[RobT]

Ola!

I've got a W reg Golf 1.8T (which used to belong to Rally_Chris from here) and over the last few weeks the car has been getting a bigger sudden flatspot when booting the car at low revs....

From low revs I floor it, the car pulls hard when the torque comes in, then about 2500rpm the it suddenly cuts like i've lifted off then comes back straight away.... it's not as violent as say... your foot slipping off the throttle but it's not far off.. it's almost like the turbo dumped it's boost.

Even my mum notices it now [:O]

The car is lovingly looked after and had a service about 3k miles ago... any ideas?

seems to make no difference if it's hot or cold.

The car is standard with the standard DV

Heeeelp!

many thanks

RobT

 

[RobT]

Popping to VW in Camberly at lunch.... gonna purchase as new DV as it's to too expensive... got a feeling this is caused by the split in the diaphram that is common... although my dv seems quiet

 

[Richy_50pence]

Hiya Rob

Ive experienced a similar problem a few times, twice on the motorway where the engine just seems to freeze!

Let me know how you get on because I have no idea whats weong, the car is in for a diagnostic test as I type!

Cheers Rich

 

[flynntech]

MAF Disconnect it and see how you get on.

 

[RobT]

OK Rich will do... going over to the stealers in 15 minutes to get the DV... wont have time to fit it until saturday though

 

[RobT]

Flynntech, what do you mean? disconnect it and drive it?

where abouts is it? sorry, not had the car that long)

 

[flynntech]

Its the sensor on the pipe going to the airbox. If you disconnect it then the car will run on default values and run better if the MAF is gone. Worth a try wont cost you a penny

 

[RobT]

Ahh cool will give that a try before i fork out

 

[RobT]

OK, disconnected the MAF, car doesn't seem to do that initial huge pull of torque but it also doesn't do the missfire/flatsopot. Pretty sure i'm getting some boost as the car is still fairly nippy

Reconnected the MAF and it's stayed the same as when i disconnected it! weird!

Think i'm gonna pop to the stealers tomorrow lunch and see if they've got time to kindly plug their box of tricks into it and see if there's a fault code or a gremlin hiding in there

 

[RobT]

Not had a chance to do anything about this yet.. still doing it though lol!

Suspect either the MAF or the standard DV... weird though cos it's like lifting off the throttle suddenly and stamping it straight down again!

Dont want to start shelling out for parts if i'm going down the wrong route.

Do VW stealers charge just to plug the diags in?

 

[Malky]

If you know someone with VAG_COM, you can do a log of the MAF readings. SHould be nice and smooth...

This is mine, it's fine....

 

[RobT]

Ahh right.. that's cool... i just read the thread about cleaning the MAF... sounds like the person has the same issue as me..... just need to find a security torx bit :S

 

[davemk]

Why don't you unplug the Maf and see how the car runs? If its the same, it isn't the MAF and problems lies elsewhere, perhaps DV? BTW, I cleaned my MAF and its made a hell of a difference. Worth a go, definately.

 

[RobT]

I did try that, it didn't do the flat spot, but also didn't do the nice rush of torque. I've already got the cleaner so i will have a go at cleaning the MAF if i can find a security torx bit.. gonna tray asda at lunch

 

[Mart4875]

Excuse for jumping in... But I keep hearing about the "MAF sensor". What is it and what does it do??

 

[boraboy]

Mine suffered from this, changing the MAF made no difference. I've put it down to the hybreed dump valve, but it is alot worse if I change from optimax to BP ultimate.

Now running optimax all the time and not noticed it for a while.

 

[J111ASE]

mart the MAF is an air flow sensor,its on the pipe that goes from the air box.i think im right in saying that put simple for thick people like me,petrol needs air to burn and the sensor check and adjust the air and petrol mix???am i right ish???[]

some one will put me in my place if im wrong[]

had a flat spot too,cleaned maf with alchol and switch cleaner and and runs much smoother.

 

[tdiconvert]

Quote: posted by RobT on 01/02/2005 12:46:22

I did try that, it didn't do the flat spot, but also didn't do the nice rush of torque. I've already got the cleaner so i will have a go at cleaning the MAF if i can find a security torx bit.. gonna tray asda at lunch

Mine was the same, more sluggish with the MAF disconnected but with consistent pull up through the revs. Sounds like you definitely need a MAF to me. Be careful though, my brand new replacement was also faulty and gave considerable flat spots! A second new one cured it.

I also recently tried dismantling and cleaning my original MAF sensor but it didn't really work. I think if your MAF has deteriorated considerably the isopropyl alcohol cleaning trick is less likely to work. Hope you get to the bottom of it.

 

[RobT]

Thanks sounds like i'm on the right track... i'm gonna clean the MAF tonight when i get home from work... i'll post with an update and probably some detailed macro photos to show the condition of the MAF and clear up any removing problems

 

[RobT]

Well cleaning the MAF sensor made no difference at all!!! back to square one.

Seems strange it's always at the same point in the revs.. never over 3k.

Dump valve doesn't make a flutter so don't think it's that.

Could be that the MAF is just knackered and changing it is the only way forward but it's an expensive assumption