Stuttering turbo - fixed

[basstard]

I think both are kaput because asides from suffering from the same problem as sssstew does, my turbo also spikes a lot and sometimes it does less pressure than required, i have the shareware version of ross tech so my testing is quitte limited.

man, the N18 controls the EGR valve so how can you say if it's bad or not judging by the turbo?? Could be just the N75 and the N18 being ok. I'm not sayin it is, but I guess it's way more prob.
Swap them and see. Then search for someone near you with full vag com [there's plenty of portugueses here] willin to help. Or buy the software.

good luck mate.

 

[Deleted member 10725]

Yeah but my car never enter in limp mode, and sometimes it does alot more boost than required and its not for a second sometimes it does for a lot more time...

I just said it could be both valves because i had stuttering and the turbo spikes a bit.

As you said maybe both valves are ok, but i think its not the turbo because the problem is intermittent, as i said befora oine time i blew a fuse and the car incredible started to perform right, dont ask me how but im certain it was because of that surge of 12v that the car started to perform right.

I read in a forum here in Portugal, that someone aplied a 12v to a bad n75 and it helped a lot, at least thats what they said.

I think its not the turbo, and if it is i still have warranty (not 20000km since the rebuild).

My guess is stil the N75/N18 or a clogged intake.

problems when car is bad
- Stutters 1000 to 2000rpm
- Its hard to reach the readline
- sometimes a bad smell comes from the exhaust
- Feels slugish to drive
- Idlle is noisier
- turbo whines a lot more than other tdi (Even after the rebuild-370 euros that i paid)

 

[basstard]

I never said both valves are ok,,, to me it's the N75 that's fuct,,, maybe both are shot but I guess it's the N75. Have you changed the coolant sensor then btw?

 

[Deleted member 10725]

My Vw mechanic said that the sensor was ok, the problem was in the dashboard.

Already ordered a N75.

Will fit next week

 

[basstard]

the mechanic can say what he wants but if the computer says otherwise and you get funny smell sometimes then I'll say the opposite,,,

 

[Deleted member 10725]

Will check the temperature sensor again, but the error apeared in the instruments section of ross tech software not under engine section....I dont know if that means anything , im a rookie at vag com.

Ok i did some tests again and i need advice.

Is the egr duty cicle controlled by the N18 ?
At idles it remains at 50/55% and when i acelerate it decreases 50%40%...20% and the minimum is 4% and sometimes it increases again to 40% then back to 4%.

I suposed that the egr should close completly 0%

Can this confirm i have a faulty N18 ?Or im completly wrong and it has nothing to do with it?
If it does i need to find the solution to my boost problem thats quitte erratic...Maybe a faulty N75.

Her is a partial log at lower rpm (It the same at superior rpm speed, if not so frequent)

RPM-DMAF-AMAF-EGRDUTYCYCLE
1617,275.0,274-56%
1659,250.0,210-58%
1680,265.0,294-53%
1701,260.0,259-55%
1743,255.0,259-55%
1785,375.0,382-46%,
1848,395.0,382-47%
1932,850.0,725.-4%



I want my power back, i may be broke when its finished but i will get there...

Thanks for all the help guys

 

[sssstew]

Dude, have you swapped the valves over to see? thats a first step.

and the log above doesnt show too much, remember when doing logging you need to do a run through the complete rev range from say 1500rpm to 4000 or so and then back down.

 

[Deleted member 10725]

But i did but i only showed this because the problem is more evident till the 2000rpm mark.

 

[basstard]

I don't know **** about the egr duty cycle sorry,,,
but let's say for a moment the N18 works bad. The EGR would work bad too and would let the turbo loose pressure if it opened at the wrong time,,, could be an idea. I doubt both valves packed up altogether,,,

If the coolant thing showed in the instument module then it has nothin to do with the coolant sensor, it's just the coolant gauge in the instument section,,, I know cos my mother has the same prob on her polo,,,

 

[mac re]

sorry stew
what have you done.
my toledo has just had it MAF changed and like your its i bit slow, jumping as you said 1k-2k rpm but if you flaw it it smooths out.
looked on the vagparts.com and can not find
sorry just re read and understand
let me get this straght you bought one vale and swapted it between N75 and N18 and that solved the problem
am i right look forward to your reply
mac re

Hi all

as you may have read ive been having fun trying to fix my stuttering turbo, but i beleive i have fixed it now finally! after having the car for a year now. So i will summarise here what the problem was and how i troubleshooted and fixed it for future reference if anyone is searching for it and has the same prob :-

Problem :-

My car was very lumpy between 1k and 2k rpm, the turbo wouldnt spin up right, it would seem to stutter up, go up and down, this would make the car a bit shakey and make it surge. In the cold mornings you can hear the normal diesel gowl go up and down in volume. If u floored the accelerator it would smoothen out, but obviosuly its not preferrable to floor it all the time

Solution :-

it went into various dealers all of whom didnt have a clue as the computer didnt report any faults, but a MAF was replaced which reduced the severity of the problem slightly, but it still surged and the turbo just didnt spool up smoothly as on other TDIs.

so i swapped the N75 and N18 valves, the N75 is the boost control valve and N18 is the EGR control valve at the back of the engine bay, they are the same items but ones got a white cap and the others got a black cap. anyway when swapped over the turbo smoothed itself out and the car felt as it shoudl do, apart from mpg which was not as good, lost about 5mpg.

So i diagnosed a faulty N75 valve, bought a new one from vagparts.com for £65 and slotted it in and put the old N18 back to its rightful position. But this only returned the surging and dodgy turbo spool up for some reason.

To test i put the old N75 (which i thought was dodgy) in place of the N18 to control the EGR and lo and behold it worked a treat!! i now have a smooth turbo spool up, and hopefully my mpg should return, havent had chance to test yet.

So the result of this was that it was a dodgy N18 EGR Control Valve, cant explain why but this must have been putting in to much exhaust gas making it lumpy.

The key to this diagnosis is that when u floor it, the turbo smooths out, now as the EGR only works when NOT on full throttle this is why.

Anyway... im now a very happy TDI owner, after a year of not running right and alot of time and money wasted with dealers. I might even right a letter to Seat to tell them about it, so they know in the future.

A big thanks to all who have helped me with sorting this problem out, especially prc (paulo) much appreciated.

mine still doesnt soot though Ian

 

[sssstew]

yes your right. they dont list it on the site, call them up.

to test do a swap of your valves before you buy.

 

[Deleted member 10725]

If the problem is with the N18, if i blocked the egr completly would it fix the problem ?
I already cleaned the egr but i think it also sticks at the open position, if i blocked it the n18 would have no use right ?

 

[sssstew]

the theory is right. give it a try.

 

[Deleted member 10725]

Well i blocked the tube that goes to the Egr with a steel sphere, and when i tried to start the car , the car had major dificulties to start.
And when it started the sypthoms i had just increased, the lack of power was more evident and aceleration was much worse.

Did i blocked the wrong tube ?

 

[basstard]

better take off the whole EGR and check its state,,,

 

[Deleted member 10725]

Well my mechanic already cleaned it as well as the intake, i guess it just the source of my problems because after i blocked the egr the car was even rougher to drive....

Must check it out better, but the solution of a new egr is quitte expensive thats why i wanted to block it.

 

[basstard]

rather than blockin it by blockin the rubber hose I'd weld a metal plate onto the EGR port at this point,,, might be better,,, cos if the EGR port is stuck open and/or moves just a little maybe you made it worse by bloking the rubber hose,,,