P0118 code and loss of power

GregBelleville

TJ Enthusiast
Supporting Member
Joined
Sep 19, 2022
Messages
556
Location
Southern California
Good afternoon all, looking for some help/advice. Over the last 2 months I've been working on a timing chain and distributor replacement. Anyway, I finished that job last weekend and the Jeep fired right up and had been running smooth all week until yesterday.

Yesterday I noticed coolant on the ground around the passenger side of the Jeep, I opened the hood and it looked like coolant had been blown around the engine bay on the passenger side, and I believe the source was the heater core hose which I noticed had the constant tension hose clamp where it meets the water pump was not in place. I put the clamp in place and drove it a short distance last night and Jeep seemed to run normal.

This morning I went back out and saw more coolant on the ground and in the engine bay, I started it and got a CEL code p0118. I opened the radiator cap and the radiator was low on coolant so I topped it off and drove it around the block. The engine ran very low on power, kind of surging a couple of times under throttle so I limped it back home. I left it running and opened the hood looking for more coolant leaking and didn't see anything. But the motor sounds a little rough and seems to be running rich at the tail pipe, with a bit of visible smoke from the exhaust.

Any thoughts on what is causing the p0118 code and if it likely related to the engine running low on power?
 
What color exhaust?

Leaks are all fixed right? Double check the coolant level and if good. Clear the trouble codes with a scanner and see if it goes back to running properly and see if the code comes back.
 
What color exhaust?

Leaks are all fixed right? Double check the coolant level and if good. Clear the trouble codes with a scanner and see if it goes back to running properly and see if the code comes back.

In broad daylight the exhaust looked a bit smoky/blue in color?

I topped off the radiator, it was definitely low after the leak, probably took ¾ gallon of coolant to top of the radiator.

From researching the FSM it looks like this could be related to the ECT (engine coolant temp) sensor voltage reading high?
 
If blue that’s a sign of burning oil.

Clear the code and see if it comes back.

Will do, from what I can tell reading the FSM, the engine may be running rich due to the ECT sensor possibly malfunctioning which may have been why I was seeing the smoke out the exhaust.
 
Ok update. I cleared the code, and ran the motor at idle until engine was warm and no code returned, but now I think I have a second issue that may be causing a loss of engine power.

After warming the engine up I took it for a test drive and it's definitely not running right. If I accelerate from a stop, the best way I can describe it is the engine feels like a turbo motor that isn't on boost yet below 2500 rpm, very little power, or acceleration, and then around 2500rpm the engine suddenly wakes up and accelerates more normally until the trans shifts and then it starts over again.

I brought it back home and although I didn't have a check engine light, I used my scanner to see that there was a pending code for P0171 for system too lean bank 1.
 
Ok update. I cleared the code, and ran the motor at idle until engine was warm and no code returned, but now I think I have a second issue that may be causing a loss of engine power.

After warming the engine up I took it for a test drive and it's definitely not running right. If I accelerate from a stop, the best way I can describe it is the engine feels like a turbo motor that isn't on boost yet below 2500 rpm, very little power, or acceleration, and then around 2500rpm the engine suddenly wakes up and accelerates more normally until the trans shifts and then it starts over again.

I brought it back home and although I didn't have a check engine light, I used my scanner to see that there was a pending code for P0171 for system too lean bank 1.
P0171 code trouble shooting
https://www.engine-codes.com/p0171_jeep.html
 
Ok, I sprayed some soapy water on the flange where the header meets the exhaust pipe and there is definitely a leak there. My question for the experts is whether the exhaust should be completely sealed at the flange? Should I expect to have zero leak at that flange?
 
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Ok, I sprayed some soapy water on the flange where the header meets the exhaust pipe and there is definitely a leak there. My question for the experts is whether the exhaust should be completely sealed at the flange? Should I expect to have zero leak at that flange?

there should be zero leakage, since an exhaust leak causes a drop in back pressure, which can lead to a decrease in power and sluggish acceleration. Plus there’s the potential for exhaust fumes to enter the cabin.
if the flange is warped you can try using two gaskets to seal it, but since you mentioned you disconnected it to remove the oil pan odds are it’s fine and you can simple use a jack to help raise the rearward exhaust pipe higher as needed….

Hope this helps…
 
Well, I did my best to tighten up the exhaust flange, but I did not completely eliminate the leak, so I'll need to see what I can do to solve that.

Anyway, I ran the motor until it came up to temp today and it ran fine, no CEL, so I took it for a drive and it ran normally, accelerated fine, no issues, so now I'm a little stumped.

I'm wondering if the stored p0171 code was related to the p0118 i was getting? I don't know if the low coolant level in the radiator that led to the p0118 may have also caused the lean condition somehow?