I have used the forum and have found a lot of help. I have not found what I have so I am going to ask. I have a 2003 X Type 2.5 auto with about 130k. I bought it a few months ago with a check engine light. Went to Autozone and had it read before buying. Was told not a big deal just a MAF. Bought car went back and bought MAF and put on in parking lot. Drove home (about an hour) and check engine light came back on. Went and had codes read and found the 0171, 0174, 0420 and 0430. Came to the forum and found what to look for. All the common things (IMT o-rings, brake booster line, etc) had already been fixed. Looked a little deeper and found the cats have been replaced as well with universal ones. I can clear codes and they will come right back. I ran into a dead end so I took it to a Jag shop. The did a smoke test, pressure test, (pasted both. He was sure it would be intake o rings) and not sure what else but 3 days later they still don't know what is wrong with it. Any help would greatly be appreciated and thanks in advance.

 

Slur, based on what you are describing, are you sure you don't have a leak in the expansion boot just upstream of the throttlebody? That would be something I would look at. Also, how does the joint where the brake booster hose taps into the intake look. I would try putting a little bit of water on that joint to see if it sucks it in. If so, you have a bad seal on that connection. After that, look on the back side of the intake to make sure that the elbow boots are on the intake. These shouldn't have been played with, but because someone was into the car pretty deep to put new cats on it, hard to say what they have done. After that, I would still look at the IMT valves and make sure that you have good o-rings in there (they should be green, not black, the green ones are the new style and the black ones are the OEM ones from the factory).

Lets see where we stand with these checks and then we can go from there. It may be that you have a bad manifold pressure sensor (or it is blocked) and you simply need a new sensor.

 

Thermo, thanks for the quick response. I know the IMT o-rings are the green ones. I don't have the car at the moment. It is still at the shop. If they did a pressure and a smoke test on it would the bad elbow show and the boots? FYI, I did a spray test on it before I took it to them and found nothing. If not I will discuss this with them tomorrow. They are thinking throttle body is messed up but I'm not sold on that idea.

 

Slur, if the throttlebody was messed up, you wouldn't be getting the P0171/0174 codes. You have a definite vacuum leak. Granted, this might sound funny, but have the shop do a load check of your battery and see what that comes out at. We have discovered that if the battery starts to get old and is loosing its ability to act as a battery, it will start throwing random codes at you. If they do a load test and it comes in at 75% or less, replace the battery and then see what you have. The car will still start fine, but it will be causing the voltage coming out of the battery to be too low while cranking and this is when the computer is setting up some of its reference values which will then throw off things later.

 

Thermo, they are putting on a throttle body they know I good to try. I don't think that what it is either but hard to argue with them. The battery is less than a year old so hopefully it is still good but I will have the check that Monday. The have smoked and pressure tested it twice with no failures. I spay tested it a few times before I took it to them and the idle never changed. If there is a way bringer rid if the limp mode in would just run it the way it is but limp mode sucks in hills. Thanks for all the help and ideas.

 

Slur, unfortunately, there is not bypass to the limp mode as that is all controlled inside the ECU. So, unless you got another ECU and then had a custom tune done to it (good luck finding a shop that can do that), there is no bypass I am aware of.

Just because the battery is only a year old doesn't mean anything. I work around batteries at my work (the one I play with is capable of powering a small town, literally). The battery can go at any time. Deeply discharging it will hurt it. Doing some periodic maintenance on the battery can help extend its life (if you want to know what to do, let me know). But, in a lot of cases, just through normal use the battery will suffer some internal problem and it will die right there with no warning. Our cars are especially sensitive to when a battery starts to show signs of a pending problem.

 

Thanks Thermo for the reply. I will have them load test the battery Monday.

 

Here's everything that has been done and we are still getting the same codes. Smoke tested twice. Pressure tested twice. Passed all test. Battery load tested. Checked ok. Tried different throttle body same codes still showed up. Other than just starting to by new parts what else to check. This is all done at an import shop that specializes in European cars also.

 

Did they replace the upper and lower intake manifold gaskets or just figured they were good because nothing showed up on the smoke test? Those are definitely wear items on our cars.

 

Alfadude, When I took it to them they were sure that was what the problem was but would verify per the smoke test. They passed that so they tried a pressure test and they passed it so they moved on to a couple other things and then did another smoke test and pressure test. They are ruling them out since they didn't smoke and it is holding pressure. Could it still be them? They are frustrated and so and I.

 

Slur, based on what you are describing, your problem is most likely associated with the accordian boot just upstream of the throttlebody. Either the boot is not on the throttlebody well enough, not tightened down enough, a small rip in the accordian portion, or, the penetrations are leaking slightly resulting in extra air being allowed in downstream of the MAF sensor.

Granted, it may still be the intake seals as the pressure test may be repositioning the seals so they seal during the pressure test, but when you pull a vacuum, they move to allow leakage and since they are deep inside the engine, it would be hard to see them sucking in any smoke. We are not talking about the upper manifold gaskets, but the lower intake gaskets (where the intake bolts to the heads).

 

Thermo, thank you for the help. I was wondering about the pressure test doing that to the gaskets. Please correct me if I'm wrong but the upper and lower use the same O-rings but most of the time it's just the uppers that get replaced. From what your saying I should have him replace both and see what happens. If nothing else it's preventive maintance.

 

Slur, upper and lower gaskets are not the same gasket. They are actually very different gaskets. Specifically, you want:

Felpro Intake Manifold Gasket Set MS 96485: Get the best Intake Manifold Gasket Set at Advance Auto Parts (aka, Felpro MS 96485)

and

Felpro Plenum Gasket Set MS 96496: Purchase the best Plenum Gasket Set at Advance Auto Parts (aka, Felpro MS 96496).

Those two sets will take care of everything that you need for the intake.

 

Thermo, do think that will take care of the codes?

 

SLur, it is hard to say. It sounds like you have a very interesting vacuum leak. The trick is finding where the leak is coming from. You are looking at a leak somewhere between the MAF sensor and the heads. This may be one of those things that you have to pull things off 1 at a time and do a very detailed inspection. It could be something as obscure as a crack in the intake manifold or something as common as a gasket that is bad on the intake. But, in short, it is going to take some time and careful looking to get to the bottom of this.

 

Thanks for all the help Thermo. I guess I will wait and see whatcthe shop finds. I will keep you posted.

 

Update.
The shop replaced the upper and lower intake gaskets and the knock sensor. I had them check the plugs and they were fine. Why they had the car down this far I also had a new belt tensioner put to stop the squeak. So after $700 the codes for the air are gone. I do get an occasional 430 code and I will probably space the O2 sensor as it has newer aftermarket cats. Glad the car is running will. Thanks to everybody for the help.