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Old 07-22-2012, 04:17 PM   #11
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Quote:
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Later style manifold is "more squarish" but fittings/functions are the same. Port marked "NA" is omitted on later style intakes.
Thanks for the pictures. Saved to my drive for future reference.

I seems to me that the only standard rubber style hose coming from there is the fuel pressure sensor line. Is that the one that goes into the sensor on the left side of the fuel rail? It disappears under the throttle and intake and so I'm not quite sure...

Everything else looks like reinforced lines with special connectors.
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Old 07-22-2012, 08:05 PM   #12
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Is that the one that goes into the sensor on the left side of the fuel rail?
Yes.
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Everything else looks like reinforced lines with special connectors.
While the vacuum tubing is some kind of special hard plastic - crimps fairly easily btw - the connectors clustered at the top of the manifold are simple push on rubber fittings (except for the big EVAP fitting). You can pull them off one at a time and inspect. Try blocking the port temporarily and see if the idle improves to try isolate any offending line.

Did you replace the PCV elbow and valve (front of the engine) when you repaired the collapsed rear hose?
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Old 07-22-2012, 09:41 PM   #13
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A plugged cat will run worse at higher rpm if it is bad enough to affect idle.

Common to check for vacuum leaks by plugging all fittings you can temporarily and then testing idle quality. Once the plugins are isolated as good then you go to gaskets and/or possible cracking somewhere to leak unmetered air.
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Old 07-22-2012, 09:43 PM   #14
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A plugged cat will run worse at higher rpm if it is bad enough to affect idle.

Common to check for vacuum leaks by plugging all fittings you can temporarily and then testing idle quality. Once the plugins are isolated as good then you go to gaskets and/or possible cracking somewhere to leak unmetered air.

See if the front O2 sensor is stuck low below .5 volt at warmed up idle. Indicative of a vacuum leak.
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Old 07-22-2012, 10:29 PM   #15
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A plugged cat will run worse at higher rpm if it is bad enough to affect idle.

Common to check for vacuum leaks by plugging all fittings you can temporarily and then testing idle quality. Once the plugins are isolated as good then you go to gaskets and/or possible cracking somewhere to leak unmetered air.

See if the front O2 sensor is stuck low below .5 volt at warmed up idle. Indicative of a vacuum leak.
That's a good tip. I'm pretty sure the front O2 sensor is getting above .5V .. in all cases it seems to be between .1V - .9V, but I will double-check.

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Yes.


While the vacuum tubing is some kind of special hard plastic - crimps fairly easily btw - the connectors clustered at the top of the manifold are simple push on rubber fittings (except for the big EVAP fitting). You can pull them off one at a time and inspect. Try blocking the port temporarily and see if the idle improves to try isolate any offending line.

Did you replace the PCV elbow and valve (front of the engine) when you repaired the collapsed rear hose?
I did replace the valve itself, but not the front elbow. It seemed in OK shape - no obvious splits or collapses.

I did another spray test this afternoon and noticed no change in idle. I also fiddled with all the connections, and again, nothing.

Besides codes, should I notice any change in performance when removing and plugging vacuum lines? I want to make sure I'm diagnosing the original problem and not noticing artifacts of the missing vacuum...

Thanks again for all the help.
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Old 07-23-2012, 09:46 PM   #16
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Besides codes, should I notice any change in performance when removing and plugging vacuum lines?
Since the removal of any vacuum line will admit air into the intake that has not been accounted for by the MAF sensor, you should produce a condition lean enough to cause a stall or low idle.

You should be plugging the vacant intake port, not the line, initially. If you plug the port and the idle improves, examine the fitting, hard plastic line and any other solenoids or valves in the path for leaks.

Another thought: Also check your EGR valve is closing and seating properly. If you apply vacuum to the fitting at the top and release you should hear an audible clunk. Not a definitive test, but at least tells you the spring loaded internal plate is moving. You could also try blocking the EGR intake port entirely.
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Old 07-24-2012, 10:00 AM   #17
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Since the removal of any vacuum line will admit air into the intake that has not been accounted for by the MAF sensor, you should produce a condition lean enough to cause a stall or low idle.

You should be plugging the vacant intake port, not the line, initially. If you plug the port and the idle improves, examine the fitting, hard plastic line and any other solenoids or valves in the path for leaks.

Another thought: Also check your EGR valve is closing and seating properly. If you apply vacuum to the fitting at the top and release you should hear an audible clunk. Not a definitive test, but at least tells you the spring loaded internal plate is moving. You could also try blocking the EGR intake port entirely.
I took the EGR off and bench tested it. Seemed OK - plunger moved freely and it held a vacuum.

I will try the vacuum test. I just assumed the symptoms of the various systems not having vacuum would be worse than my existing problem, but I guess that's not the case.

Thanks.
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Old 04-01-2013, 11:04 AM   #18
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For the benefit of anyone trying to work through a stall issue, my solution to this problem ended up not having anything to do with O2 sensors or vacuum. Thanks to a "pending" code in the ECU (which I can't remember now) I started looking at the ignition. The wiring harness the carries the wires that run to the coil run adjacent to one of the exhaust re-circulation pipes (I think that's what it is - it has a braided insulation wrap) and it had melted through the harness and exposed some of the wire. I spliced in a new piece ... I thought that hadn't done anything (idle sounded off), so I gave up and finally took it to a shop. They drove it 30 miles and told me everything was running fine (fuel trims, etc), and I've been driving with no issues. The idle still doesn't sound as stable as I would expect, but it's running fine and - most importantly - no stalls.
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Old 04-01-2013, 08:19 PM   #19
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Luck with that..........

Just went through similar myself, tries to die mostly and erratic around the idle area, turned out to be the TPS switch in my case, now idles perfectly. I had no codes showing whatever.
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Old 04-02-2013, 09:25 AM   #20
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Joboo - thanks for posting the "resolution" of your old thread!

As you mention, this can help others when trying to work through similar issues.
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