My wife and I bought a '13 XF 4 cyl for her and she loves it, but she mentioned a rough idle and I notice it too the few times I have driven it.

I can't find any discussions regarding a rough/erratic idle, especially when cold. I also notice the idle ranging between 750 - 850 RPM when stopped at different red lights. I assume some of this is related to the A/C compressor.

Anyone know of any solutions or whether it's worth spending time at the dealer?

 

What do you mean by rough? All four cylinder engines rock a bit on their mounts, fore and aft. This is a firing order imbalance that can't really be eliminated.

The reason V6 and V8 engines seem smoother at idle is more firing events. A four fires only twice per revolution. At 750 rpm that is noticeable.

 

It's definitely worth having the dealer look it over - they'd either identify some anomaly or let you know it's simply a four cylinder issue - though there are some very smooth idling 4s out there.

 

I'll have it checked out next week. The XF is going back to the dealer after getting the Cilijet paint application that put some swirl marks on the black paint and I wasn't happy with that. Wouldn't have done the paint sealant if the color wasn't black.

I will ask about the idle issue.

Thanks!

 

I completely reject the notion or even the hairbrained suggestion that just because it's a 4 cylinder it will idle rough..total poppycock and shows a total lack of real world knowledge beyond the frozen tundra way of thinking..

I had once a 4 cyclinder Toyota and a 4 cylinder Mercedes and both idled smooth as a Swiss watch..and those cars were from the 80's and 90's...the cars of today are MUCH MORE refined to say the least.

As a side note: I was at my dealer today and they were showing a 2.0 to a customer and had it running with the hood open..you could have placed a glass of Champagne on the engine and it wouldn't even of rippled, it was that smooth.

There is something wrong.

 

Depends if it has balance shafts. If it does it can idle smoothly, if it doesn't, it can't.

You cn reject all you like but physics is physics. Without balance shafts an inline four will rock front to back.

Only inline sixes, V12 and flat 8 are balanced without balance shafts.

Does the Ford four in the Jaguar have balance shafts?

No ripples in your champagne, really?

BTW, Swiss watches don't idle.

 

Cross plane V8s are completely balanced with the proper application of crankshaft counterweights, and therefore no balance shaft is needed. I could be absolutely wrong about this (shocking, I know...), but I would have to think that high tech inline 4 or V6 in premium applications would have to have balance shafts to make them acceptable and appropriate for the application. This is despite frictional losses due to the shaft that can approach 10-15 hp. The rocking in an inline 4 would be intolerable.

 

The 4 has counter rotating twin balance shafts. It is smooth for a 4. Often negated at idle when cold as not in closed loop and well, its cold. When warm the idle will flucuate based on power steering, alt, and ac needs as needed. The only issue seen so far is loose intercooler piping. Generally the drivers side bottom bolt loose or missing

 

Peanut butter and jelly don't idle either.

 

I brought the car to the dealer and the advisor said the irregular idle is characteristic of the 4 cyls. I didn't want to believe that, but they gave me an almost identical loaner vehicle when they reapplied the paint sealant to our car.


And sure enough when I started the loaner up this morning (cold engine) and put it in reverse the drivers bottom seat started gently rocking left to right. It only lasted a few seconds but it acted the same as our vehicle.


So, I guess it is the way the car was made...but I think Jaguar would have opted for a smoother start to greet the driver.

 

Four cylinder engines will always show a roughness at idle. Even balance shafts can't compensate for firing order imbalance. A four only fires twice for each revolution so at idle it will shake a little.
Apparently some people are unable to detect this vibration but any engine designer will concede you can't balance a four stroke four perfectly.

Four cylinder turbos are coming to all the European luxury cars soon. Nobody in Europe is going to afford 6 or 8 cylinder gasoline engines very soon.

 

Weird, I am not arguing with that concept just to argue but I have owned half a dozen four cylinders and never had any weird shaky idle issues. Granted, half of those were boxer engines which are known for being smooth but my wife's 4 banger Elantra is smooth as butter...

 

I guess that wasn't a option on the designing of the engine for cold starts

 

My sons Corsa's, Vectra, Astra, X type, VW Passat all have 4 cyliners and all exhibit this to some degree, some a lot less than others and some a little more

From cold and if you rev the accelerator in time you can almost rock the car a little.

It goes away after a little while, smooths out etc but it is what it is...

 

Hmmm, my 4 banger transverse mounted Toyota Carina 24V is a smooth as can be at idle, to the point where looking at the rev counter is the only indication that the car has not stalled at the lights.

Certainly I can't feel or hear anything.

To the OP, don't ever make a judgement based on a 'loaner' vehicle, we are all guilty of thrashing the daylights out of them, just to see what they can do without risk to our own hard earned.

 

Assuming 24V means 24 valve then that's quite a trick motor.

 

Some Carinas had the "Blacktop" motor with 5 valves per cylinder. Perhaps he meant to say 20V. 6 valves would be possible but perhaps a case of "engineering overkill," similar to a 2.5 liter V-12.

 

One man's rough idle is another man's what rough idle.

There is no basically way to perfectly balance a four cylinder. Various methods have been tried including active engine mounts. Balance shafts work extremely well but some rocking is going to happen whether you notice it or not.

Flat fours are very smooth because the rock in the horizontal plane only. The dynamic balance is almost perfect except the front pair of pistons moves outwards together and the rear set move together, that combined with the firing under cross crossing the block results in an odd twisting motion easy to see and easy to absorb with good engine mounts.

A flat 8 is perfectly balanced as is a flat 12 (189 degree "V" 12).

A flat six is not as it is effectively a 180 degree V6.

 

From reading the description, we may be talking apples and oranges here. The four cylinders of today are certainly more quiet than their predecessors and yes the "Ford" engine uses balance shafts, more compliant engine mounts and other assorted paraphernalia to make the engine seem more smooth and more quiet. That said, what Pete was describing was more of an idle surge, which IMHO is not the same as a rough idle. It could be something as simple as a fuel control switch or temp sensor or any one of a number of parts in the induction and fuel control system. You might take it back to the dealer, if it is still under warranty; however, you may have better luck with an experienced specialists shop in your area. Ask some knowledgeable individuals to find one. Good luck and let us know what you find out.

 

Our new 2013 has been to the sjop 3 times for rough idle. No fix yet. Last time, backing into garage after a 40-minute drive, the car stuttered and almost stopped, then suddenly lurched and almost put us into the house, if I hadn't caught it quickly. Safety issue. Bad when parallel parking, as you can imagine. Still awaiting resolution. Jag dealer jas had it fo a week, so far.


aft. This is a firing order imbalance that can't really be eliminated.

The reason V6 and V8 engines seem smoother at idle is more firing events. A four fires only twice per revolution. At 750 rpm that is noticeable.[/QUOTE]