Spool issue

[Ozone302]

Hey guys. I've been reading up on 14b's and when they're supposed to reach full boost and I've came up with 3000-3200rpms. Well, mine doesn't reach full boost till around 4000 in all gears. I'm running stock boost and don't have an MBC. But the weird thing is it'll be around 7 psi until 4k then it'll hit full boost. Is this building of boost normal? Or is it supposed to gradually build boost but faster? I don't have any boost leaks anywhere and no pre-turbo exhaust leaks. My car has NO power at all till 3k rpms which it's at about 7psi, then right around 4-4200 it hits full boost. Previous owner of the car had the turbo rebuilt (have receipts) and has about 50k on it now.

I'm thinking either the wastegate flapper is opening prematurely or it needs a new spring? Like I said, there's no leaks anywhere so am I correct to thinking this might be the problem? If so, how would I go about replacing the spring or fixing the flapper? Or would an MBC be a solution to the problem?

 

[Jason023]

The "Flapper"? You must be talking about the wastegate? check ## actuator/wastegate ppl call it both things, im pretty sure that will fix ## problem, a way to check is it to take it off the turbo and try to turn it and push it in, if it turns easly there may be a leak in it causing it to not open properly intell ## pushing more exhaust gasses in( higher rpm). hopes this helps GL

 

[Ozone302]

Yeah thats what I meant sorry. I'm new to turbos . Thanks though I'll try that. Is there anyway I could check this without removing it though? This is my DD..

 

[96 420a-t]

Check for boost leaks if thats not your problem likee you said then the flapper is most likely your problem.

 

[tron2119]

I'd be suspicious of this "rebuilt turbo". Take the intake pipe off and spin the compressor. Let me know if it spins nice and freely. Also, check the shaft play. Pinch the nut in the center on top of the compressor wheel and wiggle it side to side (from front of car to back). Now try to pull it in and out ( from passenger to driver side). Any in and out play isn't good. A tiny bit of side to side play is normal. When it has a lot of play like its almost going to touch the housing, ITS TIME FOR A REBUILD. If it has a lot of play, it will start acting funny and having trouble building boost.

If you have verified that you have no boost leaks or pre-turbo exhaust leaks then this is the route I would take.

 

[007jimmy]

Do you know if there is any cracks around the WG hole? These turbos are common to crack all the way through the turbine housing around where the flapper seals bad enough to slow spool. You would have to pull the o2 housing to see if its cracked or maybe just the flapper isn't sealing the WG hole completely.

 

[Ozone302]

I'll take off the intake piping and check for shaft play today. Even though it was rebuilt, you never know what could happen.

Is the o2 housing easy to get off? I just don't want to break anything and have it not running because I'm in between jobs right now and really low on cash. Just wanna find what's wrong so I know.

Thanks for the advice guys. I appreciate it.

 

[jb2zero0six5]

O2 housing bolts can be a pain, PB blast them well. Make sure you can't move the wastegate by hand. Wastegate and the wastegate actuator are not the same thing.

 

[mike orlando]

To check for leaks use starting fluid on the vacuum lines and any area that could leak boost.

it could be your intercooler piping if you dont have hard upper and lower piping some times theres a flex in the hose if its not solid.