hi guys, I've got a 2016 f type r with velocity crank and blower pulley, full mina gallery intake, and velocity tune. upon installation of everything I put in some heat range 8 plugs which afterwards I found out velocity recommends against because of misfire issues. after installing everything I did develope a cyl 5 misfire pretty quickly. I put heat range 7s back in it and misfire persisted. so I've changed the #5 and #4 coil packs (diagram for correct cyl is confusing) and still misfires. I've even reinstalled the factory tune and fired it up, no change. Now the weird part is, on cold start it doesnt misfire at all. you can drive it around for 10-15 mins with no issues, even do wot pulls. but after that period of time itll start misfiring so bad it's like a dead cylinder. if your driving I've noticed you have to come to a stop/idle and itll immediately start missing, and once it does it doesnt matter if your cruising, accelerating, or idling, its misfiring. Has anyone had a similar issue? I hear injectors go out often from deposit buildup often but if that were the issue youd think its misfire from startup. I'm thinking maybe like an injector seal? like it works well enough until everything is properly heated up and expanded allowing it to leak or something?

Plugs came out clean. car has right at 60k miles. and injectors haven't been changed to my knowledge ever. 02 sensors are new, cats are gutted, and the motor is also brand new. less than 3000 miles on it, but everything around the motor including the injectors I'm sure have 60k miles. any help would be great. thxs

 

update: I've dumped a can of sea foam into the tank, rocked it back n forth a bit to stir it up. and have let it idle an hour now, without it reverting to the chugging misfire. I can feel a small jerk every few mins though. I've tried slightly revving and holding it around 2500 rpms and itll run smooth for a few mins then I can start to feel a vibration show up but it goes away when I let off the gas. its definitely not running perfect but not getting the dead cylinder feel like it does after being driven. might back her out in a min and see what happens

 

false hope, moment I started driving I could feel it start to miss and as soon as I came to a stop, car shaking chugging started and continued all the way back to the garage, even at idle.

 

Though I don't have an F-type R, I do have an XKR with the same 5.0L engine and this smacks of a faulty fuel injector. The same symptoms you're reporting have happened to me twice and each time was fuel injector related. It is a well know issue on the 5.0L direct injection engines but is corrected easily with the injector replacement.

 

Sorry to hear about your problems but on a side note which plugs specifically did vap say dont fit.
I'm fitting the same plugs that The Rock 88 fitted in his car as im getting a misfire at the top end when wot and going 100 plus.
Plug model is NGK ILKAR8H6, think there heat range 7

 

I would be interested to hear about the plug recommendation as well...as they (VAP) specifically recommended the cooler plugs and even sold them on their site. This is also in alignment with general practice relating to plugs/tuning/hp. I did the same thing on my 911 Turbo after a bunch off mods that added +100 HP and it actually got rid of the mid range sputtering. Did it on the Jag, and so far running great.

Curious if they changed their position, and why? The plugs are actually HR 8 (ILKAR8H6-96024), which is one cooler that the OEM HR 7(ILKAR7C-10).

DC

 

 

Thanks for sharing, Glave! I'm running the HR 8 plugs. No problems yet, but its nice to have a data point in case I start experiencing misfire issues. Good luck and keep us posted if you get this sorted out.

 

Thanks for sharing that info. I have the HR8 (maybe before they changed?) and have no issues currently. Good info though, if I start to have problems, I will get some HR7, and go back to that! Perhaps I am not having issues because I did set the gaps to .036?

On your misfire issue....I looked through SDD and some suggested checks (possible problem areas) are: High Pressure Fuel Pumps, Purge Valve Test, Datalogging to see which Cylinder and then check injectors...Not much else listed for misfires.

Good luck.

DC

 

I had a misfire on tick over on my 2013 5.0s after re-installing a modified tune after having the car serviced with the stock tune installed. Reverting back to stock did not fix it. Took it to Jaguar who reinstalled a stock tune and the problem was cured. Sent the new stock tune to the mapper who modified it. I installed the modified file back in the car and all was fine. Mapper thinks software was modified when the car was serviced and re-installing the old modified file caused the problem.

 

So now what do i do then, spent over £100 on plugs that might not be suitible for our cars even though vap sold them and recommended them.
Now they say dont fit them!!!!

 

Just a data point....Mine have been in for ~2500 miles and it purrs like a kitty No issues at all and fast as hell too...Just FYI.

DC

 

Ok, so now that I have installed the gapped HR8's as recommended, Your now saying to go back to the HR7's? I have full bolt ons and tune. I do get a misfire now and then. So your probably correct. Whats the Gap setting on the HR7's then? .03 - .036? I was just looking at buying all new coils. Didn't think your spark plug suggestion would have been the problem.

 

sorry for taking so long to reply. busy week. this is a velocity reply regarding plug gap recommendations. I'm sure some people will have success with the heat range 8s, I doubt they all cause issues, but apparently it's bad enough that even NGK acknowledged it, so use caution.

 

So your saying to use the OEM HR 7(ILKAR7C-10) GAPPED TO .028 - .032ish on a Type R with full bolt ons and tuned to 660.

 

I have a misfire issue as well. Started with a cat code so I installed vap cats and then the tune (also vap springs). After 2 days, it started misfiring and running rough. I'm getting my 14 v8s diagnosed on the 17th. My shop is pretty busy. Hopefully not a major issue. The car has 86k miles. Never had spark plug or injector changes.

 

i found this regarding misfires our cars get, and a misfire can be caused from hard acceleration with a weak fuel pump which then causes the injector to go bad. My 1st miafire showed up during a wot pull. so im liable to find a bad pump along with my injector change.

 

and yes stuart satter that is correct

 

I wonder if this is also my issue.

 

Changed the plugs back to the 7's and its running perfect. Ran some cleaner through the gas as well. Thanks for the info!