last fill I put in MIDDLE grade gas and used most of the tank. Right before laving for TN last week the car threw a CHECK ENG. Arrrrrg, I was like this damn car, first real 6.5 hour drive each way and it does this crap. It's a sign? So I pulled codes real quick and it was showing P0153 code. Which could be many things including incorrect gas. Is this car THAT sensitive to pop the code after being run on mid octane for about a half tank? I cleared the code and and 13 hours of driving later on the correct gas it has not came back.
I really hate these cars at times. ha ha ha

 

on a very surprising note the car pulled a hair over 31 MPG on the trip. All diff types of terrain, ac on, ac off, holding 70 mph more or less most of the time with 3 people in the car.

 

By cheap gas do you mean 'low octane rating' vs. 'poor quality' or 'contaminated'?

Low octane rating won't throw any codes, so look elsewhere if it comes back..

 

Didn't you have a HO2 issue recently ? Loose pin I think?

 

I have a wire that I pulled out by mistake when I was doing my octopus home. I put it back in, but has came out a few times and caused a diff code then this one. The code never came back.
The gas I put in the car was a middle grade/octane gas, not the top grade I always put in it other then this one fill up.

Ho2 slow response? Could that be my wire that for what ever reason did not have a good connection at the moment?
Car is running well otherwise.

 

Not too sure about the gas / code....

But you did say you had 3 people in your XK8.
Please explain how you did that for a 6.5 hour drive.

 

I'm thinking poor quality petrol as opposed to low octane rating. Run a couple of tanks from your usual supplier and see if it still throws any codes.

 

I used the same gas station I usually use.
My son is 11 and can fit in the back seat is he lays across it. That said it will be the last trip like that. He is growing like a weed and even this time it was not that fun for him. ha ha. I picked up a Miata from In-laws so he only had to do it one way.

 

From reading posts for 3 years I know many use 89 rating without a problem. I know you have the torque app, put it on and check your fuel trims.

 

Will they run on 87 octane also???.....Mike

 

This engine has a knock sensor, so any grade gas will work with different levels of performance. This sensor will sense a low octane ping and retard timing to stop it. I've run 89 octane for 3 months of ownership and it seems fine. I just got back from a 250 mile trip each way to the coast with no issues and no perceptible difference in power.

 

I thought these had to run on the 93 octane or else performance goes south.

 

oh well my code has not returned. I have a 9 year old battery, perhaps that is the cause or the lose wire on the O2 plug that I have had to push back it had a moment of week connection.

 

No Jag requires 93, they achieve full rated performance on 91 as noted in the owner's manual. Putting anything higher than 91 is pure waste.

As to how much performance is lost when using lower octane, I guess you've now seen for yourself.

I know of many 4.0 and 4.2 owners who have used 87 by mistake or on purpose and noted no ill effect, even long term.

 

well I can save some $$ and go to 91

 

Another "Urban Legend" unveiled!

 

I know my gas cap door has a sticker 'premium fuel only'... since it isn't my daily driver I usually use 91/93 depending on where I stop.

 

I have a Lincoln SUV with a similar sticker on the fuel door. The original owner thought that this meant 'Top Tier' branded fuel only and faithfully filled it with Top Tier 87 octane fuel. The vehicle now has 200K Kms on it and still runs perfectly.

I wish OEMs would do away with terms like 'premium' and 'super' and just specify the required octane rating.

 

I know all you guys are going to throw up with what I've been doing for the six years of owning the 2000 XK8. I have been using the low octane gas at Walmart in both Jags the total time. Tried premium in both for a short time and found no difference in mileage or drivability. Of course I drive in a very modest conservative way. I just really enjoy the ride. If I want to feel the thrill of going fast I ride my 1000cc motorcycle. Really got the feel of speed with that. If I really want to go fast I fly my 200 mph airplane. If I want to brag about having gone fast I tell about the time the sun rose out of the west.

I just really enjoy driving both Jags.