Engine runs rough after an hours worth of driving

[sebastians]

So recently my car started running rough after about an hours worth of driving, but no codes show up and there is a heavy smell of fuel. Mostly happens right after I fill up my tank. Any ideas of what the problem could be?

03 Liberty 3.7 4x4

 

[derekj]

Could be a faulty evap purge valve slightly sticking open and pulling fuel into the intake when the tank is full.

 

[sebastians]

Could be a faulty evap purge valve slightly sticking open and pulling fuel into the intake when the tank is full.

Thats what i was thinking, but then i would also get a lean code. If I look at my fuel trims the long terms are stuck at a solid +32% on both banks. Could it still be an evap issue?

 

[derekj]

Thats what i was thinking, but then i would also get a lean code. If I look at my fuel trims the long terms are stuck at a solid +32% on both banks. Could it still be an evap issue?

If your fuel trims are that high it means your engine is running lean - trims that high should flag lean codes. Maybe see if the purge valve is leaking all the time - unplug it and pull the hose out that runs to the tank and see if you have vacuum on the tank side of the valve when the vehicle is running.

 

[dtennes]

Have you solve your problem?

If "yes" congrats. If "no" and you wish to continue the effort to solve the problem(s) read on.

I have a 2003 3.7 4x4 and have just finished an engine replacement, that was complicated by old parts that exceeded life expectancy. You can pretty much count on 150K miles being a reasonable limit for "good for the life of the Jeep" parts. Nothing lasts forever

Be methodical...

How many miles are on your:
1 Air Filter
2 Spark Plugs
3 Ignition Coils
4 Fuel Injectors
5 PCV
6 Crankcase Breathers (qty: 2)

Have you recently replaced any parts with made-in-china garbage? If yes, what were they (whether in the above list or not)?

 

[Ksat]

PCM is attempting to add fuel to a perceived lean condition, based on O2 feedback. If you were getting fuel in through the purge solenoid, you would have a rich condition and your trims would head the other direction.

+32% is a high number. Since your problem is occurring on both banks that might help narrow it down a bit. You might want to check fuel pressure for starters, though perhaps the heavy fuel smell might indicate you're getting more than enough fuel in the combustion chamber. A vacuum leak could also be to blame. When's the last time you replaced the O2s?

When you checked for codes, did you see any pending ones? Perhaps the vehicle hasn't been driven long enough to set anything.