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  #13  
Old 02-24-2010, 06:47 PM
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Re: More idle/stalling issue questions

the PCV is a one way valve. Im not sure what it sounds like either...but it sounds like its doing its job....and then the idle settles down. Im gonna say its the EGR valve malfunctioning bringing too much exhaust gas back into the intake at startup...and then again during other situations you've described above.
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  #14  
Old 02-24-2010, 06:48 PM
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Re: More idle/stalling issue questions

No problem man.

Replace PCV valve and see what she does. It should be fine idling in the 600's. If you still have any issues let me know.

Check for vacuum leaks also. I'd say it's a simple fix just have to find it.
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Old 02-24-2010, 06:50 PM
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Re: More idle/stalling issue questions

check that cannister in the rear under the fuel filler too. i think it runs on vacuum and is connected to the egr system..........
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  #16  
Old 02-24-2010, 07:34 PM
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Re: More idle/stalling issue questions

I had similar problems in my old ZJ. Turned out to be a shot oxygen sensor. believe there are several on the WKs. Is there liquid coming out of the exhaust?
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  #17  
Old 02-24-2010, 08:01 PM
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Re: More idle/stalling issue questions

if the 02 sensor was shot it would throw a code....same with the pcv and the egr? Right?
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  #18  
Old 02-24-2010, 08:31 PM
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Re: More idle/stalling issue questions

I think the EGR would... not sure about the PCV... I don't remember there being an electrical connection on it for a sensor or anything.
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Old 02-24-2010, 08:39 PM
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Re: More idle/stalling issue questions

Ive had egr problems...it def. throws a code....LOL
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  #20  
Old 02-24-2010, 08:40 PM
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Re: More idle/stalling issue questions

OK,couple of things to point out.

1)PCV=progressive crankcase ventilation. Basically is relieving pressure from the crankcase. The air in the crankcase is already measured by the mass air meter and when dumped back into the intake does not affect idle, open or closed.

2)Longterm fuel trim is an average of how much gas is being added or removed from what the computer says the engine should need. It is an average over several hours of running time. To see it spike would tell me that you weren't watching the line for fuel trim. There should be an option to check shortterm trim. That could spike BUT, your best option is to display oxygen sensor voltage only!! Clear everything but rpm and O2 voltage off the screen and check that they are swinging back and forth between 0 and 5 volts. They should constantly be jumping around but within that voltage range. Anything outside that is not normal. Also check that one sensor isn't significantly higher or lower than the rest once the vehicle has been driven for a while. Even if it is within spec and not throwing a code, if it's lazy to respond it will wreak havoc.
The sound you describe seems more like a sticky injector to me. Could be as simple as a loose injector harness or ground, OR a bad injector. PCV valves, even ones that are opening and closing really fast and repeatedly won't make that noise.
After checking your O2's you should do a check on your mass air sensor. You'll want to have rpm, engine load and sensor voltage on the screen. Make sure as the load goes up the sensor voltage rises with it. If not-bad mass air sensor. Not a common problem but also not unheard of. The sensor also runs in a 0-5V range so make sure it falls within that.
Lastly-like someone else said, do a thorough check of all vaccuum hoses and inlet tubing. Any unmetered air getting into the engine will cause idle problems. However-your description of the buzzing noise coinciding with the idle problems points me towards that not being it.

Good luck. Feel free to ask any more questions you may have.
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Old 02-25-2010, 08:38 AM
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Re: More idle/stalling issue questions

Thanks for the help!

Does the gas 5.7 engine have a mass airflow sensor? I can't find the PID for it nor can I find it in the wk_parts list (only found it for diesel).

Here's what the scan looks like with the settings you mentioned less the MAF.

I've got a pcv valve on the way and I'll try to capture an actual stall. Jeep is good and cold this morning so it should be jumping all around.

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  #22  
Old 02-25-2010, 01:16 PM
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Re: More idle/stalling issue questions

No Mass Air, we have a MAP (manifold absolute pressure)
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  #23  
Old 02-25-2010, 09:25 PM
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Re: More idle/stalling issue questions

Can you adjust the scale on the graph for the green line so it matches the blue? Also eliminate the red and yellow lines.
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  #24  
Old 02-26-2010, 04:24 AM
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Re: More idle/stalling issue questions

red line = rpms....

which values do you want to see? Just the O2S11 and O2S12 voltages?

I replaced the PCV valve today. It didn't make much of a difference. Rechecked for vacuum leaks. Noticed the breather tube wasn't on as snug as it could connected to the oil port. I snugged it up.... still happening.

I'll see if I can get some better data on the oxygen sensors. Also, how do you go about troubleshooting the exhaust gas recirc?
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