Leon FR tdi ‘miss’ over bumps/undulations

[W9SHY]

Hoping for some advice which could shed some light on an ongoing issue, currently running a 2010 Leon FR tdi(170 bhp) the problem been when going over sudden bumps or undulations on a partially open throttle, especially on a change of direction the car feels as if it is suffering from fuel starvation for a second or two then is fine. Replaced fuel filter as soon as I got car, also car has been remapped but problem happened prior & after this. Any help on this matter would be greatly appreciated. I’ve seen similar threads on other VAG forums but there was never any outcome or solution.


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[Jimbobcook]

Do you have anyone near you with vcds or a live logging program as this be able to help with requested fuel/given.

@Legojon or maybe @Sharpy may have an idea...

 

[Legojon]

Does it still do it with the traction control turned off? Since @Jimbobcook tagged me... I'll tag him back with a question... you ever been hard on the accelerator and hit a dip in the road and seen what happens in our Cupras? I wonder if it's that? If the dips big enough, mine dumps the boost and I have to build the power back up again. Really annoying.

 

[Jimbobcook]

Does it still do it with the traction control turned off? Since @Jimbobcook tagged me... I'll tag him back with a question... you ever been hard on the accelerator and hit a dip in the road and seen what happens in our Cupras? I wonder if it's that? If the dips big enough, mine dumps the boost and I have to build the power back up again. Really annoying.

I've never had this... Maybe I don't have as many bumps near me haha this a fuel pump thing? Nothing likes bumps but I've not had any issues apart from a broken spine in mine lol I would of asked if yours did the same if felt it haha

 

[Legojon]

I've never had this... Maybe I don't have as many bumps near me haha this a fuel pump thing? Nothing likes bumps but I've not had any issues apart from a broken spine in mine lol I would of asked if yours did the same if felt it haha

Haha, maybe you just don't drive like I do. But if it's what I'm thinking of, my Cupra does it, my FR+ did it. So I've never thought anything of it. Other than its frickin annoying. Only way I can describe it, it's a bit like when you hit a puddle and you have a temporary drag.

 

[Sharpy]

Mine does this from time to time, it’s normally for me when I’m low in the Rev range and light throttle application. It seems in mine to be intermittent and made worse using cheap fuel. Not sure if it’s the exact same issue though.


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[W9SHY]

Mine does this from time to time, it’s normally for me when I’m low in the Rev range and light throttle application. It seems in mine to be intermittent and made worse using cheap fuel. Not sure if it’s the exact same issue though.


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Sounds very similar, it’s almost as if the throttle can’t decide whether it’s open or not, my brother runs the exact same car as me but has no issues, previously ran an A3 2.0 tdi(same engine) & that had a similar issue but not as pronounced, another friend currently runs a 2.0tdi A3 (140 bhp) & that has the same issue!

 

[W9SHY]

Does it still do it with the traction control turned off? Since @Jimbobcook tagged me... I'll tag him back with a question... you ever been hard on the accelerator and hit a dip in the road and seen what happens in our Cupras? I wonder if it's that? If the dips big enough, mine dumps the boost and I have to build the power back up again. Really annoying.

I will try the ESP off to see if this has any effect, thanks

 

[Sharpy]

Sounds very similar, it’s almost as if the throttle can’t decide whether it’s open or not, my brother runs the exact same car as me but has no issues, previously ran an A3 2.0 tdi(same engine) & that had a similar issue but not as pronounced, another friend currently runs a 2.0tdi A3 (140 bhp) & that has the same issue!

Sounds very similar, I thought / think it could be linked to the throttle position sensor as well. As they are electronic, if the sensor is starting to age then it could cause some issues.

My other thought was EGR, when mine does it I also get a load of crap kicking out the back when I put my foot down, then it gets better. I was wondering if rubbish in the EGR was getting into the engine to cause a bit of a delay at low revs... all speculation at the moment though.

 

[W9SHY]

I thought about the throttle sensor as well, if your in 4th gear at about 30 mph it’s as if it can’t decide if throttles open or not, more often than not though it’s over bumps or crests in the road on a partial throttle opening. Tried turning ESP off today but still does it, have had it on a code reader/fault finder once but only thing that showed any variation was a spike in the fuel temp sensor the same time as the ‘miss’ but wasn’t on the roads where it does it all the time so couldn’t replicate it, may just be easier to go another way to work


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[Sharpy]

It’s sounds exactly the same as mine 30mph in 4th, change gear, all is well.

I don’t get anything on the error reader so it’s hard to track down. I’d be tempted to go with TPS and hope it resolves it.


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[W9SHY]

Yeh it’s a bit of a needle in the haystack situation, sometimes it’s worse than others to the point where the passenger can also feel the hesitation, my brother has his own garage & has just got the latest snap on fault finder so will have to take him for a ride out on the roads that it does it on, hoping it’s a simple fix, thanks for the help


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[Sharpy]

If you do manage to fix it let me know, if I haven’t resolved it in mine I’d like to know.

If I fix mine I’ll let you know.


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[jdmsx]

Have the same problem here in my 2.0tdi Ibiza, there’s a particular dip on my commute home that it always occurs at, 30-40mph, 4th gear, slightly downhill, almost like the car doesn’t want you to accelerate while already going downhill and hesitates for a second. My mate had the same problem in his VW Caddy in the exact same spot. Maybe a safety feature with the ABS. Yet to try it with the ESP turned off

 

[W9SHY]

I tried esp off & was no different, feels more like fuel starvation,but was also told about a possibly faulty throttle position sensor, hoping to take the car out with a fault finder to see if it shows anything up on that, I’ll update once I’ve done that


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