Air Bypass Valve Info and testing

Ford air bypass valve

The ford ranger air bypass valve solenoid is used to control engine idle speed and is operated by the EEC-IV control module. This valve allows air to pass around the throttle plates to control:

1. cold engine fast idle
2. no touch start
3. dashpot
4. over temperature idle boost
5. engine idle load correction.

Symptoms of a bad one:

1. Engine stalling
2. Surging
3. Poor idle conditions
4. "Check engine light" on

Diagnosis:

The signal to the solenoid should be 1 volt or less at curb idle, (with all accessory loads off). Applying 12 volts to the solenoid will cause a neutral idle speed change greater than 1000 rpm. Check for shorts between both solenoid terminals and the case.

Codes 12, 13, 16, 17 & 19 all indicate idle speed is out of spec (too high or too low). Codes 47 and 48 indicate a fuel mixture problem which could be caused by an air leak. It may be possible to clean the ports with electrical safe clearer, do not use regular carb cleaner as it will remove the protective coating. Clean port holes in the manifold also before reinstalling.

Ranger brake proportional valve

This proportional valve is next to the transmission mounted to the frame, drivers side, toward rear of engine. It will most likely take some heat to get the old line fittings out. You can get a new valve at Rock Auto online.  About $120. Use never seize on the line fittings when you replace it.

Update: Ranger power loss, bogging, no acceleration

The catalytic converter was not the only problem. I decided before spending the money for a new cat, I would beat out the inside of the old one first.  A tougher job than you might think.  Took about hour or so and I need a heavy wire hook to remove metal packing and a pipe to break the inside up and a vacuum to suck the inside out also.

Fuel rail schrader valve

On the initial test drive, the problem returned and I wound up on the side of a busy highway.  Once again finding no problem, I started back to the basics.  I checked the fuel rail (for gas) using the schrader valve on the rail. The picture is not my truck, but this is what it looks like on the truck. Much to surprise it was full of air and not fuel.

I have not checked this out fully yet. More later.

Update:
Yes, low on gas was this problem.  However, the power loss problem was still not solved. The short answer turned out to be a combination of several problems.

Clogged sensor

1. The air sensor in the intake manifold was coated with goo.  Cleaned and reinstalled.
2. The ignition module was bad.  See detail elsewhere on site.
3. The inner air passage inside the intake to the EGR valve was blocked/choked. So bad it had no flow. Use a McDonalds straw to probe it on your truck. The straw (5/16) is just the right size, the tunnel is straight.
4. The ground wire on the intake (needed for the ignition module) was weak. Replaced it.
5. The intake was very very dirty. Cleaned it.
6. Decided to replace the injectors with a set from a mustang 4 cly 2.3L. Mine were rusty and needed a cleaning. By the way, they work great.
7. The blocked cat converter was "cleared" earlier.

Look at odd shape near center - Egr clogged vent