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by Bob O’Neill and Bob Lincoln
In Chrysler cars, a solenoid is a plunger valve which is opened and closed electrically. When power is applied to the solenoid, a magnetic coil is energized which moves the plunger, opening a valve to redirect or apply vacuum or boost.
The solenoids on the Chrysler cars have three vacuum hose ports. There is one which is the vacuum or boost source port, and one which is open when no voltage is applied. The other port is closed when no voltage is applied; vacuum or boost is redirected to this port when voltage is applied.
When voltage is applied to the solenoid coil, it energizes an electromagnet which then pulls on the valve piston to direct air from the source to the ‘other port.’ Sometimes the ports are connected where vacuum or boost is routed through the normally closed port and other times it’s through the normally open port. So the ‘other port’ is, well, the other port.
The port which doesn’t have a hose connected has a foam block over it. This is to filter dust and dirt from getting into the solenoid. Many times these foam filters fall away to nothing due to age. If the port which doesn’t have a hose connect also doesn’t have a foam filter, replace the filter as these filters should always be attached. These filters could be made from open cell foam and cam be made from any dense form which air can flow through. If a ‘new’ foam filter attached to a drinking straw can flow air, it can be used. Any filter which will not flow air should not be used.
The solenoids used on the Chrysler cars in the ‘80s and early ‘90s were very robust, so finding a replacement solenoid should as easy as a visit to the local pick-n-pull junk yard. MAP solenoids can be found on the firewall and other solenoids can be found on the passenger side inner fender. These are also available from the auto parts store and the dealer. Be sure to get the right type solenoid. Some have only two ports. These are basically on/off valves which will either close or open based on type.
The Chrysler solenoids are sturdy and rarely fail, so most of the time a ‘solenoid’ problem is probably a wiring issue. But the solenoid which controls the wastegate for turbo applications sees a lot more action then the others. This solenoid opens and closes many times per second when the engine is producing boost. If there is no air flow because dust and dirt has clogged it, actuation can fail. Remove the solenoid and test for flow with voltage and without. The following steps can help decide if the solenoid has failed or is not functioning beyond repair.
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