Low Boost MS6

J

Joe_Hobbes

Greenie N00B Member
Greenie Member
Year/Make/Model: 2006 Mazda speed 6
Mileage: 106k
Location:NC
Concern:
Hey guys I’m new here. I just got a ms6 a few months ago and I need help with a low boost issue. I recently got a boost gauge installed and realized I’m only hitting like 11 psi in 5th and 6th gear. I have no boost in 1st and little in second it stops around 8-10 psi average in all other gears.

I thought it was the boost control solenoid so I bench tested it and it actuates like it should. I can manually move the waste gate actuator with my hand. It’s stiff but it does move, I think that’s normal?

Next I went to pressure test and look for leaks and I cannot find any. My pressure test meter would only go to 13psi and then it won’t build anymore. When I stop pumping in air it quickly bleeds off in like 5 seconds or less. I blocked the valve breather off on the block and the intake and spray soapy water everywhere but cannot find any leaks. No obvious sounds either. Is this normal? Could my 106k mile turbo just be going bad and not able to make boost anymore?

I thought it might be the BPV letting out too soon but I didn’t know how to bench test it. It was closed and I could push the plunger up and down with a lot of resistance so it seems to be working.

I took my first log with the free versatuner and I wasn’t sure what parameters to look for but wastegate duty cycle was at 100% during WOT pulls and knock retard only got up to like 1.5 or something.



DTC's: (please include descriptions) none
Modifications:
JBR TIP and SRI
Corksport HPFP

ECU/Tuning Software: versatune
Tuner: none
Is the concern intermittent? No
Can you duplicate the concern? Yes
Recent Repairs:
Correction:
 

Attachments

What did you use for the boost reference on your gauge? What does versatune say on a log?
 
Joe_Hobbes said:
13psi and then it won’t build anymore. When I stop pumping in air it quickly bleeds off in like 5 seconds or less.
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you have a leak you should be able to get it to 25psi and have it hold. you sprayed all the body hoses, fittings? the intake manifold gasket? TB? VC, and vvt solenoid gasket
 
Awafrican said:
you have a leak you should be able to get it to 25psi and have it hold. you sprayed all the body hoses, fittings? the intake manifold gasket? TB? VC, and vvt solenoid gasket
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I soaked down everywhere I could lol. I tried to spray under the top mount in that intake manifold area but it’s tough with the top mount in the way. Next step may be to remove the top mount and plug the hoses to see better what’s leaking.
 
when my intake manifold gasket was leaking I saw it just on the edge, then took the tmic off and connected directly to the tube into TB. sir was coming out so much I couldn't tell where the leak was had to just keep it flowing and soapy water.

the other option it's pipe in some smoke with the boost leak tester might be easier to spot
 
Awafrican said:
when my intake manifold gasket was leaking I saw it just on the edge, then took the tmic off and connected directly to the tube into TB. sir was coming out so much I couldn't tell where the leak was had to just keep it flowing and soapy water.

the other option it's pipe in some smoke with the boost leak tester might be easier to spot
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If that is the leak on mine wouldn't the car run really rough? I am seeing -21psi vacuum on my gauge, which I've read is normal. The car idles really well.
 
Joe_Hobbes said:
If that is the leak on mine wouldn't the car run really rough? I am seeing -21psi vacuum on my gauge, which I've read is normal. The car idles really well.
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Like one of the guys suggested, increase the pressure to at least ~25-30 psi to hear any noticeable leak if any.
Have you done any maintenance since you got it?
 
OMISPEED3 said:
Like one of the guys suggested, increase the pressure to at least ~25-30 psi to hear any noticeable leak if any.
Have you done any maintenance since you got it?
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I was worried about putting too much pressure in the motor and blowing out seals going that high, but I will try it, if it's safe. The other problem is I'm using a cordless compressor so it may not have enough CFM to get the PSI up quickly. It stalls at 13PSI and just sits there running constantly.

Only maintenance I did was change all the fluids. Oil, trans, PTO, rear diff.
 
Alright Im really lost now. I bought some pvc plugs and did more testing tonight. The intercooler is not leaking. I blocked one side and the BPV return and nipple and it holds tight.

I put the tester on the hot side and it kept blowing the plug out the intake tube at like 10-15psi so I’m pretty confident it’s air tight.

I put the tester on the throttle body and plugged everything else it would get to like 16psi eventually and nothing was leaking except a small leak on the VVT solenoid which I understand is normal. Still leaking quickly down after turning off the pump but again that’s normal to do that through the valves right? Intake manifold didn’t have any signs of leaks nor did the throttle body.

Could it be my injector seals are bad? Hard to tell with the foam pieces under the manifold blocking them. Or could it be the turbo is just worn out and not able to make boost? Or is it still the BPV? This is incredibly frustrating. Any help is appreciated!!
 
OMISPEED3 said:
Yes, the injector seal tend to leak under boost when they go bad. Did you replace the spark plugs?
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Yes sorry I forgot about that, I did replace the spark plugs when I bought it. That would make sense that the injector seals are leaking though because they are leaking on the cold side of the lines I’ve tested, which had the worst results. Unknown service history on this car when I bought it at 103k miles. How long are stock seals good for?
 
Joe_Hobbes said:
Yes sorry I forgot about that, I did replace the spark plugs when I bought it. That would make sense that the injector seals are leaking though because they are leaking on the cold side of the lines I’ve tested, which had the worst results. Unknown service history on this car when I bought it at 103k miles. How long are stock seals good for?
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Well, with that many miles and not knowing the history, I would suggest that you should do a little deeper on the maintenance to check the health of you engine just in case. You mentioned that it idles very well and it doesn't have any DTC's, but does it drives well around when is not under boost?
 
OMISPEED3 said:
Well, with that many miles and not knowing the history, I would suggest that you should do a little deeper on the maintenance to check the health of you engine just in case. You mentioned that it idles very well and it doesn't have any DTC's, but does it drives well around when is not under boost?
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Yes, I agree I need to do a compression test on it this weekend. It does not have any DTC and it drives really well, idles fine and comes on boost nice in the higher gears but stops building boost around 10psi. With the JBR intake I put on it I can't tell if i am hearing induction and turbo noise or if the wastegate is opening too soon and bleeding off boost.
 
You need a better compressor so that you can push more air in. Still feel like there is a leak if you can't get over 16 psi
 
Easter Bunny said:
You need a better compressor so that you can push more air in. Still feel like there is a leak if you can't get over 16 psi
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Agreed on the compressor and that there still may be a leak. Tonight, I am going to try and bench test the BPV by connecting a syringe to the nipple port and using a block off plate on the bottom of it. If I try and push air into the nipple and it bleeds around the diaphragm and out the recirc line output I think that would tell me that is the reason for my low boost. If that doesn't work, I will start saving up for a BNR S4 turbo lol.
 
@Joe_Hobbes
Definitely follow any troubleshooting advice from the guys in the thread. They definitely know what they are talking about and I have followed many of their how-to’s and suggestions doing maintenance and repairs on my Speed6.

I was having some weird boosting issues that led me to recently replacing my whole factory exhaust due to it being full of holes and I had no idea the condition of the OEM catalytic converter. Replacing my TMIC (w/ Corksport) and related hoses and replacing gaskets while doing a valve cleaning helped with holding boost after the turbo, but I had this weirdness where the car would get noisy as hell when cruising around 3000rpm and my boost would fall off on a pull despite being able to hold pressure with a leak test.

When I went to do the downpipe I discovered that the turbo I was told was replaced by the previous owner was a cheapo eBay rebuild that had failed in probably ~5K miles and that during install they broke a stud on the turbo and just left it off.

It’s a bit of a pain, but if you are fairly mechanically inclined let the car cool down and pop off the TMIC then the heat shields on your exhaust manifold so you reach down around the turbo and feel for holes, blown gaskets, broken studs, or get a boroscope and check out your catalyst condition through the O2 sensor bung.
 
DatsunZ said:
@Joe_Hobbes
Definitely follow any troubleshooting advice from the guys in the thread. They definitely know what they are talking about and I have followed many of their how-to’s and suggestions doing maintenance and repairs on my Speed6.

I was having some weird boosting issues that led me to recently replacing my whole factory exhaust due to it being full of holes and I had no idea the condition of the OEM catalytic converter. Replacing my TMIC (w/ Corksport) and related hoses and replacing gaskets while doing a valve cleaning helped with holding boost after the turbo, but I had this weirdness where the car would get noisy as hell when cruising around 3000rpm and my boost would fall off on a pull despite being able to hold pressure with a leak test.

When I went to do the downpipe I discovered that the turbo I was told was replaced by the previous owner was a cheapo eBay rebuild that had failed in probably ~5K miles and that during install they broke a stud on the turbo and just left it off.

It’s a bit of a pain, but if you are fairly mechanically inclined let the car cool down and pop off the TMIC then the heat shields on your exhaust manifold so you reach down around the turbo and feel for holes, blown gaskets, broken studs, or get a boroscope and check out your catalyst condition through the O2 sensor bung.
Click to expand...
Yes definitely appreciate everyone’s help on here!! I am very mechanically inclined but all the help and suggestions have been great!!

I bench tested the BPV. I used a syringe in the small nipple while blocking off the bottom I was able to actuate the plunger up while sucking the syringe out, and pushing the syringe in it held tight with no leaks so that’s ruled out.

The heat shields are gone around the manifold and turbo when I got it. The carfax said the turbo drain lines were replace not too long ago so I’m assuming they didn’t put them back then. I don’t see any obvious holes or missing bolts. I tested a few bolts and they are all tight.

I am now fairly confident that the turbo is worn and needs replacing. It does have 106k miles on it. The shaft play is fairly loose side to side and even a little in and out. I’ll order some injector seals as a best practice while I save up for a s4 turbo and supporting mods.

It could also be a plugged up cat, idk how many miles those are good for but a downpipe is part of my upgrade list.

Final question for you all. Would it be worth getting an OTS tune from someone right now with my low boost issue or just wait until I upgrade? It may be 6plus months before I have all the parts needed and installed.
 
Until you are able to actually test for leaks at 25 psi you have no idea what is wrong
 
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