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Unread 06-30-2013, 12:38 PM   #1
weerwolv
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Stalling and Sputtering-1993 YJ 4.0

Hi all,

Recently had a lot of fuel work done on my yj; replacement of fuel rail and cleaned injectors, etc.

Jeep ran great for three days and now have a problem.

Jeep has no problem starting and going to idle

When in neutral and I crank up the throttle to 2k or higher and come off throttle she stalls. Can't go to idle

When driving and switching gears (ax15) she sputters when I'm giving gas and I have to come off throttle a bit.

Any ideas what this could be? No codes showing

Thank in advance

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Unread 06-30-2013, 01:21 PM   #2
weerwolv
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Hi all,

My mistake on codes as I just re-checked.

It;s throwing codes

12
21
24
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Unread 06-30-2013, 05:14 PM   #3
pete1991YJ
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code 21 = oxygen sensor or circuit
code 24 = throttle position sensor or circuit

You may want to test both sensors separately, its not hard to do. I'm inclined to believe that it maybe a circuit issue because I seem to recall that they both share the same hot lead from the ECU. Don't quote me on that tho. Test the sensors separately first.

Whoops before I forget, make sure you have a good ground from the engine to the firewall or to the battery before you test any electrical. No point in testing with a bum ground throwing off your readings.
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Unread 07-01-2013, 12:38 AM   #4
VenomousMaximus
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Try performing a Distributor Sync or Indexing... #1 piston TDC on compression stroke, the tip of the rotor in dizzy should be just past the terminal #1(just scribe a line on distributor itself center of tower #1) .020", if not, remove distributor to re*index it. You may have to modify distributor a little to turn.
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Unread 07-01-2013, 12:40 AM   #5
VenomousMaximus
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That's "tip of the rotor" f@*king auto correct! LOL
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Unread 07-01-2013, 12:47 AM   #6
VenomousMaximus
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More potential causes...

* camshaft position sensor
* crankshaft sensor
* defective PCM
* defective upstream O2 Sensor
* wiring harness / ground
* ignition coil
* MAP sensor
* TPS sensor
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Unread 07-01-2013, 12:56 AM   #7
VenomousMaximus
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The PCM on this engine allows the upstream O2 sensor signal to determine 25% of the fuel control... So if the O2 sensor voltage remains too high as the PCM moves to closed loop, the controller will take away fuel. Usually in this case the O2 sensor is shorted to voltage.
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Unread 07-01-2013, 09:18 AM   #8
weerwolv
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Thanks guys for the background and help. Just picked up a new TPS and 02 from Autozone and will try them tonight.

Gonna shoot for the TPS first. If that corrects things enough I'll return the 02. If not, 02 goes in next

-Chris
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