1990 Wrangler YJ 2.5 liter with TBI --What Next? - JeepForum.com
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Unread 09-12-2013, 12:02 AM   #1
Calpastor
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Join Date: Aug 2010
Location: Farmersville, CA
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1990 Wrangler YJ 2.5 liter with TBI --What Next?

Started stalling, backfiring, idling rough...
I changed plugs, wires, cap, rotor - No change
New Battery - No change
New coil - No change
New Fuel Pump and Filter - No change
New Crank Position Sensor - No change

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Unread 09-12-2013, 05:43 AM   #2
Que89YJ
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1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: Detroit, Michigan
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Does it make any difference in the way it runs hot or cold?
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Unread 09-13-2013, 11:24 PM   #3
Calpastor
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Cold runs better...but warms quickly and then runs bad...
I replaced throttle body injector today - No change
What's this part?


image-4204404700.jpg
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Unread 09-14-2013, 12:46 AM   #4
ShArKtRaInEr
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1989 YJ Wrangler 
 
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Check for vacuum leaks, like behind the engine where the trans meets. There is a junction there. Also you can check the oxygen sensor and throttle position switch at the back of the throttle body.

That photo is the idle speed motor. You can reset/retract it with a little 9V battery, the two center pins are where you connect after disconnecting the harness.
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Unread 09-14-2013, 04:52 AM   #5
Que89YJ
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1989 YJ Wrangler 
 
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If there is a big difference hot to cold then o2 or coolant temp sensor. Not the one for the guage. Can't figure out where you took the pic?
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Unread 09-14-2013, 10:49 AM   #6
Calpastor
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Not a big difference hot to cold.

I do have an exhaust leak...could that cause the proble?
I may replace TPS today...what about EGR? Could that creat idle issues?
Pic was Idle Control Motor
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Unread 09-14-2013, 10:47 PM   #7
Calpastor
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Added new throttle position sensor - still rough idle
I have an exhaust leak on exhaust manifold...couple bolts missing, could that create a vacuum leak?
I'm also wondering about EGR valve, but it's about 110 to replace. Ouch!
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Unread 09-14-2013, 11:52 PM   #8
Que89YJ
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1989 YJ Wrangler 
 
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Location: Detroit, Michigan
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The exhaust leak is throwing off the o2 sensor causing you to run rich and throwing off the calibration. On the pre 91 yj there is a setup procedure that must be done for the tps, ais, and wot when replacing.
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Unread 09-16-2013, 12:09 AM   #9
Calpastor
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I'll update after that.
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Unread 09-30-2013, 09:21 PM   #10
Calpastor
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Ok...
Feeling dumb, and angry.

Bad Spark Plug! Not cracked, not broken. I changed plugs, wires, rotor, and cap when my engine started running rough. And it didn't help. My mechanic removed plugs and tested them and found one that just was a dud. Running like a champ now!
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Unread 09-30-2013, 09:59 PM   #11
Chrisnvegas
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1992 YJ Wrangler 
 
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That was one expensive spark plug!
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I have candy. Get in the Jeep
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