how to tell if the pre cats are bad?
07-09-07, 10:13 AM
#1
how to tell if the pre cats are bad?
So after fixing a bunch of stuff I am still failing emissions! I went down a few points but still...
-New main cat
-New split air kit
-4 month old o2 sensor
-4 month old spark plugs
-new ignition wires
-"new" ACV solonoids
-new injector grommets and O rings
-new cone filter/heat shield
-new battery
-new UIM gasket
-adjusted TPS
-steadily idles between 800-1100 depending on whatever it feels like at the moment
I run Castrol GTX HM 20w50 oil and 87 octaine gas. Could the pre-cats be bad? There is a bit of a rotten egg smell from the exhaust. It's not terrible though.
I know the above upgrades and repairs are working because I can tell a noticable power increase and about a 10 MPG boost.
All the test consists of is is a 10 second idle sample, followed by a 10 second 2500RPM hold, then another 10 second idle sample.
I'm about ready to register out of county in a no emissions county...
-New main cat
-New split air kit
-4 month old o2 sensor
-4 month old spark plugs
-new ignition wires
-"new" ACV solonoids
-new injector grommets and O rings
-new cone filter/heat shield
-new battery
-new UIM gasket
-adjusted TPS
-steadily idles between 800-1100 depending on whatever it feels like at the moment
I run Castrol GTX HM 20w50 oil and 87 octaine gas. Could the pre-cats be bad? There is a bit of a rotten egg smell from the exhaust. It's not terrible though.
I know the above upgrades and repairs are working because I can tell a noticable power increase and about a 10 MPG boost.
All the test consists of is is a 10 second idle sample, followed by a 10 second 2500RPM hold, then another 10 second idle sample.
I'm about ready to register out of county in a no emissions county...
07-09-07, 10:46 AM
#2
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Mine is essentially the same set up as yours, mine passed easily. Pre-cats have no bearing on passing.
Even though you have a new split air pipe, are you sure it is pumping O2 to the main cat?
Even though you have a new split air pipe, are you sure it is pumping O2 to the main cat?
07-09-07, 11:26 AM
#3
Don't need pre-cats for smog. I passed CA smog with no pre-cats. I would suspect the idle issue for you not passing smog. Have you checked all your vac lines? It's cheap to replace them.
07-09-07, 03:58 PM
#4
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Trim level of your FC? I know my rotten egg smell went away after I corrected the routing of all my vac lines on my 88GXL. I found out that one line off the back of my TB was off and the two small vac lines on the front below the OMP injector spider were reversed
07-09-07, 04:57 PM
#6
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If they are still the original cats and pre cats, they are probably not working at all. But when my vert was N/A, I had a gutted cat (the catalyst broke up and rattled, so I gutted it) and went in for an inspection. The guy said I actually passed in the category where the cat was needed (weird), and failed on something else. Did a tune up and bought a new cat assembly, and still failed horribly. So now it's gonna get registered where my grandfather lives, which is the middle of nowhere.
07-10-07, 12:11 AM
#7
the main cat is new. as in brand new. 200 miles on it. i took it for a little drive before the test. pre cats are originally possibly. my vac lines are good. i think im going to try one more time since i get a freebie 2nd try. lower my idle down to like 700. would running premium fuel help?
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07-10-07, 02:35 AM
#9
the main cat is new. as in brand new. 200 miles on it. i took it for a little drive before the test. pre cats are originally possibly. my vac lines are good. i think im going to try one more time since i get a freebie 2nd try. lower my idle down to like 700. would running premium fuel help?
1. DO the trans fluid trick to lub the seals some
2. Buy new plugs
3. TACH that engine out some really good right before your second try.
If that still doesn't work you must have a vac leak in the emm system or your engine is really tired. How's the compression?
