Question regarding SDD diagnostic software
 

Hello to all, I’m at a beginner level using the Jaguar SDD, I’ve used it a few times to clear codes & add make a couple changes in the configuration file. That’s about it.
Here’s the short version of what’s going on with the 2010 xkr.
I had a valve cover leak that fouled up a plug & misfire. Leak was fixed, plugs changed & no misfires. There is a occasional rough idle & I’m thinking a slight loss of power but no codes.
Is there a specific test in SDD that checks the coil packs & their outputs? I’d appreciate any input.

Sorry, I cant help with the SDD questions but I recently had a similar issue with my car. My misfire was at elevated engine speeds only. Once the car got past 4000 rpm it would start to misfire, lose power and generally not perform how it should. No check engine light came on even though it was obviously missing and no pending codes were showing. I took the car to the dealer and they diagnosed the two high pressure mechanical fuel pumps are faulty and they confirmed that the check engine light will not usually set for this particular problem. After the pumps are replaced, car is back to full health and pulling like a train. I would imagine there is a way to check the fuel pressure with SDD so this might be worth looking into.
I also have a Cayenne which are famous for pretty poorly made coil packs that crack and cause all kinds of misfires. No codes for this either so you could be onto something with the coils.
It honestly amazes me that with all the computer controls on cars that they often do not set codes with obvious misfires. Good luck with finding the fault and let us know how you solved it.

Thanks for the input. I will look into that.

Interesting, mine is doing the same thing. I'm replacing the coils this weekend but will start looking at pumps just in case.

A person CAN check the fuel pressures on any decent OBD2 scanner. I use the Torque app with mine.
However, I believe only the low-pressures can be seen.
You COULD use the Fuel Trim section to see how your car behaves real-time, if it goes lean under load and at RPM, then I'd assume that the high-pressure pump(s) are kablooie.

This is what my Fuel Trim looked like after I had the injectors changed and before the car relearned the trims. They are pretty much dead-on now.

https://cimg6.ibsrv.net/gimg/www.jag...6112ba67a5.jpg

Your 4.2 does not have high pressure fuel pumps, that's only an issue on the direct injected 5.0

If coils don't fix a high load misfire on a 4.2, I'd be looking for choked up cats.

From bad to worst. Coil was changed, car ran fine for a few days & I took it back to the mechanic for a unrelated issue.
During his test drive he could hear the timing chain slipping & then the engine died. I have not even tried to crank it since this happened. With the luck I’ve been having i just assume valves & pistons were damaged & it’s a total mess. Figuring out who to have it towed to & get evaluated. Fun times ugh

Oooh noooo, so sorry to hear!
Wasn't there any audible warning signs.
Strange and make you wonder how hard he test drove it?