Intake Secondaries - I've Tried Everything

[Brook24v]

'93 ATX - 114k

I can't get the secondaries to work properly on this car no matter what I do. The butterflies are stuck open just as if there was a vacuum leak. Here is a quick rundown of what I've tried:

1. Thought right away maybe it had a vacuum leak, replaced hoses and the black round canister (whatever you call it). Still didn't work.
2. Double checked hoses by routing them directly back into the intake, which then closed the butterflies. Hoses confirmed to be good.
3. Then assumed it was the solenoid there on the back of the intake. Replaced it with 5 (yes five) different ones lying around. Still didn't work.
4. Started wondering if maybe there was no power to the solenoid. Checked and there is power and ground at the connector, although I don't remember what the voltage was.
5. Then thought if maybe the computer grounds the solenoid or something and it wasn't doing so properly. Repaced the computer. Nothing

What's next, light the car on fire? I'm willing.....

 

[zblackbeast]

Did you replace the little vacuum canister? I know that they can go bad and not cause a good seal/vacuum..

 

[Brook24v]

Ya. And you can hear the air release out of there when you unhook the hoses.

 

[zblackbeast]

And the secondaries close when you apply vacuum straight to the intake itsself?

 

[Brook24v]

Yes. That part of the system works properly if the solenoid is bypassed and vacuum is directly applied.

And that is why you won't find a single SHO at Omaha's U-Pull-It/U-Wrench-It with any intake secondary solenoids. I took every last one.

 

[zblackbeast]

Hahahaha

 

[hawkeye18]

Note: This source refers to the IMRC as the IAC. Don't confuse that with the real IAC, which this book calls the ISC.

 

[jonheese]

There are only a handful of components involved here:

ECU -> harness -> solenoid -> hose -> vacuum reservoir -> hose -> butterfly actuator

You've ruled out the ECU, the solenoid, the hoses, the vacuum reservoir and the actuator itself, so I'd focus on the wiring. Recheck the voltage on the signal wire; I believe it should be 5V. If it's less (like say, 2-3V), it could be that there's resistance in the wires and it's not passing enough voltage to fire the solenoid.

You can also check the resistance of the wires (both ground and signal) manually by disconnecting both the IMRC solenoid and the big ECU connector and checking for resistance from pin 21 of the ECU connector to the signal pin on the IMRC connector.

Here's a pinout (sorry it's so ugly-- it's the only one I could find readily available) of the ECU connector to help you locate pin 21:

 

[Brook24v]

Damn, that is a huge help. Thanks VERY much. I had a bad feeling this was going to fall back on the harness. I hate wiring.......

I'll see what the voltage is sitting at once I get around to it and post back for an update.

 

[Brook24v]

And if you're really feeling like firing up the brain cells, be sure to check out my other car's problem: haha

http://www.shoforum.com/showthread.php?t=112095

 

[Off Road SHO]

On the vacuum canister, that you now have so many of, make sure the two little ******* get their correct vacuum hose. There will be a problem if you try and put vacuum on the wrong little ******. :laugh_ti:

Tom

 

[yamahaSHO]

I like to 'vacuum' both ******* :angelnot:

I've seen more than one canister fail. I have several spares because of this.

 

[Brook24v]

I guess I could grab the one off my parent's SHO knowing that one 100% works. I would really hope 5 in a row weren't bad....

 

[Off Road SHO]

I guess I could grab the one off my parent's SHO knowing that one 100% works. I would really hope 5 in a row weren't bad....

Maybe not bad, just hooked up wrong. They are a one way valve after all.

Tom

 

[mike25]

do they stay open or close when the engine is off?mine did that after i painted the intake they would stay open no mater what rpm come to find out i had the hoses hooked up to the canister wrong.

 

[Brook24v]

They seem to be right.

The secondaries are open at idle as if there is no vacuum.

 

[Off Road SHO]

So is there vacuum? You know where the vacuum comes from, so check it there with the engine running and on the far side of the valve. The vacuum is "passed through" to the secondary actuators while the engine is below 3950 RPM's.

Maybe you have a vacuum line clogged or broken in between the rear surge tank and the actuators.

Tom

 

[mike25]

when i hooked the vacuum hoses up wrong they stayed open at idle too. if your sure there hooked up right then there must not be any vacuum.

 

[Brook24v]

Maybe you have a vacuum line clogged or broken in between the rear surge tank and the actuators.

Tom

I've already replaced the lines. You can hook the line directly to a vacuum source and both butterflies will shut.

So is there vacuum? You know where the vacuum comes from, so check it there with the engine running and on the far side of the valve. The vacuum is "passed through" to the secondary actuators while the engine is below 3950 RPM's.

Tom

You mean vacuum coming right off the back of the intake where the hose off the canister goes into?

 

[zblackbeast]

Or the little black thingy isnt sealing correctly and letting vacuum through.. Thats all i can think at this point.