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Running rich

89XJBlue

NAXJA Forum User
Location
Denver
I have an 89 4.0 auto almost 140k on it. trying to pass emissions, what woudl make it run so rich? I am using Accel 19lb injectors, replaced O2 and Cat and MAP and many other things whats going on?
 
Usual problem is the O2 sensor.

Off-the-wall possibility: The wiring harness for the early (Renix) models apparently had a weak connection from the O2 sensor to the ECU. There was a TSB on the problem, and there's a fix kit that by-passes the main harness and has a replacement harness that goes direct from the O2 sensor to the ECU. Especially if you have an early '89 that still has the C101 connector (a huge wiring junction block that sits on the firewall just above the brake booster), if this new harness hasn't been installed it might be worth a try. I can't think of anything else that you haven't already tried.

Edit: 'Nother off-the-wall possibility. I just noticed that you're in Denver. The Renix years had a sea-level CPS and a high-altitude CPS. Denver qualifies as high-altitude. Might be worth double checking to be sure you have the correct CPS for your location. The sea-level one won't provide as much spark advance, and I don't know if this could cause a rich condition at high altitudes but it might be worth thinking about.
 
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The coolant temp sensor went bad on my dads and actuaily made it run so ritch the motor would stall and hardly start back up......just a thought
 
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