Had a nagging problem for the last year with my rig, which consistently got worse over time. Went through everything I could think of to do that was easy and still couldn't get it to quit stumbling under load at light throttle, which would lead to full throttle assaults just to get it to run.
Finally found my Factory Service Manual and started going one step at a time through the sensors. Everything checked out as good as possible, given the ancient fuel injection system Dodge used on their TBI's.
An example was the throttle body temp sensor. 9K-14.7K ohms at 70 degrees, or 500-15K ohms at 200 degrees....
Everything checked out, including fuel pump output etc. Finally found the specs for the coil and through trial and error, figured out that it was out of spec. When I pulled the coil wire out of the dist cap, it was all black and carboned up. Whether it was the weak coil, or a bad install, for some reason it wasn't making the spark go through the cap, rather just bouncing around inside the tower of the cap and making things hot.
So. I threw on the new spare coil that I carry and cleaned up all the connections, the cap and all the terminals under the cap. Voila, no more stumble or stalling at light throttle.
Sounds simple, except for the fact that a stumble can be caused by at least 4 different sensors, none of which the resistance values are available anywhere except the FSM, or very obscure threads on Ramcharger sites. Even then, the variables for the sensors are so vague, it's a hit or miss as to whether you can duplicate the conditions it takes to get the right readings.
Once again, proving that it will usually be something simple, but easy to overlook unless you have the factory scanner, which is only available at certain dealers for $100/hour minimum 1 hour charge, or finding a shop that has a scope and someone old enough to remember how to use it.
Finally found my Factory Service Manual and started going one step at a time through the sensors. Everything checked out as good as possible, given the ancient fuel injection system Dodge used on their TBI's.
An example was the throttle body temp sensor. 9K-14.7K ohms at 70 degrees, or 500-15K ohms at 200 degrees....
Everything checked out, including fuel pump output etc. Finally found the specs for the coil and through trial and error, figured out that it was out of spec. When I pulled the coil wire out of the dist cap, it was all black and carboned up. Whether it was the weak coil, or a bad install, for some reason it wasn't making the spark go through the cap, rather just bouncing around inside the tower of the cap and making things hot.
So. I threw on the new spare coil that I carry and cleaned up all the connections, the cap and all the terminals under the cap. Voila, no more stumble or stalling at light throttle.
Sounds simple, except for the fact that a stumble can be caused by at least 4 different sensors, none of which the resistance values are available anywhere except the FSM, or very obscure threads on Ramcharger sites. Even then, the variables for the sensors are so vague, it's a hit or miss as to whether you can duplicate the conditions it takes to get the right readings.
Once again, proving that it will usually be something simple, but easy to overlook unless you have the factory scanner, which is only available at certain dealers for $100/hour minimum 1 hour charge, or finding a shop that has a scope and someone old enough to remember how to use it.
