I recently had my CEL come on and it threw P1647. Narrowed it down to my upstream O2 sensors and replaced them both. Now whenever I turn the car on it will idle for about a minute and then the idle gets loopy and dies. It's throwing P0171 / P0174 and P1229.

I have absolutely no idea what is causing this. It's acting like it's Oxygen starved, but I have no idea why. Only thing I could think of was a TPS fault leading to the engine being flooded and stalling out. I have never diagnosed that issue though and don't even know where to begin.

Any help is much appreciated!

Things I have done:

Used electrical contact cleaner on the throttle sensors
Cleaned out Full/Part load breather openings
Checked to ensure tight fit on plastic air tube (Can't remember the name of this stupid thing) Goes from MAF to Throttle body

 

Hmm, not an expert but you may also need to replace MAF sensor, PCV hose and EGR Valve . We did replace egr and pcv then all these problems were gone .

 

After tightening up all of the hoses and checking the electricals it seems to be running stronger. I started it up and let it sit until it got to operating temps and no lights came on.

How do I tell if my EGR needs a replace?

 

What EGR... XJ has no EGR as far as I recall.

 

The supercharged cars have EGR instead of VVT for emissions control. Keep running it, you may have sorted it with a cleanup, report back if codes appear.

 

It throws a code or triggers engine malfunction light as far as I know

 

Intake elbow is the air conduit from the air box to the throttle body.

I am fighting the same thing, (rough idle, TCS/ACS not available) which started today. I am going to take a look at the MAFS tomorrow. The TB is clean and contacts on the TB plugs were cleaned a couple months ago.

 

So, tcap, you said you have the "same thing" but what are your codes? Are THEY the same? That's the key.

 

It was those very codes. I took off the induction elbow and found a small piece of foam which had come out of the cam cover, through the FLIB, into the elbow and wedged in the throttle plate. Removed the foam, cleared the codes, and the car runs great. Got lucky. Pulled the cam cover and removed the foam and replaced it with the original brass turnings. The left side still had the original turnings in it. I've had the car seven years and didn't even look in that compartment when I replaced the tensioners.