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10-5-5 boost pattern and checking the Turbo Control Actuator
Ran the patriot course at VIR this past weekend and something happened after the first run that caused my power to drop massively.
I finally narrowed the symptom to a 10-5-5 boost pattern, which apparently is usually caused by the turbo control actuator either not getting VAC or not getting pressure.
Here is what I've checked so far:
-pressure and vac tanks both good, no leaks with mityvac
-viton check valves: probably not an issue, but... leak down a little sometimes and if I switch between sucking/blowing () I can get them to "duck call" and blow backwards sometimes . I've ordered new ones of a different type (ball style) just to rule it out.
-directly actuated the turbo control actuator in pressure/vac right after the solenoids, so the TCA itself is good
-charge relief/charge control/pressure relief all test good
So, I'm down to the solenoids themselves it seems. I replaced the vacuum side solenoid 20k miles ago when I rebuilt the car (failed ohm test). But first I wanted to tee into the VAC/Pressure lines to the TCA with gauges and drive the car to verify before I tear off the UIM to check the pressure solenoid.
BUT... I can't figure out if I'm supposed to see ZERO vac/pressure from idle to 5k rpm then see vac/pressure after or the other way around.
The FSM says the solenoid has 12v idle to 5500 rpm, but wouldn't that mean the door turbo control door is open before 5500? I thought it should be closed at first, then open up. I'm so confused...
Also, here is some video of my slow runs. The tractor trailer turbo noise started at the same time:
Alex that's classic for TCA or TC solenoids. There are two solenoids one pressure and the other vac.
Since the TCA is good I'd replace one or the other solenoids. There's a way to test which solenoids but I can't remember how.
Another test to check solenoids is simply turn the car off while cruising restart and see if you have secondary boost. The solenoid is sticking and this may reset it.
Alex that's classic for TCA or TC solenoids. There are two solenoids one pressure and the other vac.
Since the TCA is good I'd replace one or the other solenoids. There's a way to test which solenoids but I can't remember how.
Another test to check solenoids is simply turn the car off while cruising restart and see if you have secondary boost. The solenoid is sticking and this may reset it.
I think I just ruled out turbo control actuator and the vacuum/pressure solenoids.
I teed into both the pressure side and vacuum lines supplying the turbo control actuator. Above 5000rpm I saw vacuum to one and pressure to the other. They hold vac/pressure until they drop back down to ambient at the change over rpm I set in the PFC. Same symptoms while all this was happening.
Now I'm thinking it may be something else, but I already did a hold test on the charge relief valve.
I think I just ruled out turbo control actuator and the vacuum/pressure solenoids.
I teed into both the pressure side and vacuum lines supplying the turbo control actuator. Above 5000rpm I saw vacuum to one and pressure to the other. They hold vac/pressure until they drop back down to ambient at the change over rpm I set in the PFC. Same symptoms while all this was happening.
Now I'm thinking it may be something else, but I already did a hold test on the charge relief valve.
Also if it's making a strange noise like Boooovvvvv it's the TCA (may be testing good but it isn't) so replace it and you should be good.
You mean replace the actuator itself? The new noise is just as louder turbo noise to me. Sounds like a Mack truck turbo after transition.
The sound I'm referring too is very distinct and like no other noise the car makes. Possibly somewhat similar to the moo sound from the intake but much higher pitch. It's a sound that comes from the TCA when the diaphragm is effed up or whatever the hell in there leaks.
Yep replace the TCA
I just watched the vid though and couldn't hear anything but wind noise etc.....
I have a vid somewhere when I was driving one of my cars on a skidpad and it was having this problem. I'll see if I can dig that up.
Have you tested your solenoids hot (~250 deg F)? I just went throughall my solenoids and half failed hot when they operated cold (which couldexplain losing boost after taking some laps). My TCA also failed.
Have you tested your solenoids hot (~250 deg F)? I just went throughall my solenoids and half failed hot when they operated cold (which couldexplain losing boost after taking some laps). My TCA also failed.
I'm pretty confident it's a 100% of the time broke situation. It does the same thing even before coolant temps have gotten all the way up.
If the TCA doesn't pan out I will dive into the rats nest and do the hot solenoid test... or just replace all the turbo solenoids because this sucks and I don't want to do it again.
Originally Posted by DaleClark
If you have my Viton check valves and they are bad, I warranty them for life. PM me and I'll be happy to replace them.
I would also lean towards the TCA solenoid, it's not an uncommon problem.
Dale
The TCA solenoids seem to be working at all temps. Like I said, I teed into the TCA supply lines with gauges and saw vacuum and pressure at all the right RPM's while warmed up and driving.
I may have to try a lower mileage TCA from fritz if I don't have one on hand because everything else tests good.
I had the same issue with my car after redoing all my vac lines. I would get solid boost until the secondary was supposed to come in, turns out my rubber coupler coming off the y pipe to the top crossover had a big split in it causing a big boost leak. The hose clamp likes to cut through it over time..... Well looking for an image I found a post you made regarding the same issue haha. Err
The new turbo control actuator was a no go. I also teed into the charge relief valve to make sure it was getting vacuum until 4500 and pressure after. That was good.
So recap:
Turbo control actuator bench tested good and is seeing vacuum/pressure at the right times when i tee into supply lines.
Charge relief bench tests good and is seeing the right vac and pressure signal.
I still get 5psi after transition and get a loud turbo noise.
I guess I'll look at the charge control valve on the y pipe next.if that isn't culprit I'm going to do a poor man's non sequential to rule out the secondary turbo itself.
I'm gonna spit ball and say boost leak. Check all your inlet hoses. If you still have the stock flexible rubber ones at the intercooler those are good to check too.
Otherwise, the charge control valve is anther thing to check. its what allows the secondary turbo to join with the primary in the y pipe. I think there is a key on key off check for it.
I'm gonna spit ball and say boost leak. Check all your inlet hoses. If you still have the stock flexible rubber ones at the intercooler those are good to check too.
Otherwise, the charge control valve is anther thing to check. its what allows the secondary turbo to join with the primary in the y pipe. I think there is a key on key off check for it.
Matt
The boost leak i could see if it was hard to boost across the rev range, but the boost comes on super fast and consistent on the primary.
Just tested the charge control valve. It is getting vac until 4500, then pressure after. I can see the valve rod itself moves between engine off/engine on, so it's working.
Check list:
-Pressure and Vac tanks: air tight CHECK, provide press/vac throughout rev range CHECK
-TCA, turbo control actuator: pressure/vac signal from solenoids CHECK, actuator bench test CHECK
-CRV, charge relief valve: pressure/vac signal from solenoid CHECK, bench tested for leak under heavy vacuum on outlet side CHECK
-CCV, charge control valve: pressure/vac signal from solenoid CHECK, key on/key off movement: check
-Turbo piping: silicone couplers intact, stock flex pipes do not appear to have cracks or oil residue when removed and inspected, Y pipe secured to turbo outlets
My wastegate and precontrol are run on hallman pro MBC's. I understand the pre-control is responsible for pre-transition boost level... Is it possible that my wastegate actuator is screwed up?
I get a really odd strained turbo noise after transition. Sounds like kinda like a turbo trying WAY too hard and not getting anywhere.
I finally went with my gut here and decided the sucking noise was pointing to a collapsed intake hose. I pulled the secondary pipe last night and drove in with it this morning. My boost is back and it feels amazing! I'll be ordering intake vacuum hose from mcmaster carr to replace my collapsing stock tubes. Woo!
And thanks all for the tips... at least I know the solenoids are 100% working now.
If that hose is collapsing, that usually points to a restriction, like a clogged airbox.
Think about it - the air filter in the airbox should be flowing more than enough air to keep up with engine demand. For a hose to collapse there has to be a restriction somewhere.
Mazda did a TSB on collapsing primary turbo hoses a long time ago, this is something I've NEVER seen in real life, though. I would open the airbox and make sure some debris didn't get sucked in there that's blocking the filter, inlet, etc.
Glad you figured it out! I have found that more often than not a boost problem isn't the solenoids/rat's nest/check valves/etc. it's something plain like a boost leak. Or in this case, an intake restriction.
If that hose is collapsing, that usually points to a restriction, like a clogged airbox.
Think about it - the air filter in the airbox should be flowing more than enough air to keep up with engine demand. For a hose to collapse there has to be a restriction somewhere.
Mazda did a TSB on collapsing primary turbo hoses a long time ago, this is something I've NEVER seen in real life, though. I would open the airbox and make sure some debris didn't get sucked in there that's blocking the filter, inlet, etc.
Glad you figured it out! I have found that more often than not a boost problem isn't the solenoids/rat's nest/check valves/etc. it's something plain like a boost leak. Or in this case, an intake restriction.
Dale
I agree and was having the same thought. I have the cheap bastard style mod to my intake, but I couldn't make it quite as big due to my radiator being a little wider. There is less room between my radiator and frame rail than normal.
I definitely feel more pickup with open pipes, which points in the direction of air box restriction... I'm gonna try and make the cheap bastard a little bigger, but I may just go aftermarket intake since I would like an aftermarket IC eventually as well.
K&N drop in filter was clean enough last time I checked it.
I would still pull the airbox out and check everything. The stock airbox does have some restriction which can limit power, but it shouldn't be enough to cause that hose to collapse. I really think there may be some debris in the inlet to the airbox or in the box itself that's causing the problem.
Debris as in a wad of leaves, part of an orange cone, a plastic bag, something crazy that air can't go through. Not just typical dirt/sand.
09-10-15, 11:50 AM
) I can get them to "duck call" and blow backwards sometimes . I've ordered new ones of a different type (ball style) just to rule it out.
