hesitation and misfire
 

Today I got in my truck and was able to drive a couple of miles. Then all of a sudden It started to hesitate big time and barely move. I pulled over and let it idle for a little bit. The check engine light was flashing off and on. I had one of those Bluetooth scan tools with me so I checked for any fault codes. It showed the following codes
P0320 (No Crank Ref Signal at PCM)
P0300 (Multiple Cylinder Misfire)
P0305 (Cylinder #5 Misfire)
P0306 (Cylinder #6 Misfire)

and a pending fault code
P0740 (Torque Conv Clutch, No RPM Drop at Lockup)

The truck has been running great up until this point. I am thinking it could be a Crank Position Sensor but wanted to get your input or suggestions before I start throwing money at it.

It's a 1998 Dodge Ram 5.9, Automatic with 208,000 miles

Thanks

I should also state that it starts up just fine, and will idle on its own, but the idle isn't as smooth as before all this started

Plenum fixed? How are plugs? Wire route? If it's not getting crank signal it sounds like it would be crank sensor. P0740 could be as simple as the tcc solenoid not reading the RPM drop or much more complicated and be tc failing.


I see you're from Waterloo! I'm from over by Sioux City myself

plenum has not yet been replaced. Plugs and plug wires were replaced 10,000 miles ago. Yep a Waterloo man for most of my life.

I would start with plenum crank sensor and checking that wires are routed per the TSB.

A flashing check engine light means your dumping so much unburnt fuel that it could cause catalytic converter and or other mechanical damage to motor from intense heat. It's a more severe misfire than if the CEL just comes on solid. Hence, the flashing to get your attention.

Flashing CEL just indicates engine misfire is happening consistently at the moment. PCM doesn't really care (or probably even know) WHY it is happening.

Have a look at all the ignition parts first, cap, rotor, wires, plugs. If that all seems to be good, verify that fuel pressure is where it should be. Next, unplug the front O2 sensor, see if that changes anything. If everything there seems ok, crank sensor would be a good place to start.

Never replaced cap or rotor on it, probably a good idea with how many miles are on it. Been putting off plenum for a long time but probably should do that also.

I did order a STANDARD MOTOR PRODUCTS PC127T T-Series crankshaft position sensor, from reading it doesn't look like a fun job replacing the CPS but nothing good is ever easy.

Thanks for everyone's input, I will tear into it this week.

Sorry I wasn't able to get back to working on my truck till later this week. It is still not working. I changed the crank position sensor, and that didn't help at all. I have also put a pressure gauge on the fuel rail and it reads 48 to 50 psi while cranking and at idle. I also put a new cap and rotor on.

Yesterday I had trouble even starting the truck several times and no matter what I did I could not go over 1000 RPM. At one point I couldn't even pull it up my driveway because there was no power at all. It would just sit there and either stall on me or not move an inch.

I did buy a O2 sensor socket adapter to pull off the front O2 sensor to see if the cat was plugged but so far have been able to get it off. I have been spraying it with PB blaster in hopes to free it. As I didn't want to break it off.

Does anyone know where I can go from here. Like I said it has 0 power and won't go over 1000 RPM.

Thanks

Could try to loosen the bolts on the exhaust manifolds where the "Y" pipe connects to them. This could be harder the 02 but worth a try. I think it would be wise to pull the intake off and take a look at the plenum gasket. If a large chunk came off it would would be a major vac leak.

http://www.hughesengines.com/Index/p...p?partid=27091