I need my XK8 to get well. I just got back my throttle housing from ASI and so far so good, but only 75 miles in, we shall see.
Right before I got the dreaded P1121 code the car gave me a PO175 which is bank 2 running rich, I put in a bottle of Techron and it died on me. After sitting 3 weeks, sending in throttle and now replacing it, I just was driving and check engine light came on and for a minute, limp mode on and off. I got home, plugged in my OBD2 reader and I am now getting PO172 which is Bank 1 running rich. No more Bank 2. Any ideas how to solve this or just let the Techron do it's thing? I only drove 1/8 of a tank with Techron.
Thanks
Jax
1999 XK8 convertible

 

Sitting for three weeks ......... I'd put some miles on before starting to worry too much.

These two DTC's aren't exclusively fuel related. Possible causes of both P0172 and P0175 are:

1. Blocked air filter
2. Fuel system return blockage
3. Leaking fuel injector(s)
4. Fuel pressure regulator failure (high fuel pressure)
5. ECM receiving incorrect signal from one or more of the following components: ECTS, MAFS, IATS, TPS

Items 1, 2, 3 and 4 aren't going to go away by themselves which leaves item 5 top of the culprit list. An out-of-range signal from any of those sensors will trigger the MIL and flag a DTC on the second 'trip'.

With the TB problems followed by sitting, some weird electronic behaviour initially isn't that uncommon.

Graham

 

Cleaned MAF after Code with cleaner, that code went away.
New throttle body got rid of p1121 code. Car actually sat all winter as I couldn't work outdoors on it. Put Techron in fuel tank yesterday, hoping it will clean the injectors and fuel lines.
Car did a light backfire today and went into Restricted Mode for 5 minutes. P1072 was back on my reader, not PO175. I will drive a tank of fuel and see how it acts. I have to drive it 1,100 miles on June 1 and don't want problems. New air filter and serpentine belt going on tomorrow. Your advice, put miles on car and then check.
Thanks
Jax

 

Take it out and drive it like you stole it.

 

Drove a 1/2 tank of fuel with Techron so far and the restricted performance message keeps coming and going. Glad on highway I can still do 70mph in restricted. Going to drive it 150 miles later in day hoping that will solve rich bank 1 issue. Don't have the extra cash to bring to Jaguar but I have to drive New York to Miami on June 1st and use it there for a few months and drive it back. I don't want any issues on road in area where no repair shops know this car.
New filter didn't help and all air connections are tight.
Thanks
Jax

 

As of today 5-14 it has both codes coming up, rich in bank 1&2. It also randomly goes into restricted mode for 3-5 minutes. I am also getting a pop and it goes into RM.
Ideas please?
Thanks
Jax
1999 XK8

 

Hi.

Start out with the cheap and easy.
Disconnect, spray with electrical cleaner (not WD40) and reconnect the following:
MAF Mass Airflow Sensor
IAF Intake Air Temp Sensor
ECT Engine Coolant Temp Sensor
TPS you have already done?

Connections lose conductivity over time.

Next you may clean the MAF with an appropriate cleaner. (Never touch the internals.)

 

I use electrical connector cleaner only. MAF cleaner only.
I have no idea where the IAF,ECT or TPS are?
Any hints?
Starting to get a vibration at idle and feels like the motor wants to stall. Is that part of the territory with these codes?
Thanks
Jax

 

I listened to everyone. I tried to drive it to clear it out from sitting and when I just went to start it, the motor was vibrating. I put in my scanner and 9 codes came up. PO301-PO308 (injectors) and P1316. What is going on here? It appears to be getting worse.
Thoughts please.
Thanks
Jax
1999 xk8

 

Hi again.

If you are going to do any maintenance yourself you should download JTIS, take a look at the stickies at the top of this section and look at jagrepair.com.

Lots of info and useful links.

 

As stated above you may want to check the fuel pressure regulator, I've seen a number of posts from early XK that had bad ones. Or check fuel pressure with a gauge from schrader valve

 

Hi,

I did what you said. I was not accustomed to the short letters. When I spelled them out I realized what you were talking about.
On the temp sensor, I had to replace the whole crossover sensor together in March as from age the metal separated from the plastic, not expensive.
The throttle position was rebuilt by ASI. The intake air was cleaned with MAF cleaner last month with the MAF. I replaced the air filter on Saturday.
One recommendation you have me is looking promising. I took the clip off of the MAP sensor connector and I used electronics cleaner on both sides and waited till they dried, then as always, I used di electric grease on both parts. Today I cleared the codes and I took the car on a 100 mile drive ( 45-50-60-70 mph and back and forth). Then I picked my do up from school for the stop and go drive.
I don't want to jinx it but so far no check engine light or Restricted Performance since the connectors were cleaned. I still want to get the gas gauge down to the red mark, put in another bottle of Techron, fill it up and take it for a drive. Hope this will clean out the injection system out for a while.
I kept on looking for the yellow letters "Check Engine" fingers crossed. The car runs so nice. I figure after 17 years on the road and only 75,000 miles on her, she should still give me a good ride. Too bad the paint isn't holding up.
Thanks
Jax
1999 XK8

 

So I ran 2 tanks of fresh fuel each with Techron and the codes left. I actually made it with ease from New York to Florida and more.
Thanks all!