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Engine Performance Issues

1K views 13 replies 5 participants last post by  Blue_Reverie 
#1 ·
Been having some problems recently with my 2006 Unlimited. To summarize:

1) I can open the throttle just about all the way and it refuses to accelerate. The rpm will bounce back and forth between 2k and 2.5k over and over. Then, the rpm will suddenly climb to 3.5k or 4k.

2) It shifts into second gear just fine, but refuses to shift into third. This leads to the rpm spike problem described above.

3) The max speed I'm able to reach is about 50 mph.

4) I've been using noticeably more gas than usual.

I had the codes checked and a PO133 was returned.

Also, I checked the air charge temperature sensor on the intake and saw it was covered in this black, sticky substance.

Could the failing O2 sensor and gunked-up temperature sensor be the cause of these issues?
 
#7 ·
hi temp is a common error code in the 06 auto, it generally goes away when the engine/trans are at operating temp.

I too would look into the cats but it sounds like you have a few things going on. it may be worth it to disconnect the positive battery terminal for a few mins to clear the ECU then see how it goes.
 
#8 ·
Do you have a scan tool? Have a look at the long term fuel trims if so - it’ll give you a hint as to what is going on. Also, 2006 have issues with opda gears being chewed up due to poor design from the factory - causes cam timing issues


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#9 ·
@Ironhead_Jed Really? I had no idea, so thanks for sharing that bit of information. I was worried the trans actually was overheating, so that's a relief.

@B4_685 Sadly, I have no such tool. I haven't had to deal with these kind of issues since I got the Jeep, so I never really felt the need to buy one. I can't say I'd know how to use it/interpret the readings either.

Probably should've pointed this out earlier, but I equipped the engine with a supercharger a couple years back, since the stock hp was lackluster. I had it tuned as well to compensate for the power boost. Does that change anything?
 
#10 ·
Supercharger changes the game somewhat - check for boost leaks - any hissing or unusual sounds that have started since you started feeling the problem? Do you have any photos? Also was the map sensor changed when you installed the charger? Any other mods?


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#12 ·
@Ironhead_Jed 20$ huh? And here I was thinking such a device would be more on the expensive side. Sounds like a solid investment.

@B4_685 I haven't had any issues with the supercharger since the install. I'm still using the original MAP sensor.

After some closer inspection of the transmission and engine, I believe I've identified the issues.

1: The transmission pan is clearly leaking on the driver's side, and I suspect the gasket is in need of replacing. It's a slow leak, thankfully.

2: The belt tensioner jiggles up and down while the engine is idling. Upon acceleration, a quite loud rattling sound comes from the engine compartment. Having looked into the main problems that this particular part of the belt system can experience, I'm fairly certain that the damper inside the tensioner has worn out. It can no longer maintain belt tension under load, hence its rapid shaking upon acceleration. I'm convinced the lack of belt tension is why the engine has such poor and erratic response to throttle input. Also, since the supercharger is ran by the belt, it can't even function properly and generate boost.
 
#14 ·
It's being worked on at the moment, but I'll share updates ASAP.

The guys doing the repairs also found out that the catalytic converters are most likely clogged and are heating up to almost twice normal operating temp, 900 degrees instead of 500. I have a feeling this is responsible for the gasoline odor I smelled every time I started the engine. Due to inhibited exhaust flow and the resulting improper readings from the downstream sensors, the engine was running rich to try and compensate. That would explain the increase in fuel consumption as well.

Going to have the catalytic converters replaced once the belt tensioner and transmission pan issues are fixed.
 
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