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TFSI hesitation/missfires at high rpm's
- Thread starter jon-tfsi
- Start date
JBS did suggest that i get a compression test done. More so that I can rule out any problems in that area than anything else.
These engines can use a lot of oil and can suffer quite badly from carbon deposits building up on the intake valves. Once large amounts of deposits build up on the valves it can affect the tumble flow.....or so I've been told.
Air is supposed to flow smoothly over the radius of the valve and kind of do a lap of the cylinder, mixing with fuel before combustion.
All photos i have seen of this engine with the intake manifold removed, there has been LOTS of carbon deposits on the intake valves, even with engines with only 20k or less.
As the motor in my car has done nearly 60k and uses a lot of oil, Im beginning to wonder if this is part of the problem. Im just clutching at straws with this idea but Im running out of them.
Changed the plugs again today for colder copper ones to see if that helped.....no joy!
Also removed the low pressure fuel pump at the weekend to inspect the filter was not blocked. Got a price from David at SERE for this unit for£93. Cheaper than I expected but I dont want to go changing things willy nilly.
All 4 plugs appeared to be the right colour ie not running rich or lean.
With the In-Tank fuel pump does anyone with vag-com skills know how to log the performance of this if its possible?
Booked in for compression check Friday
The compression check was done last week.
The mechanic said the results were fine.
1 2 3 4
140 135 135 140
So the problem lies elsewhere
JBS suggested it could be injectors or the in-tank fuel pump
Surely there will be a way of knowing, or at least having some idea before changing things for the sake of it?
The mechanic said the results were fine.
1 2 3 4
140 135 135 140
So the problem lies elsewhere
JBS suggested it could be injectors or the in-tank fuel pump
Surely there will be a way of knowing, or at least having some idea before changing things for the sake of it?
zyklon
Guest
On channel 103 of the vag-com, low pressure sensor, I think if there is any problem with the pressure from the tank, will reflect on channel 103. Seems that the correct values are accelerating from 4 to 6 bar.
Do you have the PDF user's Audi Germany D*P? seems very interesting, they say there are problems with the valve springs too soft.
Do you have the PDF user's Audi Germany D*P? seems very interesting, they say there are problems with the valve springs too soft.
Thanks for that info zyklon.
There has been some issues with the low pressure fuel sensor on these engines. There was a recall on sme Mk5's and this sensor was replaced with a revised version.
Mine has been swapped for one from a 57plate S3 so I would have to be the unluckyest man alive to get a second dodgy one
Injectors. I 've got same car, Seat changed most things that should cause this problem then they went dead on me. I showed them every tsb or whatever there called and they still couldnt and would'nt fix my car and then started blaming my mods. I then said i would take the car to a specialist and if they could find the problem Seat bristol said they would fix the car. I took the car all the way to APD in Dorset from Bristol and after a week of having the car they said it was injectors. After 6+ more months i battled with Seat to get the injectors done even though they said they would fix the problem. Long story short Seat changed injectors, Exhaust (dont Know why) and whatever else and the cars never been better and now running stage 2+ with absolutely no hicups.
When you get injectors changed please block off intake manifold and you may never experience this crap again.
I truly feel your pain.
Give APD a call and they will tell you exactly what i went through and how you can fix your problem.
When you get injectors changed please block off intake manifold and you may never experience this crap again.
I truly feel your pain.
Give APD a call and they will tell you exactly what i went through and how you can fix your problem.
I've been following this thread on and off. Can't remember if it's been suggested before but have you tried some injector cleaner (redex maybe)?
This problem is driving me mad...to the point of thinking about selling the car.
I dont want to just give up, especially after spending so much time and energy trying to get to the bottom of it, but I cant see me investing much more of my life on a lump of metal. Dont get me wrong I love my cars but if i dont get this sorted soon its going.....
There seems to be lots of missfires occuring on these engines for many different reasons.
We got some more logs done on the car 2 nights ago (thanks again BLADE). We checked for missfires on chanels 14,15 and 16. The car was hesitating randomly after 5000 rpm and absolutely no misfires were counted what so ever!!!!!
Went along to a rolling road day on saturday at RS tuning to see if that would shed some light on things. As expected the graph looked fine until 5500rpm then went all wavy till 7500. It AFR was getting a bit rich further up the revs too
I have put several lots of injector cleaner in the tank, and have even rigged up a vacuum line from the intake manifold, drawing redex in through a football inflation needle. Just like the good old days of pooring it straight into the carb to clean the intake valves.
The car has been to JBS twice for diagnostics which is over 2 hours away from me and still the issue has not been diagnosed.
I have been talking to a very helpfull and knowledgeable REVO engineer in the last few days about the problem. There is many things that could cause these hesitations that have been observed by the REVO guys and the list has been exhausted.
There is one thing thats shown up through logging tho that would explain why there are no misfires showing up........through the rev range the actual boost pressure meets the requested boost and sometimes when it hesitates the requested booost pressure drops right down then picks back up again.....Why would this be?
I dont want to just give up, especially after spending so much time and energy trying to get to the bottom of it, but I cant see me investing much more of my life on a lump of metal. Dont get me wrong I love my cars but if i dont get this sorted soon its going.....
There seems to be lots of missfires occuring on these engines for many different reasons.
We got some more logs done on the car 2 nights ago (thanks again BLADE). We checked for missfires on chanels 14,15 and 16. The car was hesitating randomly after 5000 rpm and absolutely no misfires were counted what so ever!!!!!
Went along to a rolling road day on saturday at RS tuning to see if that would shed some light on things. As expected the graph looked fine until 5500rpm then went all wavy till 7500. It AFR was getting a bit rich further up the revs too
I have put several lots of injector cleaner in the tank, and have even rigged up a vacuum line from the intake manifold, drawing redex in through a football inflation needle. Just like the good old days of pooring it straight into the carb to clean the intake valves.
The car has been to JBS twice for diagnostics which is over 2 hours away from me and still the issue has not been diagnosed.
I have been talking to a very helpfull and knowledgeable REVO engineer in the last few days about the problem. There is many things that could cause these hesitations that have been observed by the REVO guys and the list has been exhausted.
There is one thing thats shown up through logging tho that would explain why there are no misfires showing up........through the rev range the actual boost pressure meets the requested boost and sometimes when it hesitates the requested booost pressure drops right down then picks back up again.....Why would this be?
zyklon
Guest
Since I saw in the paper that talked about a German problem with the valve springs, misfire over 5500, I am back to find out if this could be the solution.
According to Audi. wrong valve springs other soft painted yellow / white are bad.
Painted blue / yellow springs correct. These springs are all equally responsible for S3, TFSI 200cv Leon, Leon Cupra, Golf MK5 GTI, etc.
According to Audi. wrong valve springs other soft painted yellow / white are bad.
Painted blue / yellow springs correct. These springs are all equally responsible for S3, TFSI 200cv Leon, Leon Cupra, Golf MK5 GTI, etc.
mailat
Guest
Log the fuel rail pressure. There might be a problem with the HPFP and not being able to keep the pressure up and the ECU sees that and lowers the boost for a second. That's my problem now, because I don't have the uprated HPFP and I run on boost 8 on Revo Stage 2, and between 5000 and 6000 rpm I get hesitations from the ECU lowering the boost from 1.4 to 1.2 bars. After 6000 rpm the camshaft spins fast enough for the pump to make the 120 bars needed to keep the necessary boost. So... try that, maybe something's faulty with the HPFP.
After test driving the car and doing VC logs, JBS concluded it was the N75 valve that controls the wastegate, which made sense. This was replaced but didnt solve the problem. So do you mean it could be the wastegate itself Dan?
It does hold requested boost well until things start to get messy at 5500+
This does concern me Zyclon, and it cant be ruled out yet.
After checking for missfires recently, none were recorded through VagCom.
The REVO engineer seemed sure that if it was a valve problem, misfires would be detected.
Im a bit gutted that its only just come to light that there are no misfires been recorded. If I had realised this earlier, the focus might have been in other areas.
It is the injectors, mate my car did the exact same thing your describing. Bucking from 4k rpm onwards regardless of gear, i then installed pump and car would run to 5k rpm then just start dying. With absolutely no codes unless it threw me into limp mode. Give APD a call.
For months I thought this was the issue. I just lived with it whilst the car was under warranty, knowing that at some point an uprated HPFP would be fitted, the software upgraded to stage 2+ and I would be happy with the car.
The fuel pressure was logged before the HPFP upgrade, and it did drop by about 20bar when the hesitations occured.......so it was assumed the FP was the fault.
An Autotech HPFP was installed, the car was taken out on a test drive and the symptoms persist. I was fully expecting the problem to be solved.
The fuel pressure has been logged since the HPFP has been installed and there is no drop in pressure even through the higher revs and hesitations.
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