I just bought my jag about a month or so ago, and already am having some issues, which is expected for a Jag of this mileage, however, I cannot figure out the source of the problem.
I have 2 engine codes for the car at the moment, running rich in bank 1 and running rich in bank 2. I have put on a new Mass Airflow Sensor, new Throttle Body, and changed the spark plugs and ignition coils. Nothing is solving the problem. Actually, when I put on the plugs and coils, the issue worsened.
Before changing the spark plugs and coils, the car had "Restricted Performance" quite often, but not at the beginning of each ride, and when I cleared the codes, the car seemed to run fine, I could redline it on the highway with ZERO problems.
The other day I changed the plugs and coils, and now restricted performance is on ALL the time, and now the car is having a terribly inconsistent idle(though it does stay around 600rpm) and when I put it into drive or reverse, sometimes it will drop down to 200, and I have to put my foot on the pedal to keep her from stalling.
I'm probably going to return the old plugs and coils and just buy some proper OEM ones(new ones aren't OEM), but still the issue remains.
My thought is that it is a sensor of some sort, such as an O2 Sensor or even a Fuel Rail Pressure Regulator. In fact, I've thought it could just need a tune up, because it is running SERIOUSLY rich(She sounds CAMMED) and the smell of the exhaust smoke is mad, but I've already got about $3,000 of work into her, and would like to hear everyone's ideas before throwing more parts at it

 

Just so everyone knows, I have a 2005 XJ Super V8

 

What were the original codes?

What is the make of the MAF fitted now?

There are two types of FRPS

If you have the black plastic box type check
the spigot and vac line for leaks

https://www.amazon.com.au/Junri-Inje.../dp/B09Z27RRJ6
Have you fitted a new TPS, also if so, what make is it?

 

The new MAF is by denso, I've not fit any new TPS, do you think that could do it?

 

here are the original codes, what I find odd is that it actually started out with the engine only running rich in bank 2, then it sort of progressed. Not exactly sure when it became both banks, but I believe it was while my shop was working on it.

 

P0102 & P0112 are probably hinting at what is causing the richness.

Wrong MAF? Problem with wiring? Go hunting...

Obviously you also need the right plugs etc.

 

the car stalled out completely for the first time today, i was sitting at idle, and it only stalled or starts to stall while I'm in reverse or drive. Got back home and got these codes. Everything is the same except the MAF code which actually was not there until I saw it today. Looked into a few websites online and turns out poor air intake can cause a P101 code?

 

What are the STFTs and LTFTs for Bank2 when compared to Bank1?

 

You need to be sure of the root cause before you spend any more money on parts.
Check wiring from TPS and state of air filter

Good information here:
https://www.autozone.com/diy/diagnos...-bank-1-bank-2

 

Thanks everyone for all of the help thus far!
I got talking with the owner of my shop, and apparently he noticed that the MAP sensor(Not MAF sensor) was a bit worn. Wanting to get the car back to me(it had been there for a month&#128517 he decided that since it actually ran well at the time, he would give it back to me with the repairs it already had.
In doing a quick search, it seems this MAP sensor checks every box of issues I have. I'm going to either pick up the part from them or just have them do it and see what happens. If the issue doesn't resolve, I am going to try out the TPS(I don't mind throwing a few sensors at it, since the MAP is free from my shop😁 and TPS's seem to be cheap).
In the meantime, wish me luck! I will update this post when I've got her back from the shop.

 

You have MAF / IAT codes but not MAP ones so I'd leave the MAP alone and look into those ones.

 

My deal with the MAF and IAT codes is that they don't come on consistently. The IAT code seemed to have gone away when the new MAF was put in, and I have not seen it since then. The MAF code also went away when the new MAF was put in. When I changed the plugs and coils, however, the MAF code came back(IAT did not come back yet), so I somewhat doubt that the MAF code actually relates to the sensor itself. Again though, you guys would know better than me.

 

Could be wiring / connector.

I'd still leave the MAP alone unless it's also acting up and then I'd wonder if the wiring might be shared with MAF...

 

Upon popular demand, I shall leave the MAP.

Aside from that though, I have noticed something NEW.
Cold weather is finally rolling in(30s down to 20s), and the car's idle is a LOT worse in the cold. In fact, today it nearly stalled out on me while I was in park, which never happens.
Still unsure about this all, but it makes me think throttle??

 

MAF sensor incorporates intake air temp sensor as well.
Check voltage on pin 4 of MAF sensor (IATS sensor output) as that should range between 0-5 volts depending on actual intake air temperature.
It is NTC (Negative Temp Coefficient resistor) which means the warmer it gets - the lower its resistance becomes.
Therefore as the warmer the intake air temp the lower the voltage output you would expect to measure on pin 4.
If you are suspecting an out of spec MAF causing the engine to run that rich, you would probably expect to see a voltage at the higher end close to 5 volts present on pin 4 of the sensor, possibly causing the ECM to over fuel the engine thinking it is drawing in far colder air than it actually is.
Conversely, if you have no voltage on pin 4, then I would suspect you have a open circuit wire back to the ECM plug (pin 66) and the ECM will be internally reading a 5V signal as the IATS sensor would be in effect open circuit.

I can't give you what exact voltage to expect for your ambient air temperature.....its 15 - 25 Celsius here in our spring season.

 

I should have specified. I'm over in the good old
U.S. of A, so 20s to 30s Fahrenheit is roughly -5 to 5 Celsius.
I'll definitely take a look at that pin on the maf though.

 

UPDATE:
Yesterday I changed my transmission fluid, as the car was shifting quite badly, and after doing so, I cleared my codes and went out for a little drive to get everything moving and lubricated.

The engine is now back to its old habits from before the ignition coil/plug change(Sort of), which is a good thing. I can clear the codes, hop onto the motorway, and just redline the thing through every gear and the engine runs perfectly. The codes do not come back on until I turn the car off, turn it back on, and then drive a pretty solid distance(about a mile or so). After about a mile tho, the check engine light comes on, as does restricted performance.

The only new things are the transmission fluid change(Which did clear some gear ratio codes), and I added a fuel injector cleaner, which I was recommended to do by my father, although I am very against those "snake oil" products.

However, the car still has a very inconsistent idle, though running perfectly when in motion.

Another thing, after laying off my accelerating pedal instantly after flooring it (not taking my foot off slowly), the car makes a massive jerk which is definitely audible, not sure if that's a motor mount or normal(highly doubt).

 

What codes do you have now?

 

It's not running perfectly, just coping as best it can and the problem(s) are not showing up until it is (by law) able to start flagging codes.

Stop clearing codes (& also don't disconnect the battery).

Watch the OBD monitor statuses, you want all the supported ones set (aka complete). Probably won't happen due to the fault(s) but see how many set after a few warm ups.

The more unset monitors the fewer codes it can flag, potentially leaving you in the dark as to what's wrong, but when it can't set monitors it literally does not know what it can trust & what's wrong.

Also check fuel trims to check for air leak(s).

Obviously, post the codes you get.

By all means check any live data OBD items you can for plausibility. (IAT, ECT, ...)

 

Video(my description definitely isn't enough):

Calculated load value spikes between 20 and 30%
In gear tends to be over 25% up to 35%, mostly 25-30%

STFT can be anywhere from -4.7 to -25
In drive generally tries to stay at -25, sometimes even goes to -0.8(drive only)
Still VERY inconsistent
Both banks are always different, sometimes even 13% difference, though mostly 5% difference.
Bank 2 has the lower %

Fuel pressure is all over, 357 up to 411
Mainly in 370 to 380 area, but often goes up to 390 and down to 365.

Intake air temp 60 °C

Airflow from MAF between 8 and 15 g/s

Intake MAP sensor sort of inconsistent?
In drive it stays at a solid 41 kPa, idle is between 30 and 40, mostly around 32 kPa

Ignition timing for #1 cylinder all over -8 to 15.

Absolute throttle position in gear but stationary always stays at 2.4%, in motion, between 1.2% and 3.5%
Going up hill in reverse it will drop somewhat.

Another thing, when restricted mode is on(or at least the engine light), the transmission HATES going between 5th and 6th. This is only when the light is on, not sure if it's some safety measure? I do not want to damage the transmission, should I clear the codes or leave them for diagnostic purposes?