So 2 of the past 3 days upon start up, my car produced a fairly strong gas smell for a brief period. It would then completly go away. I've did some reading around and I'm leaning towards a fault within the EVAP system.

It would have to be ether the purge valve system or the canister that stores the gas fumes leaking. It's really odd since I'm not getting any codes and the car runs fine honestly. I do however have pretty poor gas mileage. Just overall I'm still confused, I was going to bring it over to my mechanic and see if he can find a leak or fault within the system.


Along side this I've had short durations of blueish smoke come from my exhaust after startup. It seems to be intermittent, only really noticed it recently. The car really doesn't produce this smoke at any other time. My first assumption was maybe valve seals or on the worse end both valve seals and the valve guides. Shortly after purchase a few months back the car began to make a noise that could be easily be called valve tick. I've put in a liqui moly product to help with this noise and it has made it more intermittent. Maybe this could be connected to the issue above? Overall again sadly I still feel the issue isn't known 100%.


Hopefully some of you guys have input you can give to help me through this. I know enough to generate a few possible problem areas, just not enough to state stuff with confidence. Again all and any advice would be awesome.

Thanks in advance,

Andrw

 

If the canister or purge valve are bad then I would expect it to flag a DTC code. It is possible that the smoke and the fuel smell are related, but not to the EVAP system.
I would be checking fuel pressure prior to start up and during running. Additionally I would also check the STFT (short term fuel trims) and the LTFT (long term fuel trims). Any high negative numbers would indicate a bad fuel pressure regulator or one or more bad injectors leaking. The intermittent noise may also be associated with a fueling problem since the knock sensor is sending signals to the ECU and the ECU can't keep up with the changes in fuel mapping causing a rattle.
Unless the engine has been overheated I would jump to valve guides or seals just yet.

 

ANdrew, if you are thinking you have a bad valve seal, you can try removing the spark plugs and using an attachment, you can fill each cylinder (1 at a time while it is at TDC) with compressed air. You can then listen to the intake port, exhaust, and oil fill cap to see if you hear any air. If you hear air, then you know that you have air leaking past a seal on that part of the car.

If you need me to go into more detail about how to do it, let me know. The big trick is creating a momentary push button that you attach to the starter to allow you to bump the motor around as needed.

 

I should probably add the car will intermittently rpm hunt at idle, whether the ac is on or not.

Avern do I need a special diagnostic tool to monitor those numbers? I only have access to an ob2 scanner, also where can I find the correct values so I know how to diagnose whats good and what isn't? The car hasn't ever overheated, peak is always just before the middle mark. I'm assuming you meant to say if it hasn't overheated, to not check for valve seals or guides yet. The smoke had a definite blue tint to it, could that still be associated with a fueling issue?

Thermo going into more detail would be helpful if you don't mind. I don't really have access to an air compressor, any other tools I can use to do this test? I'm not very experienced so apologies in advance.

Thanks for the replies!

 

Quite a few scan tools will have settings for real time monitoring. If yours doesn't a cheap ELM unit, from Ebay or amazon, with the torque application for I-phone or android can provide real time monitoring.

 

While off the car read 0 for both stft1 and stft2. Fuel rail pressure was at 37psi but prior test read just over 40psi. The ltft1 was 6.3 and ltft2 was 9.4

at idle the stft1 was between 1-5, stft2 was 0 to -.8. Ltft1 was 10-11 and ltft was 13-14. Fuel rail pressure was at 54psi. Should be noted while it was hard to monitor the fuel trims, both banks short terms seemed close more often then not. The ltft would seem proportinate the the stft. Both banks.

Revving to 1500 and holding. Stft1 was -.4 to-.7, stft2 was showing similar numbers. Ltft1 and 2 again had comparable numbers 10-11. Fuel rail pressure at 55psi.

Revving to 2500rpm and holding. Both stft1 and stft2 sat between 8-9.5. Ltft1 and ltft2 sat at around 0-2.

I'll mention that the long term and short term fuel trims seemed to always be proportionate no matter what I was doing. One went up, other went down. I had issues monitoring everything at once, had to keep scrolling up and down. Anyway hopefully these numbers will serve as some sort of indicator. Never smelled fuel and no exhaust smoke during the tests.

Thanks!

 

From the looks of your fuel trims you have the start of a vacuum leak that hasn't gotten to the point of kicking out a code and check engine light. The positive numbers indicate adding fuel to the cycle from information provided by the 02 sensors.
I would start with the usual culprits for finding the leak. Start with the engine cold overnight. Get a can of brake cleaner and with the engine idling start at the plastic tube that goes into the back of the intake manifold and give it a squirt. You are looking for a sudden increase in RPM from the fluid.
Next move to the football shaped fitting on the line running from the manifold.
Then move to small squirts around the base of the intake manifold. Next around the rubber hose that goes from the front cam cover to the intake manifold. Then small squirts around the IMT valves on the passenger side of the manifold. And last try a squirt around the dipstick.

 

Thank you for the help, I seriously appreciate it!

Would the fact that I just put in a spacer for the bank 2 downstream sensor(goes into cat) affect anything? I did this to hopefully clear a p0430 code, heard good things about this method. Seems to have no worked for me sadly

 

Andrew, you could probably do this test with a bicycle pump. What you are going to do is find some fitting with the same thread pitch as the spark plug (most use an old spark plug). From there, you are going to weld (or if threaded on the inside, screw on or affix in some manner) to the fitting a piece of stiff tubing about 7" or so long (enough to get just above the plug well). From there, you want some sort of rig that you can attach a gauge that will go up to say 100 psi and your air source (bike pump should do since it is a small volume of space). You will attach your gauge/hose assembly to the pipe in the plug well. From there, press up the cylinder to around 90 psi. If you can stop adding air, watch the pressure gauge to see if it is dropping pressure. This would be your first sign of a problem. If you are seeing the pressure drop, press up the cylinder as high as you can get it and then put your air next to the oil fill opening. Do you hear air? If yes, then your valve seals are probably toast. Next look into the antifreeze overflow bottle. Do you see bubbles forming? If yes, then odds are you have a head gasket issue. Next put your ear next to the exhaust pipe. Do you hear air moving? If yes, you have an exhaust valve issue. Finally you can put your ear next to the intake port. Do you hear air? If yes, then you have a bad intake valve. The only trick to this is you need to roll the motor between each cylinder to get it so the piston is all the way up with both valves shut. Otherwise you will not be able to press up the cylinder.

If you don't feel confident in building something like this, then you can stop by your local auto parts store and rent (normally for free, just an initial deposit on the tool) a compression tester. For this, you are going to need a momentary switch capable of handling 10 amps and you are going to connect it between the battery post on the starter and the small wire on the starter. When you push the button, this will apply power to the small lead which will engage the starter solenoid and cause the motor to roll. Since you should NOT!!!! have the key in the ignition, the motor will roll, but not start. From here, you remove all 6 spark plugs and connect the gauge to each cylinder (1 at a time). What you are looking for is all 6 cylinders to be essentially the same pressure (should be around 150 psi). A general rule of thumb is they should all fall within 10% (ie, high one may be say 180 and the low one at 165 psi, this would be OK). What you are looking for is 5 of the cylinders to be essentially the same and the 6th one off. The off cylinder is your problem child. if you find that all of the cylinders are down at say 100 psi, then your rings are shot and it is time to rebuild the motor (not likely in this case).

 

The code 430 would indicate that the cat isn't working efficiently. The cause of that is the fuel trim state of excess fueling to overcome a vacuum leak. The upstream sensor is sending signals to help the ECU map fuel requirements. The excess fuel is burning off in the cat and the downstream sensor is signalling the cat isn't working. Spacers don't fix anything they just mask the underlying problem.
Excess fuel in the cat would also give you that occasional puff of blue smoke. The excess fuel washes out oil on the cylinder liner and combines for the puff of smoke.

 

This was actually extremely helpful. The one red flag I'm reading here is the oil being washed off the cylinder walls. What kind of wear can I expect from this? Would the puff of smoke be the only indicator of the oil being washed away? Or would you say it's happening constantly? Sounds like I should be fixing this sooner then later.

 

Most likely it is only occurring during start up and only occasionally. The biggest problem will be that eventually the cats will become coated significantly and will need to be replaced. The Jaguar fuel mapping uses an enrich mixture amount for start up when the engine is cold. This doesn't occur with a warm engine.The enriched fuel flow plus the 02 sensor adding more fuel to overcome the vacuum leak would give you the excess fueling probably in the form of that puff you see occasionally. Continual driving with out repairing the vacuum leak will damage the cats.

 

Extremely helpful, something I'll definetly try out.

Thanks!