Hello my name is Jason and I am new to this forum. Just wanted to ask if somebody can help me diagnose issue I am having with my 2011 Jaguar xjl non supercharged. When I Coast downhill while in Drive could be a long hill or short Hill the car starts to misfire. Every single time. I can drive all around town and no misfires for hours. Soon as I go up a hill and come down I get misfires. If I put it in neutral and Coast down I did not get the misfires. Does anybody have information on this

 

Which codes?

Also, are all the OBD monitors happy (i.e. set aka complete)?

What are the fuel trims at idle with a warmed up engine?

What engine size? (I don't know from your brevity, sorry).

You've posted in the wrong section but hopefully a mod will move it.

 

I was able to post in another thread and x351 or xjl and they were able to give me some good information. With all the research I've done with my scan tool and learning about it I am led to believe in an agreement with what other people are saying is that my fuel injectors are leaking. Did not want to pay a lot for them but I went ahead and got them all and I will be putting them in as soon as I get them.

 

I spent the money and bought eight brand new Bosch original equipment fuel injectors. Started the vehicle up and ran for a while. Fuel trims looked good they were around plus or minus 2 to 3 percent. one thing I did notice is that the Catalyst temperature for Sensor 2 was at 1735° f. It slowly moved to that but I put an infrared thermometer on the catalytic converters and they were reading 300 to 400 degrees Fahrenheit. I test drove the car and coming downhill it started to misfire again there was no change after replacing all a fuel injectors. I have a new question how do I know which fuel injectors to replace or maybe I should just replace them all. Those are also fairly expensive. I'm thinking this is the problem because of the high temperature reading but not the actual temperature. Any help on this would be appreciated of your thoughts. I haven't put up background on this but I had the head gaskets replaced and I don't think the mechanic replaced the O2 sensors. That would be next for me. Car runs really good outside of coasting downhill and misfiring once I am coasting a little while.

 

How do I know which o2 sensors to change or should I change them all.

 

It would be helpful to know what DTCs are stored, and what the fuel pressure is.

How many kilometres/miles are on the vehicle?

Has any other work been recently done to the engine?

 

Dtc that come are misfires for all 8 cylinders usually. Sometimes just a few cylinders but usually all 8 cylinders get misfire codes when I try to run it and push through the misfiring instead of shutting it off and let it sit for 10 minutes. It always says there was misfire on Startup. And this time it gave a different code than normal. It was a map sensor code. I'm trying to research how to find out what O2 sensors are malfunctioning because I am getting a catalyst temperature of 1500 to 1700 degrees Fahrenheit on both Banks both sensors. When I go down there with my temperature sensor infrared gun light it's saying that they are 300 to 400° f. I'm thinking I should replace all of the O2 sensors but I really just want to replace what's necessary. I am not sure how to pinpoint which ones are failing. I have an Autel Maxidas bi directional scanner but I still do not know exactly how to interpret information to diagnose. Any help would be appreciated.

 

How many kilometres/miles are on the vehicle?

Has any other work been recently done to the engine?

 

Hello I am back again and very frustrated. I replaced all eight fuel injectors. No change still misfires when I get to the bottom of the hill and ready to press on the gas again after a stop. When I Coast down the hill in neutral it will not misfire when I get to the bottom. When I Coast in Drive it misfires. Drives around town nicely no misfires no stored codes no running rough. I took the catalytic converters off and I sense they were a little plugged up by me Shining Light through them could not see a lot. Temperature of the catalytic converters were 1700 degrees Fahrenheit at idle so I clean them and put them back on. Temperature went down 1400° Fahrenheit. Test drive downhill and still misfiring once I get to the bottom. So I then took the catalytic converters off drove uphill came downhill still getting misfire. I did compression test on all cylinders and lowest was 195 PSI and the rest were 200 to 205 PSI. Compression all seems good. Anybody have any ideas I've gotten about $10,000 into it on head gaskets. All new spark plugs, all new fuel injectors,

 

See post 6 above. Having the DTCs and the fuel pressure would be very helpful for those attempting to help you.

 

I am pretty sure fuel pressure is around 490 psi or 460psi. DTCs are p0300 random misfire and usually all cylinders misfire codes p0301 ,p0302 and so on for all 8 cylinders if I were to try to press on gas while in neutral or park to get it to smooth out. There is usually a code that says a misfire was detected on Startup first hundred revolutions. Don't remember exactly which code but it says that every so often

 

Can you post pictures of the injectors and the markings on them? How much did you pay for them?

I have posted this multiple times but I had the exact same problem and I had purchased counterfeit injectors. Packaged in what looked like OEM Bosch boxes too but there are differences if you can post some pictures.

They are close and was not convinced I had bad parts for several weeks of fighting a no start condition on my car. Finally pulled them swapped back to my OEM ones after sending them out for cleaning. Currently running my OEM injectors 3K miles after the repair.

What I can't explain is how my OEM injectors went bad (At least on one side of the engine) and when sent to the injector place they found no problems and only some slight degradation of the flow. After ultrasonic cleaning they were all within 3% of each other and considered ready to go.

In the end it was my fault for buying cheap injectors and should have known the price was too good to be true compared the OEM prices.
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So the car has 112,000 Miles on it. As for injector replacement I spent about $1200. I checked numbers on bosch website and they all matched. One thing that I was told to check was that the numbers labeled are etched in there and I used some brake clean to try to remove and it would not clean off so I was able to verify that the real ones have etched numbers. Also each and every box had a kind of rainbow prism type sticker that they say is very hard to duplicate so I am confident that these are real Bosch OEM injectors. Purchase them on eBay brand new. Also by my replacement it did not make a difference on how the car Acts with the downhill test drive and misfiring.
does anyone know what the vacuum should be when going downhill. Is there a data on my live data on my Autel maxidas scanner that I can look at to see. I did a smoke test on my intake system and I cannot find any smoke coming out from anywhere. Can anyone explain to me the vacuum and the pressure that is happening in the intake system and also the PCV system when going downhill

 

Again so did I. I also got them on EBay. In fact several people looked at the pictures of my boxes and said indeed they were OEM but that the injectors inside where not. Without actual pictures of your injectors it's hard to say. It's not etched markings that tell the tale? It's pretty subtle and without having them side by side with OEM I just could not tell. They are that close of a copy.

If you can't post pictures here is what I found.
The boxes looked great!
Auction is long gone so sorry for the small photo.



But here is the real indication.

Counterfeit injectors.





Here is a real OEM injector from my 60K miles 2014 XJR.





Carefully note the small differences in the above pictures. No Hella symbol and the letters are "just" a bit off too. All in all it's real close.
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