Hey guys, I need to ask you a question.

I have a 16 F-Type R AWD. Car is great, love the looks, the performance, the sound.

But there is a thing I hate.

The idle. The damn thing behaves at idle as if it had an intermittent stutter / shake / hiccup of sort.

Absolutely nothing wrong with it when it is on the move, no issues with performance, no misfires, nothing. Then I come to a stop at the redlight and it begins.

It can be felt mostly via the seat, a hiccup / shake of a kind but with absolutely no dip in rpms. Can be felt by both the driver and the passenger. Zero faults when scanned. Sometimes it is more evident, sometimes less evident but it is there all the time, no matter if engine is hot or cold.

Several techs that I visited so far either say that it is normal or that it is not normal but have no clue what to do about it apart from throwing thousands of dollars in parts at it and trying to figure it out that way.

So far I did replace one engine mount that was damaged, no change.

New spark plugs. No change.

Coil packs inspected, supposedly good.

Injector cleaner ran through a tank. No change.

MAF readouts show exact figures on both sides so I assume they are both fine then.

Car does it in Drive, as well as in Park or Neutral.

From extensive reading of the forum (but mostly in XJ subforum) it seems as if this engine has this issue from factory, however some threads state that it may be a serious timing or VVT problem that needs to be addressed.

So here is the question - do any of you guys experience anything similar in your V8 F-Types?

Please let me know.

Thanks!

 

Have a '16R too; idle is, and should be, completely smooth and consistent in and out of gear.

 

Mine does so as well, but it's so infrequent and slight, without riding in other identical cars, I can't tell if it's normal or not. Suggest you find someone with a similar model and sit in it with it idling and then decide.

Expensive guess: Injector issue.
Cheaper guesses: I recommend the "wiggle test" where you wiggle the injector and spark plug connectors while the engine is running. If it's intermittent, that will quickly identify the troublemaker.

Beyond that, yeah it could be a lot of things. Until it gets worse and/or throws a code, it could be $$$$ making blind guesses.

 

Have you checked the O2 sensors? Evidently, on the F-Types, they go pretty quickly. The injectors also go quickly (compared to my experience w/ BMW) will tend to stick open or completely closed. In my case, the injector stuck open and dumped raw fuel into the exhaust system. After fixing and a lot of driving all is well. Another thought is that you might actually have a vacuum leak somewhere. When the SC creates the boost, the car is probably compensating with the extra fuel when you hit the accelerator, removing the rough idle.

 

Vacuum leak??
Though would expect a CEL

 

You're totally right - it would throw a CEL. The only other thing I can think of (if it's not another mount) is logging the car when it runs (OBDII) and seeing how it performs. Quick tip - you can actually go to Autozone and get a scanner/logger as a "free loaner". If you've eliminated everything else then looking at what the computer might help. According to the UK forum, the rough idle issue appears to be the vacuum lines going to the motor mounts (a new one for me personally). I'm thinking something is loose or broken. I do remember the SVR having a much beefier feel to the idle compared to the 3.0L V6.

 

Both of the items you mention, injectors and 02 sensors, will throw codes if malfunctioning. The OP states that there are no codes stored (“Zero faults when scanned”).

 

Thanks for the responses!

I bought the car last summer and it had that slight stutter in the idle since day one with me.

However, shortly after I purchased it it threw CEL related to O2 sensor in bank 2. I was pretty positive that this was the cause of the idle issue and expected that replacing the sensor (ended up replacing two, sensor 2 and sensor 3 in bank 2) wil fix the problem. It did not.

Occasionally I get „tighten fuel cap” warning on the dash but it happened only like 3 times in those last 14 or 15 months of my ownership so it does not seem related (no fault from evap was stored in fault memory anyway).

When the driver’s side engine mount disintegrated I was actually more than happy to find out about it as at that time I was SURE that this was the source of the problem. Once again, with replacement installed, vibration remained the same.

Recently I went to an indy who has some kind of special JLR test software and when he checked everything there was a recent O2 sensor fault code stored from bank 1 but there was (and still is) no CEL on the dash and when fault was cleared and driven for a while it did not show again even via this tester of his…

I have a problem finding anyone with a V8 F-Type in my area, even online listings show only some located like 200 miles away from me. I did however meet two owners of V6 F-Types (one 340 base and one 380 S) and they both vibrated more but in a more organised way, it was just a constant fairly serious vibration in the cabin, with no weird stutter, while my car vibrates less overall but has that strange shake/hiccup inbetween the otherwise normal smooth (when compared to V6) idle.

Today I took it for a spin and cold start idle was really jerky/shaky but what is new is when out and driving I noticed some sort of a thump coming from rear underside of the car under sudden load. Now this is once again a sparkle of hope that maybe my transmission mount or rear diff mount failed and maybe that’s why I started to feel the vibrations from the engine a bit more recently?

Car is booked in for checkup at official jaguar service (yeah, 120 miles away from where I live so a nice 240 mile round trip) on next friday. It will be an expensive visit I guess and knowing how official dealers are usually clueless this is a desperate last resort idea on my prt but I guess I will hold on to that hope for now.

I also hope that maybe they will have a 5.0 F-Type in stock so I can check it out and compare to mine.

 

@Sgratmtv, if there is no MIL, use a smart phone with the Torque app to connect to the ECM via the OBD port using a Bluetooth interface to read fuel trims and fuel pressure. In addition, check to see if there are any pending DTCs and list them here.

 

Mine does that too but, as you say, it's so infrequent and slight that it's barely noticeable, certainly doesn't shake the car.

 

Broken or clogged cats can cause funny symptoms (but are usually accompanied by a CEL)....might be worth checking.

 

Will do that asap, gotta get to someone with a test tool as most BT devices I tried so far either do not work with my Jag or do not work with iOS devices...

Will report back soon!

 

Yes, I’m dealing with that too. The.dealer found codes. They rearranged the coil and the plug to see if it comes back. We are waiting for a fault. This 5.0 engine is not as smooth at idle as my 5,0 Range Rover. It’s another open item.

 

Consider the transmission mount too?
I would replace the other motor mount and the transmission mount from your description of the problem.
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Hey,

just had a chance to read data from the car.

Long term fuel trim bank 1 and bank 2 are the same 3.125%

Short term fuel trim bank 1 -0.781%
Short term fuel trim bank 2 +0.781%

Short term fuel trim sensor 2 bank 1: 99.219%
Short term fuel trim sensor 2 bank 2: 99.219%

Fuel rail pressure: varies from 33.9 bar. (3390 kPa) to 34.7 bar (3470 kPa)
Fuel rail pressure desired: 34.9 bar to 35.5 bar (at all times real pressure seems to be around 0.8 to 1 bar lower than desired figure).

When it comes to pending DTC what showed up today was: O2 sensor 2 on bank 1 (rich to lean) but no MIL and this sensor was actually replaced like 3 months ago.

However, one interesting thing that I noticed was in section called: Misfire cylinder data 1-8 test value. Cylinders 1,2,3,4,6 and 8 were at 0 and cylinders 5 and 7 counted 1 (later cylinder 7 actually showed figure 2 while cylinder 5 stayed at 1 and all others at 0).

Does that make any sense or gives any hints? Attached are photos of data from obd scanner.

Thank you very much!

 

I had a bad mount for the transmission replaced a few years back. Had a thunk on shifts and a shake. After mount replacement no thunk and smoother.

 

@Sgratmtv, from the results given by your scanner, it would appear that there may be injector(s) sticking open on Bank 1 since the PCM is attempting to go lean on Bank1 while increasing fuel to Bank 2. Quite often Bank 2 will show misfire(s) as you are seeing on cylinders 5 and 7 as they are the furthest from the high-pressure fuel pumps if there is an abnormal loss of pressure on Bank 1, which is usually due to sticking fuel injector(s).

 

Now that you've put down that diagnose it seems more than logical. Thank you very much.

What do you suggest could be a proper way to resolve the situation? Replace 4 injectors on one bank or all 8 just in case?

EDIT: on a second thought. I did replace spark plugs a few days ago - NONE of the old spark plugs showed any signs of injector issue, not a single one blacker, darker or looking different than the rest.

Also, is there a chance that the corrections between banks are due to worn timing, mechanical issue that makes PCM try to correct it?

Furthermore - if misfires on cylinders 5 and 7 are due to their location away from fuel pumps, how come they manage perfectly fine under full load when much more fuel is needed?

 

Tried that route, my tech checked the mounts again yesterday, no issue present.

 

Unless the vehicle has over 200,000 km or the maintenance intervals have not been completed, there should be no issue with the primary and secondary timing chains, guides and tensioners. You can remove the cam covers and rotate the engine in a CLOCK direction when viewed from the front to verify if the flat alignment marks on the camshafts are synchronised.

At WOT the injectors are open for a longer dwell, thus the sticking ones on Bank 1 are not an issue as the high pressure pumps increase fuel pressure to both cylinder banks.

From my personal experience with the AJ133/AJ126 it's best to replace all injectors on the same cylinder bank due to the amount of labour needed to replace one or two. With the spark plugs and injectors removed, the cam cover can be removed to inspect the camshaft timing should you feel that's necessary.