LEON CR fluttering boost problem

[corradophil]

Wilksy, I'll try and get a photo for you at lunch time.

On the way to work this morning the boost looked fine and the power seemed pretty good, however it was hesitating very slightly. The boost pressure did not appear to be changing though. I'll have to wait and see if it gets worse, which will be more obvious to see on the gauge, assuming the problem is boost related.

 

[corradophil]

I haven't got access to a camera at the moment, but the N75 is located next to the diverter valve on the intake pipe just after the maf. To the rear, right hand side of the engine.

Have a look at these links for more info. Both these sites are discussing upgrading the N75, but it gives you the location and shows what it looks like.

http://www.peterbeers.net/vw_roadtrip/GTI/GTI_Mods/N75J/N75J.htm

http://www.izvw.com/n75j.html

 

[wilksy]

cheers mate but the reason i wanted to see your one is how its opposed which way its plugged in as i had seat put the j valve in and its facing a different direction.

 

[wilksy]

and was just wondering if twisting it to another direction would help but looking at those links shows that its facing the right direction for that valve

 

[corradophil]

The links certainly suggest the J type sits the opposite way to say an F type.

My N75 F is fitted in the same orientation as the one he is holding.

 

[wilksy]

yeah nice 1! at the same time as looking at the n75 i decided to turn it slighty unplugged it, unplugged the maf and what i believe tobe thye g31which i found on the top of the ic. then i put the ignition on for a few minutes.
then switched off took the key out and plugged all back in and then switched the ignition on for 5 minutes, then fired her up and left running for 10 - 15 mins and switched off. for the time being seems betterlet you know tommorrow or thursday.

 

[corradophil]

I've still not looked at my G31, after reseeting everything over the weekend I am letting the ECU re-learn it's settings without me interfearing.

It was going well yesterday, but today it feels like the power is starting to drop, but the boost levels are the same.

 

[UncleSilver]

Adding 1 more car with the same symptoms (serious hesitaton at 2500rpm) to the list.

180 LC 4WD, euro version (steering on the left side). Completely stock.

Changed so far:

N75, MAF, Plugs, DV, all filters.

Vag-Com saying only - running too rich, no other faults.

Will do next - change cat, let's see if it helps.

 

[corradophil]

UncleSilver, have you tried disconnecting the battery and leaving it for a while (mine was left for 30 mins while I did something else). So far since doing this and fitting a new N75, mine has behaved ok. No fluttering at all today.

 

[UncleSilver]

Yes, I've tried every possible thing. All the stuff you guys in this forum have done + some extra tricks.
I own a similar car so I have changed the parts from mine to the broken one - no luck.

Also I have Vag-Com cable, so all possible info is available.

Only 2 things that are in my mind still:

- engine temp, perhaps ecu thinks it's too cold/hot? Then again measurment blocks have the correct info..

- cat/exhaust related problems.

 

[corradophil]

Anyone made any progress with this?

Mine has just started fluttering again today.

Starting to really miss my old 9A 2.0 16v Corrado, that engine just worked faultlessly all the time with no stupid little glitches which the 1.8t seems to be riddled with.

 

[Scotty_b]

Mine only does it now after a good "spirited drive". Getting a the forge actuator taken off at the moment to try and fix the issue, been in for a week, another week to go!

 

[UncleSilver]

At this side of Europe the problem has been localized to a faulty lambda sensor. Unbelievable? Yes it is for me also.
This is the secondary lambda after the cat. It was ruled out before cause it was changed to brand new. Unfortunately the part purchased was not original Seat part but a regular universal lambda - experts say this will not work on this car (some veeeeeery long theory why).

Now just waiting for the new part and isntallation. Will update this thread instantly if this fixes the fluttering.

 

[Scotty_b]

Hmmmm i doubt it could be that fella as im running revo stage two so mines not used anyway

 

[corradophil]

Scotty b, for what its worth mine is doing this on the original actuator.

UncleSilver, I'd be interested to hear how you get on with the new lambda sensor.

 

[mikey_p]

I've had this boost problem on light throttle problem too for ages! (OK flat out) Not been on the forum for a while but was pleased to see some of the idea's/suggestions flying around. I recently had the spring changed (stiffer one) and the diaphragm replaced in my forge eliminator DV. This seems to have reduced the problem, i.e. made it less noticable, but it is still there.

I also replace the MAF & N75F.

From all the comments it looks like the only solution was to fiddle with the N75 adjustment. However, i'm a little anxious to try that from what others have said. After all that has been said would everyone agree that this was a bad idea???

Cheers,

Mikey P

MY02 LC180, Star Performance remap, Forge Eliminator, BMC panel filter.

 

[UncleSilver]

Changing the secondary lambda sensor did not solve the problem. The problem is still here but perhaps a little bit smaller.

Will rip the car into parts and search for leaks as the next step.

 

[UncleSilver]

Just a theory, but worth checking:

I still suspect a boost leak. We have all agreed (more or less ) to the fact, that under hard acceleration the problem just goes away.
But it is there when gently stepping on the gas. So I started thinking what happens under hard acceleration and doesn't happen under half-throttle - the engine is tilted backwards when really pushing the car.
So there is a possibility that there is a small boost leak and it is shut under acceleration/engine tilting. Now since boost leaks are hard to find I will take the car apart. This is a lot of work so when someone has done it already without any result, please let me know

Anyone with the same problems and has change all the piping/clamps?

--Utopia begins here--
A crazy idea (saturday night, you see) - would it be possible to build a additional MAF sensor to work as a boost leak finder? I mean the amount of air at the intake manifold shoud be the same as in the first, original MAF, correct? So by placing the "secondary MAF" right before the intake manifold and somehow getting the reading and comparing the readings form the original MAF should give some info.. or not..?
--Utopia ends here--

 

[corradophil]

UncleSilver, have you found any leaks? I've checked all boost pipes/connections apart from the the one coming out of the Turbo which is a pain to get to. Can't find any leaks.

I have previously been running 95 octane fuel, but for the last couple of tanks I have switched to 97 octane. At first it ran a little faster with minor hesitation, but over the last few days, the hesitation on part throttle between 2000rpm -3000rpm has come back and occasionaly their is alot more power. I'd guess there is around a 20bhp fluctuation. Occasionaly when backing off the throttle it cuts the power hard, making it feel like I've just jabbed the brakes.

 

[corradophil]

I've had this boost problem on light throttle problem too for ages! (OK flat out) Not been on the forum for a while but was pleased to see some of the idea's/suggestions flying around. I recently had the spring changed (stiffer one) and the diaphragm replaced in my forge eliminator DV. This seems to have reduced the problem, i.e. made it less noticable, but it is still there.

I also replace the MAF & N75F.

From all the comments it looks like the only solution was to fiddle with the N75 adjustment. However, i'm a little anxious to try that from what others have said. After all that has been said would everyone agree that this was a bad idea???

Cheers,

Mikey P

MY02 LC180, Star Performance remap, Forge Eliminator, BMC panel filter.

I replaced my N75F with a new N75F. As an experiment I put the old one back on and had a play with the adjustment, I could adjust out the hesitation, but this was also backing the boost right off, making the car run pretty much as it did before the remap. Adjusting back the other way to bypass the wastegate further increased power/boost, but also the hesitation.

After a few adjustments something really went wrong with the N75 and no matter where I set it, the performance was very poor, with a maximum boost of about 3 psi. I then refitted the new N75F and it was instantly back to normal again.