Faulty boost gauge,car or workmanship!

[Jofenan]

Fitted a boost gauge to my 99 t5. It's a digital one (tube from the engine bay to a remote sender that sends an electrical signal to the gauge) on tick over it reads -10 psi and in full boost only 1 or 2 psi. I have a Bluetooth obd2 reader and that's telling me the car is boosting to about 11/12 psi and peaking at 15. My car is an me7 and I connected the gauge to the pipe running from the inlet manifold (no tree on a me7) is there a better place to connect too? Is the boost gauge faulty,the car faulty or have I done something wrong?

[M-R-P]

Which pipe from the manifold did you connect to?

You need to connect it to the small pipe that runs from the gearbox side of the manifold to the recirc valve on the turbo.

[Jofenan]

I connected to the small one,used 4mm fuel line. I watched an ipd video on YouTube and they used the same place on a p2. I think I'm going to get a another gauge (about £9) that doesn't have the remote sender and see what that reads

[Jamest5r]

The Bluetooth will read at atmospheric pressure so 14.7 plus whatever your boost is so your gauge might well be right at 1 or 2 psi.

[Jofenan]

What's the best way of accurately measuring boost?

[martin_r_smith]

Buying an accurate calibrated gauge

[claymore]

What's the best way of accurately measuring boost?
I like to use ex WW2 aircraft boost gauges :)


http://i170.photobucket.com/albums/u258/claymore2k/T-5R/20170507_151125.jpg (http://s170.photobucket.com/user/claymore2k/media/T-5R/20170507_151125.jpg.html)

[martin_r_smith]

Oh I like that a lot...

[Jofenan]

I have a spare psi dial off an air compressor. Will chuck that on but it looks like I have low boost. Am in the process of changing my pipes. Have done the three to the bcv and the t shape one between the manifold,something above the radiator and a connection near the turbo What else is there? I keep reading about a bend that fails a lot?

[LeeT5]

I have a spare psi dial off an air compressor. Will chuck that on but it looks like I have low boost. Am in the process of changing my pipes. Have done the three to the bcv and the t shape one between the manifold,something above the radiator and a connection near the turbo What else is there? I keep reading about a bend that fails a lot?

Do yourself a big favour and buy yourself a Mityvac before you go wasting anymore time or money.
Chances are you do have a boost leak, maybe a hose has been disturbed when fitting your new gauge or maybe you just have an issue else where on the car. Bottom line is, all of us, including myself, are p iss ing in the wind trying to help you and there's absolutely no point anyone spouting suggestions to try this, disconnect that, plumb in this etc etc. None of us have any clue to the state of play of your engine and the Vac hoses, boost pipes etc before your install.

Have you done a 'Stage 1' before fitting this gauage of yours? If you haven't or you don't know what that is, then your playing a dangerous game and this will likely go on and on and on.

Knowing what I know about boost leaks (read my Project thread and you'll understand what I mean) my investment in a Mityvac accelerated my repair solution from days to hours!!

I personally advice to to remove (disconnect) the existing boost guage line and reinstate it. Then use a Mityvac to check/confirm the integrity of your entire system, including all Vac lines and boost hoses, One way valves, TCV lines, wastegate.

Any leaks will instantly show up on the gauge whether your apply boost or vacuum! Once you're satisfied these are all OK it would then be prudent to have your car 'Smoke leak tested' before fitting you guage.

This test will confirm the integrity of your MAF to Turbo intake pipe, PCT nipple/connection, Intercooler, inlet manifold gasket, Intercooler hoses, BPS, The one way valves only show up on a Mityvac not a smoke leak test, so confirm these are sound first!

There's bound to be some leaks big or small, none the less, now you will truly know that once your gauge is fitted, if it doesn't work or you don't get the readings your expecting, then you can put it down to faulty equipment of a poor install.

You can take my advice or leave it, but I've been where you are now only 2 years ago and believe me.....6 months chasing boost leaks is not fun! It's not only time consuming but punishing on components, keep undoing, removing, refitting etc etc.

It's also worth making a note of any fault codes your getting from the ECM. MAF related, boost related etc. These will indicate a leak and not nessesarily a faulty component. Take your time, be methodical and above all, understand what it is you're doing and why your doing it. Otherwise, you're just second guessing and taking a chance and if you accidently fix the problem (chance would be a fine thing) you'll have no clue as to what it was you did and how you fixed it. :wink:

Mityvac...

http://www.ebay.co.uk/itm/Mityvac-MV8500-Elite-Hand-Vacuum-Pressure-Pump-Kit-One-Man-Brake-Bleeding-Set-/401400637853?epid=1504162274&hash=item5d7557a99d:g:~9sAAOSwiylW~n9J

[Jofenan]

Thanks for the reply. I guess I'm just doing what I consider to be stage zero. Just making sure everything's fine before remap,exhaust,intake etc. All the vacuum lines from the bcv were perished and the outsides were like dust! So I don't consider I'm throwing money at it as they definitely need sorting. I'm just being methodical and taking advice from people who have way more experience than I do! I was going to buy just a vacuum pump to check the waste gate. I can see how having one which provides positive pressure too will be a real help. Just have to sneak it past the mrs!

[M-R-P]

Where abouts are you? Maybe someone can have a look for you?

[LeeT5]

I have VIDA/Dice.

[Jofenan]

I'm in Nottingham

[Jofenan]

Ok so I've checked my boost gauge with a digital foot pump and it's reading spot on. Moved the gauge connection point onto the turbo nipple side of the tcv and it still read 3 psi max (moved it back onto the manifold connection). Have replaced all my vacuum pipes (3 on the tcv,brake booster,manifold small one,manifold big one! And the little pipe that connects next to the radiator fan. Have I missed any?). I haven't done a smoke test yet but will be this weekend. I've gone for a run with the turbo wastegate disconnected from the tcv and I could hear boost escaping as I over boosted but my gauge still reads only 3 psi max. Any ideas?

[claymore]

I don't think you need a smoke test, with a boost leak that bad (assuming that's what it is) there must be a huge split in a pipe somewhere, first one I would check is the joiner off the turbo to the boost pipe. Also, have you checked the wastegate arm to see how tight it is?

[Jofenan]

Did a quick test on the wastegate arm and it moved freely. Couldn't check the exact pressure it moved at as I couldn't get a constant pressure with the foot pump put it was moving at around 4psi. I'm going to use my air compressor wound down with a regulator to see if I can be a bit more accurate

[claymore]

Did a quick test on the wastegate arm and it moved freely. Couldn't check the exact pressure it moved at as I couldn't get a constant pressure with the foot pump put it was moving at around 4psi. I'm going to use my air compressor wound down with a regulator to see if I can be a bit more accurate
It's an 18 year old waste gate, forget about trying to set it with a pump, take the actuator rod off the wastegate arm, a good starting point will be the hole in the rod should cover about half the spindle on the arm, and should be quite difficult to pull onto the spindle.


https://www.youtube.com/watch?v=p12g1PpIcjE

[Jofenan]

Well that's a lot easier! Will give it a go tomorrow

[M-R-P]

Basic rule of thumb - you shouldn't be able to move it with one hand but it should move when pulled with both hands.

This obviously depends on hand strength etc but it's another way :)

[Jofenan]

Didn't have time to adjust it but what you say about the one hand thing is spot on.

Decided to take pipes leading to and from the intercooler off for inspection. Little joiner one by the turbo was perfect. Worked my way along and undid the mounting bracket,undid the top of the rubber hose that goes towards the intercooler then..........it fell off the intercooler! Think I've found the problem. To the naked eye all was well. Turns out the jubilee clip had rusted all the way through from the bottom. Replaced a couple of other dodgy looking ones too and.........bloody hell this cars quick!

Must have sealed ok up to 3psi then that was enough and it leaked. My little jaunt with the actuator disconnected yesterday must have blown it off! 31814

[claymore]

Result :) , so what's it boosting to now?

[Jofenan]

To be honest I didn't look at the gauge after it got to about 6. Was too busy hanging on! Only had time for a quick go round the block. Luckily i live by a dual carriageway. Unluckily it has specs cameras on it!

Thanks for everyone's help. I at last have a car as fast as my previous Saab 9-5 aero (is that swearing on here??? Lol )

[M-R-P]

6 psi is still low. You should be at 9 or 10

[LeeT5]

So now you must clear all the fault codes and road test again.

Well done on finding the problem.

[Jofenan]

It may well have gone over 6. There was more important things to look at at the time,like the fast approaching roundabout and three lanes of traffic :(

It's safely tucked away in the garage now until Saturday when I'll next have some time to fiddle. The abs unit needs resoldering ,previous owner has jammed some shell reward cards next to the connector!

[Jofenan]

Well it did go over 6 psi.....all the way to 7 psi. Took the actuator pipe off again and now it goes to 11 no problem so I'm guessing it's the actuator that's the problem? Haven't been able to adjust it yet as the bolt right at the bottom by the bulk head is solid! Even double spannering couldn't move it. Is it easier to access from underneath and get a socket on it?

[Jofenan]

Managed to move the shield enough to adjust the actuator. Took 7 turns to get the hole half way off. Now boosts to 8 psi. Getting better! I'm guessing something's worn out?