Hello, I have a 90 z51/fx3 and I am unsure if the fx3 system is working. I do not get a src light but I do not feel any difference between the three settings. There is a stretch of highway that is tilt-slabbed that I use to test the stiffness in the shocks, I feel no difference when changing the settings.

I have checked the codes and there is nothing stored. Is it possible that the shock could be bad? And if so how can I check? The car feels very stiff all off the time and there is little if no rebound when I push down on the car.

 

How are you checking the codes? IF the SRC light is not on, then the system does not find a problem. Is the bulb for the SRC in place?

You should be able to feel the difference I know I can.

FYI, if the system detects a problem, I think the shocks go into the softest setting as a default.

http://www.corvetteactioncenter.com/...fx3/index.html

 

Thanks rubie for your reply, I read that article before I made this thread. From what I gathered by the article if the system detects a problem: ""Service Ride Control" light comes on and the shocks are commanded to 60° (MY89-91) or 30° (MY92-95)"

 

The FX3 shocks are gas charged and also have oil. It's entirely possible that the shocks have simply worn out and you cannot feel the differences.

The FX3 system is always being adjusted by the controller regardless of the selector setting. In addition to the selector switch, the controller gets speed data from the VSS at each wheel. That input determines how the individual actuators move to set the shock stiffness.

The shock stiffness in the Tour setting at 70MPH is actually stiffer than the Performance setting at 25 MPH. There are overlaps in the stiffness at each selector setting.

The FX3 shock can be rebuilt by Bilstein and the valving can even be a custom setup. Some years ago, a Corvette Forum member worked with Bilstein to create a custom valving for performance use. I think the valving is called "Morocca" or something similar.

Doug Rippie Motorsports used to have a custom controller that used a removable PROM. You could order custom chips for the controller and further customize the system.

IIRC, the FX3 system was developed from a system that Bilstein made for Ferrari. Once you understand how the system works and especially if you do some custom work, it can be a very effective shock system. It was really great "back in the day" before the advent of Magnetic Ride systems found in the C5 and C6.

 

Okay so I found the issue, the control box was unplugged. Once I plugged it in the src light came on. I ran the codes and got 33 and 34 which I believe means the rear shocks and/or actuators are bad.

Now will the front suspension work or is it tied together with the entire system, in that if one system fails nothing works? How do I go about diagnosing the problem?

 

There is a simple way to check that should only take about and hour. The fronts are easy to reach, the rears need to be unbolted.

Step 1: Remove the actuator. It is held on buy a wire clip and then pulls straight up.

Step 2: Check the shock gear. Once the actuator is off you can inspect the gear on the top of the shock. If teeth are missing than the actuator will think the shock is not there and throw a code. Also spin the gear. It should only rotate about 160° and stop in both directions. If it spins freely the shock is broke and again the actuator will throw a code if it just spins.

Step 3: Inspect the actuator gear. Look into the actuator and see if all the teeth are on the gear, and if the gear is in one piece still. The gears in the actuator are plastic and are known for breaking.

Step 4: Make sure the actuator turns. Have someone turn the key on while you look into the actuator. Make sure the gear spins for a couple seconds. If it does not the actuator is bad, or not getting a signal.

 

Those DTC's are for the rear shocks and set when the module does not sense that the corresponding electrical actuator has found the shocks finding their end stop position during initialization.

Follow what Kubs said and inspect those actuators. New ones are avalible however they are $$$. I better solution is to have them rebuilt with stronger aluminum gears.

http://captainzcnc.com/index.html

C4cruiser you are correct on the Morroca Valving. When I get mine rebuilt I will get this valving. Maybe a new prom package too...I auto-x so...

 

I had mine rebuilt and put in the metal gear. The light went out but I couldn't feel the difference. I was told that I may not notice the difference because the shocks are changing all the time. Sometimes they act the same on low settings as on high setting depending on speed and road conditions. Run a course,(any twistiy, bumpy road) on the low setting, then try it on the high setting. Try to run it the same way. See what you think.
Good luck.

 

Yes there was a chart I saw that showed the the different stiffness values at the different speeds. The shocks never went full stiff until 150 MPH in Performance mode. On my race car I took the actuators off and rotated the gears to full stiff and zip tied them in place. There was a very noticeable difference! It felt way better so I left it and sold the actuators.

 

on my FX3, which is working properly. I can definitely feel the differences between the various settings.

 

You mean these?