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Old 01-26-2013, 04:13 PM   #1
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Engine wont run when warmed up. Help

97 2.5 motor, I have replaced the crank position sensor and the map sensor and new plugs. It runs great ,drive about 30 minutes ,park and let it set 30 minutes. Get back in it and crank it up and it backfires through the tailpipe like you turned the key off and then back on. It smells rich at the tailpipe and does not want to idle. Smoothed out a little ,drove it back home and it still idles rough and smells rich. Let it cool off for 30 minutes and it runs smooth again. I do not have any engine codes, I have a code reader. Any ideas obout what to look at next. I thought about trying a coil.

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Old 01-26-2013, 10:09 PM   #2
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Any suggestions? I am at a loss as what to try next.

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Old 01-26-2013, 10:20 PM   #3
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Hammmike I am no mechanic, but from what it sounds like is that your CAT has imploded clogging the system. I know it can take it awhile to throw a code because your system is trying to correct the problem by adjusting the fuel to air ratio. There is one way you can check to see if the CAT has failed is to take it and get a smog check.

Hope this helps some and I wish you good luck.
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Old 01-26-2013, 10:23 PM   #4
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Find the resistance specs for the primary and secondary windings on the ignition coil. Check and compare yours while cold, and hot. Heat causes high resistance, and high resistance causes heat. High resistance in the secondary winding will cause a weak spark.
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Old 01-27-2013, 07:00 AM   #5
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Thanks, I had considered checking the coil today. I thought about gong ahead and putting a new one on.
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Old 01-27-2013, 08:30 AM   #6
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My guess would be pre-cat o2 or a leaking injector but leaning toward the o2. The o2's are bypassed during open loop which could explain the better cold engine performance.
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Old 01-27-2013, 08:46 AM   #7
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Another thing I noticed is the thermostat is not working correctly. When I hooked up my code reader and put it in live mode the engine temp is only 170 degrees. That seems low. What degree stst do most people run? I looked and they sell 160,180, and 195 degree thermostats. I knew the heater was not very hot. Thanks
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Old 01-27-2013, 10:36 AM   #8
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You want the 195 degree thermostat.
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Old 02-08-2013, 10:55 AM   #9
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Replaced the thermostat with a 195 and when I replace the ignition coil it fixed the problems. Have drove it daily for a week with no problems . Thanks to everyone on the forum.
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Old 02-08-2013, 11:26 AM   #10
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Thanks for updating your thread with the answer that worked for you

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