hey so im new to this forum so please excuse me if this has been discussed but i could not find it. i have an F-TYPE R and i love it. i've always had M cars and this is a whole different animal.. so i have about 5k miles on it and im noticing now that I am starting to drive it harder that when doing wide open pulls in 3rd, 4th and 5th ( all ive done so far) when it hits what seems to be exactly 6k RPM in each gear it has a slight hesitation or a hiccup, almost like traction control kicks in for a second but its not.. no check engine light and the car runs absolutely perfect other wise.. any idea of what this can be? has anyone else had this issue? im a bit concerned so please any feed back will be greatly appreciated... any service techs on this forum??

thanks

 

​​​​​​I had that with a previous BMW. It was a reasonance issue affecting an ignition connection. It was under warranty so I don't know how they trouble shot it.

 

what exactly does reasonance issue mean?

 

At that RPM it vibrates one of the ignition connections and interupts it. It could also vibrate some other imoortant connection, of course, like a fuel injector plug, a sensor, etc. It would be worth making sure every ignition coil and fuel injector connection is secure, but thats not so easy with our car.

It could also be an intermittent internal disconnect within a marginal ignition coil at that vibration frequency.

At any rate, the low hanging fruit would be to make sure all electrical plugs and connections are secure.

 

got it, needs an oil change soon so ill have them look at it.. much appreciated.. any one else opinion would be great.. thanks

 

Usually hesitation or the behavior you described at the RPM, and those conditions would point to plugs and/or ignition (Coils). Since you state you only have 5K miles on the car, that does not seem likely, unless they are/were defective.
Again, if you have 5K, it is under warranty, so I would suggest getting it to a dealer and letting them use the SDD software to diagnose and repair it.

DC

 

I was thinking the same, that the coils themselves are probably not marginal at their age, so more likely a harness plug to a coil is working its way loose, if its a coil. OTOH, our coils are hard to install with out bending them due to tight clearances, so if one was removed and replaced for any reason it could have compromised it.

​​​​​​I agree with therock, the answer with our car is to find the best scan tool, since swapping a new coil through all 8/6 cylinders til it goes away would be painful.

An interesting question is can they rev to 6K RPM with the car still, or do they have to look at it on the road? I know some tunes remove the RPM rev limit when not moving, so its possible.

 

the car is a 2015 i bought it with 500 miles in October of last year.. i have an aftermarket warranty not thru JAG.. i can still bring it to the dealer with the warranty i have but for coils and plugs,a relativity low cost fix id just take it to my guy who does my work on my other cars.. i have the warranty for god forbid the motor or tras or a big ticket items went..

 

im not sure if a scan tool will do anything since its not throwing a CEL or code.. i wonder whet the cost to replace the coils and plus would be..

 

Depending on the tool used and sophistication, you will be able to read values that are out of range/problematic, but have not yet triggered a CEL. Additionally, tools like SDD, can read any instances of any activity, and allow
data logging so you can see the readings as the vehicle is running in real time.

So while no CEL is present, most tools may/will show you the caution indicators also (items that were not correct, but did not meet threshold to trigger a CEL).

Just FYI.
DC

 

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Is it me, or has people's spell checker gone AWOL on this thread... 🤣

 

good to know.. thanks for the info...

 

Is the supercharger belt slipping? When it does its usually on a hard pull and around 6000 rpm.

 

Must be you - I couldn't see any incorrectly spelt words ...

 

it always happens at exactly 6k rpm under wide open throttle.. so maybe this is what it is.. is this something that can be tightened? i really appreciate the input guys..

 

Wow!

 

The supercharger is on the front serpentine belt, so its easy to access. I can think of three reasons it might slip -
1. Worn belt, not likely due to miles but could be an age thing. A new serpentine belt is usually $35-$50. Note how it wraps around the front pulleys with a few photos. Then you reach down to stick a 3/8" ratchet into the socket molded into the front side of the tensioner pully arm and twist to remove belt tension while you slip it off of any pulley. Reverse to reinstall. Easy DIY.
2. A smaller supercharger pulley was installed and the spring in the tensioner pulley arm isn't strong enough to pick up the slack. A new belt and/or arm should fix it. You can tell if the superchager pulley has been changed because the smaller pulleys generally have a cone shaped front face, like this one.


3. The tensioner arm spring is too old/weak. A new tensioner arm w/pulley is around $180 if memory serves. There is a single bolt that holds it on which is an easy DIY too, but for difficulty seeing what you are doing while reaching down there due to the front-hinged clamshell hood. You can stick a phone in front of the engine and take some photos.
​​​​​​
A no cost way to see if its the belt slipping is to remove the belt and flip it inside out to see if the behavior changes. Its is grooved on both sides.

 

This may help related to the belt(s).

DC

 

Thats very helpful. #3 in the bottom diagram is the tensioner arm and pulley. #1 is the supercharger pulley. Below the #3 pointer is the 3/8" square socket to twist the spring loaded arm to remove tension from the belt so you can slip it off of any pulley, then remove it. Above the #3 pointer is the single bolt to remove and replace the tensioner if needed.

I kind of doubt its the belt slipping if you only feel a blip at 6K RPM. It seems you would feel a sustained loss of power as long as the RPM was over 6K.

 

Added the descriptions to my post above. Should have done that initially.

DC