1990 cherokee smog problems
#1
1990 cherokee smog problems
1990 cherokee not passing smog. replaced the nrg valve, put a stock airbox in, ran all new vacuum hoses to slots and evap canister, and used to emission test formula that cleans the pistons and valves. still not passing smog. any common problems like this for my year cherokee? 1990 jeep cherokee laredo 4.0 4x4 aw4 tranny. im thinking the cat is bad cuz it looks old mayb like its stock.. any other reasons before i have to spend $180 to get a cat put in? its a couple hundred numbers over the max smog rate... and wen i did all this stuff it went down around 200 points but still not good enough. need to get it smogged to be fully put in my name. thanks
#2
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Year: 1988
Model: Cherokee
Engine: Rebuilt 4.0L
Replacing Cat is always a good idea for passing emissions, especially on these older cars. Save yourself some money though, pick up a new cat and install it yourself. if you don't have a welder, clamp it on. You can find exhaust clamps at Autozone and the like. you can cut the old one out with a really good hacksaw or angle grinder if you can't get your hands on a Sawzall.
#3
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Year: 88 limited
Model: Cherokee
Engine: 4.0
Do you know the actual numbers it blows?-that would help every one. On my 88 it first came back as a gross polluter,the o2 sensor was bad. Try to test yours its not to hard to ,your cat might be bad,or it might be doing overtime if your running to rich ,a new cat could give the same numbers
#4
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Year: 1998
Model: Cherokee
Engine: 4.0 stock
If your Jeep is capable of passing here is how to help it out... LEGALLY
Step #1 give it a tune up (change your oil, replace air filter and PCV valve, replace spark plugs, check wires and distributor cap and rotor button)
Step #2 Use a good fuel injector cleaner 1 tank before testing
Step #3 on testing day drive the car to operating temp preferably a good long freeway drive is best. You want to warm up the catalytic converter to make it perform best.
Step#4 air up the tires. make sure they are at the proper pressure.
Step#5 before testing make sure to turn off everything electrical and make sure the AC is off.
If after all that it still fails you can do a few.... well not illegal things but definitly not recommended things.
#1 remove air filter for testing (puts engine at risk)
#2 back off the adjuster on the rear drums (puts YOU at risk)
#3 air up the rear tires beyond recommended operating pressure (be very careful. Over inflating tires is dangerous!)
Step #1 give it a tune up (change your oil, replace air filter and PCV valve, replace spark plugs, check wires and distributor cap and rotor button)
Step #2 Use a good fuel injector cleaner 1 tank before testing
Step #3 on testing day drive the car to operating temp preferably a good long freeway drive is best. You want to warm up the catalytic converter to make it perform best.
Step#4 air up the tires. make sure they are at the proper pressure.
Step#5 before testing make sure to turn off everything electrical and make sure the AC is off.
If after all that it still fails you can do a few.... well not illegal things but definitly not recommended things.
#1 remove air filter for testing (puts engine at risk)
#2 back off the adjuster on the rear drums (puts YOU at risk)
#3 air up the rear tires beyond recommended operating pressure (be very careful. Over inflating tires is dangerous!)
#5
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Year: 2004
Model: Grand Cherokee
Engine: 4.7L V8
If you need a cat check with mudfrog (a Vendor here). https://www.cherokeeforum.com/f10/ou...nverter-45340/
#6
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Year: 1999
Model: Cherokee (XJ)
Engine: 4.0 I6
and put some rubbing alcohol in your tank before you go in. it makes your exhaust run clean. alot of bmw guys in cali do that on their cars with cats that are hollowed out. its like a half gallon a tank or something. also, if your cat is good, make sure its all the way warm or it will give out bad numbers. you have to drive it for a while before going into inspection
#7
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Year: 1998
Model: Cherokee
Engine: 4.0 stock
be very careful with putting alcohol in your tank. Alcohol absorbs water, eats seals that aren't compatible and makes the car run lean. Too much can cause engine problems and fuel system damage.
Some people have used E85 instead of other alcohol. At least E85 is meant to be a fuel grade alcohol.
Some people have used E85 instead of other alcohol. At least E85 is meant to be a fuel grade alcohol.
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#8
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Year: 1987
Model: Cherokee
Engine: 4.0
you need to post actual numbers on how it smog to be told how to fix it.example where the hc's high or the o2's they mean totally diferent things if your hc are high replacing you cat wont do a thing. Hc mean your engine is running lean wich could be multiple thing 02' running rich wich i would start with the tune up then cat.
#9
ok the actual numbers are (first numbers are 15 mph second numbers are 25 mph) HC: max 123 and 103. measured 47 and 40. CO: max .73 and .93. measured .20 and .17. NO: max 711 and 613. measured 836 and 778. that last one was the only one it failed and that was of course the emissions test. thanks guys
#10
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Year: 1987
Model: Cherokee
Engine: 4.0
ok the actual numbers are (first numbers are 15 mph second numbers are 25 mph) HC: max 123 and 103. measured 47 and 40. CO: max .73 and .93. measured .20 and .17. NO: max 711 and 613. measured 836 and 778. that last one was the only one it failed and that was of course the emissions test. thanks guys
#13
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Year: 1987
Model: Cherokee
Engine: 4.0
The bolts that im talking about are the one on the right side of the head that hold the intake and exhaust manifolds onto the head if you have to many lose you might want to replace the gasket itself, it's like 17.99 at autozone or kragens. After you tighten them if they are lose when it cold start it and spray some starting fluid around where the manifolds meet and if the idle goes up you still have a leak.
#15
ok i checked all those earlier and the wer all tight. not even one of them was loose. sooo im thinking maybe a new o2 sensor cuz mine is really old.. probably 20 years old. and then replacing the cat and running some good fuel injector cleaner and see if that does it. and if not then i have no idea what to do