Howdy
Got a fellow dodge owner that has a nice 99 ram 1500 with the 360. Ive been helping him out since day 1 when he bought the truck. Recently he was on the interstate when there was knocking noise coming from the engine compartment around 3k rpms. He then told me when he was in overdrive the rpms bounced around above and below 3k rpms and the check engine light was flashing. I grabbed my code reader and we went on the interstate with no luck of the engine light flashing. I was wondering what this might be. Only happens when engine is under load. Doesnt happen in neutral when engine is revved. Any ideas?

 

Sounds like maybe an overdrive malfunction if you feel the transmission shifting in and out of OD. If you don't feel the transmission shifting in and out of overdrive then it could be a throttle position sensor causing problems. My sisters durango would jump up & down 500 Rpm's on the Highway all the time until that was replaced. Even if no codes are thrown the TPS can still be bad.

No idea what the knocking noise you hear is, would almost have to record it so we can have a listen here. It remains to be seen if that OD solenoid is making that noise until we can get more information.

 

At 3000 rpm, OD is not on. If rpm is that high it would run about 65 t0 70 in third. In OD it should be 2100 to 2200 rpm for 70 mph. Knocking could be TCC locking and unlocking. Need a good scanner to read tranny and see what is going on. Also chec TV cable adjustment to make sure it is right.

And +1 on knocking.....kind of have to hear it.

 

No one has said it yet!?

Blown plenum possibility. Could be pinging you're hearing.

 

CEL flashing indicates misfire on one or more cylinders.

 

Alright could it be his plenum?

 

Maybe it's all three? But seriously, definitely misfiring happening under load. I had a flashing CEL and TPS code once, driving into a 40 mph headwind and hauling 1000 lb load. Also had rpm surging 200 to 300 rpms while sitting still in park.

 

Surging RPM could be blown plenum as well as misfire. And 3000 rpm is tranny related most likely.

Go to FAQ/DIY and read up on plenum and check it. Keep on driving if that is the problem will risk cracking head.

 

it was in third gear but when he was in overdrive he said lockup kept coming and going away at random times. sorry for typo

 

TC has to lock up before OD.