I have a 2004 Jaguar XJ8 with 79,000 miles on it. It's been well kept and maintained. The modifications I have on it are exhaust system, mina gallery intake, and ecu reprogram. However, I constanly had problems with the engine light turning on and saying "restricted performance." It seemed to only happen when I was going up-hill or when driving over 75 mph.

I read some reviews on the mina gallery intake and decided to take it off and install the stock intake with a K&N air filter and cleaned the MAF sensor. I also replaced all 4 O2 sensors. It seemed to have a better smoother effect on the car and the engine light turned off. However, the light and "restricted performance" appeard again when I went up-hill after a few days. What can be causing this?

P.S. I also remember that when I had the mina gallery intake, the ecu guy had to increase the fuel mixture because it was too lean and numbers were way off. Do you think the ecu needs to be reprogrammed again and the fuel mixture might be too rich now with stock intake and K&N filter? Please let me know what you think. Thank you!

 

I'd be tempted to put everything back to stock, including the ECU. Do you have any codes?

 

had similar problem, then the restrict would not go away. about 62 k miles.
had mina intake, pully and exhaust.
the problem was the cats and o2 sensors had to be replaced. I also had a full tune up because 2 ingnition coils had promblems.
good luck I hope this helps. $$$ to fix. but now the car is running well and no engine lights for 4 months. I am going to have the ecu reprogrammed in the next week or so...

 

I checked the codes yesterday and it says "system too lean Bank 2." It's the same thing it said when the mina gallery intake was installed. It sounds like I have an air leak somewhere, but I couldn't find it, but I could hear it. Did you guys hear a similar noise in your car?

What is the CATS system? I'm not sure what that is. As far as the coils, I would need to check those. Do you think it's safe to put the mina gallery intake back on? I heard that it's a hot air intake instead of cold air and it creates problems. I've always liked to work on my cars to get more power out of them, but with this one I am tempted to go back to stock except for the exhaust. What do you guys think?

 

I think you have a bad mafs, and the air leak noise youre probobly hearing is from the full load breather valve on the pass side of the engine. Looks like a pancake. And they sound like a vacuum leak but its normal. That engine is not a known vac leak problem, but mafs do create lean bank issues on all the cars. Dont ask me why 1 bank. As far as coils, unless you have a way to read misfire counts or have cylinder misfire code like p0301, p0302 etc, forget coil issues. Does your scanner monitor short term fuel trims? If so go into that and spray carb cleaner/brake cleaner in areas and watch for fuel trims so go off

 

Maybe you're right about the MAFS because I replaced it a year ago at Auto Zone and the housing (the outer shell) says Toyota. The guy told me it's the same thing and it is identical. Should I just order the original MAFS which is by Denso I think?
As far as the full load breather, thats where it sounds like the leak is coming from. I sprayed carb/brake cleaner and found nothing unusual. I'm hoping that sound is normal then. I'm not sure if I have a scanner that monitors short fuel trims, but maybe one of my friends have one. I'll check into that. Do you think I should also keep the stock intake with K&N filter or go back to Mina Gallery open intake?

 

I think you should get a true mafs that is calibrated to the car. Ie you cannot use a normally aspirated mafs in a sc car theyre physically the same and work (sorta), but not calibrated the same. Thats why theyre diff part numbers. You trusted auto zone????
Ide call who programmed the ecu and talk with them about calibrations use and under what parts. When you change things like air intake that affects fueling calibrations. Just not snapping down the air box lid creats issues as does the dual air filter engines need to air filter manufactured on the same day from the same material. We've already gone through that issue which is why jaguar know supplies only "date match" pairs for airfilters

 

Yeah i'm trying to look into getting the correct MAFS now. You are right, I should never trust Auto Zone when it comes to Jags lol. I'm having trouble getting the correct MAFS. Is it Denso or is it A-1 CARDONE Part #7450009? I can't seem to get the correct answer for this. Once I do get the correct MAFS I'm going back the the guy that does the ECU reprogramming and he could check whats going on and correct. I'm hoping after that I will be good to go. I think I'm going to keep the stock intake with the K&N air filter (cold air) instead of the Mina Gallery Intake (hot air).