metallics2000

Stock 2005 Evo 100K - No after market parts installed.
I need help on this issue. It's driving me crazy. Any help/suggestions are appreciated. What could cause intermittent boost? Most of the time it would only boost to 11 psi (probably wastegate pressure only?). If I get lucky I would get 1 day with normal boost out of the whole 5 days while commuting to work.

Things I have done:
**New vacuum line with restrictor pill
**New Evo 9 BOV
**Tested stock BCS and it clicks when 12V applied- New one ordered just in case
**I am able to move the wastegate actuator arm by pulling it. Not sure if this verifies that it is still good or not
**I can feel the difference in power when it does boost normally so I don't think its my boost gauge.

Things I have not done:
**I have not done a boost leak test yet, but would it cause something like this? Wouldn't it be more consistent if there is a leak? When I am doing a boost leak test what hoses need to be capped off?
**Bad EGR or PCV valve can cause something like this?

deylag

iTrader: (23)

Yes this issue is caused by boost leak. I would recommend doing a boost leak test.

Check all your intercooler piping and couplers if you don't have access to a boost leak tester. Make sure they are all making a seal with the pipe.

Evostyles

Also check the o2 housing, if you have a bad gasket, that can be a issue.

metallics2000

Thanks guys for the response. I need to do a boost leak test. I am unsure of what needs to be capped off to have an air tight system. I've read around and it seems like some hoses needs to be taken out and capped off? Cover the muffler tip? How long does it take for the system to be pressurized to 20 PSI. I can't seem to find exactly what needs to be capped off before applying air. I will be building a tester tonight. I do apologize if these are simple questions. This is my first turbo car and is still learning about it.

**I've checked the intercooler pipings and they do seem like they are on there pretty well.
**The top bolt of the O2 housing is missing(I think the previous owner stripped the threads). All the other bolts are on there and there seems to be no noticeable gaps. Maybe it could be leaking from here.
**Also wanted to add there is no CEL.

Evostyles

This is my first turbo car as well, so my knowledge is very limited. I would take to a tune shop, and have them check it out. I'm really think it cud be the o2 housing since its missing a bolt. Does your car sound like you have an exhaust leak?

metallics2000

Boost leak tested - Throttle body shaft seal leaked and lower injector seals were leaking bad. Replaced all the seals and it seems to be boosting okay now. I hope it stays like this.

I'm still wondering why the intermittent boost was from only either wastegate pressure or full boost? If it leaked wouldn't it boost higher than wastegate and be inconsistent throughout the boost range?. ECU detected leak and limited it to wastegate pressure?

sparky

iTrader: (1)

If you can pull on the actuator rod with your off hand and it moves this means that wastegate spring pressure is too low. Actuator needs to be adjusted tighter.

metallics2000

Interesting... Is there a way to properly gauge to see if it is actually set too low?

evoktegg

I remember I had the same problem with my evo not boosting right. Turned out my cat was melted, and the honeycomb inside was restricting my exhaust flow, which wouldn't let my car boost.

sparky

iTrader: (1)

I know that it is set too low. And, yes there is a way to gauge your turbo's actual wastegate spring pressure.

metallics2000

Update:

My front intercooler pipe popped off the throttle body while on the high way and it is now boosting low again. This has happened several times so I now have a new pipe installed with a T-clamp. Still boosting slow. I'll try to reset the ECU later to see if this helps...

How did you find out it was a clogged cat? Did it throw any codes?

How should I go about doing this is properly?

DSMolition

iTrader: (17)

Your EGR could be sticking open. A BLT would tell you that when your boost gauge wont hold psi. You will also hear air going out your exhaust.

sparky

iTrader: (1)

I don't wanna catch flak, so 1st play it safe and do a BLT. If you identify boost leaks...then proceed to fix them. Once the BLT is done and leaks are identified and eliminated and if you still see 11#, then 99% certainty it is WGA related issue.