Why can't I build boost?

[hellotbone]

OK with my 14b I was running 18 psi with an intake leak I fixed last night.

Installed t3/t4 and went for the 1st test drive made 10 psi with the way it came installed my MBC took it out again hit 15 psi and was holding like nothing. Blew the lower IC pipe I made off limped the car back to the shop and repaird. Next time out 10 PSI I just ran 15 so I assumed that the repairs I did to the pipe were leaking. Called it quits.

Next day made a new pipe and ran it same prob borrowed a leak tester last night and checked yeah I had a 2 leaks I fixed one big one on the s pipe to throttle body gasket I thought FORSURE that was the problem went out same thing.

I thought forsure I had it this morning my CE light doesn't work and I haden't checked to see if it threw a code or not so I started checking no codes so I unplugged the yellow ECU fuses in the fuse box and started off to work. Well for some reason now Im getting more boost this morning when I fist left it would make 10 pretty easy so I stopped and turned up the MBC now it will spike 15psi and hold about 12.5 psi for 1st and second gear but when it shifts to 3rd it falls back to about 9 psi then as the motor starts to rev higher and higher I get more boost. But I still cannot get it to run 15 psi like the first time I took it out and I know the MBC is wound in MORE then it was the 1st time.

What other things cause a car to not boost? I am going to get a compression gauge but I don't think its internal because when I pulled the plugs they look perfect.

If Im to lean for some reason on the afc with the t3/t4 would it stop it from making boost? I logged 2 runs when it was runnning like crap and both runs have perfect timing and 02 values .96-.98 volts.

I have totally run out of idea's here and have nothing left to trouble shoot the only thing I still have yet to try would be a new set of plugs is it possible to foul a plug where it will only work at lower rpm but higher it will not fire correctly? Im just wondering if when my lower IC pipe came off it when it went pig rich right away that maybe I fouled one or something or does the ignition have anthing to go south?

I find it odd that this morning I am able to make more boost for some reason I really have no idea's guys.

You also need a smiley with a guy with blood shot eyes from lack of sleep due to his car driving him insane!

What about the wastegate holding open a little would that cause my car to not make boost? I haven't checkit it yet but on a brand new turbo mabe the gate it not sealing tight?

 

[Lord Khan]

Sounds to me like you just have a boost leak/s. Are you 100% sure your not leaking anymore boost out of any of your intercooler pipes. If you blew one off the first time, thats probably why it didn't hold that 15lbs initially. If you hit 15lbs, then the coupler started to come off, that would cause the leak that you initially had. Go back and double-check ALL your pipes.

If it still leaks, then you'll have to do a leak test. Could be something like the wastegate or something, but considering the turbo boosted to 15 pounds initially, I seriously doubt it. I've seen a 14b with a bad waste gate, and it wouldn't boost past 6lbs.

Granted, I'm no guru of this stuff either, but from my experience of working with my own car, leaks are about 70% or more, usually loose intercooler pipes, when all else seems to be normal.

 

[hellotbone]

OK boost leaks there are none peroid. I had the tester on there at 20 PSI and soapy water on each joint when I say no leaks I mean it.

I really have no other idea's I have been over it 5 times already no idea's left.

 

[Lord Khan]

Well, it's really starting to point to that turbo then. If the car ran fine with your 14b, and now not holding with this new one, and there are no boost leaks, then it might be defective. I'm not sure.

Your saying that when you ran the leak tester, it held 20lbs right? If it did, then you have to look to the turbo for a possible problem. Thats one of those pain in the ass troubleshooting issues.

 

[hellotbone]

Thats sorta where I am looking into installing the 14b again to see if Im right or not at this point.

 

[Lord Khan]

BTW, have you checked your boost controller, and BOV as well. Also, are your caps still on your stock boost controller (Assuming you did cap the stock boost controller). Cause the way your boost is flipping around, it sounds like the car isn't controlling your boost at all.

 

[hellotbone]

Im running MBC on my car when I had the pressure on it I could open the boost controler and at the bleed point make the wg open when I tighten it then the WG stays shut.

 

[Lord Khan]

Oh. Well, sorry I couldn't help. Keep this thread alive though, I'm sure you'll get some more good feedback to help you. I would wait a couple of days before putting that other turbo on. Could be a minor issue that someone else on here might know about.

 

[hellotbone]

If I unplug my WG totally should I not see a huge boost number? Also can MBC's go south? Either way Im dropping it off at ETD tonight to get looked over.

 

[~97TalonTSi~]

I had the exact problem you mention and it was a faulty BOV. If you haven't checked it yet do so, maybe if you have another one around throw it on and see. I know you said everything was fine with the 14B but something could have gone wrong that first night you did see 15psi.

 

[hellotbone]

I don't have another BOV how would I check it? When I pressureize the system its not leaking or would it not leak unless I open the throttle?

 

[vinh766]

hellotbone, is ur car copper? or orange, sorry off subject

 

[hellotbone]

HOK Orange

 

[DSMJim]

What about the wastegate holding open a little would that cause my car to not make boost? I haven't checkit it yet but on a brand new turbo mabe the gate it not sealing tight?

Jamie look at my other thread. Yes this is very possible and probablly the problem. The wastegate setup is never tight when you get. You will have to go over that, but you wont have to take off the turbo to fix it. Read the other thread you started it went into a little more detail on it.

 

[hellotbone]

Jim now that you mention it I should have looked at that I almost bet thats it.

 

[hellotbone]

Well all is well it was the WG what happened is when I slid my stock fan in it was putting pressure on the accuator and was holding the gate open a hair can't build boost like that. All is well and now it sure is a fast car.