So here is what is going on, since I bought my XJ there have been 5 OBD2 codes that come right back when I delete them so none are freeze framed.

Here are the codes:
P0455 - EVAP System Large Leak (0.080") Detected
P1495 - Leak Detection Pump Solenoid Circuit Malfunction
P1294 - Target Idle Speed Not Reached
Other two are for 02 sensors

So what happens is after the car warms up, it only idles around 200-300 rpm. But when driving there are no issues. Once the car has been warm for about 10-15 minutes, this large whine comes from inside the engine bay. It sounds like a teapot so I'm guessing this is a vacuum leak.

Would these symptoms and codes be related? FTWDK it's an 01 w/ 4.0, auto, w/ 292k miles.

Oh and here is a video of the noise:
https://www.dropbox.com/s/rn4tm93dwu...%2046%20PM.mov

 

And just so we are clear, it's not a belt or pulleys. WAY different sound and the belt is newer.

 

The man says you can find that with a section of hose held to your ear. And yea, I'd think "large leak" and the loud whistle could be related.

 

I've had my head pressed against nearly every part in that stupid engine and I cannot find the leak. And what the heck is a Leak Detection Pump Solenoid???

 

I'm not sure the O2 sensor issues are related, but the Evap Leak can be caused by a rusted line coming from the gas tank to the vapor canister which is a boxy looking thing right under where the rear seatbelts mount, as seen here:



There is a little steel line that runs to the gas tank. This line commonly rusts out on the later models as it did mine. I replaced it with 5/16" fuel-rated hose. It requires the tank to be dropped to fix it.

But also, there's a little purge solenoid under the hood that could be the culprit as well--and the cause of the whine. Maybe.

Here's an informational thread as well.
https://www.cherokeeforum.com/f2/eva...-again-135159/

 

Check all the hose/tube connections to the Leak Detection Pump (LDP). There's a large tube (5/8") that goes from the LDP all the way back to the EVAP Canister, check it for cracks/disconnect from canister. Check the tube that goes from the intakle manifold to the LDP for being loose and obvious defects.

Lots of visual inspections required.

 

Have you tried listening through a section of hose? You can poke it right to spots your head won't fit! Sounds like full manifold vacuum.

 

Soapy water in a fine mist spray bottle...
Tiny bubbles...

;-)

 

It's a vacuum leak Bill. I suppose a guy could do that if he hooked a blowing vac cleaner to the TB! (a clean one)

 

So if it's a rusted line to the canister (or something along those lines) then the loud noise just happens to be an unlucky coincidence? What are the chances that it is coming from the intake manifold thus the reason why it won't idle well once warm?

 

Why does the tank need to be dropped?

 

I'm having a hard time understanding how a guy with 3 feet of tube to his ear can not tell where that loud whistle is coming from. Maybe you need to take it to a shop.

 

This may be why:

Chipmaker says:

“Way more problems get solved by using your five senses under your hood rather than your ten fingers on a keyboard”

 

To replace that line with hose, it connects to the rollover valve on top of the tank. See here, on the left.



This is just something to investigate. I don't think it's ultimately what's causing your "whistle", but a bad line here could throw the evap code.

 

Thanks, you've been a real help...

Instead of criticism, how about either helping out the guy who is fairly new to anything not foreign or not posting anything at all.

I have been under that hood for almost a week straight now and am having a really hard time finding the leak/noise location REGARDLESS of what I put up to my ear. I have used a stethoscope, a long screwdriver, hose, and even a smoke machine from the college. Nothing...