99 XJR "Restricted Performance"
 

Well the old addage "Don't fix it if it ain't broke" bit me. I removed and cleaned the MAF a couple of weeks ago with MAF cleaner, hoping to improve my gas milage (currently 13.8). Now I keep getting the restricted performance message and the following codes: P0172; P1111; P1797. I have cleared them about 4 times but they just show up again a couple of days later. I have rechecked all the connections and made sure the the intake tubing is properly connected. Any ideas? The P1797 for the tranny is really wierd as well.

141k miles.

RE: 99 XJR "Restricted Performance"
 

The good news is that you probably did not mess up the MAF. The bad news is that tracing this may take some work. The P0172 is for Rich combustion in A bank only, caused by a bad injector or bad sensor input (the MAFS could do this, but it would also affect B bank), it could also be caused by a bad fuel regulator, clogged air filter, or a blocked fuel return line but this also is tempered by the fact that all these problems would cause B bank to be rich too. Look at them anyway. P1797 is probably the key, it is a CAN bus fault which is a harness problem. This fault is occuring between the ECU and the TCM causing a missing token message. If you are determined, you can start checking connectors in the CAN bus for bad connections ,open circuitsand wire faults, primarily between the ECU and the TCM. The worst possibility is that either the TCMor the ECU is bad.P1111 is only a readiness code, forget it. If this is all gibberish, go to a specialist and let them take a stab at it.

RE: 99 XJR "Restricted Performance"
 

Thanks oldmots. I have seen the P0175 as well, it just wasn't in my last check. You've given me a bit of work to get started on. I'll report back when I find something. Thanks again.