I took my '99 XJ8 in for my annual smog inspection for my license tag. I have had intermittent issues with check engine lights (they abruptly come on, then disappear after two or three days). As fortune would have it, it appeared again as the technician cranked the car to take it back for the test. The following error codes were generated:

P0171
P0174
P1384

The shop wants $200 to fix the vehicle, money I really don't have at the moment (since I'm already going to be out almost that for the tag alone). Any advice?

 

From my limited experience it could be one of the following for starters.
1. PCV valve hose leak.
2. Dirty MAF sensor.
3. Leaky EGR valve.
4. Vacuum leak at the intake manifold.

Look for leaky hoses first and clean the MAF, these are the simple jobs and may cure the problem without you having to spend any cash.

 

Yes, you're getting some good advice. On this car, check for cracks in the accordian air intake tube. These accordians melt on the bottom from engine heat. It is hard to see while in place, so you need to remove the tube, place a light inside and see if you can see direct light at the folds.

The N/A AJV8 does not have an EGR so so not look for that.

Next, make sure the crankcase breather is clear on the RH bank. This is the plastic accordian tube going from the cam cover to the same air intake tube. Move over to the LH bank and check the part load breather. This is a much smaller accordian tube coming off the cam cover and routing back to the TB, usually under the intake manifold. use a small drillbit 5/32, to gently ream the tube entry to the cam cover.

Do you use an "oiled air filter"?? A couple of popular brands out there, generally the same, you wash them then coat them in oil? If so, this air filter could be fouling the MAFS, then I would definitely clean the mafs.

Finally, the MAFS can just be bad, or O2 sensors on thier way out. If ALL of that doesn't fix it, I would probably be looking at dirty fuel injectors

 

Where are the MAF sensor and EGR valve located? I gather that the PCV valve is inserted into one of the valve covers.

I do not use an oiled air filter.

 

I repeat - your MY does not use an EGR. Instead it uses VVT devices that sufficiently retard intake valve timing on deceleration and idle.

The MAFS is located in the same large intake tube that you are going to check for cracks/air leaks. The MAFS is located directly downstream of the air filter housing. If you've never cleaned a MAFS, you need to reconsider doing this yourself, or do due dilligence and research MAFS cleaning on this site. Follow procedures to the letter.

This car does not have a traditional PVC. Instead, it has steel gauze trapped underneath the CAM cover. The full crankcase breather located on the RH CAM cover does not utilize vacuum to function correctly, so just check the tube for cleanliness. THe part load breather on the LH CAM cover Does use vacuum.

Best,

 

Thanks. Will have a look at this tomorrow.

 

It appears that my XJ8 is headed for the salvage yard. After cleaning the MAP sensor did not clear the check engine light, I took it to my independent mechanic for diagnosis. The verdict: The car needs a new air flow sensor, variable valve timing actuator and gasket set, total replacement price over $3,000 - to pass a smog inspection.

 

orca, don't give up yet! Surely unless the cats are tanked, you can get the emissions to clean up enough?!? If it runs ok (no rough idle or missing) it has to be a simpler fix.

 

Like H20boy says . . . wait (unless you want to dump it really, really cheap send me a PM!).

We can help.

You have already been given the best answers to the problem(s). Do you want to work on it yourself and save the $3000?

Know how to eat an elephant?

 

Would love to do the fix. Money is an issue, plus the tag is now expired and penalties are increasing daily. I am a decent mechanic (by no means master) but I can follow instructions. I almost fell out of the chair when I got the estimate - I was figuring $200 max for the fix.

Since this car is new enough that they can just plug in, they won't do the manual emissions test. This means that as long as the check engine light is on, the car fails.

I checked the vacuum hoses and the intake and didn't find any leaks. I cleaned the MAF sensor with MAF sensor cleaner. I went over to Checker Auto Parts to see if they would clear the codes so I could see if the check engine light would go out. They told me they can read the codes but they're not allowed to delete them (which I found odd, because I can buy equipment that will erase them, and it isn't that expensive).

 

If you did fix it, the car will need several drive cycles to clear the code itself, if you want it sooner, you'll have to find a code scanner that'll do it. Keep driving down the street, check Autozone and O' Reilys, someone is bound to clear it for you.

did you remove your entire air inlet tube from the box to the throttle body? Thats the only way you'll be able to inspect it entirely. Check for other lines needing vaccum. Man, those codes could be many things.

 

Yes, and I ran a light through it looking for cracks and found none.

 

Let eat that elephant;

Remove the large hose between the air filter box and the throttle body. Check that the accordion/bellows section is fully intact. Do you see any splits in the accordion section?

If so, clean the outside with spray brake cleaner. Wrap the entire section, tightly, with black electrical tape.

Check the hose between the valve cover and the duct to the large hose between the MAFS and the TB. Any splits/blockage? If so fix it.

Remove the Partial load breather tube from the fitting on the left valve cover. Careful, you are mashing on 10 year old plastic. Clean it, ensure that there is no blockage.

The Partial Load Breather may be blocked. CAREFULLY remove it. Squeeze the release points and CAREFULLY pry the connection apart. Check that the PARTIAL LOAD BREATHER is open. If not, use a 5/32 drill bit to remove the very hard deposits. The hole is not near the exterior opening, you need get down at least an inch to the real opening.

'Bout time to buy an inexpensive OBDII reader. See https://www.jaguarforums.com/forum/s...ad.php?t=33347

 

I don't know if this is a hint or not - but I noticed during the past week when I was driving the car the Restricted Performance warning popped up a couple of times. It stayed up for maybe a minute or two, then it disappeared.

I have not noticed any difference in the performance of the car or in fuel economy - which it seems would be there if indeed the valve timing is off like the shop claims.
I inspected this and did not find a break in it. This is one of the newer items under the hood, because I broke the original one when changing the air filter (it was brittle and just snapped). I temporarily fixed it with duct tape until the replacement part came in.

You guys are the best. I was about to concede defeat when I got the verdict from the repair shop. With your help I might actually cure this beast.

 

If that piece was that brittle, I bet you just haven't found your vacuum leak just yet. There are so many air lines going to the engine and to various components. Be systematic...maybe take the next few days off, clear your head, and then start from scratch.

Check out the Part load breather cleaning link in the XK8 FAQ thread, it shows how to safely get it off and how to open it back up. Everything having to do with the 4.0L (AJ26 & AJ27 <- not sure the difference there) and the 5hp24 transmission is the same on your car, so lots of cross references and troubleshooting ideas to work from.

 

Tried one more time to get an auto parts store to clear the codes and they refused. Offered to let me rent a code reader/eraser "with a $150 deposit", I told them no thanks. Gave up and bought a code reader/eraser on eBay (because I'm sure this will come up again sometime). Will get back to searching for vacuum leaks this weekend, and follow some of the excellent tips I've been given.

 

For the experts. Will touching the negative battery terminal to the positive terminal when disconnected from the battery clear the code?

I have had air leaks in the intake hose where it joins the MAF. It is a push fit with a large clip to secure it. Make the join does not move when you push it gently.

 

It might, but it could also disable the sound system. I bought the car used, so I don't have the code to reactivate it.

With the code reader that is on the way, when each code appears on the screen you push the button that says "erase". Seems pretty foolproof (I'm about to find out).

Thanks for the tip on the intake hose.

 

Remember, although you may be able to 'clear' the code, if the car doesn't run thru the proper number of drive cycles, it still won't show the P1111 code which means, all clear, and unfortunately, it still won't pass inspection, but, it will let you know immediately if you found your problem area if the CEL promptly returns.

 

Orca, Auto Zone can not delete the codes, but will allow you to do it. If youe Auto Zone will not, go to another Auto Zone or other parts store.
Best of luck as I am having a different issue with emissions testing.