Alright, I realize we are all tired of boost issue posts. Forgive me but I have only found mention of this problem a few times while searching and nobody ever seems to post the resolution.

The symptom:

• Boost Controller OFF: so wastegate spring pressure only boost pattern at WOT full boost: ~7 - 5 - 7 - 5 - 7 (repeating)
• Boost Controller Set 9psi: boost pattern at WOT full boost: 9 - 7 - 9 - 7 - 9 repeating
• Boost Controller set 11 psi: boost pattern at WOT full boost: 11 - 9 - 11 - 9 - 11 repeating

So by now you should see the pattern... the boost pattern oscillates whenever it reaches whatever the desired boost level is. At first it seemed like maybe a gain issue on the boost controller, but turn off the bc and the issue still occurs.

Boost still builds pretty quickly and the transition between to the secondary turbo occurs later (around 5K rmp) than it probably should. The car runs rather rich at the moment as it is in need of a tune (AFRs in 11's under heavy boost). Have to figure out the boost issues prior to tune.

Using a midivac connected to the wastegate I can see the wastegate move right around 7psi. It appears to move rather freely

I am currently using a pressure test kit to test for boost leaks (I have another thread with questions about that as well). Any other ideas would greatly be appreciated. Thanks for your time,

Richard

The car: 93 R1. 95K miles; stock twins; pettit intake, PowerFC, Pettit DP, Racing Beat Catback, stock Cat, LC-1, pettit AST, pettit EBC, SS intake and IC pipes, Greddy Elbow, AWS block off plates, 99 spec crossover pipe.

 

It's probably your stock cat. Does it have 95k miles on it with the chassis?

 

Yep, everything has ~95K miles on it.

hmmm, Not sure that I can test the stock cat without finding another or replacing it with something else. That is disappointing, but I guess pretty easy to deal with if is the culprit.

Anything else I can check in the meantime?

Richard

 

Seems like you just don't have enough flow to maintain full boost at upper rpms. Even in stock form and new, the car doesn't maintain 10 PSI to redline. You can also verify your turbo control is functioning properly. The bottom most actuator:

http://www.autosportracetech.com/RX-...BigPicture.htm

 

did you try connecting the line directly to the actuator (obviously with no pill in it)? that would absolutely eliminate the controller as a source of fluctuation.

i don't agree that turning off the controller eliminates it as a problem source because it still has mechanical parts.

 

I realize it will trail off in the higher RPM's, but would it oscilate through the entire range? Also, if I am lacking the flow to maintain at 7psi... why can I hit 11psi before the boost becomes unstable?

I am kind of wondering if it is turbo control related but am still new to troubleshooting and not quite sure how to get to everything (even with the incredibly helpful troubleshooting steps on autosportracetech.com and alike).

 

Well, it has a solenoid that goes between the turbo housing and the wastegate actuator.... I did verify that turning off the EBC allows air to flow freely through that solenoid and directly to the wastegate. It is basically like connecting a hose directly from primary turbo to wastegate.

It is easy enough to do though, so I'll give it a shot.

 

UPDATE: Charge Releif Valve doesn't hold pressure above 3psi

I think there is a leak between the (99) Y-pipe and the Crossover pipe. Should there be a gasket there because apparently I don't have one? The leak might be coming from below though.

 

Yes there should be a gasket between the Y-pipe and the cross-over pipe. You can just get some gasket material and cut one out for a quick fix.

 

Its been a while since I had my efini y pipe apart, but I'm pretty sure it has a gasket.

 

Okay, thanks Mahjik and Adam C!

 

there's a gasket between the y-pipe and the crossover, there's also a rubber O-ring from the rear turbo-to-y-pipe pipe and the y-pipe, something else to check.

 

Yeah, I verified that there is a rubber O-ring on the Charge Valve assembly thing on the Y-pipe. I just have to make a gasket to go between the Y-Pipe and Crossover. Thanks!

 

UPDATE:

*The ABV (BOV) tested fine.
*I replaced the CRV with a new one from Mazda.
*I bought a metal gasket to go between the 99 y-pipe and Crossover Pipe.
*During pressure testing my oil dipstick shot out so I eliminated the PCV valve that also failed to hold pressure

I put the car back together and while my boost certainly builds quicker, I still experience the unstable boost problem. There is also a loud clicking sound at transition which I will need to search for.

Boost issues are going to have to take a back seat though as I just failed my Georgia emissions test. I passed the 50/15 test (50% load @ 15 mph) but failed my 25/25 test (failed HC and CO). The car was fully warmed up (I did boost test runs for 30 minutes prior to the emissions test). The air pump appears to be engaging fine. My plugs have 3500 miles on them and my oil has about 2000 miles on it so I'm going to change the plugs and oil, verify that my ACV is working (check for air to CAT), and try again. I realize there are a lot of threads about emissions and aside from the CAT being bad the above TODO list is really the only thing I have come up with. Feel free to chime in if you have any other suggestions (besides Alchohol, my car should pass emissions without it once everything is working again).

Emissions Results for the record:
25/25 Test
----------------- Reading --------- Allowed---- Result
HC ppm---------472-----------------132------------FAIL
CO % -----------2.62-----------------0.73------------FAIL
NOx----------------0-----------------945------------PASS
RPM-------------2883-----------------3000------------max
CO+CO2%-----15.5-----------------6.0------------min
50/15 Test
----------------- Reading --------------- Allowed---- Result
HC ppm---------87-----------------136------------PASS
CO %-----------0.03---------------0.76-----------PASS
NOx-------------367---------------1045-----------PASS
RPM-------------1702--------------3000-----------max
CO+CO2%-----13.4-----------------6.0------------min


Anyways, not sure why I would pass one test and not the other but I guess that is why they do both of them. I passed both last time without any issues and I haven't changed anything in PowerFC. Last year at this time I wasn't experiencing the same boost problems either though. When things fail, they fail together it seems. Mahjik's first post that my CAT was probably bad could also be right on the money as well. I am pretty much updating this thread to keep a record of my progress (or lack thereof) but I love to hear suggestions / opinions as well!

 

High HC meens the motor is not burning clean, plugs, wires, air filter. High CO is a sign you are getting a high fuel mixture so change our your O2 sensor.

 

I live north of atl (lawrenceville area), using stock cat passes the emission teast with flying colors. My car is running on single (RX6 turbo) using AEM EMS. Your stock cat is prob the problem. Here is a trick, do at your own risk. Connect a hose directly from the airpump to the cat, bypass all the crap in between, this will get you to pass the emissions test (provided your air pump is working properly). Make sure you undo the air hose after the test.

 

Hey guys, thanks for the suggestions. I won't be able to change the plugs and oil until this weekend. I will also verify that the CAT is getting air through the ACV, if it isn't I will eventually replace the ACV but I will likely try Trex's suggestion and connect the Airpump directly to the CAT for the emissions test.

I will also try to remove some fuel from the cells the car resides in during the 25/25 test to lean her out a bit. I will update this thread when I know more. Thanks!

 

UPDATE: Okay, I passed emissions the second time
*Replaced Plugs
*Changed Oil
*Leaned out the map a little bit in the general load vs RPM cells

Now I can return my focus back on the unstable boost. So far I have:
*Replaced the CRV (ABV was functioning correctly)
*Verified the wastegate actuator is moving with ~7psi
*Deleted my leaking PCV
*Added a metal gasket between Y-pipe and crossover
*checked for and repaired any found boost leaks.

Unfortunately I am still experiencing the same unstable boost symptoms. With or without the boost controller installed and regardless of what the boost controller is tuned for, when I reach whatever the desired boost level (whether it be wastegate spring pressure of ~7 psi or EBC tuned for 12psi) the boost oscilates between max to -2 of max to max (7-5-7-5-7-5) or (12-10-12-10-12-10)

 

It seems like a case of some system resonance/instability, maybe caused by too much lag due to too long lines from the boost pressure source to the controller, or from the controller to the actuators, or both.

 

what size hoses are you using on your wastegate?

 

Hmm, I don't remember the diameter of the hose off the top of my head. I bought a Hose Technique Vacuum hose kit a while back and I did my best to pick replacement hose that most closely matched the stock inner diameter.

The controller solenoid is mounted pretty close the primary turbo and wastegate... kind of by the fan relays on the passenger side. Honestly though, that probably did at least double the distance over stock. When I take the boost controller out of the loop I still have the same problem. Admittedly though, taking the boost controller out of the loop I still used the hose tech. hose and not the stock one. I guess I should try bringing it back to stock and see what happens.

Thanks for the thoughts guys, I don't think the size or length of hose for the EBC had even entered into my considerations!

 

The stock hose is at least the equivalent of 1/4" hose right (6mm)? The smallest vacuum hoses on the car are really closer to 5/32" or 3.5mm. You've got one of the nipples on the actuator already capped. Run a short, straight hose of about 1/4" on there without the boost controller in the plumbing at all. Buy some fuel/emissions hose from an auto parts store, that's as reliable as silicone IMO.