Boost on a 99' 1.8T quattro sport ??

Bradderz_1988

Bradderz_1988

Dont replace it, Upgrade it !!
Joined
Aug 19, 2010
Messages
4,121
Reaction score
474
Points
83
Location
North West
Right I have fitted the boost gauge to my car and seeing around 6-7psi then a drop to around 4 psi. Is this wrong or right ?

I have replaced all of the boost hoses, intake pipes, vac lines and have a forge splitR on the car, no change in performance after fitting boost gauge so I think the problem lies elsewhere.

Could it be the n75 ? Or have I missed something ?

Also what's the correct procedure to boost leak check the car via the intake ?

Thanks

Brad
 
Sounds like "150" engine boost levels rather than "180".

Whats the part number on your ECU?

An AJL should be up around 10-12psi.

You can always unplug the N75 and see if it gets slower/makes less boost. If it doesnt then the N75 is ********.
 
Cheers mate will have a look at the part number on the ecu at dinner, when I fitted the intake and removed n75, when setting off in first the car just held back and didn't rev up then suddenly it boosted after pressing the throttle a few times this happened about 3-4 times but hasn't done it sine could that of been an indication the N75 was on it's way out ?
 
Just fitted a boost gauge to my AJL and in the lower gears it usually peaks at 12psi and gradually drops off to around 10psi. Sometimes though it peaks out at 10 and that's all. In 5th gear though I've seen it hit 14psi peak.
 
So as long as get it showing around 10-12psi then, will I benefit from upgrading to the N75J if my N75 is knackerd or will I do more damage than good, also I've got the wastegate rattle will this cause any boost drop if the plate isn't sealing right on the turbine housing ?
I will be fitting the Frankenturbo so I want it to be running right for when I fit it.

It's my first turbo car so sorry for all the questions I'm still learning lol
 
as stock, my APU was also showing 12psi peak, down to circa 10psi
 
Last edited:
Forget the J valve, causes more problems and doesnt do very much.

When i had a rattly wastegate, it worked completely normally, then one day it just stopped boosting.
 
Ok thought it wouldn't just wanted clarification. Was the max pressure I can put down the intake and do I just take the engine oil cap off or do I need to block of the breather valve on the intake aswell ??

If I disconnect the n75 and still see the same boost levels it needs replacing then ??
 
Don't want to sound patronising but it's worth having another look over all your pipework for any loose connections/splits etc. Sounds obvious but I'd always start with the obvious stuff first. A loose jubilee clip or summat will leak like hell under boost. I remember working on a mates car once and an old jubbly appeared to be fully tight (you couldn't turn the screw any more) but it was goosed and the actual clip itself was fairly loose. Could be something as daft as that.

If you 've got a rattling from the wastegate, then maybe there is something else afoot. If it's not sealing properly, then yes you will lose boost.

I don't have a lot of experience tuning Audis, in fact I've got none yet, but I have a lot of experience with Subarus. I'm hoping to convert that knowledge over and hopefully most of it will work. I took my 97 Impreza from 208 to 386 bhp, but on a mega budget. Hoping to learn from my mistakes and do it more cheaply this time round!
 
Right here's where I stand,

Disconnected the n75 got an astonishing 1psi lol plugged it back on had 6psi found inlet manifold pipe to move slightly (tightened no difference).

Aragon part number of ecu is - 8do 907 558 da

Please tell me that's an AJL ecu !!
 
You should get 4psi with the N75 unplugged.

So either your guage is fubar, theres some leak, or the wastegate is badly set or knackered.
 
Aragon - If I check the wastegate with the mity vac and it drops when I fit the FT I should be ok in theory but only see around 10 psi to flow 180hp on the stock ecu ?
 
had another quick look at the car tonite and the recirc pipe has slightly caught the air-con belt but im not to sure if leaking it doesnt look like its gone through enough to be leaking have some silicone repair tape if it is but i drove the car earlier and was seeing a peak of 9-10 psi so im thinking it may be the gauge after all (but its new) but not 100% sure with the pipe ive found but it maybe something else may have to make up a diy a leak tester to connect it up and check the full system.

am i right in saying these steps as i dont want to get it wrong,

1. connect tester at intake/maf
2. block of breather and take oil cap off
3. dont exceed 0.5 bar ???
 
I'd push the pressure up past the operational range. If you only test to 8psi it might leak when it gets to 10 or 12 for instance.

Test to at least a bar.

Remove the Pancake valve, and block off the hole in the TIP.
 
Cheers mate guna get my thinking cap on and maybe use something that will hold/seal a tyre valve in (am I right that the diameter is 2.75 inch ?) or I may just blank the intake at the maf and put the tyre valve and jubilee it were the pancake valve sits, I will make something work :)
 
Right hav vac/pressure tested the gauge all is ok, same with the FPR and that's holding, tried the forge splitR and that slowly drops vac/pressure is this normal due to it being spring loaded or should it hold ?

Next its test the wastegate then the system !

Depending on the answer I get for the forge slitR ?
 
Right had another play this morning got the system pressurised couldn't here a thing so I tested the wastegate and that held at 20 inhg so started checking all the boost hoses were tight they all seemed ok, stripped the forge DV down greased the piston then sealed the top of DV and also checked the recirc pipe that caught on the AC belt wasn't leaking so just applied some silicone repair tape on just to be sure . Built it all back up and set off home. Soon as I pulled out the workshop and floored it it shot straight up to around 10-11 psi I thought to myself this is how it should be but then as I got on the motorway it was dropped to around 8psi (peak) then to 6psi as I got higher up in the revs then I got off the motorway and I'm back to square one peak psi is around 5-6 then drops to around 4 psi.

I'm getting frustrated now !!!!! :wtf:
 
Have you checked codes with a scan tool? Could be a sensor problem (maf, map, tps)?
 
No don't have vagcom, since last post I'm seeing 2psi of boost then now and again it can shoot up to 6psi whilst driving ?? Think I may chuck the original recirc on and see what happens as Looking on the net there seams to be some issues with boost levels when running the forge splitR and since stripping it It sorted it now its just dropped the boost back off, also think the n75 might be duff as when I unplugged it I was seeing the same boost as what I'm seeing now !
 
You need to get vagcom on there.

If its a sensor fault you wont get a light or anything.

Limp mode will give the same boost as a disconnected N75.
 
Can you point me in the right direction as to what I would need to run vagcom on my laptop links would be great !
 
Nigel will probably hate me for saying this, but a cheap eBay cable will do the trick, but will have limited functions. Should still code read and clear. Just buy a cable and download the free VCDS from Ross tech. Also, the cheap handheld vag scan ones work well too (k-line, not can).
 
I would rather get the full lot so I can do the alarm sounder when locking or will VCDS do that ?
 
worth a shot. you can buy a licence for VCDS with a third party (ebay) lead. cheaper than the full kit from RT. (just dont get the support) but it would do everything you need on a B5 (ie: non CAN)
 
Do you reckon vagcom of a torrent site would work with a 3rd party eBay lead as I've downloaded one but haven't installed it yet as I'm not sure it will work on my laptop and don't have a lead and is it fairly simple to use as I use lexia/diagbox (on citroens) day in day out ??
 
Compared to other systems it's a breeze, some (BMW gt3) systems can be a nightmare. I dare say a torrented one would work with a eBay interface (that's how I used to do it before I bought a genuine kit)
 
I think it's my forge splitR !

But can't rule it out as my old Bosch recirc is hissing just blowing down the thing lol what if I blanked of both ports on the TIP and turbo outlet pipe and test drove it would I do damage ???
 
Theres a risk of snapping the turbo shaft due to compressor stall.

One thaught, aftermarket DV's often have to be fitted the opposite way round to the bosch one, due to the way the boost acts on the piston. Perhaps you've fitted it the same way as the bosch one? Take a look at the instructions and see if it specifies which port should see boost.
 
You should be able to push on the valve and make it move too. which ever way it moves thats the high pressure side
 
Ordered my 007p from awesome gti may try switching it around before it comes to see what happens !

The way I have the forge valve is looking at it the bottom goes to recirc pipe then the side port opposite the dv horn into the TIP is this correct ?
 
Last edited:
Sounds like you've already taken the plunge on a new Forge one but if you wanted to test another OEM valve, I'll post you mine that I've just taken off if that would help. That was working ok but I've upgraded now so I don't need it.

The one I got was £35.99 brand new off ebay (considerably cheaper than most places and it came with 3 choices of spring). It may be a cheap Chinese copy but it seems to do the job ok.
 
im back still with this problem and im seeing around 6 psi in 1st, 8psi in 2nd 3rd and in higher gears seeing 9-10psi ive done some searching on the net and seen that i need to be checking crankcase ventilation pipes aswel ??? is this correct ???

i followed this pipe -
3101-img-0728.jpg


to here -
3098-img-0729.jpg


where the tip of the arrow is between the intake manifold on the block breather there is signs of oil where its leaking from and looks to be a hole open by about 3mm. didnt have time to boost leak test the car so this is why im asking, also could the N80 cause this as a pipe of the maifold goes across to this and is snapped on the nipple bit where the arrow is pointing below.

N80
3099-ash-heat-shield-2.JPG


And heres my gauge as i never uploaded pics ..... opinions welcome !

day
3097-img-0714.jpg


night
3102-img-0715.JPG
 
6psi in 1st might just be due to load.

The engine needs time to build boost, and it flicks thru first so quickly that it might simply never put enough energy into the turbine to get it up to 12psi.

I'd have expected 2nd to have given maximum boost though.

If you have broken bits of your crankcase breather it shouldnt leak any boost (so long as the check valves in the pipework are working) but it will mess up the fuelling when your off boost, as the check valve will open and allow the engine to draw air thru the broken breather.
 
It's a weird one as the other week after playing about I saw 10 psi in 1st but all I did was take off the splitter and grease it and tightened a few jubilee clips but since then I have replaced all of the boost hose clips and upgraded to a 007p it's really starting to **** me off. I'm going to do a boost leak test and coat the pipe work in soapy water and see if I can find it.
 
You must log in or register to reply here.

Similar threads

A
Best Remap + Exhaust on '99 1.8T Quattro Sport (180bhp)
Replies
3
Views
2K
A4TQSports
A
K
'99 1.8T Sport Quattro problems HELP....
Replies
7
Views
2K
neilA4
neilA4
S
Help with overheating 99 1.8T Quattro Sport.
Replies
5
Views
993
mwarrey
mwarrey
S
Advice on 1.8T Quattro Sport
Replies
6
Views
1K
PaulJC84
PaulJC84
I
99 2.8 Quattro - Sport suspension standard ?
Replies
4
Views
879
jdp1962
jdp1962
Top
Back