so my jeep failed smog really badly. It failed on the 5 mph and 15 mph sections by a lot. It runs really good and has a ton of power. Think it could be the cat? Its off my 96 that was rolled. What else could it be? 87 waggy with a 89 comanche 4.0 .030 over borla header and aftermarket injectors
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Failed Smog Miserably
- Thread starter XJRunner
- Start date
joe_peters
NAXJA Forum User
- Location
- Grants Pass, OryGun
Re: Failed smog miserably
Post up all the numbers or there is no way to help you.
Moving this to OEM Tech forum for you.
Post up all the numbers or there is no way to help you.
Moving this to OEM Tech forum for you.
mfascuba
NAXJA Forum User
- Location
- North Central Florida
Ah, I love Florida - no inspections. I've seen school busses going down the highway (interstate) with the roof cut off, converted to fruit picker transport vehicles. If you can get it to go down the road and pay your registration & insurance, you're in business!
joe_peters
NAXJA Forum User
- Location
- Grants Pass, OryGun
Ok, better.
HC is hydrocarbons. That means UNBURNED fuel. Either you are running too rich or the engine/ignition system isn't burning all the available fuel.
When was the o2 sensor last changed? Good for about 60k miles, no more.
Aftermarket injectors? Give details.
Last time cap/rotor/plugs/plug wires were changed?
Last time air filter was changed?
Any leaks in the exhaust manifold upstream of the o2 sensor (why I'm asking I don't know, you said it had a Borla and they always crack!).
HC is hydrocarbons. That means UNBURNED fuel. Either you are running too rich or the engine/ignition system isn't burning all the available fuel.
When was the o2 sensor last changed? Good for about 60k miles, no more.
Aftermarket injectors? Give details.
Last time cap/rotor/plugs/plug wires were changed?
Last time air filter was changed?
Any leaks in the exhaust manifold upstream of the o2 sensor (why I'm asking I don't know, you said it had a Borla and they always crack!).
kidarkitect
NAXJA Forum User
- Location
- Salt Lake City, Utah United States
Mr. Peters on point. Don't replace the cat till you gone through that stuff. Usually you'll hear pinging from the cat when it goes bad. Replacing the cat would be more like a bandaid fix, next year you'd probably have the same problem again (after it gets gummed up w/ the unburned fuel)
mfascuba
NAXJA Forum User
- Location
- North Central Florida
The O2 sensor in front of the CC is the one the engine uses to adjust the mixture - the one downstream is monitored and will throw a code indicating the cat went bad if it gets out of range. If there is a crack in the exhaust upstream of the one that counts it will dilute the exhaust and read lean, so the fuel injectors will try to richen up the mixture to get it right.
I joke about stuff from FL but I want this stuff to work right - it gets you better mileage and the vehicle lasts longer if it works within factory specs.
Mark
I joke about stuff from FL but I want this stuff to work right - it gets you better mileage and the vehicle lasts longer if it works within factory specs.
Mark
joe_peters
NAXJA Forum User
- Location
- Grants Pass, OryGun
Couple of other things on running rich: CTS--coolant temperature sensor could be telling the PCM the engine is cold; bad thermostat, the engine isn't warming up; MAP sensor.
brand new cooling system, the tech overheated the jeep on the test dyno. It has the injectors with the 4 wholes. still the same flow rate. The o2 sensor is from my old header, didnt change it dunno how many miles are on it. Should I start there? and i only have 1 o2 sensor. its a renix
everythings high across the board too. and HC is from running lean(according to my dad, worked at a jeep dealership) it has a new cap and wires on it. also new rotor, plugs were put in when I put the engine in so thei new too(jeep has never been driven on the road with this engine). We're taking to my dads friend who owns a exhaust place to ask him what he thinks monday
kidarkitect
NAXJA Forum User
- Location
- Salt Lake City, Utah United States
I'd start with the o2. That's my .02
- Location
- on the beach in Ocean View, VA
as stated previously, high HC emission is the result of unburned gas in the exhaust.
Higher than expected NO (oxides of nitrogen) is the result of lean mixture (among other things)
I'd start with the O2 sensor to make sure the ECU is getting the correct information to determine mixture. If that doesn't help, I'd verify operation of the CTS and ACT.
P.S. I didn't work at a Jeep Dealership, but I did stay at a Holiday Inn last night.
ParadiseXJ
NAXJA Forum User
- Location
- Paradise, CA 95969
atriot:...possible winnerJoe is not talking about the temp sender (gauge, back of head) on your RENIX. The computer gets it's information from here:
...was this sensor changed with the rest of the cooling system?
- Location
- Antioch, CA
One step that seems to always get looked over is to run your emission test results through a Lambda Calculator. The Lambda calculator will tell you how close, or how far off, you are from correct combustion air fuel ratio. Knowing if your engine is running rich or lean is pretty important in getting it fixed.
Sit down with your smog check report and enter the numbers into the calculator found here: http://www.smogsite.com/calculators.html Scroll down about halfway down the page to find it. Once you figure out if it is rich or lean you can start figuring out what to replace. One other thing to remember is that after your repairs, if you fail again you can check to see how effective your repairs were(if at all).
Sit down with your smog check report and enter the numbers into the calculator found here: http://www.smogsite.com/calculators.html Scroll down about halfway down the page to find it. Once you figure out if it is rich or lean you can start figuring out what to replace. One other thing to remember is that after your repairs, if you fail again you can check to see how effective your repairs were(if at all).
joe_peters
NAXJA Forum User
- Location
- Grants Pass, OryGun
NO. Get your maintenance and tuneup issues handled first, then find out where you are at.
- Location
- Rainy side of Washington
X2 on what Joe said, leave the cat till you know whether the O2/temp sensors fix it. I'm not too surprised it's special order, since RENIX sensors are different from the OBD I and OBD II sensors and all RENIX vehicles are at least 20 years old at this point, there aren't anywhere near as many on the road now.
Good luck! My bet is that the O2 sensor will fix it. With those kind of HC numbers you should be able to find out by getting the engine up to operating temp and then sniffing the exhaust, if it smells gassy still, it didn't fix it.
