Throttle flat spot issues?

[6xsteve]

I seem to have an issue where under certain conditions the car "hiccups" and then picks up again. Sent it into dealers and they can't find any faults with it on computer but I know its there as it happens regularly. Always around the 1500rpm range, usually with light pressure and acceleration.

 

Feels like the signal from pedal box is broken or turbo lag type cut out.

 

Any thoughts?

[Smeghead]

My MkI Fabia VRS used to do this (1800 - 2200 RPM).  Something to do with CO2 management to get the official figures, I believe.

 

No such issue with my TDI VRS O3 but it's got DSG which might hide that trait to a degree. I assume yours in manual??

[Mike999vRS]

I've had that too a few times. Forgot to mention it but no doubt it will be a feature!

[6xsteve]

My MkI Fabia VRS used to do this (1800 - 2200 RPM).  Something to do with CO2 management to get the official figures, I believe.

 

No such issue with my TDI VRS O3 but it's got DSG which might hide that trait to a degree. I assume yours in manual??

 

Yup, Gotta keep a log of it and submit it to dealer show conditions when its happening but they keep reverting back to the computer to see if it's a switch thing.

Edited 17 December, 2014 by 6xsteve

[6xsteve]

I've had that too a few times. Forgot to mention it but no doubt it will be a feature!

Same sort of conditions?

[meb90]

Have noticed the same thing on mine. TDi VRS manual. Haven't been able to work it out so far, but as it doesn't seem to be causing any issues I have so far ignored it. It happens to infrequently for me to worry!!

[pipsyp]

Dont know if it coincides with DPF regens? My 2.0 150 feels a bit flat and laboured when its regenning.

[meb90]

Quite possibly, I couldn't say for sure. Can't say I have noticed any difference when its doing a regeneration.

[JJBS3]

Mine is doing that too, can't identify a pattern, or trigger, so can't recreate it - VRS tdi manual.

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[fjrden]

 Mine appears to do this also. I first noticed it on a certain place on a certain road. Then my wife said to me she noticed it too. Haven't said anything to dealer as only have 6000 miles. Good to hear that it is just not me.

[GTR27]

I've noticed this in my 1.4tsi (manual). When taking off, if it bogs slightly, car appears to override throttle inputs for a bit (nothing happens it just kind of stays at 1200rpm, then it shoots off when car decides to read actual throttle inputs). It's taken me a while to get used to this, but just a few more revs taking off seems to solve it. Bit unnerving the first few times it happens as there is literally 0 power, but now I just make sure it doesnt drop below about 12-1300rpm when taking off and it is fine.

 

tbh, i'd sooner not have the "creep" function, and not have the car take the throttle input away from me ever. But not sure if there is a way to tune this out?

[Geek42]

"creep" function?

[GTR27]

If you let the clutch out in a manual, the car will pick up revs so it doesnt stall, so you dont have to use the throttle. Hence enabling you to "creep"

 

EDIT: I'd sooner it stall if it got too low in the rev department, and let me decide when to have throttle and when not to. I want a dictatorship, not a comittee

Edited 2 January, 2015 by GTR27

[Geek42]

Interesting. This is probably what I have experienced with the stop-start function. The description is exactly like yours, except that I only ever get it immediately after a SS induced re-start. If I pause momentarily before letting the clutch out it doesn't happen, and if I give a few extra revs to normal it doesn't happen. Maybe the "creep" thresholds are dynamically adjusted immediately after a start event?

[littleade]

My mk2 has an intermittant flat spot that happens on a slight trailing throttle when the engine is not under any significant load, typically around 2000 rpm when going down a slight hill, so it looks like there's something common that's not a 'fault' in itself.

[Geek42]

My previous Focus used to suffer from a hesitation when going downhill with cruise control on, and I always put it down to the throttle control not being linear down to zero but having some finite minimum, such that a demand for something between that minimum and zero would cause bistable operation between zero and that minimum value.

 

That's what it felt like anyway, and since it never happened with the CC off I didn't worry too much (well, until it started happening all the time, CC or not, up hill and down, on and off load, and the fault codes included DPF, EGR and clutch issues, then I got rid).

 

I wasn't worried about the Octy as I put it down to a function of the SS restart, but remembering the Focus I'm not so sure any more......

[6xsteve]

This is all great stuff people, Question is can it be fixed? Dealer says that unless the computer finds it as a fault code then there is "nothing for it TO fix".

 

Mmm....... :wonder:

[themanwithnoaim]

I've noticed this in my 1.4tsi (manual). When taking off, if it bogs slightly, car appears to override throttle inputs for a bit (nothing happens it just kind of stays at 1200rpm, then it shoots off when car decides to read actual throttle inputs). It's taken me a while to get used to this, but just a few more revs taking off seems to solve it. Bit unnerving the first few times it happens as there is literally 0 power, but now I just make sure it doesnt drop below about 12-1300rpm when taking off and it is fine.

 

tbh, i'd sooner not have the "creep" function, and not have the car take the throttle input away from me ever. But not sure if there is a way to tune this out?

Nope I've never experienced this but, I do have the DSG which maybe hiding the trait although having said that, I don't spend a lot of time in that rev range.

[GTR27]

Yes the dsg definitely masks this trait. I mainly noticed it when I first got the car. Now I'm used to it, doesn't really come up as an issue.

[jimmyp2]

Mine does this at times too. I imagine it is to do with getting Co2 levels down, others modern cars I know of also have a flat spot at certain rev ranges. I think only a remap will sort it.

[Gerrycan]

I've noticed this in my 1.4tsi (manual). When taking off, if it bogs slightly, car appears to override throttle inputs for a bit (nothing happens it just kind of stays at 1200rpm, then it shoots off when car decides to read actual throttle inputs). It's taken me a while to get used to this, but just a few more revs taking off seems to solve it. Bit unnerving the first few times it happens as there is literally 0 power, but now I just make sure it doesnt drop below about 12-1300rpm when taking off and it is fine.

 

tbh, i'd sooner not have the "creep" function, and not have the car take the throttle input away from me ever. But not sure if there is a way to tune this out?

I get this too with my 1.4tsi manual.

It has been mentioned a few times in this forum that sometimes when you press and release the clutch (without throttle input) the revs will lift briefly to 1300 revs. It does not do it every time with or without a gear engaged. I am not sure what actually prompts the action.

I think the combination of light throttle input and the clutch induced rev rise/fall confuses the electronic throttle control unit causing the 'flat spot' directly after a engaging the clutch at low revs. As you say a few more revs (to 1500) and it does not occur.

[deebeedee]

I get this on my 2014 Octavia VRS tdi - If I'm accelerating it never shows, nor if I'm keeping a steady speed. It's when I'm letting my foot of the accelerator slowly the engine will suddenly act like the fuel has been cut, only lasts half a second or so then the power is back. 

I've compared it to suddenly lifting my foot totally off but this is different, it's more severe.

Doesn't seem to be any pattern to it and I can't replicate it at will, which is annoying! It just does it now and again when it feels like it. 

I'd say if I'm driving at town speeds for 30 mins, it might happen twice in that time.

Does that sound about the same as your experience?

[meb90]

I get this on my 2014 Octavia VRS tdi - If I'm accelerating it never shows, nor if I'm keeping a steady speed. It's when I'm letting my foot of the accelerator slowly the engine will suddenly act like the fuel has been cut, only lasts half a second or so then the power is back. 

I've compared it to suddenly lifting my foot totally off but this is different, it's more severe.

Doesn't seem to be any pattern to it and I can't replicate it at will, which is annoying! It just does it now and again when it feels like it. 

I'd say if I'm driving at town speeds for 30 mins, it might happen twice in that time.

Does that sound about the same as your experience?

 Sounds exactly like how mine behaves, as you say much more severe than just lifting off, and completely unreplicable!

[deebeedee]

yeah man that's it! I'd love to know if it's a fault or just the engine/emissions system looking after itself. If I knew it is 'expected behaviour' I wouldn't mind.

It's not knowing that bugs me....

:-)

[meb90]

It was suggested earlier that it might be the engine/emissions system, making it expected behaviour.

 

It doesn't bother me too much, as it happens very infrequently for me too worry. Agreed the not knowing is frustrating!