Lack of boost

[Gasman GT3]

Been meaning to post this quiry for a while.

I am struggling to get boost much over 0.25 bar, what are the most likely reasons? last year I changed the wastegate capsule so I dont think it will be that. I was advised by Matteys last year of a small crack in the manifold, is it a case of that getting bigger, but it dont sound like a tractor? Or could it be the chargecooler pump? Or for that matter anything else I have forgotten.

Your best advice please lads & lasses.

[98GT3]

Been meaning to post this quiry for a while.

I am struggling to get boost much over 0.25 bar, what are the most likely reasons? last year I changed the wastegate capsule so I dont think it will be that. I was advised by Matteys last year of a small crack in the manifold, is it a case of that getting bigger, but it dont sound like a tractor? Or could it be the chargecooler pump? Or for that matter anything else I have forgotten.

Your best advice please lads & lasses.

Hmmm............... if your boost was limited to 0.6 Bar then the immediate suspects would be the chargecooler not working, or the engine coolant not getting warm enough (over 72C).

0.25 Bar is a different story...........can you hear a leak for the manifold at all?? The other thing I would suspect is a badly adjusted wastegate capsule or it's spring has gone weak.

Has it ever boosted properly since the capsule change? i.e. up to 1 Bar-ish boost - and how has this fault manifested itself, gradually or suddenly?

Phil

98GT3

[Gasman GT3]

I fitted the new capsule because of the same problem last year. After fitting the capsule (forge one from PNM) all seemed well getting 0.5 - 0.75 bar, until early this year when boost fell away. I set up the capsule as per the factory one, how do you know if it is set right?

As for the manifold I cant hear a leak, I was going to do some investigations this weekend but every time I stick my nose outside it snows. I'm wondering it is most likely the chargecooler, and a new impeller will sort it. I hope poly ones are for sale at donny next weekend.

[Dermot]

I can't be any help without a Freescan log ?

[98GT3]

I can't be any help without a Freescan log ?

A Freescan log like Dermot says will tell all. Here are notes on how the Wastegate capsule should be set...........

................................................................................

Wastegate Capsule Replacement

To remove the capsule, pull off the pressure sensing hose, remove the circlip from the flap valve operating arm to release the actuator rod, and release the two capsule fixing nuts. After fitting the new capsule, it is necessary to set the actuator rod length to achieve the specified maximum boost pressure of 0.65 bar (9.5 Ib/sq.in). For this purpose a hand pressure pump (e.g. seat lumbar support bulb) and 0 - 0.7 bar (0 - 10 Ib/sq.in) pressure gauge are required:

Apply pressure to the capsule, and observe the pressure required to produce an actuator rod movement of 0.40 mm (0.015 in).

Specification = 0.58 + 0.02 bar (8.6 rt 0.25 Ib/sq.in)

If the pressure is below specification, the actuator rod should be shortened, and if above specification, lengthened.

CAUTION: Do not turn, twist or force the threaded actuator rod emerging from the capsule and affixed to the diaphragm. Hold this rod stationary whilst slackening the locknut and screwing the extension piece on or off the actuator rod as required.

When the correct specification has been achieved, fit the rod onto the flap valve arm with the circlip, and connect the pressure sensing hose.

................................................................................

Phil

98GT3

Edited March 23, 2008 by 98GT3

[Gasman GT3]

Thanks Phil & Dermot, guess I need Freescan.

[98GT3]

all seemed well getting 0.5 - 0.75 bar.

If that was all you were getting, you car must have been slow! Boost is limited to 0.6 Bar when the engine is cold i.e. under 72C

.............If I read you correctly, that is all you have been getting??

Phil

98GT3

Edited March 23, 2008 by 98GT3

[Gasman GT3]

Yep thats right gauge went from just over half to 3/4, dont think I have ever seen it go all the way over.

[98GT3]

Yep thats right gauge went from just over half to 3/4, dont think I have ever seen it go all the way over.

My money is on the wastegate actuator not being set correctly - certainly the first thing to check and adjust if needed.

Phil

98GT3

[caulkhead68]

I had a similar problem with my car not boosting despite having the wastegate adjusted.

It turned out to be the bush inside the turbo that operates the flapvalve had become dislodged, preventing it from boosting. (I think thats how it works - thanks to Sportomotive for sorting it out)

Hope that helps with the diagnostics

Matt

[fjmuurling]

Maybe the bypass valve in the Turbo is stuck in an open position allowing the exhaust gasses to bypass the turbo instead of driving the turbine side of the turbo. Easiest way to check is to remove the actuator from the turbo and see if you can move the small lever by hand and if it is moving freely. If it is stuck use some penetrating oil to free it.

Freek

Edited March 24, 2008 by fjmuurling

[Gasman GT3]

Maybe the bypass valve in the Turbo is stuck in an open position allowing the exhaust gasses to bypass the turbo instead of driving the turbine side of the turbo. Easiest way to check is to remove the actuator from the turbo and see if you can move the small lever by hand and if it is moving freely. If it is stuck use some penetrating oil to free it.

Freek

Thanks I'll try that first before checking the adjustment, but it was moving freely when I fitted the new actuator.

[CBrownstead]

how about some viagra in the gas tank?

[Tony94S4]

My money is on the wastegate actuator not being set correctly - certainly the first thing to check and adjust if needed.

Phil

98GT3

I think I am with Phil on this one,

waste gate rod not set correcty, when everything running good u were getting .5 & .75 instead .85 & 1bar,

now u probably have some kind of faulty code so the solenoid is not venting istead getting .6 u are getting .25 bar

if u dont have the proper tools to set it u can bypass the solenoid and run the hose straight from turbo to wastegate and adjust the rod all the way till u get .6bar,

tamperarly, later fix proparly to be on the safe side

but make sure every thing on the intake is air tight first no leaks

hope this helps

tony

[Gasman GT3]

This afternoon I adjusted the actuator a couple of turns and took her for a test drive, and I now have boost peaking at about 0.6. So I guess that solves it. I just need to make up a test rig to set it acuratly. Thanks for all the advice, just shows it's usually something simple.

[t70]

I have used the "factory setting" before... now this was only once... but i found it to be too loose. I ended up adjusting 2 turns tighter to maintain .65.

[Tony94S4]

Its not a bad idea after u set the desired boost to reset the ecu

[98GT3]

This afternoon I adjusted the actuator a couple of turns and took her for a test drive, and I now have boost peaking at about 0.6. So I guess that solves it. I just need to make up a test rig to set it acuratly. Thanks for all the advice, just shows it's usually something simple.

As Tony94S4 says, you should always reset your ECU after making any adjustments to the wastegate actuator and let the system re-learn. Also, if you are only getting 0.6 Bar boost with all the electronic control i.e the air soleniod connected in circuit you should see limited boost until the engine is up to temperature, then you should see peaks up to 1 Bar. If you are only seeing 0.6 Bar then your car will be slooooooow! (relatively speaking!)

Phil

98GT3

[Gasman GT3]

As Tony94S4 says, you should always reset your ECU after making any adjustments to the wastegate actuator and let the system re-learn. Also, if you are only getting 0.6 Bar boost with all the electronic control i.e the air soleniod connected in circuit you should see limited boost until the engine is up to temperature, then you should see peaks up to 1 Bar. If you are only seeing 0.6 Bar then your car will be slooooooow! (relatively speaking!)

Phil

98GT3

How does one reset the ECU?

[t70]

Disconnect the battery for some time... I can't remember how long exactly.... but overnight will be more than sufficient.

[Gasman GT3]

Disconnect the battery for some time... I can't remember how long exactly.... but overnight will be more than sufficient.

Thanks Mark, that seems simple enough. Wish I had read this last night.

[Tony94S4]

after reset I usualy start it cold and let it idle with no load for two fan cycles,

then add full electrical load for two more cycles,

turn the ac on for few minutes,

then go for a drive with very little throtle trough all the gears

and gradualy add more throtle

not sure if it matters but I been doing this on all my factory ecu equiped cars

[98GT3]

Thanks Mark, that seems simple enough. Wish I had read this last night.

Don't worry it doesn't take that long, 15 minutes will do it.

Phil

98GT3