5.9 running rich and slightly rough
#1
04-20-2018, 04:53 PM
5.9 running rich and slightly rough
Hey everyone, we’re down to the last issue with the truck. My new to me 2001 ram 1500 5.9 sport with a loaded interior, loving it so far and I missed having a second gen. The final issue I speak of is a running issue, it takes a while to start maybe 5-7 seconds of cranking before it chokes to life and has this slight skip. Runs pretty rich which is horrible since it’s my daily driver and I need to get the best mileage I can. I’m running 89 octane, new cap and rotor and plug wires. Haven’t gotten to the plugs because I don’t want to break them off and I haven’t found what’s best for these trucks but it’s got newer plugs I was more so doing them for peace of mind. Cap and rotor on the other hand were shot. What might be my problem? I’m at a loss with it, OH and it’s got new o2 sensors.
#2
04-20-2018, 05:13 PM
What brand O2 sensors?
Swap the plugs with your favorite brand copper plugs. Skip the rare earth fellers, they have been responsible for more 'mystery miss' problems than I care to think about. Some folks have no issues with them. Others have nothing but issues with them. The engines were designed for the copper guys, so, I stick with those.
Given the condition of the cap/rotor, I would be REAL curious what the plugs look like..... However, I suspect that isn't the only thing contributing to your issue. Fuel pressure would be next up on my list of things to check..... a weak/failing pump will show itself first with long crank times, and poor performance till the O2 sensor comes in to play... then it may or may not run a bit better. Long term fuel trims will also tell the tale there. If the PCM is adding a lot of fuel, you can bet that pressure is low.
Running rich though, points me in another direction...... coolant temp sensor. If the PCM thinks its colder than it really is, it will run the mixture pig rich, also giving you hard start/poor performance.....
So, start with the cheap and easy stuff, replace the plugs, and reset the PCM, see if anything changes.
And, just out of idle curiosity, have you had a look at your intake plenum yet?
Swap the plugs with your favorite brand copper plugs. Skip the rare earth fellers, they have been responsible for more 'mystery miss' problems than I care to think about. Some folks have no issues with them. Others have nothing but issues with them. The engines were designed for the copper guys, so, I stick with those.
Given the condition of the cap/rotor, I would be REAL curious what the plugs look like..... However, I suspect that isn't the only thing contributing to your issue. Fuel pressure would be next up on my list of things to check..... a weak/failing pump will show itself first with long crank times, and poor performance till the O2 sensor comes in to play... then it may or may not run a bit better. Long term fuel trims will also tell the tale there. If the PCM is adding a lot of fuel, you can bet that pressure is low.
Running rich though, points me in another direction...... coolant temp sensor. If the PCM thinks its colder than it really is, it will run the mixture pig rich, also giving you hard start/poor performance.....
So, start with the cheap and easy stuff, replace the plugs, and reset the PCM, see if anything changes.
And, just out of idle curiosity, have you had a look at your intake plenum yet?
#3
04-20-2018, 05:34 PM
What brand O2 sensors?
Swap the plugs with your favorite brand copper plugs. Skip the rare earth fellers, they have been responsible for more 'mystery miss' problems than I care to think about. Some folks have no issues with them. Others have nothing but issues with them. The engines were designed for the copper guys, so, I stick with those.
Given the condition of the cap/rotor, I would be REAL curious what the plugs look like..... However, I suspect that isn't the only thing contributing to your issue. Fuel pressure would be next up on my list of things to check..... a weak/failing pump will show itself first with long crank times, and poor performance till the O2 sensor comes in to play... then it may or may not run a bit better. Long term fuel trims will also tell the tale there. If the PCM is adding a lot of fuel, you can bet that pressure is low.
Running rich though, points me in another direction...... coolant temp sensor. If the PCM thinks its colder than it really is, it will run the mixture pig rich, also giving you hard start/poor performance.....
So, start with the cheap and easy stuff, replace the plugs, and reset the PCM, see if anything changes.
And, just out of idle curiosity, have you had a look at your intake plenum yet?
Swap the plugs with your favorite brand copper plugs. Skip the rare earth fellers, they have been responsible for more 'mystery miss' problems than I care to think about. Some folks have no issues with them. Others have nothing but issues with them. The engines were designed for the copper guys, so, I stick with those.
Given the condition of the cap/rotor, I would be REAL curious what the plugs look like..... However, I suspect that isn't the only thing contributing to your issue. Fuel pressure would be next up on my list of things to check..... a weak/failing pump will show itself first with long crank times, and poor performance till the O2 sensor comes in to play... then it may or may not run a bit better. Long term fuel trims will also tell the tale there. If the PCM is adding a lot of fuel, you can bet that pressure is low.
Running rich though, points me in another direction...... coolant temp sensor. If the PCM thinks its colder than it really is, it will run the mixture pig rich, also giving you hard start/poor performance.....
So, start with the cheap and easy stuff, replace the plugs, and reset the PCM, see if anything changes.
And, just out of idle curiosity, have you had a look at your intake plenum yet?
#4
04-20-2018, 05:41 PM
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