Mopar ECU going into Limp Mode again.....

[ACRBruce]

I've already switched back to the factory thermostat but the Mopar ECU is still so overly protective and would go into limp mode if I hit the rev limited for longer than say just a split second. Sometimes while on track and right before or while at a turn, I prefer not to upshift and hit the rev limited once in a while but the ECU is so overly protective of the engine, it'd throw a fit and then refuse to go about 3500 RPM until I stop and restart the engine 5, 6 times. BTW I have ported intake and Belinger headers. Want to find out if anyone is having the same issue and if there's anything that can be done to avoid the limp mode coming on so soon after the rev limiter is hit.

 

[redtanrt10]

Bruce, have you checked for any fault codes? I hit the rev limiter in 4th at Fontana in the fall and it went into limp mode. Then in went into limp mode a few more times during the day an eventually I got a CEL light (and a cam sensor problem). Seems I've read here on the board that if you hit it twice it will go into limp mode. Not sure if the mopar ECU has anything to do with it? Touch base w/Dan or Mark J at Woodhouse. Mike

 

[Viperless]

Interesting. I hit the limiter several times last year at MPH and it never went into limp mode. Makes no sense to me how these ECUs can behave so differently from one car to the next.

 

[ACRBruce]

Bruce, have you checked for any fault codes? I hit the rev limiter in 4th at Fontana in the fall and it went into limp mode. Then in went into limp mode a few more times during the day an eventually I got a CEL light (and a cam sensor problem). Seems I've read here on the board that if you hit it twice it will go into limp mode. Not sure if the mopar ECU has anything to do with it? Touch base w/Dan or Mark J at Woodhouse. Mike

Mike,
The CEL never came back on after it went away but it didn't help my runs as I was short shifting to make sure I stayed away from the redline. I'll eventually talk to Dan or Mark but just wanted to see what others are experiencing first.

 

[ViperGTS]

I hit the rev limiter but no CEL light coming on. But the Gen-4 is almost stock except for HF cats...and the Mopar PCm

 

[Viper Specialty]

Check your Cam Position Sensor on the back side of the engine, 12 o'clock, right under the intake manifold. If it has a part number ending in AA or AB, replace it with the new AC sensor. It may be losing Cam Sync at high RPM.

 

[FastGuy68]

Has to be something else as simply hitting the rev-limit won't cause "limp mode". You need to scan for codes.

 

[ACRBruce]

Thanks for the tips guys. If the CEL is gone already, will I still be able to pull any codes?

 

[Steve-Indy]

If you do end up following the suggestion of "Final GTS" about the cam semsor...he has already helped you a bunch by directing you to the correct location !! Sadly, the 2008 Viper Service Manual CD INCORRECTLY shows/directs one to a knock sensor location when describing/diagramming the location of the cam sensor. However, this has been corrected on the 2009 CD.

A Gen IV cam sensor change out is about a 15 min. job...parts often in stock due to cross-over with other vehicles.

 

[ACRBruce]

My Cam Sensor part # does in fact end in "AA", so it is time to try the newer "AC" coded sensor. Thank you all for the valuable input.