90' XJ 4.0 failed emissions CO% - running 703 injectors
09-12-2011, 03:14 PM
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90' XJ 4.0 failed emissions CO% - running 703 injectors
My xj just failed the CO% portion of the emissions test. The results were reading high, 3.37@ 15mph and 2.88@ 25mph. Normally i pass with flying numbers, its a 1990 with 97k. I just replaced the original RENIX injectors with reman 703's from the motor man. I wonder if the 703's are pushing to much fuel???
09-12-2011, 05:22 PM
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My xj just failed the CO% portion of the emissions test. The results were reading high, 3.37@ 15mph and 2.88@ 25mph. Normally i pass with flying numbers, its a 1990 with 97k. I just replaced the original RENIX injectors with reman 703's from the motor man. I wonder if the 703's are pushing to much fuel???
Finding out that the 703's are pumping to much fuel into the motor....
The 703's were not a good replacement for the stock RENIX that flow at 18.6lbs. The 556's or the 943's are what I'm going to use to resolve this issue. I very certain it will pass emissions with this fix.
Last edited by turkish_XJ; 09-12-2011 at 05:25 PM.
09-12-2011, 07:22 PM
#3
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
The ECU should take care of the injectors as long as they're not too big. If they were too big, you would have driveability issues. But, the ECU can't control any injectors if it isn't getting an accurate signal form the O2 sensor....
09-16-2011, 11:51 AM
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Anyone have any other recommendations to get this baby passed emissions??
09-16-2011, 01:11 PM
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Year: 1990
Model: Cherokee
Engine: The venerable 4.0
My buddy (on this forum) had super high numbers. I tested his sensors and found a bad o2. We gave it a tune up seafoam and a new o2 and he passed like the thing was new. It was funny too because the guys at the smog place were convinced it was his cat. When he brought it back they told him it wouldn't pass and he should have replaced his cat. Passed with flying colors. http://www.lunghd.com/Tech_Articles/...iagnostics.htm try testing the sensors. I find the best way to test o2 is either warm it up and back probe the connector to se if the voltage jumps about every second, if not replace it or go per instructions is chilton or haynes and warm it up disconnect it and use a high impedance multi meter to check for a millivolt reading that jumps.
09-16-2011, 05:42 PM
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My buddy (on this forum) had super high numbers. I tested his sensors and found a bad o2. We gave it a tune up seafoam and a new o2 and he passed like the thing was new. It was funny too because the guys at the smog place were convinced it was his cat. When he brought it back they told him it wouldn't pass and he should have replaced his cat. Passed with flying colors. http://www.lunghd.com/Tech_Articles/...iagnostics.htm try testing the sensors. I find the best way to test o2 is either warm it up and back probe the connector to se if the voltage jumps about every second, if not replace it or go per instructions is chilton or haynes and warm it up disconnect it and use a high impedance multi meter to check for a millivolt reading that jumps.
Good stuff I'll check these out. Doing the injectors tmrw.
Did you pour the seaform in the oil,gas, and brake booster vac line??
09-16-2011, 05:57 PM
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Year: 1990
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Engine: The venerable 4.0
Yes. Then he ran it 50 miles or so and changed the oil with 5-30. Now his rear main is leaking... which is awesome! Means that engine is spic and span inside. When you clean out the sludge bad gasket and seals are magically revealed.
Last edited by Slick761; 09-16-2011 at 05:59 PM.
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09-16-2011, 06:33 PM
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Year: 1990
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Just received some injectors that I plan to swap out. I got the 943's and will remove the 703's that everyone was recommending. I'll put new plugs, new air filter, oil change/filter and that should do it hopefully.
Anyone have any other recommendations to get this baby passed emissions??
Anyone have any other recommendations to get this baby passed emissions??
09-20-2011, 06:09 PM
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Still running original o2 sensor.
09-20-2011, 06:56 PM
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Run 87 it is a faster more complete burn. 91 burns slower and less complete meaning dirtier emissions. 91 is a waste of money unless you have mods that make you need it.
09-20-2011, 07:01 PM
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Year: 1990
Model: Cherokee
Engine: The venerable 4.0
Originally Posted by Nor-CalJeeper
Run 87 it is a faster more complete burn. 91 burns slower and less complete meaning dirtier emissions. 91 is a waste of money unless you have mods that make you need it.
09-20-2011, 07:10 PM
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Year: 1990
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09-21-2011, 07:26 PM
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Should i change the spark plugs before or after the seafoam?
09-21-2011, 08:00 PM
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Year: 1993
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Engine: 4.0 high output straight 6
If you are only adding it to the OIL you can change plugs before. If you are adding it through the brake booster hose or the throttle body change them AFTER the treatment. Also a good idea to disconnect the cat from the exhuast stream I have seen seafoam destroy cats because all of the gunk it blows loose.
Also add it very slow to the line or the throttle body too much too fast can hydrolock your engine. Once the engine sounds like its dying or wanting to stall stop pouring and let it return to normal idle before adding more.
Also add it very slow to the line or the throttle body too much too fast can hydrolock your engine. Once the engine sounds like its dying or wanting to stall stop pouring and let it return to normal idle before adding more.