Right i took the car to get mapped a few weeks ago to get my boost sorted, as it was only making 1.3bar. Once mapping started we got the boost up to 2.0bar but soon as the car gets over 5k revs boost is dropping off to 1bar it feels like hitting a brick walk as its instant loss not just gradual. Now I've had the cr spec gt30 off and had it checked and that's fine i then found a air leak from inlet as i didn't fit o rings oops, I've since had inlet off and o rings fitted but been back out today and exactly the same problem?

Its seriously doing my head in now as I've already wasted a lot of money with fuel and mapping etc so anybody have any ideas as to why im losing so much boost?

Cheers

 

Sorry that you've not found the cause of this yet mate... losing 50% of your boost isn't good at all, hope you get the issue sorted and it doesn't cost too much.


Cheers,
Grant

 

I know mate its doing my head in now lol think i mite just put standard inlet back on and see if that does anything.

 

not good lee, hang in there mate itll be summit stupid.

no wantin you havin stupit thoughts again

 

Greig if i hadn't just taxed it lol

 

Wager something silly like MAP sensor or fuel pump voltage and it's cutting the boost.

 

thank fuck you taxed it then mate lol

come on lads someone has gotta know whats up with it, things gona be a weapon once is right

 

We are running out of fuel but it used to run 2.0bar on old turbo and standard inlet? So im on with a fuel set up in boot

 

What you using for boost control?

what happens with actuator disconnected from boost signal?

is the exhaust DEFINATELY 2.5" or more ALL the way through?

 

Using the autronic boost control system. Not sure what you mean about actuator david? And yeah exhaust is deffo 2.5 all way from turbo with no boxes etc.

 

nowt daft like a fooked dumpvalve or resurcualting valve letting pressure out on boost

 

I've had recirc valve open and can't see anything, thought maybe diaphragm could be split but its got a plastic thing inside.

 

none the rs boys near by you could have look at or borrow valve off,

 

can you not run it without the chav valve mate?

 

standard part on a frs

 

Actuator has a vacuum/boost hose going to it yea?

what happens to the boost when you disconnect it (blanking the hose) and taking it for a run...as in is the turbo capable of making the boost when it's normally dropping to 1 bar.

wastegate definately shut properly? signs its not would be boost slow to come in...

dump valve - easy to check, pull the vacuum line off and suck on it, does it hold suction on your tongue?

got to be something stupid......

 

Give Joe @gsmotosport a call mate he sort it out for or he tell you what's the prob with it on phone 07940 181847

 

Sounds like the ecu is detecting a problem eg AFR's to lean or other problem, so pulling the boost. Limp mode.
The amount of boost it pulls will depend on what type of actuator your running and how its set up.
If you were running standard boost it would still probably pull 50% just would be a lower start point.

Any fault codes in the ecu ?

 

Its on autronic mate and when mad mapped it dont think it was showing any faults.

 

+1 on management causing the trouble, for it just to suddenly cut out I'd say it's detecting a fault somewhere and cutting the boost off to prevent damage.

 

Surely mark would of picked up on that? Ill get my fuel set up fitted in boot and go from there, hopefully will pedley is gonna have a look end of month.

 

Check its not sucking a hose flat, I have had that happen and its just like you described.

James

 

have you asked mark if he can have a look at the ecu

 

Mark put it down to a turbo problem so i can only presume there were no faults at all? I've spoke to Joe at gs and he says sounds like big air leak still.

 

can you not pressure test the inlet from turbo back to find the leak then

cant be much to look at

 

hopefully will be getting it checked friday night after work.

 

You should be able to hear a boost leak that bad. Why not do a boost piping leak test.
Can you get full boost gradually, ie build up the load whilst not using wot. Have you tried to get boost above 5k without using wot ?

I don't see why 5k is the critical point here, unless your boost curve cant make max boost at lower revs. A boost leak will leak at 2k 3k or 7k . If you have 2 bar at 4k and suddenly not at 5k then i don't think you have a leak.
IMHO of course.

 

That's what i dont understand why it only loses the boost after 5k? Think i mite try the standard inlet back on see if its an inlet problem.

 

like he did on the boost leak lol.

As said get it pressurised up again and see where the leak is.

Hope its an easy fix

 

Me to bri lol not even thinking about the box till this problem is sorted out.

 

You can probably rule out alot of things yourself if you think about it logicly.
Realisticly a leak from a pipe, intercooler, d/v, inlet isnt going to manifest suddenly at 5k, as you say the circuit is presurised well before this point with no issue. With that in mind you can probably rule out pipe collapse intake side. Its failry unlikly that having small exhaust(2.5 is really too small) is going to cause that kind of issue either.

What i would do to rule out electronic issue is bypass elec. boost control and run it up again. If its still pulling back you know its nothing to do with the ecu as it'll no longer have control.

 

only time ive had something like this is when the silicon hose on the base of the inlet
split. round the back of the inlet.

 

Alright mate i would try what RS1 has said and try and take the boost control off and just put a bleed valve in. try and set it to 2 bar and see if the boost drops off to a bar. then youl see if its a ecu/boost control fault or a turbo/air leak fault.

 

Have you tried as I mentioned, ie can you get it to boost above 5k if you don't use wot. I ask because if the ECU is pulling timing and or dropping your boost via the boost controller due to bad AFR or IAT's then don't stress the engine and see what you can get.
If you put the car in 4th or 5th and do some steady pulls you will definitely be able to hear a leak that drops 50% of your boost. Also in 4th & 5th things are less hectic and you will be able to achieve full boost using throttle control.

 

Is his ecu able to read AFR? may not have a lamber sencer

 

If the ecu is open loop with no knock sensor, then no. Normally if there is a fueling problem , afr too lean, IAT problem the boost normally shuts down when a piston melts
If you are open loop, then iirc its really only sensor failure that would cause a limp home event.

My best advice is to have a boost leak test done, as we can all be arm chair mechanics.lol but you really do need to know first of all if you have a boost leak. Personally i think its unlikely only above 5k but we all live and learn.

 

Right been and done a leak test tonight and its losing a lot of air out the throttle body, but its on the side where the spring etc sits we took it apart and can't see any way how to cure that apart from change the very small o rings on each end of the brass bar that runs right through.

 

that may be it dicko, at teesside autodrome the other week I lost over 10 psi of boost I found a 2 mm hole in the dump valve diaphagrm thats all it was!

steve

 

At least you have found something. nothing worse than fault that cant be found

 

Yeah but as you say why would it only loose the boost pressure after 5k? Ill try figure this leak out and see if its any better.