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Ever notice? (reving engine in neutral)

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12K views 19 replies 15 participants last post by  03dakrt  
#1 ·
Anyone notice that while reving your engine in neutral the RPM won't go past 4(000)?
 
#3 ·
occassional flooring it should be part of break in



manual even tells you do so,
also on smaller engines usually get peek HP around 5K rpms
regularly took my neon to redline,
and +200K miles later, no engine problems and drives great

for the jeep,
have occassionally taken it to 5K-6Krpms,
 
#4 · (Edited)
#6 ·
THE TRUCK HAS A REV LIMITER IN IT SO YOU DONT BLOW UP THE MOTOR...
 
#9 ·
Same as my Charger. As gramops said, its in the PCm coding to not allow it to rev past a certain point in neutral ot park.
Its a good thing. High revving a engine under no load is not too good on it.
Hitting redline in gear is no problem.
Actually, the person that stated they never take their Patty over 4k in drive is actually doing bad for the little 4 banger, could lead to crapola build up. Engines need to have their legs streatched.
 
#10 · (Edited)
Thanks for the advice everyone. I won't rev it over 4 in N again. Actually, today was the first time I did... hence having only noticed this today. I just thought it was kinda cool that this feature was included in our Pats. edit: and Compass' right Gramps? :smiley_thumbs_up:

I've never owned another vehicle that did this... that I know of.

Cheers.
 
#12 ·
I just think MK. I don't care about the sheet metal. I don't have a clue how many times I've run it up to 6K...as needed? 0- 60 timed runs, sure; jumping on the freeway, yup; passing or pulling out into fast traffic, uh huh...as needed. It just does it, no whines, whimpers or moans, she's a good girl.
 
#13 ·
A buddy of mine has the CVT and we noticed it with his. As stated above we just assumed it was governed, so he floored it to see what would happen. Nothing happened, it stayed steady at 4k. I have not tried it in my 5spd yet, does anyone know if its limited to 4k with the manual as well?
 
#19 ·
Testing



Somebody has to test how good that lifetime warranty is.

Although, my 1960 Willys wagon with the inline flathead 6 will rev to 4K without a problem. If that old beast can do it, this new breed of Jeep should be able to.
 
#15 ·
It is a safety feature of the engine to prevent damage from over revving. The throttle is now controlled by a servo and the gas pedal is pretty much a reostat. (Accelerator by wire)

This is a common feature in newer cars. It will only allow you to get to certain RPMs in certain conditions. My wife 05 Chevy equinox and before that 02 Saturn VUE both limited the engine to 4000 in park or neutral and a redline of 6000 in gear. I can put the car in low gear, drop the hammer and will only get to 6000 rpms. Also with all of the interconnects, it wont let me shift from park/neutral to drive or reverse if the RPMs are over 1500, once again safety (and preventing your gears from being striped).

With the CVT, this allows for the computers on board to set the engine speed, adjust the pulleys in the tranny to get you to speed and then when you get to speed, lower the RPMs and make the final adjustments in the tranny. Darn computers being smarter then us average bears! :hitanykey:
 
#16 ·
Speaking as a professional computer programmer, the computers are only as smart as the programmer. And hope you don't get off into some part of the possibilities that the programmer didn't anticipate and get unexpected behavior.

The computer managed fuel injection and spark advance get tremendously better fuel economy and power over a wide range of engine loads and RPM's than the old days' carburetors and vacuum and mechanical advance ignition distributor systems. My 4,200 lb 1995 Chevy Caprice 5.7 liter gets the same highway gas mileage on regular as my 2,500 lb 1964 Corvair did on premium. Of course, the Caprice is doing 1900 RPM at 70 mph instead of 3,000 RPM like the Corvair. But I'm still amazed by the fuel mileage accomplished by the computer controlled fuel injection and spark advance.
 
#17 ·
For breakin, the 2008 Owner's Manual I downloaded from jeep.com says

Drive moderately during the first 300 miles. After the initial 60 miles, speeds up to 50 or 55 mph are desirable.

While cruising, brief full throttle acceleration, within the limits of local laws, contributes to a good break-in. Wide open acceleration in low gear can be detrimental and should be avoided.
I don't see anything there that says to run it up to red line. If you are cruising and you smoothly (moderately?) floor it briefly, that shouldn't put it up to redline, unless you have a CVT and floor it very abruptly.

Especially with a manual, flooring it "briefly" while cruising shouldn't run you up to red line unless you are "cruising" at 50 mph in third gear and hold it floored for a fairly long "briefly".

It's too bad they are not more specific about what speed and gear they mean by "cruising" and how many seconds "briefly" is.