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Jerry, Master Mechanic
Category: Dodge
Satisfied Customers: 1754
Experience:  ASE Master tech, 30 years exp. troubleshooter, driveability tech
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I have a 2011 jeep grand cherokee 5.7 liter hemi with Air

Customer Question

I have a 2011 jeep grand cherokee 5.7 liter hemi with Air Raid Cold Air intake and Corsaa cut back exhaust. I wanted some extra hp and I installed a jets stage 2 performance module. It ran good for about a week and then began missing badly under load. I removed it and took it back to stock. It has the same condition and is very bad on highway under load. I tried to reset pcm back to factory. The CEL flashes under these conditions but does not pop an error code. Any ideas? Take to dealership and have them reprogram pcm back to factory settings? Could the plugs have gotten fouled? However it runs fine at idle and is not poping a code. Also, it turns out the performace module was for hemis up till 2008 model. I am lost
Submitted: 1 year ago.
Category: Dodge
Expert:  bill replied 1 year ago.

anytime the check engine light flashes there is a code stored a basic code reader MAY NOT be able to get it and the old key cycle method WILL NOT get it, how are you determining there are no codes?

Customer: replied 1 year ago.
I have a Torque Scanner on my Android that is linked to my PCM. The light does not stay on it flashes on and off when the truck stumbles under load.
Expert:  bill replied 1 year ago.

yes flashing of and on usually means a misfire, so the pcm HAD to have set a fault your code reader may not be able to read it, there are also around 40 computers on the WK2 grand Cherokee( 2011 and up) so if the pcm did not set anything it is possible the other computers did the scanner you have is pretty basic you may need a more advanced tool to pull any codes set, a dealer level scanner can access all the computers, also did you happen to change the spark plugs to a "performance" set?

the hemi IS NOT tolerant to a different spark plug other than what was originally installed

Customer: replied 1 year ago.
I have not taken it in to the dealership. I have not yet replaced the plugs..should I first?Also, one of the external plugs into the pcm (one of 4) came lose as the red lock tab broke. I have it seated correctly now. Not sure of that could cause this condition.
Expert:  bill replied 1 year ago.

first step is see what codes are setting anything else will be a waste of time and money, IF the plug seated correctly and clicked inplace (you heard and felt the click) the red tab is not really needed it is a SECONDARY lock and is used to be sure the plug seated correctly, I have seen tons of the red tabs missing and broken no big deal it is possible the performance chip damaged the pcm internally as we made significant changes internally to the computer between 08 and 11, it is faster and the pinouts have changed a bit from 08