96ekb20

so i finally got my b20b turbo set up up and going this weekend. got the cursing tuned in. then went to slowly roll into boost to start tuning the boost area. after 2,3,5,7,9psi all of sudden it kept going to 15psi i let out right away and the ecu was hitting the boost cut i put at 11psi. set up is a b20b semi built ram horn big tube 38m tail waste gate 3" down pipe. ive tried disconnecting my ebc and just going from compressor cover to waste gate still no difference. after a few hours of reading i kept seeing people talking about how u need to try to have all vacuum lines all short as possible. so today i moved the ebc silinod and shorten all the lines. still does the same thing. then went back to reading found that the 7psi spring i have is just a ruff psi the spring will hold depending on manifold and turbo size. which is a garrett 61mm .70ar cold side 58mm .63 hot side. im stumped and only thing i can think of is the diaphragm is junk? i can move the wastegate plunger when its off the manifold so its not stuck. any input would be awesome. i dont know if my set up just wont maintain the low psi and im just stuck to that or what.

TheShodan

iTrader: (14)

Sounds like you're using too small of a gate with a large turbocharger at low boost. Then adding larger 1.75 Primaries of a Kooks-Ramhorn to the mix. That's going to definitely cause some spikes. Like you read, the spring / wastegate you're using works depending upon MANIFOLD & TURBO SIZE.

What to do? Larger wastegate size is needed to help eliminate this, and retune in warmer climate if you're in a cold climate this time of year. The dense air easily can cause overboost conditions.

96ekb20

its not spiking. the boost never stop building never tappers off or anything. just goes up til i let out of it cause its hitting boost cut.

TravisBiggie

dude... the way you're describing it, its still considered "spiking" because its going beyond the psi the spring is rated for... it stops because of boost cut, period. you need a bigger wastegate as already stated.

Turbo-LS

iTrader: (4)

By chance are you using a boost solenoid ? Could have it backwards so 0% duty is giving you maximum boost. That's something to look at but could also be wastegate issue

bergercurtis

He did say he's running an electronic boost controller, so it is possible.

What happens when you run no lines at all to the wastegate?

Turbo-LS

iTrader: (4)

It won't open and over boost LOL

96ekb20

i under stand that but i dont beleave i hear the waste gate opening. ive already said i took the ebc out of the equation and still had the same problem. trying a buddys waste gate later today.

96ekb20

how would it be hooked up backwards? i have a 3 port port 1 to compressor cover port 2 to top of waste gate. compressor line has a t which goes to the bottom of the waste gate. my ebc has a hot and ground wire and a vacuum port to see boost. which is t into the same hose that my boos gauge sees. but again dont beleave its opening.

boostjunkie757

Its definitely the wastegate. if you switch to at least a 44mm wastegate, it should correct. I had the same issue and it corrected mine...I was running a cheaper knock-off full race manifold, and it was still creeping 2 psi. When I eventually got a full race manifold, it fully corrected the rest.

boostjunkie757

the 38 mm wastegate is unable to expel the unnecessary excess exhaust gases quickly enough to control the boost pressure level. even if you attempt to run it off just the wastegate spring, it will still spike uncontrollably.

96ekb20

going to try changing the waste gate to my back up one. if same problem is there then do you guys think if i changed to my old cast iron basic ebay manifold it will help the problem ? til i can buy a nice ram horn or mini ram with a 44-50mm gate

TheShodan

iTrader: (14)

No. If anything, you'll make it worse. As boostjunkie757 and I both said, you're using a small gate with a relatively large turbocharger at low boost pressure level. If when lines aren't hooked up it still happens, its both the valve of the wastegate not opening (primary problem) size of the wastegate overall in relation to your setup (secondary problem).

If your buddy's gate is the same size as this one, and the problem persists, its the size of the gate itself you need to change. Changing manifolds to a Kooks actually makes your condition worse because now you're giving the gate MORE exhaust gasses to try and control, when it can't.

Don't change any manifolds until you get your other stuff corrected, or you'll simply complicate your issue.

96ekb20

ok thanks shodan. trying to get over to my buddys tuning shop here in chico "boosted tunning"and get it on the dyno to see if the gate is or isnot opening so it can be seen vs hearing it open as this turbo spools very hard and loud!. so looking at the manifold i have now the tube welded to it is smaller the the dump tube or waste gate size! would it be worth it to try cutting to tube off and weld on a new one thats actually 38mm or damn near it? the tube thats on there is a typical thumb size tube maybe 3/4"-1"

96ekb20

Also about changing the tube size to match the 38mm gate if its not worth to do cause the gate is far to small under any conditions to control my turbo around 11psi. should i just change the tube for the gate to a 44mm? i have a plasma cuter and a welder it mite not look super pretty when im done but at least it will function? also you say control my large turbo at low boost what psi may it beable to control it at ?

96ekb20

ok so i put my buddys waste gate on which just by feel you could tell it was softer but dont know the spring rate it is. boost would hold 12.5 never higher so i was told the tail changed there spring colors not to long ago so is it possable that my "7psi" small green spring was actually a higher psi spring?

96ekb20

btw i see tail has a different chart for every waste gate mine is a tail sport with a spring with a green paint strip on it.

boostjunkie757

to run lower amounts of boost if youre setting up a boost by gear approach, you would probably either want to go with a wastegate larger than 44mm, im thinking 60mm, or run a twin gate 44mm. im uncertain with my 44mm if I can run less than 15psi, because ive got an old school ebc that only runs high and low boost. also haven't really been messing with it enough to give you a further informed statement.

motoxxxman

this alone is probably 90% of your problem. so yes, welding on a new pipe and flange that have an ID of 38mm or larger will have a huge effect on correcting the problem. may even solve it completely to where you can still use that 38mm tial sport wg.

Aradin

^^ this. 96ekb20, That's a huge part of the issue and it's causing a massive restriction for your wastegate. I have seen this issue first hand multiple times. You should be using 1.5" pipe for the dump tube on a 38mm wastegate. Correct that and post back because I can guarantee that's a large part of your issue.

boostjunkie757

while that may address some of the issue, on the older manifold that I was running that initially had a 38mm wastegate on it that was insufficient to control boost pressure, when we made a stepper adapter to run the 44mm wastegate so I wouldn't need to get a new manifold, there was still 2 pounds worth of creep left. when I got a manifold with a 44mm wastegate flange on it, it was no longer an issue, didn't spike, didn't have any creep, and he essentially has the same turbo I have. t3/60-1, except he is running it on a b20 whereas mine is a b18c5. the vtec crossover probably created some of the issues I had, but the problem he is describing does sound very similar.

96ekb20

i deffently will right now trying to get the car tuned on the gm 2 bar sensor so i can try to make a track event im not worried about running more boost was just worried about runing 12+psi on a stock map sensor now i have the gm 2bar ill getit tuned hopefully make this farmtruck and azn hosted event here in redding ca. if not ill take it off and fix the feed tube and make it next weekend to a test n tune. thank for your guys support.

96ekb20

anyone here every have a issue with going from the stock map sensor to a gm 2 bar and the car wanting the tune to be far differentfrom the stock map sensor ? like way more fuel at idle and want a much of fuel why cruising but the little throttle areas like 11-2" of vacuum wants alot less fuel and then when i think im getting it close its all over again im so stumbed.

motoxxxman

yes, you need to change the map sensor settings in the tune.
1) what tuning software are you using?
2) what's the part number on the map sensor? theres a chance its not actually a 2bar
3) is the stock map sensor still plugged in?
4) what port do you have the gm sensor connected to? and is it connected directly to a port on the tb or manifold, or is it T'ed into another line somewhere?

P.S. I currently am running a gm 2bar in my car

96ekb20

tunning on crome, i dont remeber part number yes its a 2bar 3.8liter supercharged map sensor all 2 bar pulled it today, no stock map sensor is not pluged in. yes i changed the settings in advance boost to gm 2bar. as i cant get my knock off 3bar to read right as when i choice xenocron 3 bar. so figured why not just do a gm 2 bar as it would allow my 12.5psi and i wouldnt boost cut any longer til i can change the waste gate tube size.