Stock 14b - full boost at 5k?? WTF?

[Crazy91GSX]

Well, i seem to be having some boosting issues! i have a 90 awd talon, with teh stock 14b. stock exhaust, only a kn filter. Just got the car up and running again (blown head gasket) and now it wont build boost! well, 15psi around 4500-5000! 10 psi is almost 4k! .. I was worried that the timing might have been off, but i douple, triple and quadruple checked and it is just fine. Now, there is only 125-130psi in each cylinder, but seems to me that this should not make a 1500-2000 rpm difference in boost responce. I pulled the intake to check the turbo, and it feels brand new! no play up/down or in/out.. spins freely as well.

next on my list is to order a pressure tester from SBR and see what it shows. visually it looks to be ok, but we'll see..

anything else I should look for?

 

[xveganxcowboyx]

You're on the right track. Boost leak test. You know you can make a tester for a few bucks on your own.

 

[selmerguy]

Boost leaky me thinky. Also what are you using for a boost controller? the stock wastegate will open at about 10 psi and the hight you go in rpm with the stock o2 housing the more your boost will creep. Just a thought.

 

[Crazy91GSX]

im using a dejon MBC.. seems to be working well..

I think ill hit up home depot tomorrow and make my own tester.

 

[Apeximprt2nr]

Check your turbine housing for cracks as well as your exhaust manifold. A decent crack will effect spool up.
I would also perform a leak down test. Your compression is a little low. What was it before the HG change?

 

[2gGSX]

Check for exhaust leaks as well as your base timing.

 

[Crazy91GSX]

well i know for sure that the manifold doesnt have any cracks.. i inspected it when it was off of the car... as far as the base timing goes.. im not sure I know how to check this.

 

[Crazy91GSX]

Check your turbine housing for cracks as well as your exhaust manifold. A decent crack will effect spool up.
I would also perform a leak down test. Your compression is a little low. What was it before the HG change?

before the head was off the outside cylinders were about 130psi.. the middle two cylinders were both bleeding into each other and registering 0 compression.

during the head gasket change I did a new valve job with seals and a resurface due to a .004 warp in the head.

 

[Dream On]

Check the timing by doing this:

http://www.plymouthlaser.com/timin.htm

I would agree to check for boost leaks and exhaust leaks before the turbo. Most likely why it's taking so long. If you pulled the turbine housing to check for cracks, you could always port it and the manifold to make it spool a little faster also.

 

[Crazy91GSX]

well, i made myself a boost leak tester today and gave her a shot. found a big leak at the upper intercooler pipe to the throttle body elbow. also found both throttle body gaskets were leaking. fixed all the above and no change in boost rpm. So, I tried it again. found the the TPS was leaking, BOV flange gasket and the turbo outlet gasket. all were very small bubbling leaks, no hissing could be heard.. however, I have yet to fix these.

I guess my next effort will be to pull the exhaust manifold and exhaust houdsing to have a look.

 

[aero_sallee]

well, i made myself a boost leak tester today and gave her a shot. found a big leak at the upper intercooler pipe to the throttle body elbow. also found both throttle body gaskets were leaking. fixed all the above and no change in boost rpm. So, I tried it again. found the the TPS was leaking, BOV flange gasket and the turbo outlet gasket. all were very small bubbling leaks, no hissing could be heard.. however, I have yet to fix these.

I guess my next effort will be to pull the exhaust manifold and exhaust houdsing to have a look.

I've had issues with this on one car with two separate turbos. 14b and 16g. There is a sleeve that goes over the pivot for the wastegate arm. For some reason it shifted outwards and allowed the flapper to move out also. This caused it to not cover the hole when it was closed. Really horribly spool, but that was not consistent. It would shift back and forth, good spool one pass, then horrible and back again. Was really frustrating until I figured out what it was.

 

[Dream On]

If the TPS is "leaking", then you probably need to pull the throttle body off the car and replace the shaft seals. Try opening the throttle plate while doing the test and feel around the front and back of the throttle body for air coming out and listen for a change in tone.

 

[Crazy91GSX]

I've had issues with this on one car with two separate turbos. 14b and 16g. There is a sleeve that goes over the pivot for the wastegate arm. For some reason it shifted outwards and allowed the flapper to move out also. This caused it to not cover the hole when it was closed. Really horribly spool, but that was not consistent. It would shift back and forth, good spool one pass, then horrible and back again. Was really frustrating until I figured out what it was.

are you talking about where the actuator arom connects to the flapper?

 

[T9S1i]

Id pressurize the system and check the operation of your wastegate. Make sure it opens correctly, and make sure it closes correctly. It could be stuck open somehow.

Aero is also correct. IF you pull the A/C fan off you should be able to take a hammer (sideways) and tap the wastegate flapper back into the exhaust housing. If you look at the top of where the wastegate arm connects to the flapper, there is kind of a tube shaped piece of metal that goes from the outside of the hotside where the arm meets to where the actual wastegate flapper is inside your turbo. Sometimes that kind of works its way out and the flapper door will not operate correctly since the angle has changed. If you look at this from the top and it looks like there is more than 1-2 mm of this "tube" showing, tap it back in with your hammer and then see what happens.

 

[Crazy91GSX]

got some pics! looks like i have some cracking.. first pic is kind of hard to tell, but you can see the crack at the top and the long one at the bottom..

second pic I filled the cracks in with brake parts cleaner so you can see them easier.. however, there is a glare from the fluid making the bottom crack appear to be larger.. is this enough to cause such a dramatic difference in spool?

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[T9S1i]

take a pic of the wastegate arm/flapper from the outside, at the same angle you took these pictures, maybe slightly less of a downward angle and i'll point out what im talking about with the wastegate "walking out"

 

[I_eat_DSM's]

Almost as a rule the OEM 14b housing will crack right around the wastegate port. Check your wastegate flapper arm like the other guys are saying.

 

[Dream On]

As long as the crack doesn't go all the way through, then it's probably ok. How did the turbo gasket look when you too it off? How about the head to exhaust manifold gasket?

 

[ILLiCliPSE]

i hear there's a problem with some 14b's and to fix the problem you have to put 2-3 washers inbetween the space where the wastegate meets the compressor housing....like where the wastegate attaches to.....i might not have this exactly correct, but its somewhat along the lines of what i just tried to explain. ill try to find the post that explains all of this...its on the South Florida DSM forums.

EDIT: Heres a pic of where you put the spacers. My friend Mike has this same exact problem with his 14b, and this fixed it.
http://www.clipsekid99.com/other/spacers.jpg

let me know if this helps

 

[Crazy91GSX]

here is a pic of my wastegate arm/actuator.. i took the cotter pin out, the arm has always been connected.

http://i29.photobucket.com/albums/c296/Boorail85/wastegate.jpg


all looks normal to me?!? .. im gonna give the washers on the actuator mounting bolts a try.

 

[Crazy91GSX]

As long as the crack doesn't go all the way through, then it's probably ok. How did the turbo gasket look when you too it off? How about the head to exhaust manifold gasket?

the crack at the bottom does go all the way to where the flapper seats to the housing.. didnt take the o2 housing off to see how far it goes...

and both gaskets look to be in great shape..

 

[I_eat_DSM's]

I doubt that the crack is causing any problems but if you are concerned about it we'll definitely be able to tell with some better pics!

 

[Crazy91GSX]

im starting to doubt the cracks as well, but I need to figure this out! I guess ill have to take off the o2 housing and see how it looks on the other side...

any other suggestions?

 

[T9S1i]

yeah the w/g flapper arm seems to be right where it should be. It doesnt seem like its walked out at all.

I would try shimming between the wastegate/turbo as suggested and pictured above.

 

[Crazy91GSX]

tried the shims as well.. two decent sized washers on each side.. still doesnt hit full boost until 4500!