my results of my boost leak test...couple concerns

[91tizzy]

Ok so as some of you know I had a boost control problem last week that allowed my 153,000 mile longblock to see a whopping 26 pounds of boost...well for those who arent aware of my problem I never hit fuel cut before or while this happened (luckily I was aware and it only saw that boost for a split second) well anyway I fixed the boost control problem and now I am getting what I have deemed to be fuel cut at even sometimes below stock boost....so I started hunting for boost leaks....first of all the only way I have to pressurize anything is a bike pump because I am currently away from home. I started with the turbo and tried pressurizing that....didnt get hardly any pressure but no obvious leaks that I could hear. So I pulled all my intercooler hoses and they look fine. Well today I put the tester on my tb elbow and start to pressurize the intake and almost immediately without the bike pump gauge even holding any psi I can hear hissing from the return spring of my throttle body I can actually move it around a little (aka side to side shaft play of the tb) . Ok so My throttle body shaft seals need replaced...great. My question is CAN THE TB SHAFT SEALS BE THAT BIG OF A BOOST LEAK????

 

[No_Skillz]

Yes. If it's hissing at that bit of pressure, imagine what it's like at 15-20 (or whatever you're running) psi. With that said, doing a BLT slowly starting from your TB and adding piping step by step is great thorough way to do it. I commend you since most of the time I'm too lazy.

 

[91tizzy]

Ok riddle me this just out of curiosity. Im figuring (well hoping really) that being that I had no leaks before (well no fuel cut issues anyway) and now I have what seems to be a HUGE one at the TB shaft seals, that I would more than likely not have any major leaks anywhere else right ( meaning since those went out big time they were the weakest link)? Just tryin to ease my troubled mind about it because now I have to wait 5 days till my new tb seals/gaskets come in. no boost

 

[No_Skillz]

The chances are you will have major leaks elsewhere. Once you fix the TB, the next weakest link will reveal itself. Eventually things that didn't leak before will start leaking as you progress up the chain. Fix them all, hold a decent 20 psi for 30 seconds, and you're golden.

 

[theSicKness]

Just checking but are you 100% sure its only your TB seals? i thought i had the same problem turned out to be my FIAV.




J

 

[Black_Bullet]

I have had leaking TB shaft seals since ive owned a dsm. I mean they need to be fixed, and they are definitly considered a boost leak, but I dont think they are that massive of a leak as you make it seem.
You probably have another leak elsewere.

 

[91tizzy]

well see the thing is I never hit fuel cut before this little incident so there wasnt any big leaks before. And I am pretty sure that the tb shaft seals are leaking because when its hissing I can wiggle the end nut on the shaft itself and it changes the pitch .....it has to be a big one because I cant even hold stock boost at lower rpms without hitting it and there are no apparent leaks in the hoses or the intercooler and this is the first one that I have found....like I said the shaft seals wont even hold enough pressure to register psi on a BIKE PUMP so I am figuring that they are the major culprit....the throttle body shouldnt have any shaft play im assuming too Im just praying that my intake gasket is still ok....but like I was thinking is that if the shaft seals went then they would go before a manny gasket would and that would relieve the excess pressure on the gasket...sounds confusing but can yall make sense out of what I just wrote?

 

[Black_Bullet]

When I boost leak test my tb shaft seals and wiggle the the end nunt no the shaft it changes pitch also.

Remember the turbo itself pushes MUCH more cfm than a bike pump, or a regular air compressor, so you building and holdnig the little amount of boost you are running shouldnt be an issue on your setup with only leaking tb shaft seals...

Btw are you just using a regular manual bike pump that you push down on yourself, or an electric? You should use a bigger air compressor that can push more pressure into the system and hold it better so you can get better chance to identify all the leaks.

The fuel cut issue could be due to something else, maybe unplug your ecu for a while and reset all your fuel trims and stuff and long term octane value and see if the car runs any better.

You need to confirm that your injector seals and intake mani gasket, and bov, and etc arent leaking.

 

[91tizzy]

well see I would be sooo much better off If I actually had access to an air compressor but I am currently in mississippi where the uncle that I am helping to rehabilitate does not own an air compressor....the injectors were replaced with the 450's within the passed 8,000 miles or so....I agree on the bov etc....and yes it is a manual bike pump unfortunately....all I know is that the car boosted great before it saw that 26 psi for that split second so I know that its a major boost leak somewhere and I was hoping that it was in the throttle body shaft seals being that they seem to be leaking pretty badly....that or the bov....pulling the intake manifold would not be a very viable option at this point being that I am away from home so Im just keeping my fingers crossed.... and I would go to a gas station to do the test but figure I wont be able to hear the leaks above the compressor also before I did the intake pressure test I pulled off the negative battery terminal for a while thinking that that would reset the ecu and when I drove it it was still doing it....does that not reset it?

 

[No_Skillz]

Just because you're not hitting fuel cut doesn't mean it's not a huge leak. Do it right and fix them all. You'll thank yourself later.

 

[toojung2die]

I know from recent personal experience that TB shafts that are hissing a little during a boost leak test are probably leaking more boost than you imagine. I did the o-ring fix from the VFAQ a couple of years ago. It didn't last long and soon I was hearing a little hiss from the shafts again. I drove like that for almost two years with my boost set at 18-20psi. I replaced the o-rings with real seals and found my boost was spiking up to 26psi! That's 6psi of lost pressure through "slightly" leaking seals. The old o-rings didn't appear to have worn at all and looked like they did when I put them in.

 

[Black_Bullet]

Thats really hard to believe, but im not doubting you or calling you out or anything.

And OP when you boost leak test use soap and water and you will see bubbles were leaks are and you wont have to worry about hearing every leak because some wont be audible anyways.

 

[91tizzy]

good deal thats good to hear because I really think that is my case being that they are leaking so bad with so little pressure I can imagine how bad the leak is at boost. Its just hard to be sure because I dont have a reliable pressure source but I will definately be looking for more leaks once I get the shaft seals replaced I just hope that doing the throttle body rebuild gets rid of my fuel cut for now. At least until I can get to an air compressor. I really appreciate all the input on it guys. Any answer for reseting the ecu? Does taking the negative terminal off do it?

 

[turboglenn]

AFter you get the TB shaft seals done you still want to check the FIAV over again too. That weird shaped o-ring that seals it seams to die pretty easily and about the same time as teh shaft seals. Both of mine are bad, but beigin MAP instead of MAF it doesn't effect me that much except for teh loss of power from the turbo working harder to make up for the leak.

 

[toojung2die]

Any answer for reseting the ecu? Does taking the negative terminal off do it?

That'll definitely do it. 5 minutes is more than enough.

 

[91tizzy]

UPDATE!!!! woohoo finally something goes right on the dizzum...I dunno what did it but I took the throttle body off and apart only to realize the throttle plate screws were not coming out without having to drill and replace and guess what?? no drill...or anything to rethread the holes for a different set of screws.... so It sat for a while on my kitchen table till I figured I would just throw it back on and deal with the fuel cut issues and just putt around in the car....althewhile I had recieved a buscher racing upper intercooler pipe with the bigger tb elbow...so I throw it on the car after reinstalling the throttle body and guess what I find taking off the bov from the stock intercooler elbow.........NO GASKET! Ok so that may have been a big contributer.....anyway long story short I get everything back together and just decide to run a direct line to the wastegate actuator seeing as I couldnt turn up the boost anyway......start up....sounds fine....throw it in gear.....everything is normal....boost it up..... and no fuel cut!!!!!


I have yet to try and reinstall the contoller though I think Im gonna just drive it for a while

 

[No_Skillz]

Good to hear you got the car driveable. Now fix those other boost leaks and it'll feel great at WOT in no time.