I have a 2004 XJ8.

Since it was relatively new (15K miles) the previous owner complained of white smoke coming out of the exhaust on heavy acceleration.

I bought it in October with 31K miles, not knowing that info. I found that out later when doing some research at the dealer on the car. I don't know what the dealer did at that time to "fix" it.

I too noticed the white smoke so I brought it in. The dealer looked at it, replaced the PCV valve, and told me that should fix it. They found oil on the outlet side of the valve and assumed it was leaking.

It smoked the very next day so I called them up and they said to give it a few days - it may take some time to clear the oil out of the exhaust.

After a month, it was still smoking, so I brought it in. They pulled the PCV valve and replaced it again because it again had oil on the outlet side. I questioned this, wondering why it would have failed after such a short time, and they said that sometimes they are bad out of the box.

That was two months ago, and it still smokes. Car is no longer under warranty, but I do have a great relationship with the service manager.

Here are the details: car smokes randomly at start, independent of engine or outside temperature. Car also smokes HEAVILY on heavy acceleration, usually when car has to downshift (like making a turn out of a parking lot or moving into fast lane to pass someone). When I say HEAVILY I mean it - so much smoke billows out of the exhaust that sometimes it brings traffic to a standstill because they can't see through it. Pretty embarassing for such a beautiful car!

Problem does not always occur - sometimes you can accelerate with no smoke at all (like when I am driving it with the technician at the dealer).

Dealer checked cylinder pressures, oil is clean and not cloudy at all, and car doesn't seem to be using any oil. It now has 38K miles (I've put 7K on it).

What on earth can cause white smoke if the head gasket is intact? Are we missing something simple? Car runs beautifully otherwise.

One more thing - the other day when I really pushed it hard trying to get it to smoke I noticed that the yellow check engine light starting flashing. I returned to regular driving and it went off after about 60 seconds. It was smoking when the light starting flashing. Not sure if this is related or not - can't say I've noticed that before.

Dealer can't/won't help at this point because they don't know what else to do, and since it is now out of warranty I can't really afford to pay them to start just replacing things at my expense.

Thanks for any pointers or suggestions you can offer. This is by far one of the favorite cars I've owned, but doesn't look real great when clients are following me to lunch and I smoke them out!

 

Flashing ck engine light is from misfiring bad enough to cause engine or catalytic converter damage. And heaviy white smoke like that i would venture out on a limb and say fuel injector going static(stays open) and dumping fuel that cant be burned, this would cause a misfire and cat damage as well as basically a vaporised fuel cloud from the exhaust. wether its from a ecu fault or wiring or injector is were the diagnostics comes in

 

Thanks Brutal. You ever hear of or see any of those items? Any of them seem most likely to you when problems started showing up as early as 15-20K miles?

I assume codes are stored - which codes would you expect to see for each of those three scenarios?

 

One additional question - wouldn't the vaporized fuel cloud smell like fuel? I've never smelled any fuel when we start the car in the morning and back out of the garage - right through the white cloud...

 

I think you are burning coolant. You may have a leak into the intake from the cooling system. When the water pump spins up and increases pressure on accleration, it pushes more into the manifold. Take a look at the thermostat housing area. Huge clouds of white smoke is probably not fuel.

 

well if it doesnt smell like fuel then forget that, what does it smell like?

 

Took a whiff this morning when the wife fired it up. Very mild smell, only like exhaust. No traces of coolant or fuel smell.

There have not been any coolant drops on the floor of the garage, but I did have to add a slight amount of coolant last time I changed the oil (not sure if it was properly topped off before though). I will keep an eye on the coolant level.

Any other ideas? Thanks everyone.

 

One additional item, maybe related.

Two times when accelerating (pulling into traffic, but not too hard) the car would stumble for 10 seconds and make a very loud tapping noise - from the front of the car. During this time it would smoke a lot.

Told dealer and they replaced fuel pump. Seemed to fix it but it has now done it twice more, even with new pump.

 

Is the smoke coming out of the exhaust pipes or just from under the car? A little oil, hitting a hot exhaust pipe can make it look like an old destroyer laying smoke.

 

Out of exhaust pipes themselves.

 

Most smoke has some type of odor. What does it smell like? Since the smoke is white, I lean toward coolant. That will have the sweet sickly odor of ethylene glycol.

 

See above post about smells. Doesn't smell like coolant either.

 

well if its been doing that for awhile ide pull the plgs and look at them since the red colored Jaguar coolant WILL stain the plugs a light red tint. I the check engine light was on and flashing t should have retained a code and would say a P0300-308 depending on cylinders affected. And then ide look closely at those cylinders, compression test, leak down etc Also coolant pressue test with higher than normal pressures when idling to see if engine start to run rough, indicatiing coolant going into combustion chamber.

 

Thanks for the detailed plan Brutal. I will do just that.

Could the long hesitation and loud clicking/tapping noise every once in a while be in any way related? If there appears to be coolant staining on the plugs that means a gasket, right?

 

No that meens your getting coolant into the intake trrct, could be gasket, leak from the throttle heating circuit or some other place. But these are some of the steps i would take too diag, kinda hard on the net though

 

Here's another shot, the egr valave is also on the coolant circuit and there coiuld be a leak into the intake from this point too. Although could definitly be responsible for water into exhaust on accel, not idle. But then since its minor it may be some left in the bottom of the runners in the intake and or the silencer inside the manifold which is a corse material that absorbs oil and could coolant as well. You could temporily disc. The 2 hose at the valve and connect them toegether will a vacuum line connector or any other correct sized tune. This would take the coolant away from the valve and then go drive and see if it does it still...youre really looking to eliminate the suspects until you find the perpitrator

 

Where is the EGR located on the XJ8?

To make sure I understand - there are two vacuum lines going to the EGR...I should disconnect them from the valve and just connect them to each other, correct?

 

no theyre coolant lines and i was working on a newer XJ today and you came to mind. Now if you have the same setup on a 04 i dont know. But Ide have to ck, if you do it would be to the left on the throttle body on the front of the engine

 

Our dealer has a camera that we put down the spark plug hole we found couple cars leaking head gaskets. Early 04 xj did have a problem with loose head bolts. Are you loosing coolant ? I m curious of what you fuel trim is.. I had this happen to me and a another tech .. We had to go for a test drive in the car 04 stype v8 bt he did an oil change 1st and fogot to put the cap on... We drove around and dint notice we left cap off there was a huge smoke show in the middle of the intersection when we accelerated... Was pretty fun we thought the car was on fire. Lol

 

JagGenius:

What do you mean by "fuel trim"?

Another idea ... what happens if the oil is overfilled on the XJ? Could that cause smoking as it burns off?