CAT MXS Intake Valve Actuator Help!!!

I had code 95 and replaced the sensor and code disappeared but now I got code 93 and engine is at half power?? How can I fix this??

 

I think if I'm remembering right 93 is possibly an IVA not responding. Pull the valve cover,if you have an NXS you will see a small aluminum piece with two bolts that have a 3/8" head. Depending on which one it is,(can't remember which one is code 93). This is your oil supply connection for the actuator housing. I've seen the allen plug come loose or either the o-ring under the connector leak. This can cause a "not responding" code. While your under there check the little black connectors that are attached to each IVA solenoid. These have been known to break close to the connector point. I've sometimes seen the wire break on the inside but the insulation will still look ok. Sometimes hard to spot.

 

Sounds like your on the gremlin chase just like i was, your code 95 is your # 6 intake valve actuator, or iva system oil pressure, 93 is your #3 or#4 (IVA) This is a general application code for either 1, they are tied together. to find exactly what is wrong u will most likely have to find a tech with dioganostic, For code 93 there are an assortment of things it could be, current high, current low, current not responding ect, I chased mine even with a techs help, went back to the shop 3 times before I said the hell with it and changed the entire Rear harness inside the head, 148 dollars and a 2 hr swap to begin with would of saved me a whole lotta labor and hassle, those harnesses inside the head see some serious heat and become very brittle.. hope this helps

 

Thanks alot to both of you, I removed valve covers today and noticed that bolts were completely loose at the aluminum piece that feeds the IVA with oil so I retorqued them and checked the wires and as far as I can see they all looked ok..I'm leaving for a trip on Monday again and let's see if this problem will be gone..I would be so happy if it would..code only appears when engine is at full throttle thats why I don't know yet if it helped or not but I'm pretty sure that the loose bolts caused the code..thanks again guys!

 

Unless they were improperly torqued from the factory or a recent service repair the loose bolts aren't a good sign. I've seen a great deal of these MXS/NXS engine running with one or two broken studs. The very small vibration/VVA movement could have possibly led to the bolts loosening. Have you noticed a slight difference in idle quality? If so it could possibly be a broken stud on one end of the housing. Hope all goes well/ Yes the IVA's only work when the engine ECM "sees" engine load over 75%...So a hard pull will be about your only option for testing.

 

I replaced The intake valve acuater sensor and a new pig tail going to the harness and I still am getting a 95 code.? Should I take the valve covers off and check the plugs and spred the pins if need so be.?? Not sure -any suggestons.? Solved Problem Beore

 

I noticed that my truck(mxs) started running a little rough couple weeks ago, now have a 93 code. Any way what studs are you referring to that made the truck idle rough?

 

I have seen these iva housings crack and cause oil pressure loss. Sometimes it breaks the bolts or studs and sometimes it does'nt. I have also seen it break the hold down bolts for the vva's also. The best way to figure out your problem is a computer with cat et. The flash code doesn't break it down close enough. If the code is for not responding the vva is bad, if it says open to the vva then 9 times out of ten it's the plug at vva. They make a repair harness kit for the vva. It comes with about 4 inches of wire on a new plug and two crimp connectors and shrinkwrap. If your flash code says vva 3 and 4 you can replace both plugs and vvas and solve the issue. But I would suggest at least getting the code read and then fix it your self.

 

My cat ID says 287-5,287-7,288-5,288-7. I think those are low voltage and not responding from what I've found. Do you think its a wiring issue? Check engine goes away when I restart the truck then comes back on. And thanks for the info.

 

Yes, that's # 3 and #4 low voltage and not responding (due to low voltage), which is normally the IVA connectors, but since it's those particular two, I would also suspect a harness problem, or the connection block on the side of the head, or maybe at the ecm.

I say that because # 3 and # 4 IVA wiring goes through the same harness to overhead (rear harness) and they share one common wire from the ecm to the overhead, which splits into two for those two IVA's. (the other wire for each stays separate so the ecm can control them separately). If that common wire is broken or has a loose connection, you will get all 4 of those codes just from that alone.

Looks like this:
--------__________________________ ECM Control wire for IVA # 3
IVA # 3 __________________________ ECM Common wire # 3 & # 4 IVA's
--------___________/
IVA # 4 __________________________ ECM Control wire for IVA # 4
--------

I'd try wriggling the harnesses to make sure they're tight first, at the head and at the ECM. I've heard others recommend cleaning out the connections on the head with parts cleaner, but that usually results in parts cleaner splashing back into my eyes, so I'd be careful.