe when something bad happens they will stop making you do the rev test. When I had my Jeep Cherokee I only had to do the idle test after they had one jump out of the rollers. Even though the 4.0 could shift between full time, part time and neutral they didn't want to take a chance I guess.