(My 2002 ram 5.9 gas) Runs great no trans slip no misfire or anything But going up a long hill it down shifts and the RPMs go up to like 3500-4000 depends how fast Im going the engine roars but it loses speed or just stays the same speed I noticed today when it down shifted again the check engine light was blinking and has soon as the RPMs dropped the light stopped blinking and stood off I dont know what it could be

 

Blinking CEL indicates the engine is misfiring. Need to find out why.... Check the plenum, have a look at the plugs, and do a compression test. See what you find.

 

Ok what kind of plugs should be inuse with my engine and how much compression shod it have? Could it be anything else besides that, that is causing the lack of power?

 

Believe factory plugs were Champion Coppers. Use a copper plug if you replace any. If your motor is misfiring, the #8 plug is the most common to foul out... Check that one first.

Compression will depend on what shape your engine is in, you want all cylinders to be around the same, I'd say around 150 or so...

Clogged cat/bad O2 sensors will rob power too, but that is the usual side effect of a blown plenum and/or a bad PCV valve...

 

ok but one question whats a plenum?

 

https://dodgeforum.com/forum/2nd-gen...um-thread.html

 

Have the catalytic converter pressure tested. My money is on it being clogged.

 

Thank you but my truck does have a weird sound when it first starts like a loss heat sheild but thers not I check it sounded like it was coming from the cat when I checked and I got a code this morning for cylinder 1 misfire

 

Cylinder 1, wasn't expecting that....

If the cat's clogged you can physically remove the pre-cat o2 sensor from the pipe, and see if it runs any better.. removing the sensor will release some of the pressure built up from the bad cat...

It will be a PITA to get out more than likely...

Pull the #1 plug and see how it looks.

 

Plug 1 looks fine but its a Autolite platinum Im gonna get copper plugs and pull out the O2 sensor and see