Give up, BOOST PROBLEMS =(

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BabyGodzillaGTi-R

Member
Well been spending a good 3 weeks trying to solve this boost problem and have totally lost inspiration in trying to get to the bottom of it. Did plenty of searches in gtiroc and gtiroz forums.

Car doesn't boost more than 0.7 bar. With the boost controller on still the same problem. Just that the boost comes in slightly harder but still no more than 0.7 bar.

Engine been rebuilt.
New GT2871R turbo
New HKS SSQV
New Apexi AVCR

Checked everything. Vacuum hoses. Even tried swapping intercoolers, intake plenum, 4 throttle.
Pulled the actuator signal pipe, doesn't overboost. Even fitted a crude "fish tank valve" to bleed vacuum doesn't even work.

Worried it might be the actuator. Turbo specialist claims that my actuator is still ok. Tested to 0.8 bar.
He suggest that i should go to the dyno. Is that really necessary just to diaganose the problem?

If the actuator is broken will it overboost or underboost?

Another thing, the stock boost solenoid, if the electric socket is still in place would that be an issue? The vacuum hoses to that have been disconnected since i'm running the AVCR.
I've more or less run out of ideas.....
HELP.
Thanks in advance.
 
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geetee

Active Member
If it doesn't over boost with the pipe off the actuator, then either the actuator is weak or split inside, the actuator rod is over adjusted such that it is holding the wastegate open, or there's something quite wrong with ur wastegate so it's not sealing.

Get a foot pump with a pressure gauge on it :) Very crude but it works :)

You'll find that it'll seal quite nicely on the actuator. Slowly pump it up and see when the rod starts to move. Also try pump it to say 10 psi and hold it - should tell you if the diaphragm has given up.

Failing that, I'd be taking the elbow off the tubby and taking a look at the wastegate itself to make sure that it is seating correctly and not being held open.


<<edit>> and no it doesn't matter if the standard solenoid is still attached to it's electrics. It'll just be keeping itself exercised clicking away.

Cheers
Graham
 
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BabyGodzillaGTi-R

Member
yeah that's what i thought but too but the "turbo expert" said that my actuator is alright. He said he tested it and hold to 0.8 bar. Anyway i tested it the same results. Wastegate itself looks alright and sitting properly.

I wanted to buy a new actuator from him but he says that i'm wasting my money...
Hmm.
Plus he suggest i should go to the dyno with this problem...
Does this turbo guy makes sense or just pulling my leg?

I'm worried the thing is old.
Any more suggestions? Opening up the turbo is such a bitch. We've to remove aircon compresser and alternator to get to it.

Now if only my engine is so darn bullet proof can't i just weld the wastegate shut?
=-\
 
PaulB

PaulB

Member
if he says your actuator is fine, the chances are the rod is set too long and cant open all the way, thus only boosting to 0.8 bar.
 
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geetee

Active Member
The only thing that you may find on the dyno is that your timing or fuelling is well out of whack causing the engine to detonate, which in turn causes safe mode in the ecu which drastically retards your ignition, which in turn may mean that you can't spin the motor up quick enough to generate more boost.

Another thought (unlikely) - the SSQV hasn't got a really soft spring in it has it? May be opening and letting by at 0.7 bar. Could be worth replumbing back to the standard recirculating valve if you still have it - or remove the SSQV and simply bung it's pipe. Wouldn't keep it like that but you'll immediately know if the SSQV is the problem.

Also, with a spec like that, I presume you have a front mount IC. Have a good look at it, that also could have split and be leaking boost.
 
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low612

New Member
try eliminating the boost controller and just run it off wastegate psi only first to see if the problem is wastegate indeed. Trouble shoot from that route.
 
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sumo

New Member
sounds like the turbo ok if u looked in to it and the wastegate is sitting close then u should get big boost with the pipe off the actuator . am with geetee ur timing is out or fuel pump f****d if u go the way as low612 says u would just get .8 of a bar as that what the actuator set at. the boost solenoid just leaks off some air so u get more boost just the same as a bleed valve or the AVCR do the job but as u hav had the pipe of the actuator and it not giving u silly boost its not the turbo has this prob just started or is it been there from ur engine rebuilt
 
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low612

New Member
also you can eliminate the boost solenoid and run straight wastegate psi i think 12psi, correct me if i m wrong. if this is the case and you do hit 12psi you know its something other than turbo/actuator.
 
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BabyGodzillaGTi-R

Member
this is a check list
- stock boost solenoid disconnected
- actuator bracket further reinforced to prevent flexing
- new walbro pump and regulator
- wide band running 11:1 AFR. Engine doesn't feel like pinging. The current power delivery feels very "NA-ish" with good low-mid range at 0.7 bar. Doesn't feel like the old school "big bang" when the boost comes in with the previous stock turbo.
- new HKS SSQV non adjustable (both spare Stock Recirculating Valve not too good)

Tomorrow is a new day. See how it goes.
 
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low612

New Member
BabyGodzillaGTi-R said:
this is a check list
- stock boost solenoid disconnected
- actuator bracket further reinforced to prevent flexing
- new walbro pump and regulator
- wide band running 11:1 AFR. Engine doesn't feel like pinging. The current power delivery feels very "NA-ish" with good low-mid range at 0.7 bar. Doesn't feel like the old school "big bang" when the boost comes in with the previous stock turbo.
- new HKS SSQV non adjustable (both spare Stock Recirculating Valve not too good)

Tomorrow is a new day. See how it goes.
Click to expand...
Yo disconnected the boost sensor near valve cover right?
I know you prolly already did this re-check vaccum line routing.
try turning up gain on boost controller slowly and i think there are switches on the back of it to, make sure those are correct if it applies.
 
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low612

New Member
BabyGodzillaGTi-R said:
this is a check list
- stock boost solenoid disconnected
- actuator bracket further reinforced to prevent flexing
- new walbro pump and regulator
- wide band running 11:1 AFR. Engine doesn't feel like pinging. The current power delivery feels very "NA-ish" with good low-mid range at 0.7 bar. Doesn't feel like the old school "big bang" when the boost comes in with the previous stock turbo.
- new HKS SSQV non adjustable (both spare Stock Recirculating Valve not too good)

Tomorrow is a new day. See how it goes.
Click to expand...
Did you disconnected the boost sensor near valve cover right?
I know you prolly already did this re-check vaccum line routing.
try turning up gain on boost controller slowly and i think there are switches on the back of it to, make sure those are correct if it applies. I will put money on it it has to do controller or vaccum line orientation.
 
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BabyGodzillaGTi-R

Member
Sumo- fuel regulator is set almost 4 bar.

I'll recheck the lines and AVCR line orientation tomorrow morning.
The stock boost sensor that is next to the right black box near the rocker cover, the hoses been disconnected but the electric socket is still in place.

As for AVCR boost controller. Right now set 90% duty, 9 feed back for all 5 gears.

Another thing, if i disconnect the actuator signal hose and it doesn't over boost, does it suggest an actuator problem or a leak in the system?

Ok let's be more specific, hope u guys can suggest which hose 1 by 1 i need to check so that i can check it with a fine tooth comb.
Cheers.
 
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low612

New Member
if you disconnected actuator hose from its nipple it should overboost.
Since your boost controller get signal from same line . If it doesnt overboost, I would think it means either your wasgate is not completley closing or may have some type of leak/crack in wastegate flapper area or something is obstructing compressor/turbine wheel.
 
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youngsyp

Active Member
All your symptoms point to an actuator/wastegate issue or massive boost leak between the turbo and plenum !

Have you adjusted the actuator so that you know it's fully closed, with the engine off ? If not, do this, disconnect the actuator vacuum hose and take it for a drive. Carefully apply throttle and see what the boost level does.

Have you tried what geetee suggested with the bicycle pump on the actuator vacuum nipple ?

If it's not overboosting with the actuator vacuum hose disconnected, it's nothing to do with the boost controller so, don't waste your time looking at that.

If this all fails, your next move should be to remove the turbo elbow, to physically inspect the wastegate, again as suggested before !
 
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sumo

New Member
i cant see it being the turbo u hav look at the wastegate and u said its sitting right the turbo lad has looked at the actuator u hav change the inter cooler for a uther one and u say its running 4 bar of fuel pressure but is ur fuel pump standard or what if it standard it might not be giving u the flow of fuel that u need what the plus like new or old just some ideas
 
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youngsyp

Active Member
sumo said:
i cant see it being the turbo u hav look at the wastegate and u said its sitting right the turbo lad has looked at the actuator u hav change the inter cooler for a uther one and u say its running 4 bar of fuel pressure but is ur fuel pump standard or what if it standard it might not be giving u the flow of fuel that u need what the plus like new or old just some ideas
Click to expand...
What has the fuel pressure and amount of fueld that's flowing got to do with the level of boost ?????

Sure it could have gone into safe mode and caused the chain of events mentioned back up the thread but, then the engine would not be behaving as it should. You'd notice the car running rough. Plus, you'd still get an initial surge of power, before the car went into safe mode !!!
 
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BabyGodzillaGTi-R

Member
Er nope. Engine to me sounds sweet after the rebuild.
I dont think the car is going into "retarded map". Even if it does i dont think boost will go down coz the stock solenoid is disconnected. Am i right?

I forgotten to ask what's all your vacuum reading at idle.
AVCR reads around -280-300mmhg at idle. Reading taken from the throttle body where there's 4 thingys sticking out with a rubber cap over it.

But my apexi mechanical gauge is reading around -0.4 x100KPa. That is tapped from this air chamber thing below the throttle body. The same where the stock boost gauge read from.

Hmm how do i show u a pic of it? U can see this in the EC engine and fuel workshop manual. My point is does this air chamber thingy or any of the hoses under the throttle body can cause sluggish boost/ boost problem/ can't boost higher?

I checked the Samco website, hmm they dont seem to have any pipes for the back bits. Any idea how much are those intercooler pipes?
 
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