Misfiring, Shuddering, No Power, Code 300
#1
Success! - Misfiring, Shuddering, No Power, Code 300
2001 RAM Sport 5.9L.
About 9 weeks ago, I put in a new CKS, CPS, distributor cap, rotor, plugs and cables.
As of Tuesday morning (last week), the truck was running fine.
That afternoon, I ran an errand and pushed it pretty hard (lots of sharp curves and hills) and it ran fine.
That evening, was going up a hill and it shuddered really hard three times - like WHAM, WHAM, WHAM.
No more trouble that day, buy shook really bad going up a hill the next day. By Friday, it would barely make it up a hill and top speed was about 45. Any faster and and the engine would start shaking really bad.
Friday evening, the CEL came on with codes 300, 304, and 306. (Misfires on cylinders 4 and 6.)
I pulled the forward O2 sensor to verify that it is not a clogged cat.
Fuel pressure is good.
The only other clues are:
1. If you try to rev it up a little, you will get the sulphur smell of excess gas hitting the cat.
2. I was never happy with the way the replacement distributor cap (or rotor) fit. It felt like it was too short or the rotor was too tall. That is probably a red herring as it has been running fine with it. I ordered another new one and will swap it out just because.
Ideas?
About 9 weeks ago, I put in a new CKS, CPS, distributor cap, rotor, plugs and cables.
As of Tuesday morning (last week), the truck was running fine.
That afternoon, I ran an errand and pushed it pretty hard (lots of sharp curves and hills) and it ran fine.
That evening, was going up a hill and it shuddered really hard three times - like WHAM, WHAM, WHAM.
No more trouble that day, buy shook really bad going up a hill the next day. By Friday, it would barely make it up a hill and top speed was about 45. Any faster and and the engine would start shaking really bad.
Friday evening, the CEL came on with codes 300, 304, and 306. (Misfires on cylinders 4 and 6.)
I pulled the forward O2 sensor to verify that it is not a clogged cat.
Fuel pressure is good.
The only other clues are:
1. If you try to rev it up a little, you will get the sulphur smell of excess gas hitting the cat.
2. I was never happy with the way the replacement distributor cap (or rotor) fit. It felt like it was too short or the rotor was too tall. That is probably a red herring as it has been running fine with it. I ordered another new one and will swap it out just because.
Ideas?
Last edited by IronAge; 04-18-2012 at 10:34 PM. Reason: Success!
#2
#3
Let me phrase it this way: Other than the slight volume increase, the symptoms were not lessened at all by pulling the sensor.
The distributor cap is a long shot. My guess is that if it was going to be an issue, it wouldn't have waited 8 weeks to do it. The new cap and rotor will not be here until Wednesday. I will swap them then and see if anything looks weird inside the cap.
I am also thinking about replacing the the forward O2 sensor and the MAP sensor. I kind of hate to just start throwing parts at it though.
The distributor cap is a long shot. My guess is that if it was going to be an issue, it wouldn't have waited 8 weeks to do it. The new cap and rotor will not be here until Wednesday. I will swap them then and see if anything looks weird inside the cap.
I am also thinking about replacing the the forward O2 sensor and the MAP sensor. I kind of hate to just start throwing parts at it though.
#4
#6
I will check out all your ideas.
Something to keep in mind though:
Fuel pressure is good. I tested it with a gauge Friday evening. It did bleed down pretty quick, but that is because the connection from the hose to the gauge leaks pretty bad.
I believe I have the wires routed correctly.
I could definitely support the idea that an injector or two are stuck open (based on the sulphur smell).
My other thought was that either the MAP or the O2 sensor might be causing it to run extremely rich.
Something to keep in mind though:
Fuel pressure is good. I tested it with a gauge Friday evening. It did bleed down pretty quick, but that is because the connection from the hose to the gauge leaks pretty bad.
I believe I have the wires routed correctly.
I could definitely support the idea that an injector or two are stuck open (based on the sulphur smell).
My other thought was that either the MAP or the O2 sensor might be causing it to run extremely rich.
#7
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#8
#9
#10
I'd check and make sure cylinder 4 and 6 plugs are firing. If not, go from there. Might be a problem with some of the replacement ignition parts (cap, wires, or plugs). Check to make sure wires are still seated properly, etc. Maybe clear the misfire codes, swap a couple of plug wires, and see if the misfire codes move.