My car has 120,000 miles and I have an error code of P0174. I decided to do some digging and I found some common issues and I had some of those. The P0174 code is a "bank 2 system lean" error. That means more oxygen is getting into the engine than needs to be there and this can do some very weird things to Jaguars. Jaguars have VERY finicky computer systems that run the engines and if all levels aren't perfect, well your car is going to freak out.

Anyway, my PCV hose had never been changed and it had a large crack in it all the way through the hose. Next my IMT (intake manifold tuning) valves were leaking. Well only one was, but I changed both gaskets. I checked my brake booster vacuum hose, and it is perfectly fine, so we can rule that out. Also I checked the front three spark plugs and they were nice and clean with no oil or black on the electrodes. I can't get to the back three because you have to take off the intake manifold and I don't feel like doing that unless I have to. My problem is that the code came back after I cleared it, and my car is acting weird still. My car idles fine whether in gear or not, but when I give it gas my car will stumble until I get to 2,500 RPM and then it will act normal and drive better, but will still stumble a little bit. It does this whether I am shifting the gears manually or if it's in drive. It shifts perfectly fine and there is no slipping in transmission. The engine just feels like it doesn't have the power while trying to accelerate. Any tips on what might be causing this? Possibly a large leak in the intake manifold gasket? I can't hear any leaks while running, but just because you can't hear it doesn't mean I don't have one.

 

I purchased some Mass Air Sensor cleaner and cleaned the sensor thoroughly. The car runs better, but still isn't quite right. When the AC is on, it is worse, but still better than before I used the cleaner. Does the AC run off a vacuum system? If so, what should I check?

Also, I noticed that when I put the mass air sensor back on, the O Ring is stretched. You can't simply pop it back on, you have to take a small flat head and squish the O Ring little by little going around the sensor till it all fits into the hole (no pun in tended). Does anyone think that could be causing a leak right at the sensor and could be throwing it off since the O Ring is stretched?

When the car runs over 2,500 RPM the engine runs at 99%. Below that it has the stumble issues. It feels like the car isn't getting enough air (which we know its getting too much), fuel, or not enough spark. I have had the throttle body changed with a brand new one about a year ago, so we can count that out of the equation as well.

Please help.