Intermittent-pulsating power delivery ?

[mazza7282]

Evening all

Car = 2005 GTI 200 DSG

A few months ago I had my high pressure fuel pump replaced along with cam follower as I was getting sporadic power delivery, feeling jerky pulling away which in turn lead me to call out the AA as the car was undriveable, foot would be flat to the floor and i could barely climb above 4000rpm in any major hurry, reading here its a common fault anyway.

Problem seemed to go away for a few weeks but then it happened again after filling up, I thought OMG dodgy fuel but then problem went away for many weeks so I ignored it.
As I thought car was running hunky dory, I then took my car to get a stage 1 remap + DSG map, managed to get 236.6bhp and 306lb's ft which I was happy with, and along with the DSG box performing a lot better (all be it more jerky than usual) I carried along my way.

Then a few weeks after than the original problem I descibed earlier happened again, my vagcom displayed all sorts of error codes 04243 and 00665, along with 002-lower limit exceeded.
Problem was as I dont use the car regulary and the problem was so intermittent it was barely noticeable so I left it eventually I then returned it to my mechanic who then hooked it up to the laptop and performed an ODIS upgrade and was able to keep my stage 1 dsg map, I was advised that this was an update for the fuel pump and that the main ECU map would be bypassed.
I did however have the stage 1 DSG map removed, and put back to the latest map (also done with ODIS) as the gearbox was too jerky for my liking, around 50% faster but it wasnt smooth anymore.

The jerkyness/intermittent power delivery was most often than not felt when the car had just started up and I would give a decent amount of throttle, although since the update that problem has definately gone away.
Although today I went out in it, allowed the car to warm as I was driving before a more "spirited" drive was to commense and all was well until I came up to a set of traffic lights. Went to pull away and the original problem occured.

So i've had a new HP fuel pump, cam follower, ODIS update ....... despite my stage 1 engine map or not as the problem was there before I am unsure of how to proceed further, anyone out there that can help i'd be forever in your debt ! as this problem has been going on for almost 3 months now.

Thanks all :)

[mazza7282]

Just to add, i plugged this into my cheap vag code reader off ebay today and i got no codes, took into my vag mechanic and hes got no codes either on ODIS.
Strange that it didnt even record a fault :(

[mo]

Symptoms sound to me like your maf is faulty tbh. May be an idea to run some logs. Do you have a copy of the scan you did ?

[mazza7282]

Hey

No I don't i'm afraid my cheapo code reader doesn't record logs only codes. Didn't think of that TBH.
I would have though if it was the MAF, it would be more prominent than non existent, driving it today hasn't done it once.

Definitely food for thought though

[mo]

Had the same symptoms on 2 previous cars. Next time it bogs down try pumping the gas to see if it picks up any quicker than if you just left your foot down. Does it ever stall when coming to a stop ?

[GrayMK5GTI]

You need to do some proper logging with VCDS to find out exactly what's going wrong.

If the guy that mapped your car knows anything about the TFSI engine he should have logged the car afterwards to check the map wasn't asking too much of your components.

Tbh I can't believe you took a poorly car to get tuned 

[mazza7282]

The map was done at R-tech as per reading/recommendations on this forum, the car only played up once after my high pressure fuel pump & follower was changed so then I just forgot about it didn't do again for many weeks until a short while after the stage 1 map.
As I said I had the DSG stage 1 map taken off as the gearbox didn't like it too much, although after similar reading on this forum my woes with the gearbox seem to be common place.

It's been plugged into VCDS, ODIS and I know the car has been driven around and logged as my Vag mechanic had the car for a week I got it back only just last week, and there wasn't anything untoward recorded.

Problem is the fault is so intermittent it happens like once or twice a month, which obviously makes it harder to diagnose 

[GrayMK5GTI]

If it's intermittent then it's going to be difficult to trace. Does it do it when your low on fuel or any other conditions?

Logging with VCDS (not reading fault codes) is the way to do it.

Is everything tight on your HPFP?

[mazza7282]

Yea all things tight on HPFP, no leaks or anything.
I think your right btw on the MAF sensor, car started doing same thing again yesterday (just as I was bloody pulling away aswell !) which in turn lead me to break down.
This time car would continually cut out, when you rev'd the car the rev's would increate very gradually/intermitent at a random rate. I decicded to unplug the MAF sensor and behold car hold's revs and I was able to drive it home, I would have thought the car would cut out aswell with no sensor plugged in but nope I was able to get it home.

I started to get worried as no engine management light appeared, although when I arrived home, restarted the car it came on and the engine was able to rev freely, when plugging MAF sensor back in again car would cut out.

So i'm going to obtain a new one, see here what engine was doing when MAF sensor plugged in and foot hard down on accelerator

A new OEM one from euro car parts is £126 or a 2nd hand one for £50 off ebay do you think ?

[GrayMK5GTI]

Unplugging the MAF and finding the car works better confirms its the MAF.

Get a genuine brand new one, wouldn't waste your time with second hand one, could have same problem again.

Let us know if it's fixed once and for all then 

[mazza7282]

That said .......

What if I have a boost leak somewhere, and plugging the MAF in detects this therefore making the car hunt  around ?

Do these even fail much on the TSFI ? these parts aren't exactly cheap :(

[mazza7282]

In the end decided to get a used MAF, managed to get one for £30 from someone breaking a car. Decided to remove the airbox to clean/re-oil the pipervcross air filter and also noticed the plastic funnel rattling around inside (the silly plastic clips have snapped off).

Binned that, as it serves no viable purpose...Anyway refitted and same with MAF, reset the codes with chepo tool, started car with no issue.
Booted it around for a bit after warm up and seems to drive fine (but ill drive it a bit more as remember the prior issue was intermittent).

Checked for more codes again and the other mish mash codes have disappeared as per the air mass sending dodgy reading to various other parts of the car...... apart from the lamber sensor 0537-033 which keeps comming back. Why has this started showing up now ?

Car still drives fine and now I guess I might have to fork out for one of these now, £70 for a bosch part.