2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

another way to tell ports are opening?

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Old Nov 15, 2004 | 08:42 AM
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Rex7
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another way to tell ports are opening?

Is another way to tell your 5th and 6th ports opening is when you hit 3800rpm you start to hear a whining sound, for example like Honda's VTEC kickin in?
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Old Nov 15, 2004 | 08:53 AM
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I can't imagine how the ports opening would cause a whining sound... the only movement is the ports rotating open.

-=Russ=-
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Old Nov 15, 2004 | 08:56 AM
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have someone rev the motor while you look at the solneiods. They should move when the motor goes between 2k and 4k and back.
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Old Nov 15, 2004 | 09:07 AM
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Originally Posted by 2ndGenV8RX-7
have someone rev the motor while you look at the solneiods. They should move when the motor goes between 2k and 4k and back.
That only works on the S5s, and I believe you have to disconnect the MAP sensor to fool the ECU into thinking it's under load.

Revving in neutral on the S4s won't pop the ports open (just like it won't really spool a turbo).

I'm working on designing a little system (based on Kevin's system) that will work well, not rely on any exhaust back pressure or an air pump, have adjustable opening points (plus a manual override), and not be limited by compressor duty cycle (if you want to keep 'em open all day long, nothing will burn out). Hopefully the kit will be under $100 when I'm done (less if you find some of your own parts & can solder).

-=Russ=-
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Old Nov 15, 2004 | 09:36 AM
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You can't on a S4. But you could use a air compressor to blow air into the ports and see if they move. Then you at least know the ports work. That or you could dyno the car.
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Old Nov 15, 2004 | 10:25 AM
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just unbolt the actuators (solenoids) - its two bolts, 10mm i think. take the palm of your hand and press down on the rectangular black plastic piece that normally would move up and down when bolted to the engine (it connects to the little rod). if it moves in and out freely and you can hear a 'whooshing' sound, then they are in good condition.
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Old Nov 15, 2004 | 11:31 AM
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I followed coldfire's write up on opening 5/6th ports.
(Search: Air pump auxilary port activation )

Once I purchased the parts, it only took me a short time (1 hour or so) to assemble, install it and gauge it for the proper rpm level.
note: It's really easy to do when you have a second person in the cab to hold the tach at specific levels while you adjust for air flow.
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Old Nov 15, 2004 | 01:48 PM
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on an S5, with a cone filter instead of the stock air box... if you mash the gas at 3K, at about 4.5K you should be able to hear what sounds like a muffled chain saw from the passenger side of the motor, especially if you are running next to a gaurdrail or bridge wall.
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Old Nov 15, 2004 | 02:05 PM
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Once I installed my header I could tell when they opened. There's a big change in the exhaust note at 3800. It goes from sounding rumbly and mellow to sounding mean and throaty. (I'll bet you didn't know that a header is a diagnostic tool!)
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Old Nov 15, 2004 | 02:11 PM
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That is probably just the Secondary Fuel injectors kicking in isn't it?
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Old Nov 15, 2004 | 03:44 PM
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it could be many things , but im sure its the ports opening. if the injectors opened up while the ports are closed, the exhaust note would just sound as muffled as it did before. the throaty noise is simply intake charges flying back out the intake funnel of the car. but i know what you mean. basically its like a chainsaw noise.
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Old Nov 15, 2004 | 04:31 PM
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Well my ports are stuck shut... i can open them up manually but they wont close by them selves.. the main reason why i can tell that they are closed is because when i get around 3800rpm.. the car has like this hesitation... simular to the feelin when you down shift and dont give it any gas.. but not as much as a pull back.. i still manage to pass that 4K rpm my holding my food about 1/8th of the way on the gas.. and once it gets about 4.5k i give it a little more gas.. but that's just for now.. until i get my s5 intake manifold and throttle body im goin to unlock them.. and me car will be as fast as a turbo.. :-P
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Old Nov 15, 2004 | 05:01 PM
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this has been covered a zillion times, but here ya go anyway. to check aux port operation:

put a fingerful of grease on the shafts of the actuators. drive like hell for a mile or so, try to vary load and engine speed. open the hood and look at the actuators. if the ports are working, the grease will have bunched away from them. if they dont work, it will still be in the same place.

its surprising how many times ive given this advice. cant people think of this on their own?

pat
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Old Nov 15, 2004 | 06:21 PM
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that's kinda shitty advice though. just because the ports open slightly at 7.5k rpm one time through a whole session of driving doesn't mean they are working correctly.
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Old Nov 15, 2004 | 06:48 PM
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you can fine tune by only revving to 3900 under load if you want to, genius.
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Old Nov 16, 2004 | 01:12 PM
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Originally Posted by rs_1101
it could be many things , but im sure its the ports opening. if the injectors opened up while the ports are closed, the exhaust note would just sound as muffled as it did before. the throaty noise is simply intake charges flying back out the intake funnel of the car. but i know what you mean. basically its like a chainsaw noise.
I know what you're thinking and the intake DID get louder with the aux ports open, (After I ported my TB, intake noise was GREATLY reduced) but the change in the EXHAUST note is what's really apparent. It gets louder, sharper and not at all like a chainsaw.
Yes, the easiest way to positively test a S4 is to grease the actuator rods and go for a drive. BTW, when you check those grease marks, check to see if the actuators are moving all the way. If the rods aren't hitting the stops, your sleeves aren't open all the way. (They may not open enough to match the aux ports anyway... )
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Old Nov 17, 2004 | 06:02 PM
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Originally Posted by pontious
That is probably just the Secondary Fuel injectors kicking in isn't it?
There will not be any change in exhaust note (or any other sound) from the secondary injectors coming on.
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