2000 TJ 4.0L Running Way to RICH - HELP! - JeepForum.com
 
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post #1 of 7 Old 03-09-2007, 02:23 PM Thread Starter
Goose346
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2000 TJ 4.0L Running Way to RICH - HELP!

2000 TJ 4.0L/auto, 96K miles -

My Jeep is running way to rich - the engine light came on so I took it to Autozone so they could pull the code. They stated the #2 O2 sensor was bad - so I changed both.

I cleaned the plugs of all the soot and re-gapped them. There is acceleration hesitation around 1800 rpm while accelerating and the idle is choppy when sitting at idle. Black exhaust pours out the tailpipe (like a diesel engine) when I step on the gas.

Could the MAP sensor be shot? Where is this located? or . . .
Should I check the fuel pressure just in case the fuel pump is going bad?

I need help guys . . . what is your guess?

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post #2 of 7 Old 03-10-2007, 07:35 PM
Nonya
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1st check the fuel pressure,if its much higher than 50 psi it will cause the troubles you discribe.A big vacuum leak could cause similair troubles but it would idle terrible.If you have a vacuum gauge check the manifold vacuum.I would look closely for a broken vacuum line or cracked hose etc.The lower the vacuum the higher the MAP signal,that will make it run very rich.
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post #3 of 7 Old 03-13-2007, 06:51 PM
oldmanscherokee
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vaccum leak would lean it out not richen it up. the number 2 sensor doesnt do anything but monitor the after cat emmisions to determine if the cat is working it does nothing for air fuel ratio. the #1 sensor does all of that it self. a faulty map sensor could cause that. as well as high fuel pressure, a leaking injector. black smoke is raw fuel through the exhaust. a bad coolant sensor could as well. not the one that feeds the gauge but the one that feeds the pcm signal.

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post #4 of 7 Old 03-14-2007, 08:52 PM
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Also check for a stuck open injector. Getting that much fuel and black smoke, there would almost have to be one stuck. You could pull the fuel rail and injectors off as a unit. Charge the line but don't start the engine, see if one flows.

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post #5 of 7 Old 03-15-2007, 12:57 AM
Nonya
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vac leak will cause a rich condition,because of the map sensor
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post #6 of 7 Old 03-20-2007, 07:43 PM
tjstroker
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Quote:
Originally Posted by RAG48
2000 TJ 4.0L/auto, 96K miles -

My Jeep is running way to rich - the engine light came on so I took it to Autozone so they could pull the code. They stated the #2 O2 sensor was bad - so I changed both.

I cleaned the plugs of all the soot and re-gapped them. There is acceleration hesitation around 1800 rpm while accelerating and the idle is choppy when sitting at idle. Black exhaust pours out the tailpipe (like a diesel engine) when I step on the gas.

Could the MAP sensor be shot? Where is this located? or . . .
Should I check the fuel pressure just in case the fuel pump is going bad?

I need help guys . . . what is your guess?
I just changed my cat converter becasue of these symptoms. The cat was shot, which caused the o2 sensor to read wrong due to carbon, and that caused a max rich condition. The Error codes I received was a bad map and o2 sensor but a map replacement failed to fix. Once I changed the cat, cleaned the o2, it ran great ever since.

How many miles? Do you have gas on the ground under the tailpipe and a black exhaust tip? mine did...
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post #7 of 7 Old 03-20-2007, 08:18 PM
oldmanscherokee
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Quote:
Originally Posted by Nonya
vac leak will cause a rich condition,because of the map sensor

and the the upstream o2 will read its leaned out not rich as the map would indicate, thats why all these sensors are here to have more then one baseline for ocassions like that

full time tech for chevy, part time trail rider
95 Ford Lightning (sold), 09 Caddy CTS-V, 04 Buell Firebolt XB12R w/true flame paint, 00 harley XL chopped, 81 Trans Am, 85 K5 Jimmy 4 inch w/35s, 92 cherokee
10,000 original miles
4.5 inch RC lift
32 11.5 bfg muds
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