I’ve been following this thread with a somewhat detached interest until today. After returning from a 30 minute drive I was backing into my garage and was coming to a stop when all of a sudden the throttle surged. Thankfully I was almost fully on the brake and it only bucked a bit. The surge lasted for a few seconds till I punched the P button and just immediately shut the car off. I restarted the car and no surge happened and briefly put it in drive and no change was noticed so I put the car again in park and shut it off. Did not drive it for the remainder of the day today, but will take it out tomorrow to see what happens.

Gotta admit it shook me a bit as well. It’s never done anything remotely like that before and had it’s annual service in April.

 

Yep, the four times mine has surged now varied a little in extent, ranging from around 3 seconds to around 6 seconds.
It hasn't done it for three or four days now so maybe it was the Oxicat which has now all burnt off.
But I am in the middle of another little experiment - CRC intake valve cleaner plus oil change straight after.
Half way through the 60 minute heat soak then I go for a 10 minute drive then change the oil as soon as I get back, will be interesting to see what happens (or I hope doesn't happen!)

 

Thanks Oz I look forward to hearing your results. I haven’t put any cleaners in so I am ruling that cause out, so I’m interested in seeing if it’s the throttle or the sensor or even a spurious engine computer code. I’m bone stock so I can also rule out any tune being the cause unless the OEM one just went wonky.

The irony is that this is one problem I dread having manifest itself again to be able to diagnose, but then again not knowing why will haunt me as well. Guess I’m standing on the brakes for a while!

 

We’ve not encountered this issue in the past. Suddenly, 3 such occurrences. Marko recently had his car in for service. Oz, did you recently have yours in for service?
Maybe a transmission software update is the culprit.

 

 

Nup, I have never had a service done at a JLR dealership (and never will!), the last service (or any work on the car at all) done by anyone other than yours truly was going on two years ago at an independent workshop when I had the crank pulley fitted.
The car has never had a trans software update.

 

That's certainly a very scary experience

It may be an unpopular viewpoint - but is there any possibility you're clipping the accelerator pedal by mistake? I had a very similar issue 4 or so years ago with the Land Rover. 2-3 times over a month it suddenly surged Eg when pulling up at traffic lights. Had to stand on the brake to stop it moving and put it in neutral. I was adamant it was the car. But - on the third time I forced myself to lift up my feet (no cars in front) and it immediately stopped. The very edge of my shoe had caught the accelerator
Afterwards I researched this extensively and that seems to be the most common cause

 

That thought has occurred to me but in 5 years of having this car I’ve never done it before and can’t fathom that I did it now. But I certain,y will take that thought into account as it is a possible reason for the surge, but ultimately the surge only stopped because I shut the engine off even though I was completely on the brakes.

 

Hard to believe that 2 long term F-Type drivers (Oz and Marko) suddenly forgot where the pedals are.
Have the two of you started to wear clown shoes?

 

That depends on who you talk to.......

 

I think we may have a winnah!
I just checked, and yes when the brake pedal is lightly depressed it only takes a minor wiggle or twist to the right of my right hoof (while still firmly on the brake pedal) and suddenly I am pressing the go pedal down a fair bit.
Thing is I have MS and I have very little feeling in my fingertips or toes, exacerbated by "smoker's leg" such that I have poor blood circulation in my feet.
Also, the Porterfield R4-S pads I fitted a couple of years ago need a fair bit more pressure than the stock pads before they start to bite, which means I am pressing the brake pedal maybe 1/2" more/lower that I would with stock pads when slowly coming to a stop, AND the VAP tune is quite sensitive to small throttle openings (which is how I like it).
I reckon I'll just have to be more conscious of the placement of my right hoof when braking to a stop and make sure I keep it over to the left side of the brake pedal.
But Marko's recent incident still worries me.

 

I’d like to say it’s something as straightforward as slipping my foot, but it’s really not possible the way I was pressing the brake pedal to hold the car in place. I stab the brake pedal down with the tip of my foot to hold the car when this happens, I don’t think there was any way I was hitting the gas as well.

 

Left foot braking avoids the throttle pedal overlap, so long as you keep your right foot well away!

 

The problem with left foot braking is during panic stop situations. You’ll instinctually brace with both feet. Not good.

 

I think in a panic stop situation my muscle memory would force me to brake with the right foot (that always happens when I shut my eyes!).

 

About to head out in the next hour or so. Will definitely take note of vehicle reactions and foot positions. If you hear about a car backing through the wall of its garage “it wasn’t me”.............

 

Update: Travelled in the car for an hour, same settings and almost the same routine as yesterday. No instance of the issue this time at all. Of course as Oz has noted it may be intermittently I will remain vigilant

Clown Shoes Option: Ok as a nod to the possibility that it’s my fault, though I loath to even consider it was me This time I wore boat shoes instead of my recently purchased New Balance running shoes which possibly could have clown shoe qualities.....was that the difference? Barnum and Bailey remain skeptics.

 

Nothing happened which is good news!
Other than the CEL flashing for a few seconds early on in the CRC treatment and the usual bunch of misfire codes. Codes cleared, driven three times since roughly 30 km each time, codes didn't come back.
In fact something good happened - the throttle response is now better than ever, just a light prod and she flies! With a really solid and immediate "kick in the back" in D that previously I only ever got in S mode.
Back on topic, no more "surge" occurrences and the more I think about it and experiment with the placement of my right hoof and moving it from go pedal to whoa pedal the more convinced I am that it was driver error all along.
Of course if it happens again I am back to square one!

 

Minor update.
No more surging, I am now 99% convinced it was my right hoof slipping over the right edge of the brake pedal and onto the go pedal while still pressing the brake pedal. Even when not wearing clown shoes.
So this is now a plug for the CRC intake valve cleaner.
The car now goes better than ever in every way - better throttle response, better push under WOT and at the top end, but most of all smoother throughout the rev range and amazing at idle. Absolutely zero vibration at idle, the best it has ever been, if it wasn't for the tacho and the exhaust noise you would never even know the engine was running!

 

I think I’ll give that a go.