View Full Version : My 2nd turbo boost problem, part2........
I was wondering if those more knowledgeable than myself could give me some advice on how and what to check on my car in relation to my boost problem on the second turbo. I fitted the second decat last night (both fitted now) without a restrictor ring as I don't have one, BUT more importantly the previous owner said it ran fine without it (this is what CW told him as he serviced it and fitted decats). I took it out for a drive last night and it had not made a real difference to the second turbo boost.
Its doing funny things, sometimes it does not seem to dip at 4000 and there is no 'kick', it just stays at 0.7/0.8. Then other times it seems to dip at 4000 then just go back to the same pressure of 0.7/0.8. On the VERY rare occasion it will actually work how it should...like on the way to work this morning: I put it in third and floored it, as I hit 4000 it dipped and the second tubby came in with a MASSIVE kick...up to over 1bar, traction control kicked in as the back end tried to get loose! I then did it again, and it worked fine. But as soon as I got onto the marsh road where I had space I tried it numerous times and it just acted like it normally does... 0.7/0.8 on both tubbies :(
I have had a brief look around the bay but it was dark so could not see much. The only think I noted was that the rubber vacuum pipe that comes from the steel pipes that goes to what im pretty sure is the WG VSV (rubber pipe is 1/4" I believe) has been cut and a bolt put in both ends, the VSV has also been unplugged??? The previous owner told me that the boost controller is not wired up right now, so I assume this is where the solenoid would go. Is this supposed to be like this? Even if its not I cant see it being the cause of the boost problem, especially as its an intermittent fault.
Any ideas because im sooo, confused :(
Chris Wilson
14-12-06, 13:08
Put the plumbing back to stock for a start.
Tricky-Ricky
14-12-06, 13:11
Hmm bit of an odd one but first off the pipe you say has been cut and plugged, i would replace it with an intact piece and see what happens, also it could be down to a pressure tank problem, after a run pull the pipe off the IACV and see if it makes a sucking noise momentarily, if so the pressure tank should be ok,
the other thing you can try is, providing the last test was ok, put it in quick TTC mode (if you do a search its easily found) and see how it behaves, if it makes more boost then that has eliminated the EGCV and its actuator and VSV and also the IACV and its VSV
which will leave the EGBV and it VSV and the waste gate and its VSV.
I don't want to confuse you to much but i had very similar problems and the only way i get more than .8 bar is in TTC mode and bypass all the VSVs i have yet to re test the waste gate VSV as this is what it would seem to be but i also suspect a the ECUs control of that VSV.
I will say be careful when testing without a restrictor ring especially in TTC mode as you could reach a dangerously high boost if things are ok!
If you coming to the RR an sat i'll take a squint and see if i can spot anything if you haven't got it sorted by then.
Yup i'd go with Tricky-Ricky, my money is on a faulty IACV, run the car in TTC (Hose method 5 min job) and take it for a drive and let us know how you get on.
Once done, the tubbies will then run in parallel and the exhaust note should change, you should see full boost at 4k rpm.
Full decat, no restrictor ring, and wastegate actuator disabled. Surely that's a recipe for disaster once no2 does come online?
Full decat, no restrictor ring, and wastegate actuator disabled. Surely that's a recipe for disaster once no2 does come online?
No one's telling him to boost it at wot up until 6K RPM, he has a boost gauge, so all he has to do is keep an eye on the boost gauge, the moment it goes past 1.0 Bar he should back of the throttle.
Sean, this is the easiest way to find out if your sequential system has a problem, most of the IACV's are bypassed.
Tricky-Ricky
14-12-06, 13:42
Full decat, no restrictor ring, and wastegate actuator disabled. Surely that's a recipe for disaster once no2 does come online?
The waste gate actuator is not disabled, just the VSV the actuator which will behave as its intended ie open at its pre set pressure which AFAIKR is about 17.5 PSI.
The waste gate actuator is not disabled, just the VSV the actuator which will behave as its intended ie open at its pre set pressure which AFAIKR is about 17.5 PSI.
As the man says.:)
Hmm bit of an odd one but first off the pipe you say has been cut and plugged, i would replace it with an intact piece and see what happens, also it could be down to a pressure tank problem, after a run pull the pipe off the IACV and see if it makes a sucking noise momentarily, if so the pressure tank should be ok,
the other thing you can try is, providing the last test was ok, put it in quick TTC mode (if you do a search its easily found) and see how it behaves, if it makes more boost then that has eliminated the EGCV and its actuator and VSV and also the IACV and its VSV
which will leave the EGBV and it VSV and the waste gate and its VSV.
I don't want to confuse you to much but i had very similar problems and the only way i get more than .8 bar is in TTC mode and bypass all the VSVs i have yet to re test the waste gate VSV as this is what it would seem to be but i also suspect a the ECUs control of that VSV.
I will say be careful when testing without a restrictor ring especially in TTC mode as you could reach a dangerously high boost if things are ok!
If you coming to the RR an sat i'll take a squint and see if i can spot anything if you haven't got it sorted by then.
I pulled the pipe off that comes from the pressure tank to the IACV VSV and it was pressured (made a sucking noise), i pulled the one from the VSV to the IACV off and it did not make any noise. I assume this is right as the VSV is not open?
I am confused as to why the WG VSV would not be connected, does this mean the gate would not open...or just open at spring pressure...how much is this?
Or am i on the completely wrong path?
Carlos. I have too been worried about running without a restrictor ring and full decat. But previous owner said it was running within limits without one or atleast he said thats what CW said when he fitted the decats.
Can you shed any light on this CW?
The waste gate actuator is not disabled, just the VSV the actuator which will behave as its intended ie open at its pre set pressure which AFAIKR is about 17.5 PSI.
woosh! Right over my head :D
I'm getting confused with the setup on my ex UK car, where I let the bleeder-valve hose vent to atmosphere. This let the car hit stupidly high boost (20psi without even trying).
woosh! Right over my head :D
I'm getting confused with the setup on my ex UK car, where I let the bleeder-valve hose vent to atmosphere. This let the car hit stupidly high boost.
its not venting to atmosphere, its plugged so there is still pressure.
The waste gate actuator is not disabled, just the VSV the actuator which will behave as its intended ie open at its pre set pressure which AFAIKR is about 17.5 PSI.
If the WG opens at 17.5 PSI (about 1.2bar) then how can there ever be a risk of overboosting?
If the WG opens at 17.5 PSI (about 1.2bar) then how can there ever be a risk of overboosting?
I think it's because the Jap-spec wastegate is rather small. It can only evacuate a limited amount of excess boost. UK cars have a larger WG.
I have to agree with Chris on this one Sean. You should get all plumbing back to stock. From there you'll have a better idea.....(hopefully)
Tricky-Ricky
14-12-06, 13:56
I pulled the pipe off that comes from the pressure tank to the IACV VSV and it was pressured (made a sucking noise), i pulled the one from the VSV to the IACV off and it did not make any noise. I assume this is right as the VSV is not open?
yes thats correct
I am confused as to why the WG VSV would not be connected, does this mean the gate would not open...or just open at spring pressure...how much is this?
If there is no connection to your waste gate VSV then your answer to the last question is not correct as this is also directly connected to the pressure tank, so it would not hold pressure, so this could well be you problem as the system would just be relying on the EGBV.
Or am i on the completely wrong path?
Carlos. I have too been worried about running without a restrictor ring and full decat. But previous owner said it was running within limits without one or atleast he said thats what CW said when he fitted the decats.
Can you shed any light on this CW?
!!
Im confused Tricky on this bit "If there is no connection to your waste gate VSV then your answer to the last question is not correct as this is also directly connected to the pressure tank, so it would not hold pressure, so this could well be you problem as the system would just be relying on the EGBV."
The way it is plummed in at the moment is: 1/4" pipe coming from pressure tank that goes to WG VSV is plugged with a bolt. The connection on the VSV that this should go to is also plugged with a bolt. The other side of the VSV is still connected to the WG from what i remember, but will have to check. The power connecter to the VSV is not connected.
Im still confused as to if this is the reason for the boost issue, then why is it intermittent?
Also how do you do the pipe method. I take it you need 2, 1 way valves as per MKIV.COM FAQ, where can i get these from locally?
Tricky-Ricky
14-12-06, 14:58
Sorry Sean, ignore the last comment about the waste gate and pressure tank i had my wires crossed, have a look at this pic and tell me where the pipe is cut and disconnected?
Is it cut at one of the black lines ?and did you get pressure escape at the red line ?
http://www.imagestation.com/picture/sraid220/p217aec3523e48b2564290a7291650dd0/eba07bd0.jpg
yes it is cut at the TOP black line, and yes i had pressure escape at the red line.
Do you think its safe for me to run without a restrictor ring, in sequential or TTC mode? what is the limit the ceramics can take safely?
Tricky-Ricky
14-12-06, 16:27
Before you do anything else re connect the pipe and try it in sequential first and keep a carefull eye on boost, you may be ok without a restrictor ring, the std turbos i think will take 1.2-1.3 at max maybe the odd 1.5 but not for long, at anything over 1.1 its a risk.
:yeahthat:
Maybe that bolt plugging the wastegate VSV isn't holding pressure everytime causing a boost leak from the wastegate pressure feed.
It's only the IACV and EGCV that have a direct feed from the pressure tank. The EGBV and Wategaste are connected in line with the pressure tank pressure feed and will only be pressurised on boost.
Well i tried plummed the WG VSV back in as normal...no change.
I then did the TTC mod using just pipes...TTC is awesome!!! Only after a while when in 3rd+ it was boosting to 1.5bar! obviously i let off straight away! :)
I then plugged back up the WG VSV as it was before, i think part of the pipe was cracking around where it the pressure side met the VSV, so there was probably a leak that was causing it to go to 1.5bar+.
I finally took it out again in TTC mode and it boosted awesome, only problem is it seemed to be getting to approx 1.3 which is dangerous...right?
so whats wrong with the sequential system then? how do i find out if its the IACV VSV or EGCV VSV?
Oh and if i want to leave it in TTC mode i take it i need a restrictor ring? If so, what would it take the boost down to if i put 1 cat back in?
Tricky-Ricky
14-12-06, 21:25
Well i tried plummed the WG VSV back in as normal...no change.
When you reconnected the pipe to the waste gate VSV did you happen to check the other vac/pressure pipes to make sure that they are as the diagram?
I then did the TTC mod using just pipes...TTC is awesome!!! Only after a while when in 3rd+ it was boosting to 1.5bar! obviously i let off straight away! :)
I then plugged back up the WG VSV as it was before, i think part of the pipe was cracking around where it the pressure side met the VSV, so there was probably a leak that was causing it to go to 1.5bar+.
OK are you saying that you had it in TTC mode but with the waste gate VSV bypassed like i did with mine?? if so i did not intend you to use this method! it was just as a example of what i did to gain boost, but i'm glad nothing whent[COLOR="Blue"]
I finally took it out again in TTC mode and it boosted awesome, only problem is it seemed to be getting to approx 1.3 which is dangerous...right?
[COLOR="Blue"]Now do you mean just the normal TTC mode, without the Tricky-Ricky nuttier mod? if you got 1.3 then a restrictor ring should get it back to 1.1
so whats wrong with the sequential system then? how do i find out if its the IACV VSV or EGCV VSV?
If i am right about you last test, then nothing!
Oh and if i want to leave it in TTC mode i take it i need a restrictor ring? If so, what would it take the boost down to if i put 1 cat back in?
Yes you will either need the ring, or yes you could put cat 1 back, to do a permanent TTC mod then you really need to wire the IACV actuator fully open and also the EGCV actuator fully open, the is a guide around somewhere.
Well i checked that the IACV was connected to the VSV correctly, same with the EGCV and VSV.
What is the Tricky-Ricky nuttier mod and what does it change? The way i did it was vac pipe straight to the IACV, and vac pipe straight to the EGCV, keeping them pushed open constantly.
How can there be nothing wrong with the sequential system? 1 minute its only making 0.8 on second tubby. the next its making 1.1ish. how is that right?? :(
if i put a cat back in, what would this take the boost down to?
Tricky-Ricky
14-12-06, 21:51
This is why i thought you had done the same as i have,
"I then did the TTC mod using just pipes...TTC is awesome!!! Only after a while when in 3rd+ it was boosting to 1.5bar! obviously i let off straight away!
I then plugged back up the WG VSV as it was before, i think part of the pipe was cracking around where it the pressure side met the VSV, so there was probably a leak that was causing it to go to 1.5bar+."
As it implies that you bypassed the waste gate VSV.
My reference to the TR nutter mod means bypassing all VSVs and in effect connecting both the waste gate and the EGBV actuator in a loop so all they see is a manifold pressure.
You also have to remember that throttle position, RPM and engine load will have a big impact on how the turbos behave in as far as what boost they ultimately make,
i would be inclined to either fit the cat or a restrictor ring and then re conduct the tests.
You can check the resistance of the VSV's which should roughly be around 25 - 35 ohms depending on temp.
You can hook power up to them and make sure they are operating whist blowing through each port making sure the valves are operating correctly.
You can also hook up an air supply (10-12PSI)to each control valve and check the operation although TTC has tested the IACV & EGCV. The EGBV is abit more involved.
as the WG VSV ha been cut and plugged, doesnt this mean that the WG does not see ANY pressure? how can this be right?
i have not done anything with the EGBV, i assumed that this was obselete when running in TTC?
This still does not help me get to the bottom of why the boost is not staying the same on tubby 2 when in normal sequential mode...
Tricky-Ricky
14-12-06, 22:29
as the WG VSV ha been cut and plugged, doesnt this mean that the WG does not see ANY pressure? how can this be right?
OK what you have to remember is that there are TWO feeds to the waste gate and EGBV actuators so even though you have blocked the VSV the waste gate actuator is still seeing manifold pressure!
i have not done anything with the EGBV, i assumed that this was obselete when running in TTC?
In order to operate in TTC mode you need to bypass the EGCV VSV so that will make a big difference!
This still does not help me get to the bottom of why the boost is not staying the same on tubby 2 when in normal sequential mode...
Like i said in the other post i think you need to put in a restictor ring in order to have a constant, but having said that some rings need to be fettled to get the desired boost.
The waste gate actuator has a pressure feed off the turbo pipework (big red Dot) then it's connected to the VSV which you say is cut and blocked both ways. That means the wastegate is seeing boost pressure and operating on it's own.
48578
TBH it sounds like a faulty vsv on the IACV or EGCV either one not opening fully will restrict tubby 2.
The EGBV will cause tubby 2 not to come on line till after 5k revs and make the engine feel very wrong and unwilling to rev.
I'd have that wastgate connected as it should then diagnose the seq system.
Seeing as it was fine in TTC, this has so far proved the IACV & EGCV actuators, pressure tank and hose connections.
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