Lets see if anyone has any thoughts.

First I have no codes beyond an older occasional over voltage on bank 2 sensor 2 O2 sensor that is now replaced (as of Thursday) and should solve that problem.

I have a slight rough idle or slight tremor when I am in idle that I never had before. It happens when I engage the compressor (which is new from May 2012). If I put in neutral it is almost gone. I always am the worry wort about small issues that may morph into larger ones.

From a data standpoint my fuel trims at idle and 2500 and in general driving will tend to be Short Term on idle from about +2.3 to - 2.0 and LT% about +1 to -2. At 2500 (and general driving) LT are +.o8 on one and -.08 on the other- Clearly no problem with lean or rich conditions.
My rpm at idle are about 785 and when I engage drive and the compressor will drop to about 705 and run between 695 to 725. I do not know if this is normal or not?

In the past 7 months I have done the following.
1. Replaced all coils and plugs- using Denso/Jag coils and the NTK iridium
2. I replace the air filter every 3 month no matter what.
3. I clean the MAF once a month
4. New cats both sides
5. New O2 (Denso) sensors upstream/downstream both sides.
6. New PCV valve
7. New gas filter
8. Have looked to clean and did slightly the throttle bottle, but is was not really dirty in any way except for a few small areas of slight discoloration.
9. New AGM battery
10. New serpentine belt

Everything works fine, no ac problems in cooling or noise from compressor. Engine sounds quiet and the same as always.

No engine mount problems.

I use only Shell Premium
I have used at Gus's suggestion the BK (no change I could tell).

So what gives. I have been told by one of the Jag dealers (but I trust them not at all) that these cars do not like the ethanol in the gas and it causes problems for them- so I tried an ethanol stabilizers or whatever they call it and that changed nothing.

Could it be a small problem with the throttle position sensor, although everything else indicates the throttle is fine and everything in the car is smooth on acceleration at full load from 0 to about 125 mph before I pulled it back.

I have reset the battery/ erased my P1111 after I replaced the O2 sensor- so relearning to see if any change.

Suggestions and creative thoughts appreciated.

Tom in Dallas/Plano
2005 S-Type 3.0 84K

 

My car has always had that tremor at idle with the A/C compressor running. Many cars have it.

 

Understand. Mine did not use to and perhaps as I said it is more me than the car.

Thanks

Tom

 

As several of my friends are fond of saying, 'if it ain't broke, don't fix it!'

 

Which does not mean in our attempt to fix we can break it even worse. IE- you are saying leave well enough alone???? (and that perhaps I am being too picky)?

Thanks

Tom

 

It sounds normal but you could run it briefly missing the belt(s) then you'd find if it's one of the accessories etc rather than the engine.

 

I sorta did that and used the long stethoscope and nothing hears out of whack on any of the accessories.

Out of my curious nature what does the 3.0 suppose to idle at rpm-wise and how much should the a/c compressor pull from a rpm standpoint??

Tom

 

These functions are controlled by the PCM given input from several sensors. What exactly are you attempting to accomplish?

 

Other than general maintenance, I never had a slight rough idle or tremor (ac on or not) and one has now developed. I never like things on electro-mechanical devices to develop a problem it did not have before- as I generally think it is a precursor to potentially more serious problems. That is why I was asking what I might be missing (no intended play on words) that is causing the mild rough idle?

Hope that answers the question the way it was meant to be answered.

Thanks

Tom

 

Have you changed the IMT seals?

It is also possible you have a coil unit or spark plug that may be starting to fail without setting a DTC or triggering the MIL.

Why do you feel the need to clean the MAF sensor monthly?

 

And why are you replacing your air filter quarterly? Unless you are driving across the Sahara Desert on a daily basis, you are throwing money away....

 

Since we're beating up on your O/C tendencies, your dealer is an idiot. For all it's other shortcomings, E10 cannot and would not cause this. The 'stabilizers' if anything would make matters worse, not better.

 

IMT was done twice by dealer under extended warr. (I had oil pan leak and they redid many seals and as expected they did not get it right and had to do more and replaced those again). There are no water or oil leaks in this car at all.

I clean the MAF monthly (all of 3 minutes of work) as early on I had a dirty one when I got the car originally at 31k and it created RP at several wrong places in driving and so I made it a part of regular maintenance.

Funny story- here. I had a friend of mine that has an 04 LS430 that goes (use to go) to the same dealer. I had cleaned his MAF which was filthy and when he asked the dealer about this after having a cheap Lexus battery fail in the middle of the night after 6 months of use and a clogged air filter (despite their high charge for semi annual maintenance) and he asked the service department manager about it- he was told by the manager that he had never heard of any procedure fro cleaning the MAF and they just wait for them to code out and then replace- (despite the fact that their parts dept. sells 3 different types of MAF cleaners).

On the plugs and injectors. Some 6 months ago I had new plugs and 2 new coils (#1 and #3 put in- due to the manifold removal issue and the fact I had a crimped trigger wire or some such that was throwing me into RP and destroyed one of my cats). This last weekend I replaced the other 4- looked at plugs and they seem more than fine and the car drives as well as when I first got it with more spiff and response than before I changed them. Anything is possible, but the idle problem is the same as before the change as after.

Any other potential ideas?

Tom

 

Small cost to keep a clean air filter running at optimum. I am generally a big one for preventive maintenance that does not cost much time or money.

Tom

 

First you are wrong about the dealer, they are COMPLETE idiots, unethical, liars, arrogant, overcharge and have the worst quality control of any business I have ever associated with in my life. I would rather give the car away than deal with them other than perhaps the part's department for something I needed immediately vs. waiting for an online shipment.

So you may be very right, although I have heard this from 2 other Jag independent mechanics (one of which is well known in Dallas) I tried the stabilizer, which I used for one tank that seemed to do nothing, which I suspect is the best they can do- nothing. Just another negative point and lie from the dealer.


Thanks

Tom in Dallas

 

As for other ideas: go back and check over the wiring loom where it was crimped to make sure any repair to the wiring is still functioning correctly.

Do not add any other cleaners, conditioners and additives to the fuel system.

 

I generally do not add that sort of thing to the system. Just tried for a tank to see any difference.
The crimp was completely repaired by a very smart independent (great common sense) that had been a Jag tech. It was located under some of the black plastic electrical covering and I would venture much on a bet that it came from the factory that way and finally bit the bullet. It is not in a location anyone could easily get to, although I could blame the Jag dealer as they have the worst business practices I have ever seen (but I do not think they were even in that area). If it were a problem I had dropped out cylinders had multiple misfires, flashing CEL and all sorts of problems on passenger side bank. He did a thorough job and the wire that he repaired looked great when he showed it to me- spliced in and soldered correctly. had to use a snake camera to show me, but that has not re-occurred.

Maybe I am just being too picky. the car runs great, has all the pickup when I first got it in 2009 with 31 k on it.

This is really only a problem when in drive and the AC compressor comes on and at idle. If I go to neutral- not really any problem. At idle it adds abut 6-7% load- I know not if normal?

So such be our life in Dallas with the Jag.

Tom

 

The AJ30 V6 engine is very robust and is a proven performer in the Jaguar S-Type, so it may be best to just enjoy the vehicle and stop anticipating problems.

The Ford Duratec version has seen service in Ford and Mazda vehicles as well.

 

Should you again have a flashing MIL, do not drive the vehicle under the conditions that produce such conditions.

 

Of Course or I can get new cats as I did before. Only one went bad, but I replaced both. That much I did learn the hard way.

Just curious- is my rpm at idle with and without the ac on in the normal range? Is is possible to clean or even replace the TPS without replacing the while throttle body?

Tim In Dallas.