I had posted a thread awhile back that seemed to dry up. My current symptoms that seem to be getting worse:

Knocking noise (sounds like arcing) when going steady and pressing the gas enough to drop 1 gear, so moderate acceleration.

When this happens, the car falls on its face... The revs still climb very slowly, but it feels almost like I am hitting the rev limiter or as if it were misfiring.

If accelerating onto a highway, around the 3-4 shift, the car loses power and feels like it is misfiring. This happens with enough force to throw you forward in your seat.

I have replaced all of the plugs, coils, and manifold gasket due to leak. The previous owner supposedly put an aftermarket pulley on the S/C and put a cold air intake on. My local shop has given up (without any effort, only replacing things I have asked to have replaced - they seem completely uninterested). They noticed the knocking noise I referred to, but have no idea what is causing it. This is the only shop that works on Jaguar here and they are recommending that I just go to the dealer (4 hours away). I am at the point where I just want to get rid of the car and the problems and move on. The problem is, I really like this car when it is driving well. Does anyone have suggestions? I have only had the car a few months.

 

wasnt there a post about aftermarket pulleys affecting the supercharger snout??? ill have to poke around for it

 

almost reminds me of a MAF problem that have affected some of the 2.0TSI vw/audi engines in the new VW's

 

Would that cause a knocking noise?

 

Seems to me you need to be sure what the noise is. Sounds like it might be misfires from when & how you say it occurs but you want to know so you chase the right problem. The dealer can read extra data to check but expect to drive the car for them to show them. 4 hours away is sure a problem.

Are there no codes?

You could maybe use a good OBD tool where you set it recording, cause the fault and then take a look at the data. If you don't already know OBD this is probably not DIY. Or at least not easy DIY. I'd want to see the fuel trims as it occurs.

 

The feeling I get when it is making the noise and losing power is like when the spark plug boot in my 3 series had a crack in it and was arcing inside the cylinder. It didn't throw misfire codes, but acted very similar. I have already replaced the plugs and coils though and the boot is built into the coils with this car. The noise sounds to me like arcing, but I can't be sure because it doesn't do it during idle. It only happens under load. The mechanic said there are no codes being thrown by the computer or the transmission and they updated all of my software already. I am just at a loss as to how to fix my car without pouring thousands more into it. It was $1500 for plugs, coils, and the gasket. I paid $13500 for it 3 months ago and don't know how much money I can justify putting into it before giving up and trading it in.

 

That's a lot of money to avoid driving to the dealer

Does your guy not have a tool that's specific to the S-Type/STR and thus can do advanced diagnostics?

I'd look at the TB connector next if using proper diagnostics is not an option. And then maybe MAF. But it's very expensive to throw parts at any car instead of using diagnostics. (hmm, well, cleaning TB connector - not the TB itself - is near enough free.)

 

Change the fuel filter...

 

First lets do some simple low cost stuff.

Take the supercharger belt off and drive a bit or rev the engine. That will tell you if the super charger is involved. Just from the noise I almost am thinking the front coupler is worn? At higher miles some SCs will start to clatter as the rotors contact the case.

Then I would change the fuel filter and check the fuel pressure. You have a 2003 STR but how many miles? A few fuel pumps have been replaced on STR's. These cars have a different system from all other S types. Just a comment. The STR has dual high output fuel pumps and at 3K rpm the second one is suppose to kick in. Can you see anything RPM related to the loss of power??

With no error codes it's kinda hard to know. I would get the codes read myself just as a backup check. Any Auto zone will do it. Make sure they clear all codes after they read them. Even if no codes are present still have them clear everything.
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I have a basic OBD reader and am not getting any codes. The car has 65,000 miles. Is there a write up on how to remove the SC from the equation? I am not opposed to going to the dealer, I just don't want to waste 8 hours worth of driving and end up where I am at. I run my own business and work over 80 hours a week, so it is difficult to find time.

 

I will drive it to the store shortly and see if it shows during a certain RPM.

 

Ok, happens most frequently on a down shift that puts it in the 2k-3k range with it seemingly subsiding at 3k. It also still pulls very strong above 3k without a discernible knocking. Just the normal engine and SC noise. Could a baf main fuel pump make a knocking or spark knock sound? Perhaps if not enough fuel is available without throwig codes?

 

Also of note, the last time I cleared codes was 3 weeks ago due to a lean condition (P0171 I believe). The code has not returned and am still getting P1000, so the computer is still not reporting everything to be fine, right?

 

To contradict what I had just said: acceleration briskly from a stop, the car presents the same loss of power when changing gears (from 2-3 most likely) as soon as the revs drop from 4500 rpm to 3000 rpm. Major loss of power yet the revs continue to raise very slowly and almost seem to be wavering, if that makes sense? I apologize for the onslaught of updates, I am just trying to get them down before I forget. Thank you for all help!

 

Again to test the super charger remove the belt for just a temporary test.
Then I would get the fuel pressure measured. You have a test port to check pressure. Have you checked or changed the fuel filter yet? It's still a possible problem here?

Also P1000 just shows all the drive cycles have not been completed and the 5 systems are not in the ready position yet. When the drive cycle is complete you should get P1111. So it looks OK so far. Just remember you can't pass emissions testing until you get the P1111 code. You got this because you cleared all the codes which also resets the readiness monitors.

One other question; Does it seem different depending on how full the gas tank is? Will it give you problems with a completely full tank??
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If it was running lean and you still have what seems to be a misfire it sounds fuel related. I would check the fuel pumps too. In my turbo mr2 a bad o2 sensor would cause fuel problems also.

 

I would be happy to remove the belt for the supercharger, but am unsure which belt it is and how to remove it. Can you help? It seems to have the same issues regardless of fuel tank capacity. I have not yet done anything with the fuel filter but can schedule an appt to have it done. How would I go about measuring the fuel pressure?

 

jagstr03, definitely install a new fuel filter and be sure the top of the air filter box is properly secured. Worn/failed O2 sensors will make her surge, etc. and cause funky shift patterns too. I also almost want to suggest going over the plug/coil install looking for errors here too. Don't give up. You're likely very close to figuring this out and will likely be surprised as to the simplicity of the cause and repair.

 

Change the fuel filter...

My parrot BINKY who is wise only provides answers and then I have to go search for the question. I couldn't find it on **** sites, political blogs, my own forums and here it was. I guess that's why BINKY hit me again when I walked in the door.

BINKY

 

is it me or does this sound like the ABS/Traction control is activating on its own???

from his explanation it almost sounds like that to me.......almost like when i was trying to drive in the snow with my godawful goodyear tires....

Im kinda tired but is it possible it sounds like that also??? just wild guessing here

oh and to expand, maybe changing the fuel filters will get rid of the p0171 too. That is a trim 1 lean code if i remember correctly and the vehicle will go into restricted performance from it. Did this car sit for a while before you got it?