emissions
#1
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Car: 1991 RS
Engine: 305 TBI
Transmission: auto
emissions
I just got back from the emissions station,my HC is still high. The guy at autozone told me it is probably burning rich.. how would I find out. it is the 305 with TBI.
Thanks Scot
Thanks Scot
#2
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Car: 82 Berlinetta/57 Bel Air
Engine: LS1/LQ4
Transmission: 4L60E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
List all the readings they gave you on the printout.
Also, your modifications/settings/recent maintainance would be helpful.
Also, your modifications/settings/recent maintainance would be helpful.
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Car: 1991 RS
Engine: 305 TBI
Transmission: auto
HC 1.8572 allowed; .8
CO 7.7715 15.
NOx .0016 2.
Open element breather
was running quite a bit of Heet during test
According to the Supplemnetal Diagnostic Info sheet they gave me:
Ignition misfire, fuel distribution problems, grossly advanced timing, and/or mchanically induced misfire
I haven't done any mods except for the open element breather. I run regular unleaded gas.
Thanks Scot
CO 7.7715 15.
NOx .0016 2.
Open element breather
was running quite a bit of Heet during test
According to the Supplemnetal Diagnostic Info sheet they gave me:
Ignition misfire, fuel distribution problems, grossly advanced timing, and/or mchanically induced misfire
I haven't done any mods except for the open element breather. I run regular unleaded gas.
Thanks Scot
#5
Originally posted by RB83L69
You need a new cat. Not the kind that meows.
You need a new cat. Not the kind that meows.
#6
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Car: 1991 RS
Engine: 305 TBI
Transmission: auto
will a catco be sufficient or should I get a stock one. I currently have the stock exhaust, but am going to a flowmaster 80 series three in pipes and a set of headers soon
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Car: 4
Engine: 6
Transmission: 5
The Catco should be fine.
Looks to me like the engine is running right but the cat isn't cleaning up the last little bit. I wouldn't mess with the timing becasue it doesn't just jump out of tolerance all by itself. If the O2 sensor was bad such that it was telling the ECM that the exhaust is lean, the ECM would richen it up, but that would result in high HC too. If both of those were way high, then the sensor would be suspect.
If you're planning on changing the exhaust, I'd suggest doing it now and getting the right size cat for that, otherwise you'll just have to buy another one of the larger size when you do the exhaust upgrades.
Looks to me like the engine is running right but the cat isn't cleaning up the last little bit. I wouldn't mess with the timing becasue it doesn't just jump out of tolerance all by itself. If the O2 sensor was bad such that it was telling the ECM that the exhaust is lean, the ECM would richen it up, but that would result in high HC too. If both of those were way high, then the sensor would be suspect.
If you're planning on changing the exhaust, I'd suggest doing it now and getting the right size cat for that, otherwise you'll just have to buy another one of the larger size when you do the exhaust upgrades.
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#9
Originally posted by RB83L69
Looks to me like the engine is running right but the cat isn't cleaning up the last little bit. I wouldn't mess with the timing becasue it doesn't just jump out of tolerance all by itself. If the O2 sensor was bad such that it was telling the ECM that the exhaust is lean, the ECM would richen it up, but that would result in high HC too. If both of those were way high, then the sensor would be suspect.
Looks to me like the engine is running right but the cat isn't cleaning up the last little bit. I wouldn't mess with the timing becasue it doesn't just jump out of tolerance all by itself. If the O2 sensor was bad such that it was telling the ECM that the exhaust is lean, the ECM would richen it up, but that would result in high HC too. If both of those were way high, then the sensor would be suspect.
timing shouldn't go out of spec on its own, but some people we buy these cars from are real idiots, so i have had to adjust it on my first run through emissions before.
Last edited by patrickm00; 03-25-2003 at 02:00 PM.
#10
Originally posted by CrispyClutch
Yeah retards have bad timing.
Yeah retards have bad timing.
#11
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Car: 82 Berlinetta/57 Bel Air
Engine: LS1/LQ4
Transmission: 4L60E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Hmmm, I've always seen allowables given in round-ish numbers, and actuals to a few decimal places.
If that assumption is correct, then you indeed are running rich. Since the NOx is low, I tend to believe that even more (if NOx was high, I'd go along with the cat diagnosis).
O2 sensor, plugs, perhaps wires/cap/rotor. If it has been running rich for a while, then a new cat may also be required (running rich, especially a misfire, will cook out a cat).
I'm no TBI expert, but I believe there is an air inlet temp sensor in the factory air cleaner, right? Did you transfer that over to your open element?
If that assumption is correct, then you indeed are running rich. Since the NOx is low, I tend to believe that even more (if NOx was high, I'd go along with the cat diagnosis).
O2 sensor, plugs, perhaps wires/cap/rotor. If it has been running rich for a while, then a new cat may also be required (running rich, especially a misfire, will cook out a cat).
I'm no TBI expert, but I believe there is an air inlet temp sensor in the factory air cleaner, right? Did you transfer that over to your open element?
#12
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Car: 1991 RS
Engine: 305 TBI
Transmission: auto
Yes I kept the air inlet sensor.I know I'm in need of a good tune up, plugs, wires cap, rotor..the whole nine yards. I have also been contemplating going on ahead and replacing the O2 sensor.
Guess I will do those things then worry about the cat later. I want to go to a 3 in exhaust and headers but need to wait a few months before I do the whole exhaust. If I change the cat now, I would just have to buy another one in a few months, so I want to avoid that if I can.
Thanks for all the input guys
Guess I will do those things then worry about the cat later. I want to go to a 3 in exhaust and headers but need to wait a few months before I do the whole exhaust. If I change the cat now, I would just have to buy another one in a few months, so I want to avoid that if I can.
Thanks for all the input guys
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