secondaries stuck open

[benjammin]

Ive done a few searches on this and tried everything I read but still no luck. They are definately stuck open, ive used the TB to go WOT and they dont move.
Ive changed the accumulator and the switch from another SHO. The vacuum lines are not pinched, and It doesnt feel like the butterflies are sticky at all from manually moving them. One of the accumulators that Ive tried has a rattle when you shake it, the other doesnt but both have vacuum going through them so I dont know if that even really matters. What should I look at next?

FWIW...The other switch and accumulator were off a boneyard SHO.
Ive had the car about 2 weeks. When I first got it I could hear the secondaries opening sometimes and other times not.

 

[Racer X]

Grab a handheld vacuum pump, and apply vacuum at the vacuum motor side of the secondary vacuum lines (basically, unplug the vacuum line leading to the secondaries from the solenoid, attach to vacuum pump, apply vacuum). If they close (and stay closed) when vacuum is applied, I'd look at your secondary solenoid and reservior tank again. If they don't close, or don't stay closed, check the vacuum lines and two vacuum motors for leaks.

 

[Devin]

I freed mine up by squirting a bit of WD-40 into the actuators.

 

[VortecGT]

there is a plug on the back of the intake that controls them. I would look at that first.

 

[benjammin]

Plug on the back of the intake?

 

[VortecGT]

its where the vacuum lines go to.

 

[benjammin]

Do you mean the inlet where the short hose from the accumulator connects to?...I tried cleaning that out and it wasnt clogged at all. I had the intake off for the top 60k and it wasnt excessively dirty.

 

[VortecGT]

yes there should be an electrical plug going into that

 

[benjammin]

So you're talking about the switch. Like I first said, Ive changed that out with one from a boneyard SHO. Not very likely that mine and the boneyard one are both bad. At least I hope not because I havent been able to locate one from a parts store.

 

[sdpatt]

Check the hose routing on the accumulator. You are not getting vacuum to the diaphram actuators. The secondaries are closed by the application of manifold vaccum.

"The routing of the secondary butterfly vacuum lines is from the center tap on the intake's rear plenum to the front (forward) tap of the black plastic accumulator tank [NOTE: the two "prongs on the accumulator tank should be oriented forward, towards the manifold, to properly engage the manifold mounting bracket]. From the rear tap of the accumulator to the bottom tap of the solenoid. From the top tap on the solenoid to the "T" fitting under the idle air control valve. From the side post of the "T" to the rear bank secondary vacuum diaphragm valve and from the front post on the "T" to the front bank diaphragm valve."

Can you rotate the secondary shafts by pressing on the linkage cam with your finger? If not, there is an obstruction blocking movement of the butterfly plates.

 

[benjammin]

Double checked the routing...its good. Yes I can manually move the butterflys
and the only resistance I feel is the spring. I guess I just pull the intake again, There has to be something Im overlooking i guess. Can the actuators in front of the butterflies go bad?

 

[Marccus]

I've had this same problem for years and haven't been able to figure it out.

Instead of the vacuum pump, I just applied vacuum to the secondaries with my mouth and the secondaries closed and stayed closed.

I've tried three different sets of accumulators / electronics / hoses, etc., from junked SHOs and that didn't work. It would seem highly unlikely that all three sets and combinations thereof would be defective.

I checked the wiring from the connector all the way back to the pins on the PCM. There is continuity in the lines, so the connector seems to be OK. Still can't get the secondaries to close.

I've let it go for awhile to tackle some other problems but will get back to it again.

If you find a solution, let me know.

But anyway, if the secondaries are open all the time, shouldn't that be OK? Then you never have to wait for the increased air requirement.

 

[benjammin]

No its not ok(for me anyway)...its a slug at lower rpms. If one of the actuators went bad it would affect the other since they are connected....correct?

 

[Devin]

I've had this same problem for years and haven't been able to figure it out.

Instead of the vacuum pump, I just applied vacuum to the secondaries with my mouth and the secondaries closed and stayed closed.

I've tried three different sets of accumulators / electronics / hoses, etc., from junked SHOs and that didn't work. It would seem highly unlikely that all three sets and combinations thereof would be defective.

I checked the wiring from the connector all the way back to the pins on the PCM. There is continuity in the lines, so the connector seems to be OK. Still can't get the secondaries to close.

I've let it go for awhile to tackle some other problems but will get back to it again.

If you find a solution, let me know.

But anyway, if the secondaries are open all the time, shouldn't that be OK? Then you never have to wait for the increased air requirement.

I had that exact problem, and all it was was gunked up actuators.

I can't imagine what it'd be like to have closed butterflies all the time. What would be the point of the engine?

 

[jonheese]

I can't imagine what it'd be like to have closed butterflies all the time. What would be the point of the engine?

I think you're thinking of it backwards.

When the IMRC system (i.e. secondaries) fails, it defaults the butterflies to open, not closed. So a failed system (either due to an electrical problem or a vacuum problem) has the secondaries open all the time.

Here's a quick illustration of this: Go out and open your hood and watch the secondary butterflies while you have someone start the engine. You'll see the secondaries close when the engine starts, and open again when it shuts off.

The only way to have permanently closed secondaries is to change the computer programming for their opening to a number higher than the RPMs the car sees, or to physically bind the butterflies closed (like wire them closed). As far as I know, there is no accidental way (i.e. no failure mode) to have permanently closed secondaries.

Regards,
Jon Heese

 

[Devin]

I know how it works. Mine would stick closed. They would be open. The engine would pull a vacuum, they'd close, and then they wouldn't open again. I'd have to manually open them. Eventually after sitting they would slowly open but not during a drive, and definitely not at 3950. All because they were gunky.

 

[jonheese]

I know how it works. Mine would stick closed. They would be open. The engine would pull a vacuum, they'd close, and then they wouldn't open again. I'd have to manually open them. Eventually after sitting they would slowly open but not during a drive, and definitely not at 3950. All because they were gunky.

Gotcha. My apologies for assuming that you misunderstood the "normal" failure mode.

Right after hitting "Submit", I re-read your post and considered the possibility of "gunk" causing them to stick closed, but figured that was probably rare, since they're only closed when the engine is running (under 3950 RPM), and since any engine is almost certainly off more often than in that condition.

I'll admit though that I don't actually know how common a "stuck closed" condition is.

Regards,
Jon Heese

 

[Devin]

No problem. I've had quite a lot of wierd problems with my car, but luckily I've solved most of them so maybe at some point I can help someone else.

 

[joesho_gb]

Ok, dumb question, but after reading this, I think I may have this problem (secondaries being stuck open). I'm getting a left and right bank lean codes, and it runs like junk under 3500 rpm.
When looking at the motor, what does the secondary butterfly look like? Is it that round thing on the back of the intake?
I tried searching for pictures, and came up to no avail. I'm thinking this may be my problem ...

 

[jonheese]

Ok, dumb question, but after reading this, I think I may have this problem (secondaries being stuck open). I'm getting a left and right bank lean codes, and it runs like junk under 3500 rpm.
When looking at the motor, what does the secondary butterfly look like? Is it that round thing on the back of the intake?
I tried searching for pictures, and came up to no avail. I'm thinking this may be my problem ...

The secondary butterfly units themselves are mounted between the surge tanks and the secondary "snakes", but the unit you're probably referring to is the vacuum reservoir that feeds the IMRC valve, which gives vacuum to the vacuum solenoids, which is what opens and closes the butterflies themselves.

Here's a picture of my intake with the butterflies circled in red and the vacuum reservoir/IMRC valve (currently not in its right place) circled in green:

However, if you had a problem with your secondaries (i.e. stuck open), that would not cause a lean condition. Fuel is metered based on the amount of air that flows through the MAF sensor, and all of the air in the intake, whether it's coming in through the primaries or the secondaries, has flowed through the MAF sensor, so it's all being considered when the fuel injectors fire.

If your engine is running like crap under 3500 RPM (or more tellingly, under 3950 RPM), it certainly could be because the secondaries are open all the time, but the lean codes are almost certainly due to another failure.

Did you get any other codes other than the lean bank1 and lean bank2?

Regards,
Jon Heese