'94 Seville SLS High HydroCarbon output

[Jake35]

so much for trying to make a nice pretty chart for you....lemme know if you cant follow that and I'll try to re-do or explain

[Jake35]

After talking to the mechanic about a possible vacuum leak, he's still leaning towards a bad cat. Not heeding the advice of the mechanic, I've tried to identify vacuum leaks with a can of carb cleaner (disengaging the tps sensor first..dont ask) but Im afraid I couldnt tell between a vacuum hose or any other hose so may be missing something...otherwise, not able to find a leak. Wouldnt a bad cat get some kind of error code if it went bad?
One symptom/issue not mentioned before; if I fill the tank more than 1/2 full, a strong fuel smell permeates the cabin...eventually going away. Problem with the evap? And would that cause the HC's to be high at idle?
Another "issue" is intermittent hesitation at various accelerations, like a cylinder cuts in and out whenever it wants to. Even though I ohm'd the coils and all seem to be in range, after lifting the hood and staring at things like a deer caught in headlights, I notice a rapid clicking sound coming from the 6/7 coil. Idle's smooth...not necessarily "cadillac smooth" but smooth enough for the girls I go out with.
I've had a p030 and a p070 code, but cleared them and they havn't come back yet. The p030 came back once after some above average driving, cleared it again and it hasnt come back since. Could either of these codes (I know what they are) have anything to do with high HC's at idle?

[Ranger]

One symptom/issue not mentioned before; if I fill the tank more than 1/2 full, a strong fuel smell permeates the cabin...eventually going away. Problem with the evap?

These cars have been known to rot out the fuel filler pipe. That could cause the gas smell as well as an EVAP problem as the tank would no longer be air tight.

[Krashed989]

Originally Posted by Jake35

... Wouldnt a bad cat get some kind of error code if it went bad?...

Not on a 94. The 94 is OBD-I and only has two O2 sensors (one on each exhaust manifold). 96 is when they started putting a Post-cat O2 sensor to monitor the cat-converter efficiency.

he might be right that the cat converter is loosing efficiency. But if it is, it's just because it's getting old and not because of the explanation he offered.

[Jake35]

Hey Ranger...

Saw you involved in another post on another site called Caddyinfo.com. The conversation went something like this:

"The rest of the EGR must be cleaned out, too."

"REST of the EGR? All that needs to be cleaned is the pintle valve."

"This is a 1994, with the EGR passages under the intake manifold through trenches in the heads. Over about 100,000 miles they fill up and clog. In the 1995 and up Northstars the EGR passages are metal hoses external to the heads but they still need to be cleaned out once in a long while."

"Oh! The "mouse holes". I thought you where talking about the valve, but Angela's is a '96"

So I cleaned my EGR's pintle valve, but knew nothing about mouse holes. Is that something I should have cleaned out to reduce the H/C output? And if so, how does one clean out the mouse holes?

[Krashed989]

You see those black rivers of carbon in these pics. Those are the EGR passages on a 94 engine. The "Mouse holes" are in between the EGR valve and these "rivers." It might be a pain in the butt to clean them out. It took me almost 2 whole cans of carb cleaner and some pipe brushes to do it.

[Ranger]

Thanks Krashed. A picture is worth a thousand words.