Can't sort a boost problem, N75?

[LSL]

Hey everyone, I've got a '02 1.8TQ and it's having a boost problem, I've had a search around but can't find much.
By the feel/sound of it it's getting to a certain pressure then dumping, so if I floor it from under 2k to redline it'll boost up and dump several times, you can feel and hear it losing power each time it does this although it's less noticeable at high revs.
I've changed the MAF, replaced all leaking pipes and fitted a Forge 007P, last thing to change is the n75 right?
Any help is much appreciated.
Cheers, Luke.

 

[Dani_B19]

Have you scanned for any fault codes?

 

[LSL]

Not recently as I don't have the kit myself. Last time it had 16706 engine speed sensor G28, 16514 pre-cat lambda sensor, 17544 too lean and multiple misfire fault codes. I replaced the speed sensor, MAF and fitted the 007P.

Edit: Also changed the thermostat as that was faulty, ****** sensors.

 

[<tuffty/>]

The too lean code maybe a clue have you fixed that? sounds like an air leak

You will need to scan for faults again really... copy the codes and clear then check to see what comes back in case there are some codes that are sorted and haven't been cleared... fault code info can be found on the ross tech wiki... there is a link in the thread in the stickies (thread link in my sig also)

<tuffty/>

 

[LSL]

I fixed two leaking pipes so that should have sorted it running lean.
I was hoping it would be something common I could fix myself, looks like I best get it looked at by the local VAG boys though!
Thanks for the replies.

 

[Dani_B19]

Where you based? You can buy a cheap copy cable and just scan for codes from ebay.

 

[LSL]

I'm in Bedfordshire. Ok I'll check them out, is there any particular type I should go for or just any OBD2 vag one?

 

[<tuffty/>]

.....is there any particular type I should go for or just any OBD2 vag one?

Follow the link in my sig (not my build thread obviously) as mentioned before... all info is there...

<tuffty/>

 

[LSL]

So as suggested I checked my fault codes,

16706 - Engine Speed Sensor (G28): No Signal
P0322 - 35-10 - - - Intermittent

I had this and one show up and one from where I'd disconnected the battery, cleared them and have been driving around for a couple of days now. Had no fault codes come back. Kind of disappointed haha!

 

[<tuffty/>]

16706/P0322/000802 - Ross-Tech Wiki

16706/P0322/000802 - Engine Speed Sensor (G28): No Signal
Possible Symptoms

Engine shuts off
Engine doesn't start
Speedometer inoperative
Glow Plug Indicator Lamp (K29) flashes

Possible Causes

Engine Speed Sensor (G28) loose
Engine Speed Sensor (G28) faulty

Possible Solutions

Check Engine Speed Sensor (G28)

Special Notes

The Engine Speed Sensor (G28) is also used as a reference sensor for the crankshaft position.

This would normally prevent the engine from starting at all as this is a particularly important sensor but what were the other codes you had?

<tuffty/>

 

[LSL]

The only other code was the one due to me disconnecting the battery.
I had the crankshaft sensor replaced a while ago so the fault I cleared must have been old, unless it's cropped up again :s

 

[<tuffty/>]

T...I had the crankshaft sensor replaced a while ago so the fault I cleared must have been old...

That what it will be then... phew

<tuffty/>

 

[LSL]

Well I must have tempted fate!
Driving home from work today my engine cut out then quickly came back to life (the rev counter hit 0 then came straight back up to where it was), EML came on. Checked when I got home and it's the Engine Speed Sensor (G28) again...
Now because I had that sensor replaced and the fact that you said it should be a show stopper I'm guessing it's faulty wiring, that's unless they changed the wrong sensor or fitted a duff one. Anyways I shall be having a search around the forum for people that have had similar problems and try and check the wiring!

 

[LSL]

Sooo I had the crankshaft sensor replaced again under warranty with the garage and it's still not boosting right, I'll have to wait and see if it stops throwing sensor fault codes though.

I'm all out of ideas at this point so far I've...
fitted new MAF
fixed all boost/vac leaks
forge 007p
new crankshaft sensor

I have a video of what it's doing if anyone's interested.

Also I'm going to be ultrasonic cleaning the FPR, injectors, cleaning TB and sump, fitting a catch can and new fuel filter soon but not expecting they'll fix it!

 

[Vwdan80]

I think the next best thing will be to do some logs and post them to see if anyone can spot anything wrong

 

[LSL]

Didn't realize you cant log certain blocks without paying for the full vcds. I was going to log 002, 003, 020, 115 and 118 as they were the recommended ones to start with in another thread.

Are these the correct blocks and if so is there a way of logging them without having to buy a full vcds?

cheers.