I've heard very good reviews of Textron brand cleaner.

john

 

Best is probably not to start with the expectation that some product is going to solve true problems. You seem to suggest there are error codes. Those are your friend, mostly because they are specific and easy to search by. Feel free to post them here for more specific help. And welcome to the group.

For fuel, this area has ethanol added (at least in the winter months), so water contamination should not be a problem. If you use premium gas, the additives put in by the fuel manufacturers should normally render these store additives unnecessary. Has the car been sitting a long time before you bought it?

Best of luck, keep us posted.

 

Fuel treatments may be pointless, depending on the codes - so, what codes?

 

FWIW, Techron is the only fuel additive which I've personally seen have ANY effect on a known injector problem. But you have to get the stronger "Complete Fuel System Cleaner" not the "Injector Cleaner" .

And use the large 20 oz bottle, or two of the smaller bottles per tankful of gas.


You are paying for the convenience of not having to take the injectors out to clean or replace them, so expect to have to repeat use of the Techron 2 or 3 times in successive tanks of gas.

Z

 

What are the codes?

The only injector issue I've ever had ended up being electrical inside one injector (the one at the front left of the engine above vertically of the PS pump). Luckily, it was what looked like only one of 2 that could be replaced with the supercharger installed. Someone here posted how to test injectors, an excerpt from the Jaguar software, and it failed the test indicating injector replacement. A bottle of anything would do nothing there, anything short of injector removal and replacement would have done nothing.

 

If you want your fuel system cleaned then get it Terracleaned. Its not an additive its a process. In the UK we have to have our cars emissions tested each year and since my engine was Terracleaned its been spot on. I do not mean good I mean excellent.
Will see if I can find a video for you.

Here you go

I do not work for them etc. Its one of the very very few treatments I would recommend.

 

 

Thanks to everyone for the responses! Here are some more details on what I saw. I bought the car last Monday and drove it home on highways from Manassas VA to Bowie MD (about 50 miles). It ran great. It took me a few days to get tags, etc in place, so next time I drove it was Saturday. Was a ~10 mile drive on back roads (no high RPM), and after driving through a rain downpour, i noticed it running rough and then saw the check engine light and "Restricted Performance" warning on the dash. We took it to AutoZone to get codes read the next day and read P0302 Cylinder 2 misfire; P1316 misfire rate; P0352 Ignition coil B. We bought a code reader and confirmed the readings, then reset the codes. It was running great and the codes did not come back. I have a new coil pack on order (the prior owner just replaced plugs and coil #8). Tuesday I drove it to work and Check Engine light came on again, but this time the code read P0174 Fuel system too lean. I just reset that to see if it comes back.
The previous owner drove it fairly regularly, and filled the tank just before I brought it home. Maybe some faulty fuel? although he said he always uses Premium from reputable vendors. Today I put in about 1/2 tank of Shell premium. It feels and sounds great (awesome), but I have not driven it again since I just reset the codes tonight.
I appreciate that the additive might be a temporary fix but at this point, i just want to get it through MD state inspection. I have the Lucas brand, which the guys at the shop said is the same thing as the Seafoam. I am also wondering if I should do nothing until I drive it a few more times and see if the codes come back now that I have put new fuel in.
Thanks again for all of the help. I never thought I would actually own a Jaguar!

 

I suggest you post the codes, which may lead to more specific advice.
The coils (one per spark plug) are known to fail - I have replaced a few due to misfire code, and always keep a spare on hand.

 

 

This code means there are very likely air leaks somewhere in the intake, or less likely, a faulty air flow meter. Fuel cleaner will not help. Some air is not measured by the computer (air flow meter) so too little fuel is injected. That lean condition is detected by the wide band oxygen sensors in the exhaust and fuel is added until the lean condition is no longer present. This is the whole fuel trim feedback setup that makes modern car so much more efficient. Thing is that if that feedback system comes to a point where 25% or more fuel has to be added, it determines that it is outside of normal conditions, and a code is thrown (P0171 or P0174 depending on the side). This fuel trim number should ideally be something like 5% or less. An yes, once that trim number is reduced, the car will run so much nicer.

In short, you need to figure out where the air leaks are (they are cumulative, and each one contributes to the code). Start with cleaning the air flow meter (by the air box, use a dedicated spray from the parts store), check top and bottom of the big intake pipe (and all resonators) for cracks. Also check ALL connections going to and from the heads and the throttle body. On my later car, these are all Norma connectors that pinch/pull easily and can be fixed with new o-rings (Harbor Freight has great kits of o-rings for cheap). Check the dip stick seal. I am less familiar with this, but the supercharger has seals too that are known to leak if they are of the original design. A later part is available.

Also, now would be a good time to make sure you have a code reader that can read Fuel Trims. Do a search for ELM327 on eBay or Amazon for a CHEAP wireless reader you can pair up with a mobile phone app. This small device will pay for itself MANY times over. The idea is to observe/confirm the idle fuel trim number going down as you fix each air leak.

Best of luck, keep us posted.

PS: Also check for oil leaks around the head. Oil leaking out means air going in...

 

I am surprised nobody has advised Sharon to first replace the battery. Trust no codes until you trust the battery.

A good AGM battery is less than $200. The Advance Auto in Bowie has it in stock. Order it online for store pickup and you can get 20% off.

BTW - good color choice. One of the few colors that never gets old.

 

 

Do NOT run an XK8/XKR through an automated car wash - EVER. Too many extremely sensitive electronics in the engine bay and the slightest bit of water in there can cause all levels of havoc, as you have already experienced. Take the time and effort to hand-wash the car and be stingy with the garden hose around the windshield and hood areas. Your electronics will be most grateful....

 

Some of those codes are "2 trips", so these problems might still be around, but the computer is waiting to be sure to tell you about it. OTOH, if you see P1111, rush to the inspection station.For this, be triple sure the big bins by the windshield in the engine compartment drain properly. There is a rubber hose hanging on a peg that directs water and a drain at the bottom of each bin. If the drain is somehow clogged, water can rise in there and flood sensitive electronics (ECM, TCM, etc.). Not a good situation. A coat hanger can typically free the drain if necessary.

Best of luck, keep us posted.

 

Jon that has not been my experience so far on my 2004. I have carefully sprayed the engine bay with a water hose many times with no issues. I do it to remove sand that seems to get into every crevice. Also blast the hood liner regularly to keep it clean.

Wondering if it has to do with how old the car is and/or how the environment has affected sealing rubber. Here in humid Florida rubber seals seem to hold up well.

I do agree that hand washing is preferred.

 

Just replace the battery before you do anything else. Otherwise you could be chasing phantom electrical gremlins forever.

 

You have been fortunate if you have washed your engine bay without compromising your electronics. I never washed my now-sold S-Type's engine bay during 9.5 years of ownership, and I have never washed my wife's XK8's engine bay either. I clean them periodically with a bit of silicone spray, some old cotton towels, and plenty of elbow grease....