K guys so slight hiccup , my car idles high and fluctuates down to 500 rpm but then goes back up to like 1100 or so, my vacuum is also low at idle, this screams vac leak I know any places where I should look first ?

whats your vacuum at?

Like 12 at idle and my bovs don't work while boosting it just all goes out the turbo

A leak for sure, I pull 20 at idle. Your best bet is to do a boost leak test but if you don't have the equipment you need to inspect manually.

Check all the couplers/tbolt clamps, vacuum lines to/from BOV and wastegate, check lines on the intake manifold.

Also I know people have trouble getting a good seal on the intake manifold, spray some carb cleaner around the base of the intake manifold/runners (I know this is difficult to do with our car). If your idle jumps its a leak.

I cleaned my manifold gasket really well and used some spray on RTV to coat the gasket, then I torqued it down in order as per FSM to factory spec, 8 ft/lb, use a torque wrench!

It's an exhaust leak....I know had the same issue. Check the clamps on the piping. When I had it up on the lift ,running, I could fill the air flowing out. My vacuum pressure went from 20 to around 11. Then the other side started leaking and the boost went from 9 to around 6. You can only tighten those so much before they have to be replaced.

Thanks guys !!

Well we couldn't find the leak, and now the engine idles at 1100 ish and I got the code lean bank 2 afr stays at 15 ish and vac is at 12 at idle I also can only boost to about 4 psi

And on top of that the bov don't open and the compressor surges eveytime

having the same problem in my customers sts 370z , we tried everything to make it boost again we even made a direct hose form the turbo to the wastegate so it can give the maximum psi of the turbo and it gave 3psi , no leaks , we made a smoke test , their was a history of a bad pcv valve which made oil come out from the exhaust ,went all the way to the intercooler,maf sensors, piping etc etc , fixed that and cleaned everything and still doesnt build boost , check engine comes back on and idle at 1100 , spoke for ben STS went step by step with a confrence call with my mechanic and it looks like the 3 port solenoid is messed up since we made a and its suppose to make a ticking noise and its not , this is the last solution if not then its a bad turbo which went bad after 1000 miles or so , although their is no smoke,shaft play or anything , so lets see what happens after changing the 3port solenoid . wish you the best .:shakes head::shakes head:

p.s all of this took place after loads of exhaust leaks that happened and fixed them then changed tha bad place of the boost controller which was under the back bumper . since then problem after problem has been happening .

^^^If you connected the wastegate to the compressor, and the boost gauge to the IM, you will not see max boost pressure. You need to connect the lower half of the wastegate direct to the IM to see max boost pressure.


Where did yo guys get the BOV vacuum source and wastegate boost source?

If the wastegate source is right at the turbo compressor, then you will not make wastegate spring pressure for boost. This is due to pressure drop across the entire system, in this case a lot of piping. So there maybe 8psi at the compressor outlet, but only 4-5psi (or less) at the IM. The wastegate should be hooked up as close to the TB as possible.

BOV must go to the IM as it uses vacuum to open. However, if the manifold vacuum is up in the -12 in/hg, then the wastegate will not open. The spring inside it (assuming it is a Tial type BOV) is rated for vacuum, and it will not open unless the set vacuum for that spring is reached.



http://www.streettunedmotorsports.co...ring_chart.jpg


So with the VQ, vacuum should be in the -19 to -20in/Hg (at idle fully warmed up) and the -10psi spring is optimal. It will never open if the lowest vacuum you see is -12in/Hg.

There must be vacuum leaks present, and it would explain the high idle. Exhaust leaks will not alter the a/f ratios unless they are pre O2 sensor. In this case if the OEM sensors are used on the headers, it should not make a difference.

What's the 3 port solenoid ?

we tried all kind of ways to make the turbo build boost to the maximum by making a direct hose from wastegate to the turbo , this way should give us the maximum psi possiable of the turbo , but it also didnt , we closed the exhaust side of the wastegate to see if vents air we said it might be a bad wastegate spring but its closed and no air , the solenoid am talking about is the pcv swith
we applied 12v to the post on the PCV switch and listened for a click , their was nothing , the hose that was in the intake we pulled out and everytime we go on boost it spills alot of air/oil out side like crazy which means the crank case is getting filled with boost insted of the turbo ,

The PCV switch is grounded when the body is bolted down (Normally open)and then a 12v signal is applied when 1psi of boost is applied (switch closes) then it vents to the atmoshere through some small filter on top of the switch

i guess this is our problem , if its not then i dont know wht is the problem other than the turbo it self . i am waiting on STS BECAUSE we changed both pcv but didnt change the switch , and hoping they can send us the switch , it looks like it has 3 ports or something similar

we are not in california and i am really intersted in deleting this pcv switch thingy once and for all , i know its against some states in usa such as california , all info is appreciated in getting this switch or deleting it completely .

thanks

How could you be building boost in the crank case? 0_0

i kind of didnt understand when BEN was talkin to the mechanic about it , but when i read this thread it made sense , now i am looking to get this switch or away to cancel this headache once and for all .

STS turbo kit smoking like a chimney, ?? - LS1TECH

everything makes sense , not the same vehicle , but same kit kind of , and same issue almost .

My symptoms are different then that tho, mine doesn't smoke there is no oil anywhere it just idles at 1100 with vac at 11-12 and can't boost past 3

Just figured to share that's all :hello:

Car goes back in the shop today hopefully it's some thing small , did you check the intake manifold gasket?

yup all good , the pcv switch should make a ticking noise and its not at all , so i guess this is the problem , if not then :shakes head:

Well I dropped the car off let's see what they can find , hopefully it's minor

What's tb stand for?

Just a little info to maybe simplify the functionality of the the Forced Induction systems. I am sure this is on the boards, but maybe we can really break it down so troubleshooting the set up becomes easier. I keeping the terminology and concept basic so we can get the fundamentals going.

The turbo consists of 2 wheels...compressor and the turbine enclosed in their respective housings. These wheels are linked via a shaft, however they are sealed from one another. The exhaust gasses from the motor spin the turbine, or Hot Side. This, in turn, spins the compressor(cold side) and produces boost. Now we need to control the boost...

Try and think of the Wastegate as a literal 'boost controller' The Gate has a spring in it applying pressure to the piston, or flapper depending on style of gate. This spring will hold closed based on the mechanical rating of the spring. Once the pressure exceeds the spring rating, exhaust gasses are diverted and boost is limited. So, an 8PSI spring should produce 8PSI of boost. There are many things that can effect the actual boost, but for our purposes this example is OK. We will com back to this concept in a few.

The wastegate is ofter controlled by a secondary solenoid. This is known as a Boost Controller(BC). The BC can be in the form of a solenoid(electronic) or manual valve(ball spring/bleed/etc). So literally, the boost controller is a Wastegate Controller.

So back to our controlling of the actual boost...
The WG(wastegate) can be run with a port from the compressor housing of the turbo (or as close to it as possible) connected to the WG(bottom port or only port on the swing type). This orientation will run only the mechanical rating of the spring in the WG.

With the BC(boost controller) in line between the turbo(cold side) and WG. This will allow us to divert compressed air to the side of the WG valve opposite the exhaust gasses. This basically makes our WG spring behave like a far heavier spring, thus increasing boost. This can be done in a few ways, depending on the BC style. EBC(3 port) designs allow for 2 main styles of routing. Typically, one port comes from the Comp housing, a second comes from the bottom port on the WG, and the third port on the EBC is vented toi atmosphere or plumbed to the intake(does not matter). This is a very simplified explanation of the boost control system. An EBC assumes the ECU has a table to control it...we can go over tuning in another thread if anyone is interested.

The one variant that 95% of all Forced Induction systems has is a BOV(blow off valve). These come in many different flavors and styles. The main purpose of the BOV is to give the compressed air a place to go, after the throttle is closed, thus protecting the turbo. The BOV has a diaphragm or a piston, a spring and one(or more) ports. The idea here is a little different than the WG. The port on the WG should not see vacuum, so it is not an issue(because we are using a pressure only port...ie the comp housing) so you can run an 8 psi spring at sea level without the fear of a leak. We want a spring for the BOV that is stiff enough to stay closed at idle, and no more. A spring that is overly stiff, can lead to poor throttle response and decreased performance. In this example, we see the Tial Q. The spring should be selected based off of your ambient barometric pressure. The closer to sea level, the stiffer spring you will require. You may find the Tial Q requires a shim on the stiffest spring(11psi) to preload the spring a bit, keeping it closed at idle.

On a MAF or metered air based system, it is critical to make sure you have no vacuum leaks. Ideally, you want a BOV that recirculates back to the intake, so the ECU does not need to make dramatic fuel corrections at transient throttle conditions. Basically, the ECU sees X Airflow at the MAF and provides Y amount of fuel. If you dump it to atmosphere you have fuel Y and and not the metered X volume of air resulting in a rich condition. This over fueling can lead to stumbling, misfires, and poor driveability. This same concept applies to boost leaks after the MAF sensor.

Now we run VTA(vent to atmosphere) BOVs all the time, and can tune effectively for it, so I am not saying you have to run one or the other, that is up to you and your tuner.

I hope this breaks down the system in a very easily digested manner. There are a number of boosted Zs' so we should have a good understanding of how to set it up.

I hope this did not hijack the OP, I only intended to add to the discussion. Good luck, and if anyone needs help, feel free to drop me a line anytime.

-John :tup:

This is great info but sadly doesn't help with what's happening with my car

Pcv switch and solenoid was full of oil from the blow back that happened , the oil blocked the solenoid which made the air compressed back to the crankcase thus flow oil back to manifold,throttle ,piping,cooler etc etc we cleaned that as well we will run it tomorrow and see wht happens ,if it's all good we are Hana delete the Pcv system and make it directly going to the catch can , let's see

Hmmm interesting was your vacuum low at idle as well?

yes its -9 to -12 , before the problem it was -19 to -20 in that range .

Yea same as me I think I'm just gonna run a catch can

Black I'm sorry about are the trouble your having, but I have to be honest this thread is giving me a bad feeling about this kit.

Kits sweet man just a couple hiccups

Turned out to be a bad blow off valve go figure

You and me both. Even STS can't seem to get the tune correct on mine. I've had the kit for 8+ months and no one can seem to figure it out. Problem after problems but I've found a good tuner and I'm hoping he can solve what no one else can seem to figure out. Maybe it's time for the new Subbie coupe....hmmmm

The kit is good and has been proven it just has to be installed correctly , we just took the bov apart and reseated the seal and now it's fine

we cleaned the pcv valve, same problem , tried to delete it and for some reason the hose it self flows so much air that you cant close the hose with your finger , it means the boost is going is flowing in routes where it should not go to , such as catch can and every single place it can leak from . compression test is up , maybe just maybe its a bad ring piston .

While you got it open may as well do some internals!!!!

i hope i am wrong being something internal , but lets see wht the compression shows , because all the air is flowing back to the crankcase not going to where it should to , which means this might be a burnt ring piston , but the car idles,fine,drives fine, no smoke , so not sure yet , i just hope its not with 1500miles only on the car , and the owner was on 7 psi only and a week only on 11psi , so no matter how beat on it it should have held it, it had 500 miles when he got it and he broke it in till 1000miles or so , so 500miles boosted miles .:icon14:

If you are having some issues with trouble shooting, give me a call at the shop. We are there Tues - Sat. I would be happy to help out.

John
732 326 0090

Surely the motor didn't pop?

Very unlikely but a possibility

I can't see how the kit itself would be the cause of the problems seen here. It's only touching the intake and exhaust of the motor. Can't blame STS hardware for a blown ring, etc. Now if the tune was F'ed up initially, that could have caused problems.

the tune was done by sts then UAM did a good job with the tune by retuning it and taken off the meth kit it had for some problems they had , the car came and the tune was good air fuel was perfect , the check engine came up after some time but ppl say thats normal with forced inductions , although in the others customers gtm kit it never had any check engine , i did notice once misfiring , and another code cant remember it but if u u guys look at my posts i think i posted the code that came up , anyway the mechanic was too busy didnt do a compression test yet , i still have hope the its not internal because having oil on plugs doesnt mean ring piston right away it might mean alot of stuff , such as cylinder walls or excessive clearance in the valve steam , and if the pcv is plugged or inoperative it can cause building up crankcase pressure which will force oil and oil vapors past rings and valves guides into the combustion chamber which will blow oil like crazy on plugs for example ,

am just going nuts because i took of the pcv from its route and closed all hoses with screws , and air filled with little smoke is coming up from every single way it can reach which means all the boost is leaking out for some reason , even if the engine blew , in the world of power 7psi ,11psi or 1000psi **** happens , we just have to live with it and learn more and more , i hope :tup:

did a compression test , dry and wet and results are so nice loool , its inbetween 140 to 200 , i guess the normal compression test should be 200's , two of them are 200's the rest are 140 , 150,160 etc etc , so engine is messed up thats why all the boost is not building up and going to the oil pan i guess not where its suppose to go to , i am shocked , but again as i said shi* happens , time to open up the beast :(