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Unread 12-07-2013, 09:36 PM   #1
tommy12241
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1988 YJ Wrangler 
 
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Injecting WAY too much fuel

I own a 2000 wrangler tj with the 4.0 in it. Over the last few months its had a problem that gets more and more frequent. It will start missing and backfiring. It starts sucking air like a jet engine. Somethings telling it to inject too much fuel (im pretty sure. If you think im wrong please tell me what you think). Tried one o2 sensor so far. (Money is tight). Cant afford to get it scanned on a live scanner. Its not throwing fault codes though. But im pretty sure its a sensor and crystlers famous electronics are to blame for the no code. I want to test my sensors with my meter (i have all i need. Im a mechanic). I know the o2 sensor is supposed to be between .1 and .9 volts. But i need to know the voltage/resistance for the TPS, CTS, MAP, and CKP.
Im going to take apart the intake manifold and clean it all up. Maybe my cat is no good, any way to check?
Any ideas, voltage/resistance specs, and any other info would be greatly appreciated. Thanks in advance.

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Unread 12-08-2013, 02:15 AM   #2
jnicewan
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Sounds like you really need a scanner that can monitor sensors in live data. By that I mean a scanner to see what the sensors are doing when the problem is there. You will at least need to know what the normal values are. Running rich like you mentioned could mean certain sensors are failing ( MAP, IAT, ECT) for a few examples. Things like the TP, and O2's dont usually cause these issues but they can. Im not sure how bad your jeep is running so I cant make a determiniation on how its running or what might be wrong.


Check all your vac lines, and make sure there are no cracks or broken lines anywhere. check electical connections to sensors too for loose or unplugged connections.
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Unread 12-08-2013, 06:35 AM   #3
tommy12241
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Thanks for the advice. It runs so bad that it wont even move. (A pain in traffic) i cant afford to get it hooked up to a scanner. Or buy one.
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Unread 12-08-2013, 07:52 AM   #4
CJ7-Tim
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Spend $8 for a Factory Service Manual at www.pacificcoastmanuals.com/jeep_service_manuals.html . Full test procedures and specifications are given. Test the sensors with multi-meter.

Google.com also knows how to test things, just ask a question on Google.
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Unread 12-08-2013, 08:01 AM   #5
tommy12241
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Thats perfect! Thanks a lot. I already bought a haynes manual a while back. Sensor specs are vague or non existent. Thanks again!
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Unread 12-08-2013, 08:29 AM   #6
CJ7-Tim
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Once you get beyond oil changes and tune-ups, Haynes and Chilton's are pretty much useless. Not to mention they are full of errors.
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Between 2009 when Obama took office, and 2013, median annual household incomes have fallen by more than $2,100.

Progressive Liberalism: Bringing you new Healthcare ideas so wonderful, they have to include mandatory participation ......

Originally Posted by Ronald W. Reagan: Government is not the solution to our problems; Government is the problem.
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Unread 12-08-2013, 08:40 AM   #7
tommy12241
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I noticed that. Theyre alright for normal stuff. Just not enough detail. More of a laymans book.
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Unread 12-08-2013, 01:39 PM   #8
tommy12241
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Still no luck. Butterfly is clean. When it starts acting up it starts bogging out (from too much fuel). It starts sucking air. Sounds like a jet engine. If you open the butterfly just a hair itll rev up and go back to normal. Any ideas? Im stumped and pissed.
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