2003 Lesabre rough idle and studder on hills
#1
2003 Lesabre rough idle and studder on hills
My 2003 Lesabre has rough idle and studder on hills. This is what I have done so far.
At first I got a SES, had code read at Autozone - Miss fire #5 cylinder.
So,
- Did wire and plug change - same issue, SES light now out
- Cleaned MAF, replace PCV and MAP sensor - same issue
- Cleaned fuel injectors and replaced fuel pressure regulator - same issue
- Replaced forward O2 sensor - same issue
- Pulled each ign. coil cleaned ICM post, checked Ohm at ICM plugs .5 and posts 5.5 on each (good) - same issue
I am out of ideas especially with no SES displaying. Seems to happen with engine hot and pulling a load up a hill but also rough idle.
Up next replace ICM, TPS, IAC
At first I got a SES, had code read at Autozone - Miss fire #5 cylinder.
So,
- Did wire and plug change - same issue, SES light now out
- Cleaned MAF, replace PCV and MAP sensor - same issue
- Cleaned fuel injectors and replaced fuel pressure regulator - same issue
- Replaced forward O2 sensor - same issue
- Pulled each ign. coil cleaned ICM post, checked Ohm at ICM plugs .5 and posts 5.5 on each (good) - same issue
I am out of ideas especially with no SES displaying. Seems to happen with engine hot and pulling a load up a hill but also rough idle.
Up next replace ICM, TPS, IAC
#2
Senior Member
Are you loosing coolant? That engine is famous for ingesting coolant at the upper and lower intake manifolds. Cylinder 5 is right next to a coolant port as well.
#3
My 2003 Lesabre has rough idle and studder on hills. This is what I have done so far.
At first I got a SES, had code read at Autozone - Miss fire #5 cylinder.
So,
- Did wire and plug change - same issue, SES light now out
- Cleaned MAF, replace PCV and MAP sensor - same issue
- Cleaned fuel injectors and replaced fuel pressure regulator - same issue
- Replaced forward O2 sensor - same issue
- Pulled each ign. coil cleaned ICM post, checked Ohm at ICM plugs .5 and posts 5.5 on each (good) - same issue
I am out of ideas especially with no SES displaying. Seems to happen with engine hot and pulling a load up a hill but also rough idle.
Up next replace ICM, TPS, IAC
At first I got a SES, had code read at Autozone - Miss fire #5 cylinder.
So,
- Did wire and plug change - same issue, SES light now out
- Cleaned MAF, replace PCV and MAP sensor - same issue
- Cleaned fuel injectors and replaced fuel pressure regulator - same issue
- Replaced forward O2 sensor - same issue
- Pulled each ign. coil cleaned ICM post, checked Ohm at ICM plugs .5 and posts 5.5 on each (good) - same issue
I am out of ideas especially with no SES displaying. Seems to happen with engine hot and pulling a load up a hill but also rough idle.
Up next replace ICM, TPS, IAC
#4
Senior Member
I would do a coolant pressure test and take a hard look at the lower intake gaskets.
You might also have a vacuum leak somewhere causing a lean missfire which also can be caused by the lower intake gaskets. They were a crappy plastic design from the factory. The gasket has since been updated with a aluminum gasket.
You might also have a vacuum leak somewhere causing a lean missfire which also can be caused by the lower intake gaskets. They were a crappy plastic design from the factory. The gasket has since been updated with a aluminum gasket.
#5
Senior Member
After I thought about it for a bit if the EGR valve is stuck open a little it will cause it to idle rough and miss up hills as well.
#7
Retired
X3 on EGR. But a minute coolant leak into a cylinder can still cause a misfire. Did you check your coolant reservoir?
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Retired Administrator
2002 *-10 5.7 V8
2023 Jeep Rubicon Diesel
Retired Administrator
2002 *-10 5.7 V8
2023 Jeep Rubicon Diesel
#9
Senior Member
If I remember right, by 2003, wasn't the redesigned upper plenum, with a larger EGR hole used?
Plus, he says he is not losing coolant.....
Certainly sounds like a misfire.....he changed plugs and wires(OEM?), but did he check spark output for each coil terminal?
He should drive the vehicle on the highway, at 55 mph, up a slight grade....then, SLOWLY accelerate(to keep the TCC engaged).....if this can induce a misfire, then it'* generally secondary ignition......
Plus, he says he is not losing coolant.....
Certainly sounds like a misfire.....he changed plugs and wires(OEM?), but did he check spark output for each coil terminal?
He should drive the vehicle on the highway, at 55 mph, up a slight grade....then, SLOWLY accelerate(to keep the TCC engaged).....if this can induce a misfire, then it'* generally secondary ignition......
#10
Retired
He said he didn't NOTICE a loss of coolant, thus why I SPECIFIED to look again.
BTW Gus, did YOU get my PM?
BTW Gus, did YOU get my PM?
__________________
Retired Administrator
2002 *-10 5.7 V8
2023 Jeep Rubicon Diesel
Retired Administrator
2002 *-10 5.7 V8
2023 Jeep Rubicon Diesel