not burning all fuel

[bbqsauce]

I cannot pass inspection because Pepe (my Festy) will not burn all of his fuel at low idle. I've got my idle speed set about 1200 RPM. New plugs, wires, cap, & rotor. Have I forgotten something and is it something a shadetree mechanic can fix or must I visit a true mechanic.

[Gforcefd]

alittle more information would be good, what do you mean you are not buring all of your fuel? No car burns "all" of its fuel, or our cars would be way more efficient.

A new catalytic convertor would take care of any extra emissions though.

[bbqsauce]

That's probably the answer I need. More specifically, I was shown on the read out that the low speed emission results were 281 vs a 220 read out while the vehicle was idling at 925 RPM and the only other thing they told me was that I was not burning all my fuel as it sat idling. Can I put a new Cat converter on or is it a muffler shop deal. I can cut and clamp but no welding facilities. Thanks for the assist.

[Gforcefd]

You can clamp it if you want, but if it leaks it will sound like crude. I can't remember if the festiva stock cat is welded on or not, but I believe it is bolted on at at least after the flex pipe.

[FestYboy]

stock cat replacement bolts to the downpipe and clamps to the midpipe. if you're not burning all of your fuel (running rich) you may wnat to replace the o2 snsor first because if the o2 goes bad the ECM will command rich condition to keep engine from pinging/detonation. looking at the numbers you posted, that's probably the better bet as a non-working cat will show in the 4-500 range.

[Pu241]

Thanks Festyboy,
I knew the voice of reason should prevail.

Additionally, if the oxidation portion of your cat where bad I would expect high CO (carbon Monoxide) levels, instead of just high HC levels. Actually, your not that far from passing. And with the new O2 sensor you should be able to drop your idle to the normal rpm range.
The O2 sensor makes more sense and is the cheaper solution.
But probably the more difficult to remove.

No car burns "all" of its fuel, or our cars would be way more efficient.

Gforcefd,
Thermodynamics wasn't your strongest subject in college was it?
I guess the Carnot cycle efficiency and frictional losses would all go away if we just burned the last few PPM of gasoline!

FWIW the OEM festiva cat is bolted to the down pipe and uses a "donut" gasket between the down pipe and the cat. At the back, the cat is flanged and bolts to the flanged mid-pipe using the same compression gasket that is used at the front side of the muffler to mid-pipe connection.

[25Horseplay]

FWIW the OEM festiva cat is bolted to the down pipe and uses a "donut" gasket between the down pipe and the cat. At the back, the cat is flanged and bolts to the flanged mid-pipe using the same compression gasket that is used at the front side of the muffler to mid-pipe connection.

Thats how mine is, easy to change maybe 10 min.

[miami man]

my 91 failed 5 times and a new cat got the job done

[Pu241]

FWIW the OEM festiva cat is bolted to the down pipe and uses a "donut" gasket between the down pipe and the cat. At the back, the cat is flanged and bolts to the flanged mid-pipe using the same compression gasket that is used at the front side of the muffler to mid-pipe connection.

Thats how mine is, easy to change maybe 10 min.

10 minute job now that I've replaced all the nuts with stainless steel ones and used MIL spec anti-seize on the the bolts and studs. Otherwise, I've had to use a torch to burn off the rusted nuts to replace the mid-pipe and re-wield the down pipe flange back on! Strangely enough the cat seems to be pretty durable unless you hit it on something.

[Pu241]

my 91 failed 5 times and a new cat got the job done

Yes, there are times when the cat does fail, but I'll bet your your CO levels were also high instead of just your HC levels, and maybe your NOx levels as well. Indicating the the oxidizing portion of the cat has failed, and replacing the cat is your only recourse.
However, in the above case when there are high HC levels and do NOT have corresponding high CO levels then something else is amiss!
Actually, when people say they fail emissions I'd like to see all the numbers HC, CO, and NOx.

[miami man]

good thing here pretty soon they will not reqiire an emmisions inspection on 95 and older cars

[Pu241]

good thing here pretty soon they will not reqiire an emmisions inspection on 95 and older cars

Yeah, then I can have a straight pipe fabed-up between the down pipe and mid-pipe!
Oh, yeah, forgot I don't have emissions anyway!

I remember going to a ford dealer a few years ago and while I was there, getting something else,I asked about the cost of a new cat. for the fester.
Thinking it might be a good idea to have a new on the shelf, just in case!
The guy had to look twice and then said "do you think you really need one!"
They wanted $300!
But thankfully, you can get one from a Mcparts for about $100!