MK5 Golf GTI

All Things Mk5 => How to Guides / Troubleshooting => Topic started by: AlexRennieGti on March 01, 2019, 06:21:49 pm

Title: Loss of power
Post by: AlexRennieGti on March 01, 2019, 06:21:49 pm
Hi guys looking for some help with a weird fault.
I have a mk5 gti with 2.0tfsi engine. I was driving along motorway yesterday and car lost power. Engine won’t rev passed 4000 rpm. Car struggles too pull to any speed. Also car struggles too start. Had a garage scan it today no fault codes showing up at all.

Any suggestions what I should look at next ?

Thanks

Title: Re: Loss of power
Post by: muff1991 on March 02, 2019, 12:05:13 pm
Are you only having trouble starting in the colder weather? I’m having power cuts at 4K too and also cold start issues, when freezing it starts but cuts out, when milder it starts but laggy throttle.
@pudding has been helping me out with this issue, and I think it’s come to the conclusion it could be fuel cuts (maybe a tired hpfp) and an air leak or some other electrical issue for the cold starts. I also have no codes flagging up! But issue sounds very similar... let me know if you find a fix, and/or I’ll let you know too!


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Title: Re: Loss of power
Post by: pudding on March 04, 2019, 12:28:47 pm
High pressure fuel pump I reckon.  You won't always get a fault code for that unless it fails to meet the required pressure for a set period / rpm window.   But that's what a lot of garages do isn't it.  No codes, send you on your way.  Was deeper analysis not offered?  Such as a road test with sensor logging?

Critical sensors like cam, crank, throttle and pedal are fault coded.  Emissions related faults such as lambda, cat efficiency etc throw a CEL.  There are a lot of items that aren't fault coded, so more investigation is required.
Title: Re: Loss of power
Post by: AlexRennieGti on March 07, 2019, 08:19:25 am
I have replaced my Hpfp and have regained most of my power but now if I push the car at 90-100mph the power is dropping away again. Put foot down and nothing. Think maybe need upgraded Hpfp as standard one not supplying enough fuel.

Thoughts?
Title: Re: Loss of power
Post by: pudding on March 08, 2019, 09:52:52 am
It won't hurt to add VIS internals but if it's standard, it shouldn't be doing that.  Time for some data logging of the boost and fuel rail channels I think.
Title: Re: Loss of power
Post by: AlexRennieGti on March 14, 2019, 09:55:52 am
Thought I had this issue fixed but not sure if it’s back or this is a different one now. Driving the car yesterday and was running fine then power went very flat as if no boost pressure. The power came back after a minute or 2. Went home all was fine. Came back out this morning car ran ok first 5 min then flat again. Turning the engine off and back on seems too make the power return as if it’s resetting something. Could this be caused by a bad dv ?
Title: Re: Loss of power
Post by: Chesto18 on March 14, 2019, 12:50:51 pm
Thought I had this issue fixed but not sure if it’s back or this is a different one now. Driving the car yesterday and was running fine then power went very flat as if no boost pressure. The power came back after a minute or 2. Went home all was fine. Came back out this morning car ran ok first 5 min then flat again. Turning the engine off and back on seems too make the power return as if it’s resetting something. Could this be caused by a bad dv ?

Doesn’t sound like the DV. They tear causing a permanent boost leak. Turning off/on won’t affect it.

TBH it sounds similar to an issue I had with an A3 many years ago and I believe is turbo related. The car would lose power out of nowhere, as if it had lost all boost pressure. A quick turn off and restart and it would be back to normal. No engine fault light either.  If so it sounds as if your car is cutting the boost pressure. I’m not sure why this would be, but someone will be along to help. Hopefully it’s just a dodgy sensor somewhere.
Title: Re: Loss of power
Post by: dazza on March 14, 2019, 01:01:07 pm
Sounds like its going into limp mode. My alhambra does this and only restarting the engine resets it. It goes into limp mode to protect the engine. The error i get is turbo overboost.
Title: Re: Loss of power
Post by: muff1991 on March 14, 2019, 01:46:45 pm
It might be worth chucking a new crank sensor in.. even if it’s just a Euro car parts one. They’re only £13


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Title: Re: Loss of power
Post by: pudding on March 14, 2019, 02:33:33 pm
Mine's been like that for years.  It can be really good for days and really flat and unresponsive for days, but stopping at the shops restores the power again.

No fault codes, everything logged, nothing out of the ordinary.  Beats me.

My tuner mentioned years ago he'd upload a map to a customers car, and then a few weeks later they'd ring back saying it's lost all it's performance.  He's also mentioned in the past about Revo maps leaving footprints in the ECU you can't get rid of when overwritten with a new map.  Maybe there's a correlation there.  Either way, the ECU is adapting down. Possibly because the 'driver demand' torque strategy it uses is confused by the requested boost and HPFP numbers of a remap.  Not sure!

Welcome to the inconsistent world of VW turbo engines.
Title: Re: Loss of power
Post by: AlexRennieGti on March 14, 2019, 02:37:32 pm
There are times the power kicks back in itself. Its not showing up any faults either.
Title: Re: Loss of power
Post by: AlexRennieGti on March 14, 2019, 02:40:04 pm
Mine's been like that for years.  It can be really good for days and really flat and unresponsive for days, but stopping at the shops restores the power again.

No fault codes, everything logged, nothing out of the ordinary.  Beats me.

My tuner mentioned years ago he'd upload a map to a customers car, and then a few weeks later they'd ring back saying it's lost all it's performance.  He's also mentioned in the past about Revo maps leaving footprints in the ECU you can't get rid of when overwritten with a new map.  Maybe there's a correlation there.  Either way, the ECU is adapting down. Possibly because the 'driver demand' torque strategy it uses is confused by the requested boost and HPFP numbers of a remap.  Not sure!

Welcome to the inconsistent world of VW turbo engines.


Your right it can have days even weeks of running perfect and then boom no power
Title: Re: Loss of power
Post by: pudding on March 14, 2019, 03:12:09 pm
With my ED30, it feels like all the power moves to the top end.  On a good day there's responsive torque everywhere, even off boost.  On a bad day, it can't pull the skin off a rice pudding below 3000rpm and feels really heavy and reluctant to get moving.

I've checked everything.  Binding brakes, flat tyres, boost leaks, PCV, DV, data logging.....everything.   

A new ECU that's never been flashed is my next port of call, but the faff of coding my key to it is putting me off.

One thing I and Muff1991 have noticed is the performance improves as the weather gets warmer!  Should be the other way round with turbo engines  :grin:
Title: Re: Loss of power
Post by: AlexRennieGti on March 14, 2019, 05:42:42 pm
Well guys driving home from work and power goes flat again. If I press accelerator on and off a few times power comes back briefly then disappears again.

Feel like just finding a big wall and crashing into it 😂😂
Title: Re: Loss of power
Post by: muff1991 on March 14, 2019, 07:10:16 pm
Alexrennie... is your car going flat at a certain point (rpm)? are you describing flat spots when pressing on or car just feels dead and laggy?

As pudding said, I have been chasing an issue with mine since November time! But unfortunately it’s only weather related so really hard to have the weather on a day and convenient time I can diagnose.

Mine started here:
We had a low (above freezing) morning and I started the car... idle dropped a lot quicker than normal.. and as I throttled to go I noticed the throttle was LAAGGGYY as hell.
Might be worth reading my cost start issue post for full detail.
But it was basically laggy up to 2k rpm and above seemed more normal.
Then even know engines fully up to temp, the car still drove like this!
When I booted it... it would reach 4K rpm and litterally CUT the power as if someone turned the boost off!! The DV psshhh can be heard and although I keep it pinned it can take a good few seconds which feel forever and then the power kicks back in like someone’s just give back all the boost it’s lost  ALL in one go!

After all that above started I noticed this...
As soon as the outside temperature is below 0 degrees the car starts on the button and the revs just die down and cuts out! Start it back up.. dies!
Even tried throttling to keep the engine running... but the pedal didn’t do NOTHING! Beats me mate! Done Throttle body, all the usual stuff.. logged all I know. And still no where!

My little experiment:
I took the ECU out the car today and wacked it in the freezer for 5 hours, plugged it back into the car and started it.. didn’t make any difference! I thought by freezing it would create below 0 for the ECU so that eliminates my theory of the ECU playing up when freezing! It’s something telling the ECU to draw back or the ecu is faulty and/or it’s the software!

I am going to send my ECU off to be tested and then if no difference I’ll be having a standard map put back on the car! Or as per puddings idea, grab a second hand ECU but will need to speak to some matey that has access to the Immobilizer, key coding and all that rubbish.

Throw around any ideas or more info. We gotta get to the bottom of all this! I’m certain your problem is the same if not very similar and on the same lines as mine!





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Title: Re: Loss of power
Post by: AlexRennieGti on March 15, 2019, 07:26:04 am
Hey guys new development with this issue. Came out this morning for work and started the car and warning light came on. Is it weird this kinda made me happy since it can point me in the right direction now 😂 so scanned it and got code P2138 which is throttle/pedal position sensor/switch D/E voltage correlation.

Anyone had this fault before ?
Title: Re: Loss of power
Post by: muff1991 on March 15, 2019, 07:29:33 am
Trust me.. I’ve been praying for the EML to come on too haha!

Get a new pedal and see how it goes mate.


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Title: Re: Loss of power
Post by: AlexRennieGti on March 15, 2019, 07:33:36 am
Trust me.. I’ve been praying for the EML to come on too haha!

Get a new pedal and see how it goes mate.


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Where am I best too get a pedal from mate ?
Title: Re: Loss of power
Post by: muff1991 on March 15, 2019, 07:56:20 am
Personally, I’d just get a second hand one off eBay for £30 ish otherwise TPS for new.


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Title: Re: Loss of power
Post by: AlexRennieGti on March 15, 2019, 09:40:34 am
They aren’t just out of golf the pedals are they when searching the part number it’s bringing up eos and tt ones too. Is it just a plug and play job ?
Title: Re: Loss of power
Post by: muff1991 on March 15, 2019, 09:49:01 am
I would type part number in and just get one that way I guess it doesn’t matter which car it’s from if it’s the same, I was told the latest revision part number for my 06 GTI manual is: 1k2721503am
If that helps at all.


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Title: Re: Loss of power
Post by: AlexRennieGti on March 15, 2019, 11:41:29 am
Where can you find out the latest revision you can fit mate ?
Title: Re: Loss of power
Post by: muff1991 on March 15, 2019, 01:06:13 pm
Where can you find out the latest revision you can fit mate ?
You can contact TPS or VW for the latest part number. But I got that part number from a mate a few weeks back who works at Audi so I would have thought you’d get given the same number.


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Title: Re: Loss of power
Post by: AlexRennieGti on March 16, 2019, 11:08:04 am
I done a check on the accelerator pedal with my obd eleven scanner it’s weird it’s working when ignition is on but soon as start the car it’s only going too 20%
Title: Re: Loss of power
Post by: muff1991 on March 16, 2019, 12:50:33 pm
That’s basically what mine does too but only really when weathers colder! I turn ignition on and can here throttle body doing what it should when I press the pedal.. as it all should! But when I plug vcds in and start the car the throttle pedal is showing it’s working where as the throttle body isn’t opening all the way! (I replaced TB but didn’t make any difference).

Throttle pedal defo sounds like it’s your culprit though mate! Might be worth just checking the electrical connectors/ plug and all that’s clean near the pedal before replacing though. I heard they can get a bit dirty and that and cause issues.


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Title: Re: Loss of power
Post by: AlexRennieGti on March 16, 2019, 07:01:06 pm
I’ve ordered one of eBay mate. £35 comes tested and with 30 day warranty so not bad. Should have it by Tuesday. Will report back once fitted

Thanks for your help mate
Title: Re: Loss of power
Post by: muff1991 on March 16, 2019, 07:02:18 pm
I’ve ordered one of eBay mate. £35 comes tested and with 30 day warranty so not bad. Should have it by Tuesday. Will report back once fitted

Thanks for your help mate
Nice one... defo report back, let us know how it goes


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Title: Re: Loss of power
Post by: AlexRennieGti on March 18, 2019, 06:21:09 pm
Hey guys good news. Replacement peddle fitted. Been out a wee drive and issue is now fixed. Thank god. Now means I can focus on all the other wee niggles now like the wheel bearings that are away and the rattle from front suspension 😂 it never ends does it
Title: Re: Loss of power
Post by: muff1991 on March 18, 2019, 07:57:21 pm
Hey guys good news. Replacement peddle fitted. Been out a wee drive and issue is now fixed. Thank god. Now means I can focus on all the other wee niggles now like the wheel bearings that are away and the rattle from front suspension it never ends does it
Good news mate! Literally always something that needs sorting on these lol but that’s part of the fun I suppose.


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Title: Re: Loss of power
Post by: pudding on March 20, 2019, 10:53:43 am
Interesting!  I reckon the pedal potentiometers develop a dead spot, which the ECU can work around up to a point.....and then throws a code when it can't.   I think in VCDS you can plot the pedal movement in the graphs section.  You will see if there's a dead spot with that.  Same thing happens to in-tank fuel pumps.  Sometimes you can whack the petrol tank with a hammer, which will jolt the motor onto a different part of the commutator and hey presto, it starts!
Title: Re: Loss of power
Post by: BURGEY on August 03, 2021, 01:32:17 pm
Having the same problem here, I suspected a turbo issue as many of you are also thinking and it seems when I looses power my boost drops form 25psi to about 5, going to start by replacing the dv to the gfb one see if that solves the problem