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Old 11-07-2010, 10:08 AM   #1
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Need some advice on '01 tj. 2.5 auto

So I bought this money pit a few weeks ago. 2001 tj se 2.5 auto with 50k miles for my wife. She had a bucket jetta and this should be a better car for her. It had been sitting for a couple years. Soon as I buy it I get a p0505 code. Idle air control system. I replace the idle air control valve. Seems to idle fine as it would idle low and stall when cold. We had a nice day so top off, get the dog in the jeep and hit the mountians. Jeep looses all power at 55 mph. I managed to turn around and coast down the mountian to an area where i get cell service. Tow it to Portland. Bad fuel pump, and a bad coil. 20 miles later light on again . It idles high and if I hit the gas it stays stuck at 3000 rpm. Also I notice its cold blooded and I have to cycle the fuel pump a couple times for it to start after sitting for a while... Any ideas?

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Old 11-07-2010, 10:24 AM   #2
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Location: Riverton, Wyoming
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Sounds like a vacuum leak somewhere on the intake, a hose perhaps? This allows extra air to get in and causes uncontrollable high idle, and usually sets a code, usu. "problem with IAC." (Computer closes IAC, idle won't drop, so it thinks the IAC is malfunctioning.) This also explains the cold-bloodedness, as the fuel mixture will be too lean, esp. when cold.

I'd start by examining all intake vacuum lines and make sure that any replaced component has an airtight gasket intalled. I once pulled an EGR valve for cleaning, and installed the gasket crooked, which caused a massive air intake leak. I got the same symptoms you have along with a code indicating a problem with the IAC. Reassembling with the gasket intalled correctly was the fix.

Check to see of your model year used an external fuel filter. (it's likely that it's integral with the pump.) If so, change it out.

Also, if you haven't already done so, clean the throttle body bore with a decent throttle body solvent, ie: CRC. Dirty throttle bodies that are so bad that the venturi sticks open are a bane. (I always clean ours at every oil change.) This would explain the poor idle quality.

Check for a throttle cable that might be sticking or kinked as well. And the obvious...check for a misplaced floor mat.

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Old 11-07-2010, 10:34 AM   #3
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I didn't have time to replace fuel pump my self due to work so I had a shop I know do it. He said the fuel filters were replaced along with pump. I guess there id 2 of them. Not sure if pressure regulator was changed but I would assume it comes with the new pump. I did notice when I changed the idle air control valve that the throttle body was pretty dirty. Also the new valve auto zone gave me was a little shorter than the one I pulled out. is that common on replacement parts?
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Old 11-07-2010, 12:05 PM   #4
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Location: Riverton, Wyoming
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On the '01's, I believe the fuel filter is integrated with the pump; the regulator is a separate part and very rarely needs attention.

Oh man, don't get me started on the poor quality of aftermarket parts. KEEP THAT RECEIPT! You may end up taking it back if a mechanic later finds that it's junk. In the future, go with OEM if at all possible.

And keep the old IAC around; you may want to swap it back in if you find that it wan't the problem.

It sounds like it's time to clean up that nasty, black throttle body. Use a soft toothbrush and an old T-shirt, some CRC TB spray and be patient. Use plenty of spray and scrub the plate clean as well, top and bottom. When done, give it one last spray to wash it all down shiny-clean.

Expect a rough start until the solvent clears out.

If this doesn't get it, check codes again. If the IAC error keeps comming up, it's time to search for an intake vaccum leak. Keep us posted.
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