Poor engine performance under light and heavy load

PALiftedKK · **Posted:** Wed Aug 14, 2019 5:00 pm

So the title issue begun roughly 3 weeks ago. I changed nothing driveline related weeks prior to that. My issue is that wheather or not in gear, I can come to a complete stop (eventually). It literally feels like I’m towing my trailer but heavier. Acceleration going up hills is non existent as I actually slow down while in gear and at above 4K rpm. I have no noticeable transmission issues as in slipping gears. Jeep comes out of neutral no issue. Brake pads/rotors are all close in temperature to each other. I do believe I have a failing u joint on my driveshaft but can not look at it till I arrive at home later next week.

I’m honesty at a loss guys as to the issue. I have thoughts but that is all.

Any ideas or even questions would be greatly appreciated!

PALiftedKK/kkthejeep

lfhoward · **Posted:** Wed Aug 14, 2019 9:49 pm

Well that sucks. Sorry to hear.

Like you my first thought was a stuck brake caliper. But having them all be the same temp sort of eliminates that. Unless all your brakes are engaging at once. Does the pedal feel like it comes back up fully? Bad brake booster or something?

The other thing I was wondering about is the parking brake sticking. It would make the rear hubs/drums hot but not the calipers. Might be worth checking those temps.

Do you smell anything hot like brakes after driving it?
How’s the engine and transmission temps from the scangauge? All normal? Does the engine idle and rev normally?

Nobody has gone and swapped in 3.23’s while you were asleep, right? :-)r

If none of the above, try putting the Jeep on jack stands in neutral, and spinning the wheels by hand. Any crazy resistance would help you pinpoint a bad wheel bearing or stuck brakes.

That’s all I have at the moment. If I think of something else to check I’ll let you know.

PALiftedKK · **Posted:** Wed Aug 14, 2019 10:03 pm

lfhoward wrote:

Well that sucks. Sorry to hear.

Like you my first thought was a stuck brake caliper. But having them all be the same temp sort of eliminates that. Unless all your brakes are engaging at once. Does the pedal feel like it comes back up fully? Bad brake booster or something?

The other thing I was wondering about is the parking brake sticking. It would make the rear hubs/drums hot but not the calipers. Might be worth checking those temps.

Do you smell anything hot like brakes after driving it?
How’s the engine and transmission temps from the scangauge? All normal? Does the engine idle and rev normally?

Nobody has gone and swapped in 3.23’s while you were asleep, right? :-)r

If none of the above, try putting the Jeep on jack stands in neutral, and spinning the wheels by hand. Any crazy resistance would help you pinpoint a bad wheel bearing or stuck brakes.

That’s all I have at the moment. If I think of something else to check I’ll let you know.

Engine and tans are hotter and get hotter easier now but I’m in assumption that that is due to the driveline (or what I believe to be) resistance.

Pedal feel is normal! E brake hasn’t worked for years and does not engage to my knowledge. Rotor temps are all within 20 degrees of each other which I dream is completely acceptable. No odd/funny scents according to my friend that drove his motorcycle behind me a few days ago. Once I get back home next week my plan was to throw the rear up on stands and remove the driveshaft to spin and test the rear ended by hand. Im honestly hoping it’s a bearing and not transmission or transfer case.... also, diff fluids show no sign of gear wear so that’s good I guess. Haha :juggle:

I will be removing the driveshaft tomorrow to inspect it an will pop it in 4hi and see if I have the same issue. My preference is to not do this diagnosis but I’m far away from home and need more leads then “it could be this” type solutions.

Thanks for putting more ideas in my head Lauren!! :-)r

Lando-Liberty · **Posted:** Thu Aug 15, 2019 4:53 pm

I don't know. You say it is running almost 4k RPM's as you go down the road that sounds like a transfer case stuck in low lock, or a trany giving up the ghost to me.

lfhoward · **Posted:** Fri Aug 16, 2019 4:56 pm

Any news?

PALiftedKK · **Posted:** Sat Aug 17, 2019 4:25 pm

Update:

Regapped the plugs to .040. Previously had them all at .043. While removing plugs, the intake intercooler I have has to be removed to get to the plugs. While removing the intercooler I inspected the throttle body and noticed I had a wire cought in between it and the manifold.... :roll:

I last replaced the throttle body more then a month ago without a single misfire nor check engine light... my power is mostly back but I may still have a large drivetrain resistance. I'll be home later this week so I'll dig deeper into the issue there. I'll save removing the driveshaft for when I'm home. That will at least diagnose u joints and the transfer case. I'll put the rear up on jack stands too to diagnose if I can reasonably turn the yoke. Diff fluid is clean so all I could think about if it is a diff issue is a bearing.

Small diagnoses, one step at a time. Engine is all squared away so that's one less variable now!

PALiftedKK · **Posted:** Sun Aug 18, 2019 7:56 pm

Welp, my thoughts are my transfer case is a leading issue. I’m back to my original issue. No clue how I could feel like the power is back and now have the same issue as before. 45 degree incline, foot to the floor and I’m still slowing down. Mpg is also all sorts of wack.

lfhoward · **Posted:** Sun Aug 18, 2019 11:40 pm

PALiftedKK wrote:

Welp, my thoughts are my transfer case is a leading issue. I’m back to my original issue. No clue how I could feel like the power is back and now have the same issue as before. 45 degree incline, foot to the floor and I’m still slowing down. Mpg is also all sorts of wack.

I’m stumped. Just a few more wild guesses...
A really poor tank of gas that has way too much ethanol in it?
Fuel pump not providing enough fuel pressure when gas pedal is fully depressed?
No misfires or pinging or anything like that when losing power? If so it could mean a carbon cleaning is needed.
Plugged catalytic converter restricting your exhaust (and combustion)? The floor would get really hot over the cats if this were true.
Torque converter not locking up? Thus wasting power keeping higher speed.
A free thing to try is to remove the battery cables overnight to clear the computer’s memory, then have it relearn your driving style. That’s if the issue is electronic rather than mechanical in nature. It should reset a glitch.
Any pending codes on the scangauge?

PALiftedKK · **Posted:** Mon Aug 19, 2019 6:21 pm

lfhoward wrote:

I’m stumped. Just a few more wild guesses...
A really poor tank of gas that has way too much ethanol in it?
Fuel pump not providing enough fuel pressure when gas pedal is fully depressed?
No misfires or pinging or anything like that when losing power? If so it could mean a carbon cleaning is needed.
Plugged catalytic converter restricting your exhaust (and combustion)? The floor would get really hot over the cats if this were true.
Torque converter not locking up? Thus wasting power keeping higher speed.
A free thing to try is to remove the battery cables overnight to clear the computer’s memory, then have it relearn your driving style. That’s if the issue is electronic rather than mechanical in nature. It should reset a glitch.
Any pending codes on the scangauge?

Thanks LF!

This issue has been on going for the past almost 2 months... no misfires are being reported but she definitely is misfiring on at least one cylinder. Spark plugs are ngk copper core (oem) and have less then 5k miles on them. Gapped at exactly .040 three days ago. Cats have not been verified yet on input and output temps yet. Transmission in my opinion feels 100% fine. It locks up perfectly fine. Ecu was reset while pulling spark plugs and throttle body.

Only code shown is a wheel speed sensor but I have proof that all 4 wheels are reporting correct values. I am assuming atm that it is a faulty hub as I just replaced both fronts. The code is for the passenger side. I already have plans to rma the hub for a new one shortly.

I also just spent a bit on the obdjscan app which shows me just about everything about the vehicle. It was supposedly reporting 1.20 volts and 4.96 volts for the fuel level. I just filled up this morning; my fuel volume should be around the 16ish gallons so I don’t know if those values being reported are correct or wrong.

I also can tell from the app that the throttle body is able to open fully but the engine just doesn’t sound as “throaty” as it used to be before this issue.

On a lower fuel volume in the jeep, once the jeep is shut off the tank fills up with air (it seems to be under a large vacuum while driving) I’m honestly thinking that particular issue is related to the vent line from the canister to the fill tube.

Maybe fuel delivery issue paired with the vent issue, but misfires in the rpm range of 1500-2500, idk...

Now, I don’t call myself an idiot on these things because I do know a good bit, but this time around, I’m 110% stumped...

update:

Sooo, being curious I just put my temp gun on the cats.... gun cut off is 556 degrees keep in mind. Both cat exhaust inlets are over temp. The drivers side temp out is 356 and passenger side at 415.... in my untrained opinion, I think I have a nightmare ahead of me since I’m 3k miles over the epa warranty of 80k miles..... :banghead:

tomknight · **Posted:** Fri Aug 23, 2019 8:25 pm

I had an almost identical issue on the KJ, and it was something simple like a PCV or camshaft sensor. I'm trying to remember exactly. I found the answer, I believe, and jeepkj dot com.

I will look to see if I have it bookmarked. I struggled to figure it out, found that thread, swapped the part, and it was fine after. It did the same thing - low power, and worse at higher rpm's.

I'll see if I can find it, but I think that's what it was.

PALiftedKK · **Posted:** Sat Aug 24, 2019 4:15 pm

Well I feel like a buttercup sometimes... engine still has a slight misfire but I'll wait till a code is thrown for it
As of now, power loss seems to be linked with a binding cv shaft. I've had no noise to make me believe that was the issue but during diagnosis and suspension replacement, the shaft was binding to the point of being unable to spin the shaft/wheel. I'm hoping this is the main issue and It just part of a bigger issue. Jeep currently does feel like power is back but that also may be temporary. Time will tell. If I do not report back in a week or so, the issue was the CV shaft oddly. Thanks all for the diagnosis assistance! !

PALiftedKK · **Posted:** Fri Aug 30, 2019 10:10 pm

Update:

Air filter and CV shaft weren’t the issue unfortunately... I went on a 250 mile drive today up and down mountains. I stopped at a scenic view overlook to take a hike. I started the jeep and for some reason I thought to check the exhaust flow. Now I know by feel as in approximation how much air should be coming out of the exhaust, flow at idle I could have my hand an inch from the exhaust outlet. Curious now to see if I’m crazy I had the engine rev up to 2400 rpm and airflow was roughly the same. Soo it’s a 50/50 now. It’s either intake related or exhaust related. Still no codes at all... she’s going to be sitting more frequently now till I can fully diagnose the issue. I already purchased a bottle of oxicat on amazon moments ago. Once that comes in the jeep hits the road for another 250 mile trip as a test to see if the issue improves. My mind set is already into cutting the cats off and visually inspecting them. I’m hoping to see nothing but if I do the honeycomb better be intact but blocked.

This still has my mind racing on why I’d have a clogged cat as the engine since it has been bought has had absolutely zero issues. Doesn’t even drink oil or coolant.

I’ll report back in a few weeks time with any further information and or diagnosis. :POPCORN:

PALiftedKK · **Posted:** Mon Sep 16, 2019 6:05 pm

FINALLY CHECK ENGINE LIGHTS!!!!!

Almost 3 months with the performance issue and today I FINALLY got a CEL! Usually most hate the CEL but not when no codes are thrown for months with noticeable issue.

Codes are as follows:

P0133, P0153, P0420, B1851, B2204, and the usual P0456 ->(P0456 is weather dependent as I’ve noticed but has never been a worry to me).

I will be doing a visual inspection of the O2 sensors and their respective wires later today when the Jeep is cooled down.

In regards to the B2204 code, I’ve had the code as pending/active since I believe May but am not 100% sure. I’ve been reading up on the code every once in a while but am not 100% sure if it’s related to my key or not. If it is a key issue I have noticed that I have to be right on top of the jeep to unlock the doors remotely so the battery will be replaced shortly.

In regards to P0153, P0133, and P0420; O2 sensors will be visually inspected for wire damage, resistance, and fouled sensors. I will probably end up pulling all of the O2 sensors instead of just the upstream ones. My inexperienced mind is telling me that my catalytic converters are fine but I’m expecting the worst till a visual inspection is complete.

In addition, the Cataclean honestly did improve performance. My only proof for this was multiple 0-60s, same road and same direction, and with A/C turned off. Prior to treatment I did three tests; all tests had a 0-60 of 14.3 seconds. Post treatment came back with consistent 12.2 seconds; which were conducted roughly eight times. No improvement over 12.2 seconds since treatment ended.

I also will cease to use Lucas fuel additive since it does not contain P.E.A. Little did I research till I had this performance issue. I will now continue to use the Gumout 510016W as a monthly treatment.

Thank you all for the past and for potential feedback!

EDIT: First photo is coasting at idle. Second is floored. Cleaned MAP sensor. O2 wires are fine. Spent all night reading the FSM and will later this week check voltages at the harness as well as O2 resistance.

https://photos.google.com/album/AF1QipNU3gNoJTurjKLMguWHNxcDCcqK-pivPmDlfRHg

PALiftedKK · **Posted:** Fri Sep 20, 2019 2:19 pm

I know this topic is dead but I’ll still post for future members that have an issue.

Under further investigation with unrelated issues, I checked the MAP harness. 5 volts to it, no ground. Coolant temp sensor that uses the same ground has a ground but reads at 9.92k ohms and should read below 5 ohms. I traced back the wire harness connectors and the one I need to inspect ends up being right below the heater core ports at the back of the engine. And as I think about it I had a lot of coolant leak out of the ports months back so I’m going to say it’s save to say there’s my issue... :furious:

I do not have any MAP codes. The O2 sensors are reporting back as they should be and are not slow as the OBD codes have suggested. Jeep runs richer then a millionaire atm.

I will diagnose the harness and report back. Let’s hope I don’t get my hands to cut up trying to access the connector at the rear of the engine... :dead:

lfhoward · **Posted:** Fri Sep 20, 2019 7:13 pm

Thanks for continuing to update the thread! Even if it looks like no one is listening, I’m sure I’m not the only one.

I’m glad you have a solid lead!

PALiftedKK · **Posted:** Sat Sep 28, 2019 5:35 pm

Cats are clogged. Jeep stated Oll Thumper is not eligible for the EPA warranty. Next plan of action is to cut the cats off and give em a good cleaning before I spring for new ones. Cleaning will be done by soap water and when that doesn’t work sodium hydroxide will be the last resort before a new exhaust. I have high hopes for sodium hydroxide working, though not 100% carbon removal, I’m hoping at least 50% removal and towing my trailer up a 15% incline with a highly concentrated tank full of Cataclean will break the rest of the carbon build up off.

Went camping this past weekend and the Jeep didn’t like it one bit towing the trailer. Engine temps rose and fell from 205-218. Unfortunately I had no way to safely pull over for going up a winding mountain till the top and the trans saw 219... typically it would see 210 then dip down. Trans fluid since being changed is still it’s pink color with no burnt fluid or scent to it luckily.

Parts for the rednecked fix will be in a few days from now. Hope that works, if not, Mopar gets the credit card.

Also, P0430 showed up shortly after my initial codes appeared. I’m thinking this cat issue is in direct issue with gas station fuel quality. Jeep has never let me down with reliability as it should because the engine and trans are bone stock (basically) and has no oil or coolant consumption issues. Fuel quality or contamination is my leading issue at the moment. Hope all goes well with the cleaning.

Drifter · **Joined:** Thu Feb 05, 2015 1:41 am **Posts:** 32

Before cutting everything apart, our local Napa sells a product called Cataclean in a silver bottle that seems to help a lot. We sell it pretty regularly and have had zero complaints with its effectiveness. You run fuel down to about 4 gallons or so then add to your fuel. Worth a try if it helps and won’t be out a whole lot if it doesn’t compared to the alternative.

I suppose if it’s not carbon buildup it might not help since in some cases the catalyst melts down. Good luck. Mines a 12 so hope to never have that issue. We are an emissions state so it would get costly fast. :POPCORN:

PALiftedKK · **Posted:** Thu Oct 03, 2019 5:13 pm

Cut the cats off yesterday. Didn't even clean them because they looked brand new. Very very minimal honeycomb melted and are not clogged. Installed all new O2 sensors. Here's the kicker y'all, P0420 and P0430 came back today as pending... spent forever on the phone with my mechanic and he mentioned it could be a few things but had also mentioned it could be a collapsed muffler which in his 30 years of being a mechanic, he's only seen one collapsed muffler. I'm going to check that out later today. Check injectors. Still have zero clue on the MAP sensor if it has a ground or not. No FSM is helping me diagnose the wiring to and from the MAP.

It's all just a headache now since I'm not at all well versed in anything emissions related. I've been looking at sensors such as MAP and O2 data to diagnose this instead of seeing the codes and immediately assuming something false. O2 sensors were replaced yes but once this issue is resolved hopefully soon I might send them back as they are reporting the exact same data as the OEM ones. A vaccum and back pressure gauge will hopefully show the issue clear as day... :POPCORN:

PALiftedKK · **Posted:** Sat Oct 05, 2019 1:48 pm

Had a success today! Installed a new MAP sensor and cut off 2 seconds from my 0-60 time! There is an extremely steep mountain by me that I’ve been using to test my performance during this issue. All tests done on that mountain have been sub par with power. I will be heading up that mountain shortly and will edit this once I get back from the drive in regards with power.

Since I tested the MAP I’ve always been hesitant if it was broken or not but the computer was showing voltages and vacuum levels. The old sensor had a bad ground internally. All of my research during this issue of mine since day one has lead me to believe it’s a MAP related issue. Welp, time to get on the road and test the new one!

EDIT: Jeep is fixed. Well mostly. Test drive proved I got my power back as it seems. It did a lot less shifting up grades. I still have a 420 showing so we’ll see over the next week or two if it disappears on it’s own or not.

PALiftedKK · **Posted:** Sun Oct 27, 2019 3:14 pm

UPDATE:

Since my last post I have had near complete power back with the MAP replacement. I say near because since cutting the catalytic converters off I had to use tubular style clamps to hold it in place. I knew this would be a bad exhaust leak at the clamps prior to cutting the cat off so I rednecked it and used aluminum foil to seal it up. I’m working on the exhaust currently and will wrap the foil around 4 times to get a better redneck seal on. :-)r

I had also cut the muffler off and sounds darn good! PA legal no but I’m not residing in PA at the moment so all is good for now. Lol. Transmission also seems to be my biggest issue atm as it prefers / sticks in higher rpms but also may be because of the jeep running rich. Fixing the clamp post o2 sensor will definitely help the rich issue. All is well with the jeep besides that. I’m just still happy I got back most of my power back!!

Poor engine performance under light and heavy load

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