failed emission test twice
Howdy Fellows, failed emissions last week with the "88 Pioneer" everything passed but the CO. Limit is 25.0000 GPM and I got 39.0926. Running rich it seems. I checked the air filter and it was pretty gummed up so replaced it with new, also added a can of CRC to clean up inner workings, then added new Champion RC12LYC spark plugs. Went for a retest today and it was worse. That doesn't make sense to me, restricted air = richer mixture.
Within the past 8-9 months I have replaced the IAC and the TPS and gut feeling leads me to the TPS, any thoughts on this? Should i try resetting the TPS. Also, didn't think much about this being a problem but the pioneer runs a bit cool. I put a new 180 thermostat in it last summer but the heater air never gets better than warm. Any connection there??? Thanks
Within the past 8-9 months I have replaced the IAC and the TPS and gut feeling leads me to the TPS, any thoughts on this? Should i try resetting the TPS. Also, didn't think much about this being a problem but the pioneer runs a bit cool. I put a new 180 thermostat in it last summer but the heater air never gets better than warm. Any connection there??? Thanks
Howdy Fellows, failed emissions last week with the "88 Pioneer" everything passed but the CO. Limit is 25.0000 GPM and I got 39.0926. Running rich it seems. I checked the air filter and it was pretty gummed up so replaced it with new, also added a can of CRC to clean up inner workings, then added new Champion RC12LYC spark plugs. Went for a retest today and it was worse. That doesn't make sense to me, restricted air = richer mixture.
Within the past 8-9 months I have replaced the IAC and the TPS and gut feeling leads me to the TPS, any thoughts on this? Should i try resetting the TPS. Also, didn't think much about this being a problem but the pioneer runs a bit cool. I put a new 180 thermostat in it last summer but the heater air never gets better than warm. Any connection there??? Thanks
Within the past 8-9 months I have replaced the IAC and the TPS and gut feeling leads me to the TPS, any thoughts on this? Should i try resetting the TPS. Also, didn't think much about this being a problem but the pioneer runs a bit cool. I put a new 180 thermostat in it last summer but the heater air never gets better than warm. Any connection there??? Thanks
Thanks XJlimitedx99. I sure didn't know that. What's the connection between the cooling system and the fuel injection system? Will get a new thermostat this evening and put her in tomorrow. What do u think caused those numbers to get worse on the test when they should have gotten better, I would have thought. The thermostat change was done back in the summer due to the housing being cracked and needing replaced so just grabbed a summer thermostat at the same time. (50's and 60's mentality LOL.)
Senior Member
Joined: Mar 2012
Posts: 974
Likes: 14
From: Racine, WI
Year: 1997
Model: Cherokee
Engine: 4.0
Please see this link for any information you may need (especially numbers 5, 8, and 11): https://www.cherokeeforum.com/f51/cr...x-tips-153657/
How is your O2 sensor?
How is your catalytic converter?
How is your TPS?
How is your MAP sensor?
How is your O2 sensor?
How is your catalytic converter?
How is your TPS?
How is your MAP sensor?
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CF Veteran
Joined: Jun 2012
Posts: 1,250
Likes: 3
From: California
Year: 1989
Model: Cherokee
Engine: 4.0L
A Renix is capable of almost unreal low numbers. I know it's expensive but after initially failing I replaced my cat (in 2012) and O2 sensor (in 2014) mine passed with flying colors.
Seasoned Member
Joined: Aug 2014
Posts: 486
Likes: 1
From: Lehigh Valley PA
Year: 1989
Model: Cherokee
Engine: 4.0 renix
Mine has been passing emissions, but if it hadn't - I would have been arguing the fact that it should be emissions exempt - it's pre-obd1 - some states will allow pre-obd 1 vehicles to be emissions exempt I think. If that didn't work, I'd just say screw it and register it as an antique/classic car. Emissions and inspection exempt lifetime plates, and many states have that.
I'll be doing this in a few months when inspection/emissions is due. I'm done with this Pennsylvanian yearly inspection racket.
I'll be doing this in a few months when inspection/emissions is due. I'm done with this Pennsylvanian yearly inspection racket.
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Howdy Fellows, failed emissions last week with the "88 Pioneer" everything passed but the CO. Limit is 25.0000 GPM and I got 39.0926. Running rich it seems. I checked the air filter and it was pretty gummed up so replaced it with new, also added a can of CRC to clean up inner workings, then added new Champion RC12LYC spark plugs. Went for a retest today and it was worse. That doesn't make sense to me, restricted air = richer mixture.
Within the past 8-9 months I have replaced the IAC and the TPS and gut feeling leads me to the TPS, any thoughts on this? Should i try resetting the TPS. Also, didn't think much about this being a problem but the pioneer runs a bit cool. I put a new 180 thermostat in it last summer but the heater air never gets better than warm. Any connection there??? Thanks
Within the past 8-9 months I have replaced the IAC and the TPS and gut feeling leads me to the TPS, any thoughts on this? Should i try resetting the TPS. Also, didn't think much about this being a problem but the pioneer runs a bit cool. I put a new 180 thermostat in it last summer but the heater air never gets better than warm. Any connection there??? Thanks
Plugs, wires, cap and rotor done along with a throttle body cleaning and intake manifold bolt tightening done?
Vacuum harnesses in tact?
Mine has been passing emissions, but if it hadn't - I would have been arguing the fact that it should be emissions exempt - it's pre-obd1 - some states will allow pre-obd 1 vehicles to be emissions exempt I think. If that didn't work, I'd just say screw it and register it as an antique/classic car. Emissions and inspection exempt lifetime plates, and many states have that.
I'll be doing this in a few months when inspection/emissions is due. I'm done with this Pennsylvanian yearly inspection racket.
I'll be doing this in a few months when inspection/emissions is due. I'm done with this Pennsylvanian yearly inspection racket.
I'm in Denver, Colorado and they want every penny they can get u to **** for them but I do believe the Pioneer is ready for Antique Plates this year for a few bucks more and I won't have to worry about it for 5 years. Thanks again to the group for the helping hand.
Mine has been passing emissions, but if it hadn't - I would have been arguing the fact that it should be emissions exempt - it's pre-obd1 - some states will allow pre-obd 1 vehicles to be emissions exempt I think. If that didn't work, I'd just say screw it and register it as an antique/classic car. Emissions and inspection exempt lifetime plates, and many states have that.
I'll be doing this in a few months when inspection/emissions is due. I'm done with this Pennsylvanian yearly inspection racket.
I'll be doing this in a few months when inspection/emissions is due. I'm done with this Pennsylvanian yearly inspection racket.
I'm in Denver, Colorado and they want every penny they can get u to crap for them but I do believe the Pioneer is ready for Antique Plates this year for a few bucks more and I won't have to worry about it for 5 years. Thanks again to the group for the helping hand.
LOL, the jokes on me, these S. O. B's changed the eligibility for "collector plates" to 32 years, did it in 2013.
Seasoned Member
Joined: Aug 2014
Posts: 486
Likes: 1
From: Lehigh Valley PA
Year: 1989
Model: Cherokee
Engine: 4.0 renix
Seasoned Member
Joined: May 2014
Posts: 375
Likes: 3
From: Nor Cal
Year: 1993 & 1994
Model: Grand Cherokee
Engine: 4.0
When was the last oil change? Old oil can have fuel in it from the small amount that gets past the piston rings over time and that can make the HC Higher as well.
Max
Max







