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89 xj runs really rich until engine is warm

bcmaxx

NAXJA Forum User
My 89 runs really rich in the mornings, raw fuel smell out the tailpipe, goes away once its warm, this sound like a coolant temp sensor for the computer? where is the little devil?? I have covered all other bases.thanks!
 
thats what its supposed to do. until the temp sensor reqaches around 200 degrees (don't remember the exact number off the top of my head) the computer runs the engine in "open-loop mode", and does not look at the O2 sensor at all, instead giving the negine a very rich mixture.. once it reaches operating temperature (allwing the O2 sensor to work accurately), it changes over and leans out.

if the temperature sensor is bad, it might make it run open-loop longer, but wouldn't change fuel usage much.
 
h2opete987 said:
thats what its supposed to do. until the temp sensor reqaches around 200 degrees (don't remember the exact number off the top of my head) the computer runs the engine in "open-loop mode", and does not look at the O2 sensor at all, instead giving the negine a very rich mixture.. once it reaches operating temperature (allwing the O2 sensor to work accurately), it changes over and leans out.

if the temperature sensor is bad, it might make it run open-loop longer, but wouldn't change fuel usage much.
for a renix machine the temp sensor for the ECM is on the side of the block, it's supposed to go to closed loop around 170. The one on the top of the head near the firewall is just for the guage.
 
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