Here's the story.
Brother in-law inherited a 99 xj from his dad.
Dad had driven the jeep for 40 miles with the check engine light on. Then had it towed to the dealership the next day.
It was taken into the stealership. They diagnosed blown head gasket, cracked intake manifold, and low fuel pressure. 30psi when 49 was supposed to be stock. Dealership replaced fuel pump.
I towed XJ to my house and diagnosis began. Head gasket confirmed as shot with bubbling exhaust through overflow tank. I tore it down and confirmed a shot head gasket. We replaced gasket and had head machined flat (.019) then it was magnafluxed for leaks. No cracks were found on the head.
I replaced the cracked intake manifold
We reassembled the engine and flushed radiator and block, changed the oil. topped off all fluids.
Jepp started up fine (whew!). Temps stabilzed to the 210 range that my own 99 sits at.
We immediatley noticed a rough idle.....then upon test-driving noticed some hesitation off the line. But otherwise driving fine at speeds between 25-55...but rough idle still doesn't seem right......BAM...check engine light illuminates. We headed to Auto Zone and they pulled a p171 code: "lean on 1st bank."
I did some reading here tonight. posts indicated things such as vacuum leaks, MAP sensor, O2 sensor.
I swapped the original MAP sensor from the original intake manifold to see if that would clear up the rough idle. No dice. Then, suspecting I'd nicked a vacuum line I ran some propane around all the vacuum lines in an effort to diagnose a vacuum leak. No change in the rough idle occurred.
At this point I'm kind of stumped.....and quite tired.
O2 sensor? Is there a way to check this without just swapping in a $60 new one?
Any other ideas?
Could this lean condition have led to the blown head gasket? If i remember correctly, lean=hot...thus the head gasket.
Thoughts?
Tips?
Brother in-law inherited a 99 xj from his dad.
Dad had driven the jeep for 40 miles with the check engine light on. Then had it towed to the dealership the next day.
It was taken into the stealership. They diagnosed blown head gasket, cracked intake manifold, and low fuel pressure. 30psi when 49 was supposed to be stock. Dealership replaced fuel pump.
I towed XJ to my house and diagnosis began. Head gasket confirmed as shot with bubbling exhaust through overflow tank. I tore it down and confirmed a shot head gasket. We replaced gasket and had head machined flat (.019) then it was magnafluxed for leaks. No cracks were found on the head.
I replaced the cracked intake manifold
We reassembled the engine and flushed radiator and block, changed the oil. topped off all fluids.
Jepp started up fine (whew!). Temps stabilzed to the 210 range that my own 99 sits at.
We immediatley noticed a rough idle.....then upon test-driving noticed some hesitation off the line. But otherwise driving fine at speeds between 25-55...but rough idle still doesn't seem right......BAM...check engine light illuminates. We headed to Auto Zone and they pulled a p171 code: "lean on 1st bank."
I did some reading here tonight. posts indicated things such as vacuum leaks, MAP sensor, O2 sensor.
I swapped the original MAP sensor from the original intake manifold to see if that would clear up the rough idle. No dice. Then, suspecting I'd nicked a vacuum line I ran some propane around all the vacuum lines in an effort to diagnose a vacuum leak. No change in the rough idle occurred.
At this point I'm kind of stumped.....and quite tired.
O2 sensor? Is there a way to check this without just swapping in a $60 new one?
Any other ideas?
Could this lean condition have led to the blown head gasket? If i remember correctly, lean=hot...thus the head gasket.
Thoughts?
Tips?