Car Wont Hold Boost.

[Jordanbutter]

I know there is a million threads on this but mine is different from all the rest. The turbo will spool to 14psi (what I set the mbc to) but then drops off to 10psi. I took the mbc out and ran the line just from the LICP to the wastegate and it did only 10psi but dropped to 9psi. Keep in mind its only holding the max psi for a second. Also it never maxes out again, i.e. if the max is 14psi it only does 13-13.5psi the next time it spools. Any thoughts? Wastegate? Actuator? Flapper? Not turbo related at all? Oh p.s. I did a boost leak test and found nothing.

 

[mitsu-luver]

its got to be your inter cooler piping one of your couplers are loose. beacause if you think about it it will hold boost for a second because i cant let it all out in a split second. go check all your piping and tighten all of them thats got to be it

 

[forcefed 95]

I would lean more towards your wastgate. I would check and see if its stuck open, or if it is sticking open.

Also it would not be your intercooler piping casue you would have found a leaky coupler when you did your boost leak test.

 

[kenamond]

Are you sure that's not just a boost spike?

What MBC do you have? If the bleeder hole in the MBC (ball and spring MBCs should have one) is clogged or the MBC doesn't have a bleeder hole, the WGA will be pressurized and open when you first boost, but then the pressure has no where to go (ball closes the door, so to speak), so the WGA stays open.

The 10psi dropping to 9psi with the line from the LICP to the WGA doesn't sound abnormal.

If all of that checks out, I agree that you should check the WGA. Make sure the actuator arm isn't interfering with anything and that the WG flapper moves freely (disconnect the arm on a cool motor and turn the lever with your fingers). You can also put a pressure tester on the WGA nipple and check that it opens at ~8-10psi.

 

[Jordanbutter]

Yeah I'm going to take the turbo off and look at it. So what should I look for when checking the actuator arm and flapper. Also I feel I should add that 6 months ago I ported out the metal above the flapper so I can open better, I don't think that has anything to do with this but just in case.

 

[Jordanbutter]

So I switched out the boost controler and it did the samething so I know its the wastegate for sure. So with out spending $$$$ to get a new turbo or external wastegate is there anything I can do to fix the internal one and keep it from opening prematurely?

 

[u6t9]

before you go and buy a new turbo i'd check the actuator.

I had a 91 gsx that would do the exact same thing. turns out the actuator was bad, replaced it and everything was peachy!

 

[Defiant]

You're out-running your turbo.

 

[Apeximprt2nr]

Contact Mr Peepers about an adjustable WGA. http://www.dsmtuners.com/forums/showthread.php?t=267309
You could do that, or just shim your wastegate so the flapper doesn't prematurely open up.
There are plenty of threads on how to shim, just search.

 

[Jordanbutter]

What do you mean out running the turbo? Its an evo III 16g at 14lbs, I thought that was damn near perfect boost for that turbo.

 

[bling5tatus]

if the wastegate is kinda open, then for your turbo to push 14psi it's working a LOT harder... that's what over running your turbo is.

 

[Jordanbutter]

Ok, so should I not really drive it then till I shim it or am I not over running it that bad?

 

[Jordanbutter]

Ok well I shimed the wastegate and now it spools to 14lbs and slowly falls back to 10lbs by redline. I put two washers on each bolt just by the way. So will I need to replace the actuator or could it be something else?

 

[Jordanbutter]

I just had an ECU diagnostic code come up that I had a while back and forgot about. 1104 Wastegate Solenoid Malfunction. I had taken the solenoids up on the firewall out for a show and just left them out. Is the Wastegate Solenoid one of those or is it another name for the Boost Control Restriction Solenoid? Could it be why the wastegate is messed up? Even though its been driving without it for about six months.