Hi everyone.

I was hoping you could help me with some questions on my XJ. If I put the boot in I sometimes get a flash of the 'restricted performance' message, before it goes out again. This is most common when accelerating from low to high speeds rather than on the motorway (maybe linked to revs?), though I did also get it once while idling in the car park. The car can idle a little unevenly, but nothing very major.

The error code is intermittent and comes up as P0328 (Knock senor, 1, bank 1, high input). I was wondering if this is something that is expensive to get seen to, or indeed something I can approach myself? It didn't look like new parts were too expensive, if it is the sensor itself that is throwing the fault.

Thanks in advance for your help!

 

Update - I am now also getting P0333 too, the 2nd bank 2 knock sensor high input. Car has engine management light illuminated, sigh.

 

If you have an XJR then it is supercharger out time to do the knock sensors. If you don't have an R then it will be a bit easier due to no supercharger.

 

Cheers. To my regret she isn't an R, just the naturally aspirated! As I understood it, the sensors are 'plug and play', so as you say should be easier.

 

Managed to find this thread helpful thread:

https://www.jaguarforums.com/forum/x...acement-85473/

Looks like manifold off for the knock sensors on an X350. Tinge of regret at not buying an X308, which is far more straightforward:

https://www.jaguarforums.com/forum/x...t-1-2-a-76815/

 

Yes the knock sensors are located under the intake on the V8. It's one of those "while you're in there" jobs where you'll also want to do the coolant hose and maybe the plenum gaskets. I've had my intake off a couple of times, it's not terrible, but helps to have a 2nd set of hands. The MAP sensors connects on the back and is not accessible until the intake is partly out.

If you're getting codes for both sensors at once you might try cleaning the connector for the knock sensors 1st. That is accessible on the LH side of the engine, you'll see a connector with 4 wires going down under the intake.

 

Oxford posted
Tinge of regret at not buying an X308, which is far more straightforward:
Just remember the PLASTIC CAM CHAIN ADJUSTERS !!!!!!!!!!!!!!!!!!!!

 

Thank you! Good to know what else to do if I have the manifold off. I will take your advice though and take a look at the connectors - it would be great if it was just an easy fix (I have only had the car 5 days haha).

 

Hahaha, good point!

 

In case anyone was curious, I managed to get this all fixed at GDP Jaguar Specialists (https://www.gdpindependent.com/). Really great service and very fair price. Both sensors were corroded, probably from the classic leak inside the V (there was evidence of antifreeze). Leaky thermostat replaced and inlet gaskets done at the same time.

 

Hey, don't know if this is slightly off topic, but we were low on gas with only one station nearby. All they had was regular (87). Car ran great under all normal conditions (around time, normal freeway). However, yesterday my wife took the car to Santa Cruz on Hwy 17 in California (up to 2,000 ft elevation from 250ft and back down again in 12 miles), and she got a lot of knocking on the way up. Of course this doesn't happen when using 91 (driven this many hundreds of times). What I don't understand is that I thought the knock sensors are supposed to detect detonation and retard spark to counter it. Is it really retarding it but I'm still getting detonation climbing up a hill? Or is something just not doing its job and not retarding ignition (but correct resistance so no reduced performance error)?

There have only been a few cases where we've had to put 87 in it, but I've assumed that it was retarding ignition in the past so assumed I just had lower performance (drive it pretty gingerly the few times I've had 87 in it). As soon as we get to half a tank I'll put 91 in it (so it will be closer to mid grade 89 and won't have any more problems). There have been a few cases where we had to put 89 in it and never noticed any detonation (but might not have the conditions that might cause it).

Or, I guess I could purchase an octane boosting additive for this tank since there is still 3/4 of a tank.

Thanks,

Gordon