Cleaning has caused problems (If it's not broken - don't fix it!)

Vex182

Vex182

1x S3 and 3x Fiestas.
Joined
Apr 23, 2012
Messages
1,159
Reaction score
169
Points
63
Location
Sapcote, Leicestershire.
Thought I would clean my throttle body today / never done it before. Wipped off the battery and removed the Tb. Very dirty both side, a good clean with carb/ intake cleaner, all dried out and refitted. Battery back on and reset the throttle in VCDS. Started ok and then drove like almost no boost! Went out for 1/2 hour and no change, checked for faults and all were good. Left it for a bit, took it out again and still it's very poor, in a quick logging session on block 115, it asked for 2,500 mbar at some points and it never went above 1,580! Can't see anything damaged and can hear the turbo spooling. Had a boost leak test just last week at r-tech and all was good.

Open to all ideas.
 
Any ideas? I disconnected the battery last night, went out for a spin this morning and it's all the same, currently got the battery out checking down near the TB to see if I knocked anything but all is well. All pipes under the manifold are correct or blocked up as required. Top boost hose from turbo is fine too. Car pulls as normal until about 2,800-3,000 and then just feels flat.
 
I had a simular problem after swapping the maf over. the car was idling all over the place. Worked for me but disconnect the battery for about half hour, connect it up and leave it idling for about 5-10 minutes. worked a treat for me so worth a try at least
 
half a bar of boost, sounds like actuator pressure or there abouts to me mate. As if it's somehow dropped down to limp mode for some reason.

Not unplugged the N75 for any reason and forgotten to reconnect? Any fault codes this morning?
 
Ok cheers, ill get it back together and let it idle for a while and see if it sorts itself out. I thought my drive around yesterday would have woke it up.
 
No fault codes even after 20 minutes of driving, up to temp etc. throttle does go to 100% too. Aligned it twice and it said ok. Just checked the smic's are tight.

Edit: Car is all back together and everything was tight, I have reseated the boost pipe from the map sensor to the TB and cleaned the hard pipe out of a small amount of oil. It's just idling now and only code so far is because of the battery being off.
 
Last edited:
Here is a quick picture of a log I have done, the laptop I am using does not have much on it to make it easier to see. Yellow is requested boost and red is what is being given. Seems to limit at 1,580 mbar. No fault codes still on full scan and the N75 is connected as normal - it was not touched yesterday anyway. Throttle body was realigned and still seems to have made no difference. This really does seem odd as nothing else was moved or knocked.

photo_zps923d4a76.jpg
 
Last edited:
Is there a way I can test the n75 valve via VCDS? Anything else I should be looking for before it gets dark? No other fault codes show.
 
Not sure if this will help you fix it right now, But my old pre facelift S3 had a similar issue and it turned out that the throttle body was faulty even though it did not show up as faulty on VCDS.

Do you know anyone locally that has the same engine as you in any version of a VAG car as you could try out there TB on your car to eliminate it as the issue.

If you do find its the TB at fault you can grab a cheap second hand one off ebay VW Audi 1.8T 20v Engine Electronic Throttle Body Golf Gti Audi S3 | eBay
 
vrbob said:
Not sure if this will help you fix it right now, But my old pre facelift S3 had a similar issue and it turned out that the throttle body was faulty even though it did not show up as faulty on VCDS.

Do you know anyone locally that has the same engine as you in any version of a VAG car as you could try out there TB on your car to eliminate it as the issue.

If you do find its the TB at fault you can grab a cheap second hand one off ebay VW Audi 1.8T 20v Engine Electronic Throttle Body Golf Gti Audi S3 | eBay
Click to expand...

Cheers for the link. Not really, also some people might me put off incase theirs has a problem afterwards lol. It was all fine until I took it off to clean it, never had an issues before.
 
can you hear the TB move when you do an allignment in VCDS?

Also have you tried unplugging the MAF and seeing if it runs better?
 
vrbob said:
can you hear the TB move when you do an allignment in VCDS?

Also have you tried unplugging the MAF and seeing if it runs better?
Click to expand...

I've not tried unplugging the maf yet, yeh the throttle is adjusting when i ask it to, it opens to 100% when foot is down to. I have just been out and logged block 118, the n75 duty cycle stayed at 0% even at 4,500 - 5,000rpm, should this not change?
 
yeah i think it should change so maybe unplug the N75 and see if anything changes as if it runs the same then i would say the N75 is fubard. So maybe just coincidence that it failed after you cleaned the TB.
 
Vex182 ........not to sound like an **** but I would think there has got to be a problem with your maf/n75 or turbo as your only running 254 bhp with your mods and stage 1 map on a 225 s3! .? ?? would we not expect to see yours running 265 ish mate?



Sean
 
vrbob said:
yeah i think it should change so maybe unplug the N75 and see if anything changes as if it runs the same then i would say the N75 is fubard. So maybe just coincidence that it failed after you cleaned the TB.
Click to expand...

Just been out with the N75 disconnected, a fault code came up for the n75 but the car drove exactly the same. Sounds like this could be it then, very odd! The maf readings are a lower than normal but would that be expected to keep air to fuel correct? With the maf disconnected the cars exactly the same so I guess thats ok.
 
Vex182 said:
Just been out with the N75 disconnected, a fault code came up for the n75 but the car drove exactly the same. Sounds like this could be it then, very odd! The maf readings are a lower than normal but would that be expected to keep air to fuel correct? With the maf disconnected the cars exactly the same so I guess thats ok.
Click to expand...

If it does the same with it unpluggged then i would say yes its the N75 at fault you can get a replacement off ebay for less than £30 second hand just make sure you get the same part number as you already have on the car as the last letter is the version which i think is an F but i could be wrong lol
 
s33nyboy12 said:
Vex182 ........not to sound like an **** but I would think there has got to be a problem with your maf/n75 or turbo as your only running 254 bhp with your mods and stage 1 map on a 225 s3! .? ?? would we not expect to see yours running 265 ish mate?Sean
Click to expand...

Its alright, the turbo has done 103k but its always been fine. I think a new n75 will be in order first, maf I replaced last year from Audi. N75 looks original due to its faded colour of the plastic. About 30 for a second hand one? Whats the approx cost of a new N75?
 
Take part number off it mate and ring tps, or ring tps with your reg number and ask them (euro car parts or gsf aswell)

Sean
 
You can also do an output test on the n75 valve using vcds to see if it is working properly, hope this helps
 
If you do an output test on it without the engine running you can hear the valve clicking in and out, that's the test I meant
 
Vwdan80 said:
If you do an output test on it without the engine running you can hear the valve clicking in and out, that's the test I meant
Click to expand...

Oh right, not actually done that. I go on output and then block 118 and press go and then should hear it with the bonnet open?
 
Go into engine then select output test instead of measuring blocks, click on start and you can cycle through different actuator tests one of which is the n75 valve. It should click quite loudly if its ok. :)
 
hi mate.
i did the throttle body clean.
had your issues.
turned out to be the electrical connection to the throttle body (connector block radiator side) was loose.
clean the connector and use a zip tie to connect it tight.
all good after
 
Ok cheers, everything seems to point to the n75 being broken and some stuff seems to confirm it but more stuff confirming it is always helpful - good to make sure!
 
jezzy said:
hi mate.
i did the throttle body clean.
had your issues.
turned out to be the electrical connection to the throttle body (connector block radiator side) was loose.
clean the connector and use a zip tie to connect it tight.
all good after
Click to expand...

Do you mean the one on the start of the inlet manifold? I think my throttle body only had one connection itself, from behind and kinda under it.
 
Last edited:
Well genuine new n75 fitted and the cars even worse. Less boost and sounds different, confirmed by changing it back to the original. No boost leaks and no fault codes. I disconnected the sensor on the front of the inlet and it gave a fault code but did not drive any different. Out of ideas now and fed up like we all get!
 
I know your not getting any fault codes but i still think that your TB might be not working correctly as this is exactly what my old S3 did.

Symptoms were it felt like it had a boost leak and would hold back under acceleration bringing on both the traction control and ABS lights on the dash.

I had to give it to Audi who spent hours swapping bits for new bits (they tried 6 different MAFs!) in the end they tried a new TB as just a trial and it fixed it straight away it was something to do with the butterfly valve not closing properly even though it told VCDS it was.

So is there anyone local to you that you can borrow a TB from for 5 mins? as this will confirm or deny my theory.
 
Its not like a boost leak, it's like really gently struggling as if i accelerating in 2nd rather than 1st etc. No one near me that I know to try. No abs or ESP lights too. Think ill just get it booked into r-tech again.
 
Managed to try another throttle body from a guy I used to work with! Forgot his S3! Unforuntaly it made no difference, his was a little dirty but no worse than mine was to start with. Doing some logging and the new N75 fitted still shows a 0% duty cycle ALL the time.

Edit: Could for some strange reason, the wastegate be stuck open? Really can't figure this one out. I tried a new DV now too (standard Audi one) and that made no difference.
 
Last edited:
Your not having much luck mate! If you have vcds search the threads to see if there is a way to check waste gate position on that?

Don't throw your new n75 yet , when you fix the underlying problem the n75 may still make improvements from before....
Sean
 
s33nyboy12 said:
Your not having much luck mate! If you have vcds search the threads to see if there is a way to check waste gate position on that?

Don't throw your new n75 yet , when you fix the underlying problem the n75 may still make improvements from before....

Sean
Click to expand...

Thanks! Nah I'm not. Around town it dries like normal, it so only above 3.5k it's different. Yeh I am keeping it aside - yes it is plumbed in right too! :p

Niki is going to have a look for me next week, I've got a week off and wanted to head away to Wales with the mountain bike.
 
You must log in or register to reply here.

Similar threads

Mi11ar
How do I fix the rubbing caused when lowering...
Replies
8
Views
2K
Grale1
Grale1
N4THW
If it ain't one thing it's another
Replies
7
Views
722
N4THW
N4THW
yellowgti
as if weve not got enough problems!
Replies
21
Views
1K
NHN
NHN
L
Just bought an S3 but not sure if it's 265bhp
Replies
11
Views
2K
1animal1
1animal1
Paradox1
Nick has done it again!!
Replies
17
Views
1K
CharlieRCupes
CharlieRCupes
Top
Back