This car has a replacement ECU now but still runs very poorly w/MAF connected and better when disconnected. Radio no longer asks for CODE and no longer works either. Everything went wrong while Dealer was replacing the head gasket, including their allowing a tree to fall on the car while in their care. Car may be totalled if I cannot get it to run right - they sent it out w/a number of vacuum leaks in the intake system also (put it together w/silicone, not the proper gaskets). Is the security system making it run so poorly by not entering the CODE? Thank you.

 

I would start with getting all of the vacuum leaks sorted. Not sure what they did with the ECU but as far as I know, the radio code only affects the radio and not the engine or ECU for that matter. The security system would not allow the car to start if it were giving trouble. Others will chime in im sure who know more than me. Good luck!

 

Get a 3 to 4 foot long piece of flexible plastic tube roughly 3/16 or 1/4 inch inside diameter.
With the engine running put one end close to your ear and put the other end around the possible sources of the vacuum leak.
When you hear a "hissing" that is where the leak is.
Unless you get these leaks stopped you cannot get the MAF/ECU problem sorted out.
As etaent says the radio problem is separate from the engine problem.

 

I agree, I would start by getting the vac leaks all plugged. It's a fairly simple system but some of the lines are hidden on the intake side. I recently found a leak at my EGR valve where the gasket had failed. This after replacing most of the small lines around the AIR pump because they were all Just Old. Don't tell anyone, but I used brake clean to find it- and yet I live. Good luck

 

Brake clean to find the vacuum leak first then pinpoint finding it with a piece of tubing and your ear. The radio code has absolutely nothing to do with the ECU.

 

Note that the popular CRC Brakleen I use is non-flammable so won't work for leak testing.

Bill's "hose stethoscope" method is good for some leaks, especially large ones. Some leaks are so small that any hissing is swamped by normal engine noises.

A smoke test can be very helpful in identifying air intake/vacuum leaks. You can build your own smoke machine for little cost - see YouTube for various designs.

One common leak point is the accordion hose that connects the air intake to the throttle body. It's easy to not get it properly fitted on the underside of the intake pipe, or to over-tighten the hose clamp and cause a bend in the plastic pipe that creates a leak.

Other common leak points are cracks in the crankcase breather hoses, a stuck-open cruise control dump valve (if your cruise control doesn't work, suspect this valve), loose hose clamps, cracked or disconnected vacuum hoses, etc.

Regarding the radio, if you do not know the security code, this procedure from paulajayne at the XJ40.com forum is a workaround:

HOW TO REPROGRAM JAGUAR Alpine Radio Code

From paulajayne on XJ40 Interior forum Feb 11, 2014
To recode the Jag Alpine Radio AJ 9200 R the onboard jumpers (they can be seen hidden under the label - run your finger over the label and push the soft spot, this will create an oblong hole) need to be changed.They need to be all bridged - so out with a small soldering iron and a small cross point driver.

First remove the top cover to reveal the cassette deck. There are two screws that need to be removed before removing the other side; they match up to very obvious points on the base cover.

Once they are out remove the four base cover screws and then the cover.

Identify the jumpers that were visible through the hole and solder any unsoldered pairs.

Check with a multi-meter after soldering.

Reassemble - put in car and when CODE is requested enter 6543 - Radio should now go.

Cheers,

Don

 

I recently discovered that the last time I had my fuel rail off that I must have damaged some of the o-rings on the bottoms of the fuel injectors when I was re-installing the fuel rail back into the manifold. I.E. the o-rings that seal when the injector is inserted into the top of the intake runners. I ended up replacing two or three damaged o-rings with standard fuel injector o-rings available cheaply from O'Reilly or rockauto.com. The part number is SK14 from Standard Motor products (well know aftermarket autoparts brand).

BTW, I would NEVER consider having a Jaguar dealer do this sort of work on a car. They might know how to work on new Jaguars but I would never have a dealership do some job as serious as a head gasket replacement.