Engine running rich, what would cause this?

[ksdaoski]

TBI 2.5L

Running rich, cat turning bright red!!!!!!!

[Sequel]

Bad O2 sensor?

[JeffsJeep04]

I also have a rich 2.5 tbi, and my O2 is good.

[laybackman]

A cat burning bright red is usually a clogged cat. If you are running rich wouldn't you also smell it and see it (black or blue smoke under load)? Hope this helps

[ksdaoski]

the cat is brand spanken new

[grubb92]

Yep Ii'd agree with the clogged cat. Mine runs rich, and has black crap coming out of the exhaust, but no glowing cat.

Since it's new, I wonder if perhaps there could be something stuck in there, or maybe in the pipe directly after the cat.

I've had clogged cats on a couple vehicles, and they both glowed red.

[laybackman]

I wonder what a cat would do if it is installed backwards?? Would it "light up"? Not pulling your chain just tossing out ideas.:agree:

[ksdaoski]

i have problems believing a brand new cat would be clogged. It is installed the correct direction!

I'm guessing the O2 sensor has never been replaced....and if I remeber right, the check engine light bulb has been pulled! :puzzled:

[OB_WAN]

to check the engine codes(maybe the lights just not coming on because it's not bad enough) follow the instructions on the below link. I just did this and it seems to work(although I had disconnected my battery so it just told me that the codes were wiped out).

http://www.bc4x4.com/faqs/yj.cfm?cat=5&faqid=37#faqtop

And you can have a new cat that's clogged. Just depends on what the muffler guy did during install. I had one in a new saturn. my symptoms also included hesitation and sputtering(like engine is out of gas).

[JeffsJeep04]

Now correct me if I'm wrong, but those codes don't work on the old style YJ's, right? I've got no cat, a new o2 sensor, and black junk coming out of the tail pipe. The junk was coming out before the cat removal. No smoke, just crappy gas milage and residue on the pipe.

[OB_WAN]

You might want to try it and let us know. I don't see why not, it's still a computer controlled system.

[JeffsJeep04]

Just like I thought, tried it and nothing. I think the term computer controlled is used losely on the old YJ's. :brows:

[YJbogey]

I had similiar running rich problems in my '89 YJ 2.5L TBI.. here is a list I went through when trying to fix them.

Check your vacuum lines and hoses. Replace any that are cracked or old. If your breaks suck, the diaphram in the brake booster could be bad. Plug the line to the brake booster to see if this is bad or not.

Check your PCV valve. Take it out and shake it. If it doesn’t rattle, it is bad.

Check your EGR valve and make sure it isn't rusted shut.

Compression test on your engine.

Clean your fuel system. If your Jeep has or had a steal gas tank, you need to take some action here. The rust from the steal tank will clog the fuel filter and injector. Replace the fuel filter if you haven’t done so in a while. Use some fuel injector cleaner. Finally, take your fuel injector out and clean it with some throttle body cleaner.

Check your sensors and replace the bad ones.

O2 Sensor Test: Should be between 5 and 7 ohms. If infinity reading, replace sensor.

Coolant Sensor Test: Should range from 100,700 (100.7K) Ohms at –40°F to 185 Ohms at 212°F.

MAT Sensor Test: Should be less than 1000 ohms with warm engine.

MAP Sensor Test: A is ground, B is output voltage and C is 5 volts. With ignition switch on, engine off, A+B should equal 4-5 volts. Start engine and run till warm/hot. The voltage should drop to 1.5-2.1 volts with hot neutral idle. Also test A+C, should be 5 volts +/- .5 Volts.

Crank Position Sensor Test: With engine off, A+B should equal 200 +/- 75 ohms with hot engine. Also, when measuring voltage, volts should spike when engine is cranked or is running.

Knock Sensor Check: Make sure the knock sensor is snug and all the wiring is intact.

Check the purge valve on your charcoal canister.

Hope this helps.

[ksdaoski]

thanks those are great. But with so many things to check, makes me just want to slap in a 5.0! :)
-=- originally posted by YJbogey -=-
I had similiar running rich problems in my '89 YJ 2.5L TBI.. here is a list I went through when trying to fix them.

Check your vacuum lines and hoses. Replace any that are cracked or old. If your breaks suck, the diaphram in the brake booster could be bad. Plug the line to the brake booster to see if this is bad or not.

Check your PCV valve. Take it out and shake it. If it doesn’t rattle, it is bad.

Check your EGR valve and make sure it isn't rusted shut.

Compression test on your engine.

Clean your fuel system. If your Jeep has or had a steal gas tank, you need to take some action here. The rust from the steal tank will clog the fuel filter and injector. Replace the fuel filter if you haven’t done so in a while. Use some fuel injector cleaner. Finally, take your fuel injector out and clean it with some throttle body cleaner.

Check your sensors and replace the bad ones.

O2 Sensor Test: Should be between 5 and 7 ohms. If infinity reading, replace sensor.

Coolant Sensor Test: Should range from 100,700 (100.7K) Ohms at –40°F to 185 Ohms at 212°F.

MAT Sensor Test: Should be less than 1000 ohms with warm engine.

MAP Sensor Test: A is ground, B is output voltage and C is 5 volts. With ignition switch on, engine off, A+B should equal 4-5 volts. Start engine and run till warm/hot. The voltage should drop to 1.5-2.1 volts with hot neutral idle. Also test A+C, should be 5 volts +/- .5 Volts.

Crank Position Sensor Test: With engine off, A+B should equal 200 +/- 75 ohms with hot engine. Also, when measuring voltage, volts should spike when engine is cranked or is running.

Knock Sensor Check: Make sure the knock sensor is snug and all the wiring is intact.

Check the purge valve on your charcoal canister.

Hope this helps.

[YJbogey]

How bout a 4.0L? :D

http://www.chrr.ohio-state.edu/~bogrees/html/tech/40swap.html