I have had a few problems thinking they were all related, well let's see what you guys might think.

It started with DTC codes indicating lean on banks 1 and 2. The consensus was to check all air intake to make sure there was no leaking, this I did. Obviously not well as you will see later on.

I decided to change all my O2 sensors and that did make a major difference. Before I could come up to a stop light and the engine would cut out, coasting downhill, engine cut out.

Now lets go back a week or two.

Some days she would be as smooth as could be, other days I have no idea how I managed to get to my destination; sheer luck.

So I decide, after ordering the O2 sensors, to take another look under the bonnet. Lo and behold there was a loose pipe (pictured). It was actually hanging out and I have NO idea how I missed that. Might need new glasses. Anyway. I seated the pipe correctly and the stalling got WORSE, every time I went below 800rpm she would stall, coasting downhill, stall, stoplights, stall. nothing would keep her running below 800rpm.

Jump to last Friday and I change out the O2 sensors. OH MAN what a difference, no DTC codes, smooth as can be. Driving is a pleasure again. Fuel consumption went down

60 miles later, DTC codes P0171 and P0174 banks 1 and 2 running lean and the rough idle is back to being intermittent. She is not cutting out on me now, which is a good thing and the pipe is seated correctly, to my eye (which we all know isn't very good).

Plugs are going to be changed SOON but I do not think they or the coil packs are the problem. Unless you know different.

I am not getting any misfire codes.

Guys, please point me to the next step.

THANK YOU.

Mark

 

I don't presume to speak for Jaguar because we've had our 2005 S-Type for only a couple of months now and it has been problem-free, but the symptoms you describe turn up frequently on the Lexus forum that I've been on for years with our 2004 RX330. The most popular fix that seems to clear up your symptoms almost every time is to clean the Idle Air Control Valve (IACV). The second most popular fix is to clean the Mass Air Flow Sensor.

Hopefully one of the actual Jaguar techs who frequent this board will be along shortly to nail this down so you won't be stuck for too long....

 

Have you cleaned the throttle body? What year and engine size? The air flow meter was a good idea, too.

 

Sorry guys.

I keep forgetting to post year etc.

She is a '01 3.0

I did clean the MAF a month ago. All that did was decrease my fuel consumption which I enjoy.

Have yet to clean the throttle body. Hopefully I will get to that this weekend.

 

Just put your car info in your signature. That way you never have to mention it. Let us know how the TB cleaner goes.

 

Consider it done Ken, thanks for the tip.

Will clean TB as soon as I am able and will let you all know.

Mark

 

Guys let me chime in on this thread.
I have had three units in my shop with the same code.
In each case I filled the manifold with smoke from our smoke machine to find leakage at the O rings where the sandwich plate arrangement is fixed to the head(s). The last unit defied the repair and still flagged a code (P0174) Having looked at the history & scanner on interrogation I found that it was bank B that was again running lean. The same hose as your had failed previously!(fixed by another shop)
From experiences I opted for the maf sensor as being the most logical failure point although I confess it at the time it was a crap shoot since I would have expected it to show a lean mix on BOTH banks. Currently a "head cratcher" because a maf change fixed it! Gone for more than a week with no problems or codes pending.
As a footnote another shop has reported in Califonia through the iATN network a similar experience with the same fix--Change the MAF!
Must look into this more deeply
Dennis

 

Thank you all for the input.

Mechanic is taking her on Saturday and replacing all gaskets, plugs, checking all hose connections, and doing the oil too. Basically promising me he will find a cure by Monday.

Will keep you posted.

Mark

 

keep us posted, I had the same codes and gutted cats and some sprak plug nonfouler on the o2 sensors finally cured it.

 

Update,
I picked her up this evening, I have not heard her running so sweetly on idle.

It seems I had a few problems;
Spark plugs seemed to be original one, changed.
Three pipes were changed (told you my eyesight was bad) one was totally disintegrated. In my defence, it was at the back of the engine.
Throttle gaskets changed and body cleaned.

I am in love again. The next 100 miles will be the real test.

Mark