Truck runs great until it warms up
#1
11-13-2020, 01:27 PM
Truck runs great until it warms up
I have a 96 ram 1500 5.9 4x4 it'll start and run great until it gets around 140-170° and then it'll start to idle rough and if I apply any gas it'll raise the rpms up a little but it'll start to backfire and run very rough and it then die and I won't be able to start it until the next day and then the same thing happens and no codes are present
parts I've replaced:
IAC valve
TPS
Both coolant temp sensors
Crankshaft sensor
Ignition coil
Wires
Rotor
Cap
Pick-up coil
fuel pump assembly
both o2 sensors
and messed with some vacuum lines
I had ran it to brake-in my new brake pads and it was fine during probably 45 to an hour of braking them in and then I parked it and the next day it rained and then the day after it rained I went to start it to bleed my brakes one last time and this has been happening since. Also my downstream o2 sensor is stuck at 1v and it was stuck at 1v before I replaced them.
parts I've replaced:
IAC valve
TPS
Both coolant temp sensors
Crankshaft sensor
Ignition coil
Wires
Rotor
Cap
Pick-up coil
fuel pump assembly
both o2 sensors
and messed with some vacuum lines
I had ran it to brake-in my new brake pads and it was fine during probably 45 to an hour of braking them in and then I parked it and the next day it rained and then the day after it rained I went to start it to bleed my brakes one last time and this has been happening since. Also my downstream o2 sensor is stuck at 1v and it was stuck at 1v before I replaced them.
Last edited by David 0512; 11-16-2020 at 03:34 PM.
#2
11-13-2020, 02:43 PM
Please clarify: You changed all these things at one time or another, or did you replace the parts after the problem appeared ?
Sounds like you have a decent scan tool that can read live data, what do intake air temp, engine temp and the O2 sensors show when it dies ? Also what does the MAP sensor read ?
The rain could be just coincidence but a lot of older trucks are missing the foam that keeps water from dripping down into the PCM area so that might be another thing to look at.
Sounds like you have a decent scan tool that can read live data, what do intake air temp, engine temp and the O2 sensors show when it dies ? Also what does the MAP sensor read ?
The rain could be just coincidence but a lot of older trucks are missing the foam that keeps water from dripping down into the PCM area so that might be another thing to look at.
Last edited by DerTruck; 11-13-2020 at 02:48 PM.
The following users liked this post:
David 0512 (11-14-2020)
#3
11-13-2020, 09:47 PM
Please clarify: You changed all these things at one time or another, or did you replace the parts after the problem appeared ?
Sounds like you have a decent scan tool that can read live data, what do intake air temp, engine temp and the O2 sensors show when it dies ? Also what does the MAP sensor read ?
The rain could be just coincidence but a lot of older trucks are missing the foam that keeps water from dripping down into the PCM area so that might be another thing to look at.
Sounds like you have a decent scan tool that can read live data, what do intake air temp, engine temp and the O2 sensors show when it dies ? Also what does the MAP sensor read ?
The rain could be just coincidence but a lot of older trucks are missing the foam that keeps water from dripping down into the PCM area so that might be another thing to look at.
#4
11-13-2020, 10:16 PM
Please clarify: You changed all these things at one time or another, or did you replace the parts after the problem appeared ?
Sounds like you have a decent scan tool that can read live data, what do intake air temp, engine temp and the O2 sensors show when it dies ? Also what does the MAP sensor read ?
The rain could be just coincidence but a lot of older trucks are missing the foam that keeps water from dripping down into the PCM area so that might be another thing to look at.
Sounds like you have a decent scan tool that can read live data, what do intake air temp, engine temp and the O2 sensors show when it dies ? Also what does the MAP sensor read ?
The rain could be just coincidence but a lot of older trucks are missing the foam that keeps water from dripping down into the PCM area so that might be another thing to look at.
#5
11-14-2020, 02:15 AM
Freeze frame is a function of the PCM, it records all relevant data when it throws a Diagnostic Trouble Code. I don't think you can snapshot the data at will, unless the scan tool itself can store the data.
MAP sensor around 10 in HG looks ok (assuming idle). Upstream O2 is on the lean side, in closed loop it should register going back and forth between lean and rich (which the PCM controls). If it is consistently lean that might be a symptom. The downstream O2 is only used to monitor cat efficiency so let's ignore that for now.
When starting it from cold have a close look at the loop status. Trying to figure out if it runs fine in open loop and starts to stumble when it goes into closed loop, or if the problems start later when the engine gets warmer.
MAP sensor around 10 in HG looks ok (assuming idle). Upstream O2 is on the lean side, in closed loop it should register going back and forth between lean and rich (which the PCM controls). If it is consistently lean that might be a symptom. The downstream O2 is only used to monitor cat efficiency so let's ignore that for now.
When starting it from cold have a close look at the loop status. Trying to figure out if it runs fine in open loop and starts to stumble when it goes into closed loop, or if the problems start later when the engine gets warmer.
The following users liked this post:
David 0512 (11-14-2020)
#6
11-14-2020, 08:29 AM
The following users liked this post:
David 0512 (11-14-2020)
#7
11-14-2020, 02:14 PM
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#8
11-14-2020, 02:16 PM
Freeze frame is a function of the PCM, it records all relevant data when it throws a Diagnostic Trouble Code. I don't think you can snapshot the data at will, unless the scan tool itself can store the data.
MAP sensor around 10 in HG looks ok (assuming idle). Upstream O2 is on the lean side, in closed loop it should register going back and forth between lean and rich (which the PCM controls). If it is consistently lean that might be a symptom. The downstream O2 is only used to monitor cat efficiency so let's ignore that for now.
When starting it from cold have a close look at the loop status. Trying to figure out if it runs fine in open loop and starts to stumble when it goes into closed loop, or if the problems start later when the engine gets warmer.
MAP sensor around 10 in HG looks ok (assuming idle). Upstream O2 is on the lean side, in closed loop it should register going back and forth between lean and rich (which the PCM controls). If it is consistently lean that might be a symptom. The downstream O2 is only used to monitor cat efficiency so let's ignore that for now.
When starting it from cold have a close look at the loop status. Trying to figure out if it runs fine in open loop and starts to stumble when it goes into closed loop, or if the problems start later when the engine gets warmer.
Last edited by David 0512; 11-14-2020 at 02:36 PM.
#10
11-15-2020, 01:10 PM