EVAP issues

[Fiestafajita]

I changed EVAP purge valve and hoses on the purge line as well.
Now I'm getting some wacky RPMS whenever Im in neutral, revs go up and dip so low my car will stall out.
Oriellys test my alternator/battery/starter--all passed. Older fellow said I have a hell of a air leak somewhere, recommend I take some carb cleaner and break cleaner to find the leak.

What else should I be mindful of when checking for air leaks?

 

[Handy Andy]

Keep it away from the exhaust manifold.

Otherwise you have a vacuum pump in your toolbox?

The one that allows brake bleeding and one man fluid changes?

The tool isn't cheap but it's not too expensive - I have used it to suck out tranny oil and even change brake fluid - so the system is a hand pump and you just need to get a fitting you can take off the valve, and put this in it's place and start pumping to see if you can develop a vacuum.


There is a vial that can hold fluid you "pull thru" in the system so it doesn't damage the pumps diaphragm.

The Pump is also reversible, you can PRESSURIZE the lines to check for leaks, but since this is a fuel line, using gas would be a problem for it can damage the system and the pump let alone being the fire hazard.

That may help, or try to find a simple manifold vacuum gauge and install a tee and simply look for vacuum - if the gauge goes flat and never rises, suspect a leak the typical Evap system generates u[p to 2~4"Hg of pull but not much more than that to prevent the tank from getting crushed.

The only reason I mention the above is not only is it able to detect a plugged line, open line, or you can see if you even have fluid in it - it will get drawn towards the pump - if you can, you can also check the lines going into the manifold, see if they breathe - if they leak, (hear hissing) or are plugged . then you know how to fix it.

 

[scotman]

That "rolling idle" condition sounds like the throttle position sensor.
It would be interesting to connect a scan tool with the capability to do a functionality test on that purge valve.

 

[Fiestafajita]

That "rolling idle" condition sounds like the throttle position sensor.
It would be interesting to connect a scan tool with the capability to do a functionality test on that purge valve.

So my culprit after all this was.....
Missing 15a fuse for one of the Power Control Module in the fuse box.


Codes I was getting were
-failure to communicate PCM
-throttle position sensor internal communication failure
-petal position sensor communication failure

 

[LionsTooth]

Glad you found the answer. Now one must wonder...did the fuse head to Jamaica for some long-deserved vacation time? ;-}

 

[Fiestafajita]

Glad you found the answer. Now one must wonder...did the fuse head to Jamaica for some long-deserved vacation time? ;-}

View attachment 5462

It had to have lol, cause that sucker was outta there,
I guess I don't have to worry about my alternator and battery due to me replacing them to get to my problem.
I still wanna clean my fuel injectors

 

[scotman]

Glad you found the answer. Now one must wonder...did the fuse head to Jamaica for some long-deserved vacation time? ;-}

View attachment 5462

Yup. Or Cabo! Fuses prefer a low resistance atmosphere! That's an electrical joke.

 

[Handy Andy]

How did it even run?

LOL!

​

Well, thanks for putting that to rest...

 

[Fiestafajita]

I have noooo idea how it even ran before hand- good riddance grimlen

 

[WillieWapper]

Sorry for digging up this old thread but I am having similar problems. Could you remember the location of the fuse perhaps?

 

[Handy Andy]

A "missing" 15A fuse?

Well, ANSI/SAE/IEEE places the color code to be "blue" ...


Here's a working Template...
Go find that missing "fuse" - or whatever...