Cherokee 1999 4.0L P0455

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jmalwitz
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Joined: Sat May 06, 2006 4:56 pm

Cherokee 1999 4.0L P0455

Postby jmalwitz » Sat May 06, 2006 5:01 pm

:shock:

For the past few months I've been getting a "large vacuum leak" trouble code (P0455). I keep resetting it and have replaced the gas cap with no avail. Where should I be looking for common vacuum leaks.

Thanks for your imput.


jeff compton
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Postby jeff compton » Mon May 08, 2006 7:43 am

cherokee or grd cherokee? Check for any damaged vaccum lines around the engine compartment and going to the rear of the vehicle
Might require using a smoke machine to pinpoint the leak, Any work performed recently?

jmalwitz
Posts: 5
Joined: Sat May 06, 2006 4:56 pm

P0455 Jeep Cherokee

Postby jmalwitz » Mon May 08, 2006 8:02 am

No recent work, the Jeep has 95,000 miles on it. How can I perform a smoke test, sounds scary? I'll have to look at the hoses again but my inital inspection revealed no cracks. Lastly, t's a regular cherokee not a grand.

Thanks for the reply.

jeff compton
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Postby jeff compton » Mon May 08, 2006 9:38 am

smoke testting requires a special machine, Is the gas cap a mopar part
#, some jobber/aftermarket caps have incorrect valving and don't seal properly.

jmalwitz
Posts: 5
Joined: Sat May 06, 2006 4:56 pm

P0455 update

Postby jmalwitz » Mon May 08, 2006 5:15 pm

The gas cap came from a local parts store, Advance Auto, $8.00. Can any mechanic do the smoke test or is that more of a dealership specific thing?

B. Cash
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Location: California

Postby B. Cash » Mon May 08, 2006 11:28 pm

Any shop can smoke test it as long as they have a smoke tester.

jmalwitz
Posts: 5
Joined: Sat May 06, 2006 4:56 pm

P0455, leak test, Jeep Cherokee 1999

Postby jmalwitz » Tue May 09, 2006 4:15 am

So its a common test? I've never heard of it before for an engine leak, I've heard of leak testing refridgerant systems, but never for the engine vacuum.

jeff compton
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Location: Kingston Ontario Canada
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jeep po455

Postby jeff compton » Tue May 09, 2006 6:18 am

what a smoke test does is pressurize the evaporative emissions system
with a smoke that can then be seen leaking out or in some cases not flowing. Look for a vaccum tee under the hood with a green cap over a test port and start doing a visual inspection of the system from there, under the air box and down around the frame are common spots under the hood for the system to leak. Lots of aftermarket caps fail the tests right out of the box so it might be worth trying a known good chrysler cap before paying some one for diag or throwing parts at it! Filler necks, fuel pump seals, cannisters, pumps, valves, are potential places for system to leak. A dealer isn't the only place that can perform the tests but as a mechanic that works at a chrysler dealer we get alot of vehicles sent to us from other shops that don't have the equipment of time to fix those codes, Normally most leaks are found in about an hour, often not an expensive repair unless it requires fuel tank removal or something similar

good luck and keep me postted

Jeff

jmalwitz
Posts: 5
Joined: Sat May 06, 2006 4:56 pm

P0455 smoke test

Postby jmalwitz » Tue May 09, 2006 6:35 am

Thanks so much Jeff. In an age of high gas prices the last thing I need is a vacuum leak.

Jonathan

jeff compton
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Location: Kingston Ontario Canada
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cherokee po455

Postby jeff compton » Tue May 09, 2006 8:51 am

shouldn't affect fuel consumtpion at all but will not fix itself. Like I said get it looked at and get your check engine light off!


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