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Running Rich after motor install (89 Lebaron...again)

1K views 6 replies 4 participants last post by  curly5759 
#1 ·
Not a Hot Rod (Sisters car), but I figured there'd ba a few Mopar guys who can help me.

I just installed a 2.5 from a 93 Spirit into an 89 Lebaron. Starts up fine but is running amazingly rich. I don't know if it has one, but it's seems like it's in limp mode. It's got TBI and you can see it dumping in fuel at idle.
I cleaned the 2 electronic connections on the throttle body and rechecked the rest of the wiring harness. Looking at the setup, I don't see any proisions for measuring air, air temp or any other factor that would determine how much fuel should go in.

...So I have two questions: why is it dumping fuel, and how does it measure air
 
#2 ·
Probably uses a map sensor (Manifold Air Pressure). Look for a sensor connected to a vacuum line. Could be any number of reasons its running rich. You really need a scanner to properly diagnose the situation.

Does it seem to get better after its warmed up and has been running for a few minutes? Is the oxygen sensor connected? How new is it?
 
#6 ·
Yes, many of them are. All it needs are the power supply, and reference wires, as well as a vacuum signal to calculate air pressure.

Other systems use a Mass Airflow sensor in the intake track, while other systems utilize both.
 
#7 ·
Some Chryslers of that vintage mounted the map sensor piggy back on the computer, under the dash. The map needs a vacuum signal to calculate load. With no vacuum, it will think you are running wide open and add fuel to compensate. Usually they run very poor with map disconnected.
 
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