P0455-related question

[98SF19]

This will sound somewhat nebulous, but before I go through the process of elimination of where the evap leak is occurring, I'm hoping somebody can narrow it down . . .

I went to a shop to have exhaust flow tested (thought the original cats may have broken up to the extent to cause a constriction). They said it checked out but that there was an evap code. It was the p0455. I hadn't had any codes over the last year (other than the misfire a few weeks back). It was after I'd gotten the car back from the shop and driven for a few days that the CEL popped on. So naturally, I'm wondering if during the shop's diagnosis of the exhaust system, they put strain on or diglodged something that would have caused the evap leak and the subseqent code. Are any parts of the evap system close enough to exhaust components to be likely culprits?

About a year ago, I installed the upgraded DPFE sensor, which requires an awkward re-alignment of the hoses. So this may be it, I just haven't looked yet.

Anybody have any ideas?

Thanks!

 

[98SF19]

I think I found it; a broken small vacuum line. Comes from the vacuum junction box on the driver's side (to the right in pic) and perhaps goes down to the cannister on firewall? Should be an easy fix, I just hope this was the only problem.

 

[98SF19]

Reconnecting didn't **** CEL. This was after 3 restarts. IIRC, when I replaced the DPFE sensor, the light for that code went off right away.

 

[GEN 3 SHO FAN]

Hi Kenny,

I recently changed my gas tank because I have the P0453 code for a missing pressure sensor on it. I started the at least 3 times too and the code stay on (don't know why). I erased it with an OBD-2 reader and it never return. Maybe the car needs more than 3 starts for some codes. My P1413 go away by himself (SAI pump).

(Do you know what is the test for a coggled cat ? If yes, PM me, I want to make one on mine.)

 

[98SF19]

I'll erase it this weekend and see if it pops back up.
As for the test for clogged cat, je ne sais pas! I think there are tools that shops have that can input maf signal and compare to exhaust flow/o2/etc. but this is based solely on the impression I got from talking to the muffler shop secretary over the phone.

BTW, it's Ryan, not Kenny. My handle subtext is simply a wishful (albeit fantastic) play on words.

 

[sperold]

In the OBD2 system, the O2 sensor after the cat monitors the cat and reports any problems.
The only sure way to diagnose a cat to make sure it is working is by taking a thermo reading before and after the cat and the temperaures should be pretty close. There are hand held temperature readers that make this an easy task.

 

[GEN 3 SHO FAN]

Ok, sorry Ryan. (It's seems that I'm not the only french speaking person here...)

For the cats test, I suppose that if the temp is a lot higher before the cat than after, I have a prob ? I hear them crakling a bit after a ride... I deleted the 3rd because it was obstred at 85%... However, an hammer test revealed nothing for 2 others.

Thanks guys,

 

[98SF19]

Hehe, I know very little French and it's a faded memory from high school. Living in FL I should know Spanish much more than I do, but sadly, I am not fluent in either . . .

Sperold, is this handheld device something specific to this task or are you talking about the general IR detectors?

FYI, I cleared the code yesterday morning and after several restarts, it's not returned. So hopefully, that one small hose break was all that was causing it.

 

[sperold]

It is a regular IR reader, which used to be a big deal to get. Now they are cheap and available at all the places like Harbor Freight. If my memory serves me right, I think the cats are somewhere around 600 degrees and the output end will be lower, but close; but don't quote me.

 

[98SF19]

Cool. Maybe I'll use my next Speed Perks rebate on an IR reader. Would you happen to have a ballpark figure of what kind of difference between hi and low temps would indicate a constriction or other issue?