So I just got my 2000 STP back and had the following done:

- All 4 cam tensioners replaced
- New heater valve
- New control arms and ball joints
- Shift linkage adjusted

While it was in the shop, I suspected the car had a serious manifold gasket leak or manifold crack on the driver side. Under heavy throttle, there is a sound that is best described as a "fluttering" that immediately sounded like an exhaust leak to me.

Jaguar mechanic, bought a new manifold with the other parts but upon examination said it was NOT a leak from the gasket or manifold (given that he bought the part I would think he would be incented to install it)

He did say that the Jag has a new stainless steel CATGO exhaust system and while he saw no leaks in it either suspected it was "just how the exhaust sounds" which I am having a very hard time believing.

I cannot believe anyone would produce an exhaust system that sounded like this... its not flattering to the car

So if it is not the manifold or gasket and not the engine (mechanic was 100% certain of that) where else should I look?

The Cats?

Anyone have experience with this fluttering sound on acceleration?

 

67 views and no help?

I am no Jaguar expert but I fear my problem might not be exhaust system related and be more along the lines of a leaky injector and/or injector seal. I get a faint smell of exhaust when the heater is on and the aforementioned fluttering sound appear to be related.

My google-fu search continues but if any real experts want to chime in, it would be appreciated.

 

I'm not a real expert but I've never heard of this issue before nor can I imagine what it sounds like. A video would be helpful.

A leaking injector or seal would release raw fuel, not exhaust gas. Doesn't sound like an exhaust leak in any case.

 

Good points. Would be nice to find it is not an injector problem. I have also read others with a similar problem talking about the EGR valve and an associated tube that goes bad.

I am convinced the two symptoms are related at this point.

Since the car is only 60 days old (to me) and the "fluttering" under acceleration has always been present, I have no baseline to compare performance. That said, I am pretty sure the acceleration is effected and I would expect more from this 4.0

Here are the details as I know them:

1. There is no CEL currently

2. I am going to pull codes anyway but was delayed when I learned that the dealer installed sub and amp has a sub volume control installed right in front of the ODBII connector... smart.

3. The smell is mainly present at stop lights, when idling in park, etc.

4. There are no issues with starting or idling. When starting the car jumps up to 1.2-1.5k for about 10-12 seconds then settles in at a very quiet 600rpm and never varies. I assumed this to be normal.

5. Aside from the lack of true acceleration power and the sound, the car seems to behave almost perfect. Again note that this is my first SType.

6. I am averaging about 25mpg mostly highway and light driving, nothing heavy.

 

#4 and 6 sound normal.

 

I'm 1 of the 67 but there was nothing about the smell or injectors back then so nothing to say, really!

Injector looks very unlikely. No evidence for it.

Is it exhaust or maybe burnt oil? You will need to figure out which because you'll be looking endlessly at the wrong things otherwise.

You're likely to need OBD and to be able to record data on the move, which may make it non-DIY depending how handy you want to be and how much time & effort you're prepared to put in.

Modified cars are the hardest to diagnose, by far, so you're likely to want a good tech with in-depth jag experience of that specific model and engine. Don't assume a dealer has anyone like that.

 

As I mentioned in your other post about this, considering the symptoms you are having the first piece I would take a look at would be the Purge Control Valve.