What does a particular VSV do? See excellent attached diagram.

[robgagnon]

So there is this VSV on the passenger side of the engine bolted to the side of the head that takes a vacuum from the intake manifold and switches that vacuum to the fuel pressure regulator. And this interesting attached diagram shows that there is a variation of the system where it is NOT present, see the box in the diagram that says W/O COOLER. So can someone please explain this to me? What cooler? I thought fuel pressure was regulated by the ECU maybe telling this VSV to switch on or off. Or does simple direct manifold vacuum control fuel pressure, and the VSV disables that when the cooler is in the system? Also, if the intake manifold has filtered air already, then why is there a filter (part #23265) needed? To keep the VSV from gumming up maybe? By the way, all these issues are because my 1987 van with 4YE does feel as zipping as my 1984 with a 3YE.

http://i8.photobucket.com/albums/a23/timsrv/TVT%20pics/Engine/VacuumDiagram_zps560fe7ba.png

[robgagnon]

It seems like my diagram gets shrunk when I post on the forum, sorry about that.

[robgagnon]

Also, does anyone have the part number to the filter that threads into the intake plenum that connects to this vacuum line I am talking about? The diagram shows it as part number 23265 but why does it only show 5 digits I wonder...

[timsrv]

I'm not sure why............perhaps it's because it's a png file and the forum automatically converts to jpg? Regardless, I edited your post to display full size. That VSV (EFI VSV) is part of the system designed to combat hot soak. It would be easier to understand if you read through the "HOT SOAK" (http://www.toyotavantech.com/forum/showthread.php?289-Is-it-the-infamous-hot-soak) thread 1st, but I'll elaborate a bit here.

Basically the van has a bit of a challenge when it comes to dissipating heat from the engine compartment. Now add a hot day, a steep hill and the problem becomes exasperated. As long as everything is in tip top shape and the van remains running, no problem. Now add an air conditioner (more heat) to the system, & heat related problems ensue. The particular problem the EFI VSV is there to combat is Heat Soak. As long as the van remains running heat soak issues are kept at bay, but when you shut the van off, the loss of venting (fan) & coolant circulation further complicate things. This extreme heat with no place to go soaks into the fuel rail causing the fuel to boil/vaporize (resulting in a vapor lock condition). The problem is realized when you try to restart the van. It's mostly annoying & embarrassing, but also takes a toll on starter life. The van will start & stall, requires excessive starter cranking, runs rough, and the exhaust stinks. This lasts about 1 - 2 minutes then goes away. This was a problem back in the 80's when Gasoline had higher boiling temps, but is even worse with today's gasoline.

Okay, so here's where the EFI VSV (AKA Pressure-up VSV) comes into play. On each start up the ECU checks an engine temp switch (only on vans equipped with AC). If the switch is closed (happens at 230 deg F) it knows there's a potential heat soak issue. When a hot soak condition is detected the ECU activates the EFI VSV. When activated this VSV prevents manifold vacuum from reaching the FPR (Fuel Pressure Regulator). When vacuum is removed from the FPR the fuel pressure jumps from ~30psi to ~40psi. This increase of pressure reduces the potential for fuel boil (more pressure = higher boiling point). The ECU activates this VSV for only about 2 minutes, as this is enough time to offset the problem until restored coolant circulation & air ventilation can resume/reduce engine temperature. When the 2 minutes are up the ECU cuts power to the VSV, vacuum returns to the FPR, fuel pressure drops, and the ECU will not monitor the temperature switch again until the next time the van is started.

So this was the plan, but perhaps they underestimated the effects of hot soak. A changing fuel market certainly hasn't helped matters. It wasn't long before Toyota realized this was a bigger problem than originally anticipated. They responded by replacing the 230 deg F temperature switch with a 140 deg switch, but they only did this on vans that came into the dealer with chronic hot soak issues. Most vans never got this new switch (which is now NLA). In the "hot soak" thread we discuss alternate methods to help combat this problem. Tim

[timsrv]

That filter is Toyota part #90917-11022. It's not there to prevent dirt from getting in the VSV it's there to keep things out of the intake manifold. Not sure why it's necessary unless they're anticipating a failure (like the FPR diaphragm or something).

[llamavan]

And this interesting attached diagram shows that there is a variation of the system where it is NOT present, see the box in the diagram that says W/O COOLER. So can someone please explain this to me? What cooler?

"COOLER", in this case, refers to the A/C. So if your van did NOT come equipped with air conditioning, it has the "W/O COOLER" variation.

Gwen

[robgagnon]

That was a GREAT explanation Tim, I completely get it now. That also make me think I better hurry up and get that filter: the tip broke off and the filter has a bit of glop on it to plug the hole and the vacuum hose has a golf tee in it. This is how I got the thing, and my 1984 also has a similar fix (but it runs great). So therefor I am running too high a fuel pressure which would cause a too rich condition.

Also: it seems to me that for a van that has heat soak issues chronically, one could introduce a push button switch connected to the fuel pump tester connector and if you had an issue and just activated the fuel pump for a bit of time, it would push to the too hot fuel down the line back into the tank, but I might not be thinking correctly.

Thanks much.

[timsrv]

Having higher fuel pressure won't make it run rich as the ECU will compensate by cutting back the firing time of the injectors (it adjusts injectors based on the input from the O2 sensor). If however the O2 sensor had failed, the ECU would be in the "limp" mode (already rich), then yes, having no vacuum on the FPR would make it run richer. Your idea on activating the fuel pump before cranking might actually work, but IMO it's somewhat taboo to mess with these systems (potential safety issues). I prefer ventilation as a solution. Keeping the engine bay cooler will also prolong the life of your hoses & little plastic parts. Tim

[robgagnon]

And when does it do it?

I am talking about the "pair" of devices on the passenger side of the intake plenum.

It would appear to me that the VSV is controlling a diaphragm operated valve which is also in essence a VSV, but rather than be a solenoid triggered valve it is a vacuum triggered valve. And that diaphragm valve has a larger hose on it suggesting that the need for a higher RPM boost was wanted by the designers. But when does the VSV activate and why, and is there any reason to ever adjust the screw on a diaphragm?

Thanks!

[timsrv]

The diaphragm when activated increases engine idle speed. It can be activated via that VSV (which is activated with the AC compressor). The other way it's activated is via the power steering pump. There is a vacuum valve on the power steering pump called the "air control valve" (it's the one marked 17630 in the lower left corner of the diagram posted above).

Example: Lets say you're in a parking lot at an idle. Now you start cranking the steering wheel. Steering the front wheels on a hard surface without the vehicle rolling takes a bit of energy (enough to stall the engine). Exerting such energy causes pressure in the pump to spike. This excess pressure opens the "power steering air control valve" which allows vacuum to flow from the manifold to the idle-up diaphragm. The diaphragm changes position and the result is increased idle speed (enough to compensate for the load and prevent engine stall). There is an adjustment screw (plastic bolt sticking out the side with a spring on it). This screw is used to set the idle speed while the diaphragm is in the "idle-up" mode (typically set while the AC compressor is running & the "idle-up" system is activated). Tim

[robgagnon]

Let's call these VSVs by name:
1) VSV fuel pressure regulator controller
2) VSV RPM Increaser

And then there is a 3rd VSV which is over by the air filter, and that I believe is commonly called the ISC VSV or Idle Speed Controller, which in your own words somewhere "increases RPM by about 100" as I recall.

Then there is the 4th VSV which is part of the pair for VSV #2, and would call that an Vacuum Amplifier if I were naming it because it seems to provide a more hefty amount of air bypass than just the electric VSV can do, on account of the increased hose size.

So is there ever been a reason to change the screw setting on this VSV #4? What are some of the effects of a bad VSV #2 or #4? Some people talk about too high an idle, in other threads. I would think a faulty diaphragm in #4 could cause all kinds of idle issues, or a stuck open VSV #2 could perhaps cause high idle.

I am going to modify the vacuum diagram I posted above to remove all the part numbers and instead have descriptions of what the components do and it will be much easier to read. I just want to understand the system before I post anything wrong, and of course you can review the diagram for correctness.

Thanks - Rob

[robgagnon]

Tim,

Per the electrical schematic for 1987, you have the following VSVs:

- EFI VSV
- ISC VSV
- AC Idle Up VSV

The AC VSV is clearly connected to the AC Amplifier (the computer for the AC). It is also connected to the EFI computer. There is no reason why both devices cannot drive the same VSV. I believe Tim said that the AC VSV operated for about 2 minutes upon start up, but I would not be surprised to learn that the AC Amplifier also activates the AC VSV when the AC compressor is engaged, otherwise you might stall out the engine. This is the same idea as increasing horsepower when the power steering is active, of course.

The EFI VSV and the ISC VSV are controlled solely by the EFI computer.

That's about as far as I can get without probing the ISC and EFI cables with LEDs leading to a place where I can actually see them might under what conditions. I could also disconnect the connectors and see how it degrades the performance.

[robgagnon]

1266

[timsrv]

The factory service manual refers to the VSV (top right in your diagram) as both the "EFI VSV" and/or the "Pressure-Up VSV" (depending where you look). I personally like the term "Pressure-Up VSV" because that's exactly what it does. The one shown lower right of the diagram is ISC VSV (Idle Speed Control Vacuum Switching Valve). This is also a good name. The one that controls to the diaphragm is simply called VSV but the AC section schematics refer to it as the "Idle-up VSV". That diaphragm is also referred to as "Idle-Up Diaphragm". After reviewing the AC schematics I think we should call this VSV "AC Idle-Up VSV" but continue calling the diaphragm "Idle-Up Diaphragm" (because it's also activated by the power steering pump).

Since we're on the subject of Toyota changing terminology, I found several references to the 230 deg F temp switch that's part of the hot soak pressure-up system. Here are some of the names I found: "Idle-Up Temp Switch", "Water Temperature Sensor", and "Switch, Water Temp". I'm sure I could find more names for these things if I looked. I wish they would stick to single names as changing terminology only serves to confuse :dizzy:.

Here's some snap shots I took from the manual. If you look closely, you can see each one has it's own characteristics (nipple configuration & length/shape of body). The diagram you posted shows enough detail to match these up.

http://i8.photobucket.com/albums/a23/timsrv/TVT%20pics/Engine/aPressure-UpVSV_zpsb0045fce.jpg

http://i8.photobucket.com/albums/a23/timsrv/TVT%20pics/Engine/aISCVSV_zps6611b477.jpg

http://i8.photobucket.com/albums/a23/timsrv/TVT%20pics/Engine/aACIdle-upVSV_zps52c84820.jpg

In addition, here's another interesting schematic I found that may help enlighten:

http://i8.photobucket.com/albums/a23/timsrv/TVT%20pics/Engine/aIdle-upcircuit_zps640275ec.jpg

[robgagnon]

Tim,
Name on VSVs changed - suggest deleting previous diagram.1267

[timsrv]

The part you have labeled "Temperature Valve" is better known as the BVSV (Bimetal Vacuum Switching Valve). It's also known as the "Oh crap I broke it Valve" because the plastic nipples get brittle and break off if you look at it wrong :rol:.

[robgagnon]

Updated.
1268

[djshimon]

Excellent diagram! Could someone post a picture of the intake/head/block from the passenger side so I can see where all these hook into my intake, etc.? I have 2 of the vsv's mounted, but that diaphragm-21908c-I can't tell where it goes into the head or intake and if it uses air from the head.
Thanks, Aaron.

[timsrv]

AC Idle-Up VSV
http://i8.photobucket.com/albums/a23/timsrv/TVT%20pics/Fuel%20system/IMG_2093_zps2b664f0f.jpg

Idle-Up Diaphragm
http://i8.photobucket.com/albums/a23/timsrv/TVT%20pics/Fuel%20system/IMG_2094_zpsbffb75b6.jpg

[djshimon]

Thanks so much. So neither of these would keep my van from starting it looks like :no:.

[timsrv]

No. There are several recent threads about no start issues. You might try checking those out. Good luck. Tim

[gushaman]

Lol my plastic screw thingy is broken as well. I may invest some time in it. During a recent changing of a leaky fuel filter, i found what i think is the a/c clutch wire dangling in between the ac clutch and idler. I cant see the connection point, but the previous owner said the a/c never worked as long as he had it, i wonder if this is why, maybe it still has freon and i can get it goin. The chinese fuel filter had several pre crushed copper washers, im amazed it didnt leak before. i found a replacement for the e.f.i. forklift engines at work.

[ninz30]

Oh crap I broke my BVSV... Are replacements still made? This is a great thread btw!

[llamavan]

That's why it's most commonly called the "Oh crap I broke it" valve. Toyota part # 90925-05017. Still made as far as I know.

Gwen

[ninz30]

That's why it's most commonly called the "Oh crap I broke it" valve. Toyota part # 90925-05017. Still made as far as I know.

Gwen

Thanks Gwen!

[JDM VANMAN]

Wow this is an excellent thread!! Definitely a 5 STAR thread....

I don't understand the the detailed mechanics and operations but the easy explanations and pictures makes it comprehensible to a non-wrencher.

Just my 2¢- I give this thread

The 5 VAN THREAD AWARD :silvervan::redvan::yellowvan::greenvan::bluevan:

Thank you

[williamfowers]

hey my plastic screw broke as well... anyway i can buy a replacement somewhere?

[timsrv]

If you're talking about the idle-up diaphragm, they have these on www.rockauto.com. Just drill into their database for van parts and in the "Fuel/Air" section you'll find it under "Idle Air Control (IAC) Valve". The expensive one actually is the air valve, but the cheap one is the "Idle-up diaphragm". Use the picture beside the part to help identify. Tim

BTW: The early idle-up diaphragms have an adjustment screw but the later ones do not (preset). I personally like the earlier ones. Tim

[IronViking]

Anyone know why my ISC VSV would go on and off nonstop after my van dies? It does this for several minutes after running for a few minutes then it dies.
I replaced the switch with another and it continues to rapidly switch back and forth.

[coronan]

Is vacuum low enough at full throttle to raise fuel pressure???

[spacecruisers]

Does anyone know an alternate part that can be used for the Air Control Valve (part number 17630-28010)?

looks like Toyota has it but its around 250-300 dollars :nono:

theres quite a few of these (http://www.ebay.com/itm/TOYOTA-LEXUS-NEW-GENUINE-AIR-CONTROL-VALVE-ASSY-OEM-17630-16040-/172266987172?fits=Make%3AToyota&hash=item281be99ea4:g:evEAAOSwXYtYvatQ&vxp=mtr) on eBay and they're only 45 bucks, but who knows if they'll fit or not.... (p/n 17630-16040)

not sure how part numbers work but they both have the 17630 part name code

[timsrv]

Is vacuum low enough at full throttle to raise fuel pressure???

Yes, every time you step on the gas the fuel pressure goes up ~ 5 PSI or so.


Does anyone know an alternate part that can be used for the Air Control Valve (part number 17630-28010)?

looks like Toyota has it but its around 250-300 dollars :nono:

theres quite a few of these (http://www.ebay.com/itm/TOYOTA-LEXUS-NEW-GENUINE-AIR-CONTROL-VALVE-ASSY-OEM-17630-16040-/172266987172?fits=Make%3AToyota&hash=item281be99ea4:g:evEAAOSwXYtYvatQ&vxp=mtr) on eBay and they're only 45 bucks, but who knows if they'll fit or not.... (p/n 17630-16040)

not sure how part numbers work but they both have the 17630 part name code

Not sure how compatible that eBay part would be, but these things hardly ever fail. Practically any van found in a salvage yard would likely have a good one. I'd recommend going HERE (http://www.picknpull.com/check_inventory.aspx?Address=84101&Lat=40.756393&Lng=-111.898592&Make=Toyota&Model=Van&Distance=50) to see if that 86 van has got one. If so I'm guessing they'd let you have it for under $20. Tim

[spacecruisers]

mines probably okay, what would be a symptom of a bad one?

i probably don't actually need to replace it, I'm just in "replace everything in sight mode" because of the PO's negligence and lowest bar possible approach to their work on the van ha ha

[timsrv]

It mounts to the power steering pump and it opens/closes an internal valve when power steering pressure goes up/down. The valve blocks/allows vacuum flow to the idle-up diaphragm (same thing the AC idle-up VSV does). The increased RPM keeps the van from stalling due to momentary heavy loads imposed by the power steering pump.

For instance, say you're sitting in a parking lot with the van idling. For whatever reason you grab the steering wheel and start cranking it (without rolling forward). This creates a pressure spike and momentary heavy load from the PS pump. If the idle speed were not increased the engine would likely stumble or stall. The job of this part (in conjunction with others) is to prevent that from happening. Tim

PS: Read posts #10 & #19 (1st page of this thread)

[spacecruisers]

Oh man whoops, i must have skimmed past those. :doh:

I'm learning a lot from your comment and those referenced posts (and this whole thread) about how all this stuff works. Very valuable knowledge.

I'm always amazed at your intimate knowledge of every aspect of these vans. Thanks Tim for all your contribution to the forum.

[timsrv]

My pleasure :). What good is knowledge if it cannot be shared? :wave2: :thmbup:

[dogger562]

OK so there are 3 VSV parts that I have to check. Right? The ones on post number 14. Whit an hmo meter, that I have never used but that I'm going to buy because I have a feeling it's a good tool that's gonna come in handy.

My roadster has those symptoms, first out of nowhere it started idling really high like at 1400rpm whit out me adjusting anything, then I had to adjust air screw for temp relief but it's all out of wack.

Symptoms 1=when cold most time I have to give it gas and will turn on, on fith or six try
2= I have to keep pedal down a little to stay keep 1200rpm to warm or else it would drop to rpm500

3=if I adjust screw to 1200 when cold to warm up. When does warm it stay around high rpm like 1400

Can someone tell me if I'm at least heading the right direction as far as the process of elimination to deal whit this problem? Than you
Dogger

[timsrv]

An ohm meter will only tell you if the coil inside is good. I prefer to test by blowing through the vacuum port (with my mouth), then I'll apply 12 VDC to the terminals and blow again. If the VSV is good you will hear a click when voltage is applied, then you will notice the air flow changes. Some VSVs will allow/prevent air flow (depending on valve position), others will direct flow to a different port and/or vent it out. Bottom line? as long as flow changes with voltage it's good. Tim

[dogger562]

Thank you Tim, I dint know how important VSV system is and the impact it can have on the performance of our vans. Definitely on my to do list.
Dogger

[markhmcb]

If you're talking about the idle-up diaphragm, they have these on www.rockauto.com (http://www.rockauto.com). Just drill into their database for van parts and in the "Fuel/Air" section you'll find it under "Idle Air Control (IAC) Valve". The expensive one actually is the air valve, but the cheap one is the "Idle-up diaphragm". Use the picture beside the part to help identify. Tim

BTW: The early idle-up diaphragms have an adjustment screw but the later ones do not (preset). I personally like the earlier ones. Tim


Tim, how does one go about adjusting the earlier one with the adjustment screw? My 1989 2wd LE has one.

Thanks,

Mark

[timsrv]

Tim, how does one go about adjusting the earlier one with the adjustment screw? My 1989 2wd LE has one.

Thanks,

Mark

The "Idle-up" diaphragm's job is to increase idle speed to compensate for loads that would cause the engine to stall or stumble. A properly adjusted one will simply aid the engine in maintaining the correct idle speed when these loads are present.

With the AC off, set your idle RPM using the idle screw adjustment on the throttle body. Then turn on your AC, wait for RPM's to stabilize, then set the idle speed again (to the same spot as before) using the adjustment screw on the "Idle-up" diaphragm. Tim

[armorrell]

Here's a question.... where are you guys getting these amazing diagrams? Are they downloadable somewhere?
Man, I'm hoping they're not somewhere obvious. ;)

[Gambit]

This is a great thread. I've got a problem that I haven't been able to troubleshoot yet and am hoping someone may be able to point me in the right direction:

'88 4wd w/ AC (AC is non-functional and condenser has been removed)
I'm having a high idle issue - around 1200rpm when warm. This has been going on for months but didn't realize how high it was until I installed a tach.

When first started and cold, it idles around 600-800 until it warms up and then goes to 1200. I also am having a cold start issue (which may or may not be related where it feels like it needs to build fuel pressure for the first start of the day - and completely goes away after the van warms up).

My thought is a vacuum line may be installed backwards? Which would make it idle low when cold and warm when hot? Is that even possible?

Or maybe a valve is stuck open or closed?

I've replaced the following:
- Cold start valve
- Idle up diaphram
- Bimetal VSV
- TPS

Also within the last 100 miles recently:
- Plugs
- Cap
- Rotor
- Wires

Would greatly appreciate any additional direction - and thank you!

[xrs135]

This is EXACTLY how my '88 4WD runs. Same cold start RPMs and warm RPMs as you.

I'm almost certain that it's the air valve causing the issue. Unfortunately, it's so hard to find an air valve these days, and the job to replace it is difficult enough that I don't know if it's worth it for me to pursue fixing it.

I'm considering adjusting my warm idle down to acceptable RPMs, and just getting used to using the gas pedal after cold starts for a couple mins.

[Gambit]

Yeah the air valve is on my possible list of why it is happening - but am hoping it is something else.

I have adjusted my idle down on the throttle body pretty much all I can, and it still is around 1200 RPM at idle. I have a California smog test coming up in the next few months and won't pass with that high of an idle... Did you have another means for lowering it?

[originalkwyjibo]

I don't know how thorough your Cali smog inspections are but when I still had to smog mine in Wa state I had idle issues. I eventually determined mine to be a bad tps. Prior to that when I would get a smog test I would turn on the rear heater fan while they weren't paying attention. It brought the idle just under there 1100 rpm maximum and got me through the test. Obviously the best solution is to troubleshoot and repair but if you need to pass an inspection in the meantime so you can keep driving it this trick may be worth a shot.

[stolz]

So I adjusted this guy on my 1984 TV

9036

But I opened it as far as it would go, if I went further it sounded like air was coming out.

I turned the van on and listened to the normal idle without any electronic loads on the battery and then I turned the AC on and let it idle for a bit before I just the plastic screw.

But it still doesn't seem to be idling high enough to keep the battery from dying with AC on.

It definitely kept it from dying as fast as it was before but it slowly starting creeping down into the low 13v range.

Anything else I can do or maybe I did something wrong?

[timsrv]

I seriously doubt it's low voltage causing it to die........that takes place somewhere around 10 volts. If your battery is strong enough to restart after it dies then you can rule out the charging system. Sounds to me more like you have a vacuum leak. A vacuum leak will cause the van to run rough AND can prevent the idle-up VSV/Diaphragm from operating as designed. Carefully check all vacuum lines and if you have a vacuum gauge, take a vacuum reading at idle and report the results. Tim

[originalkwyjibo]

And check the intake tube for cracks!

[Gambit]

For what it is worth, I pulled 2 Auxiliary Air Valves from junkyard vans yesterday.

1 from an 86 and 1 from an 87. Both were part #22230-73011 and not #22230-73010 which I had expected. Mostly putting this out there to say that those part numbers are likely interchangeable.

[Gambit]

Would the AC Idle Up VSV cause high idle issues if it was bad? Enough to keep the idle up at 1200rpm?

[JDM VANMAN]

For what it is worth, I pulled 2 Auxiliary Air Valves from junkyard vans yesterday.

1 from an 86 and 1 from an 87. Both were part #22230-73011 (tel:22230-73011) and not #22230-73010 (tel:22230-73010) which I had expected. Mostly putting this out there to say that those part numbers are likely interchangeable.


Can you post post an actual photo of the part and where is it located?

Thank you

JDM

[Gambit]

Another auxiliary air valve question - At what temperature roughly does this close? Does the thermostat need to be open to reach this temperature controlled switch?

Thanks

[timsrv]

The auxiliary air valve is supposed to be fully open when coolant is @ or below 68°F. It's supposed to be fully closed @ or above 176°F. It's on the heater hose circuit which bypasses the engine T-stat (it gets flow regardless of engine T-stat position). Tim

[whatvan]

Some of this comes from the “what is this/part number” thread. Posts 259 and 260.


From Member AD2101:

Tim,

Any idea if there is a functional difference between Idle-up VSV 90910-12003 (tel:90910-12003) vs 90910-1200 (tel:90910-1200)5? I searched ToyoDIY and it appears it has the same application just a different last digit.

https://www.toyotavantech.com/forum/attachment.php?attachmentid=9721&d=1575614363

TimÂ’s response:

Not sure. It's very possible, even likely there are multiple VSV's used by Toyota (and others) with the exact same function. I'm guessing the only difference between some may be the configuration of the mounting bracket. If you find one that you think may work, you can test to see if it's functionally identical. Just try blowing through the nipples to see if air flows (normally open) or if it does not flow (normally closed), then activate it with 12V and blow again. Once you know how it functions you can test other similar type VSV's found elsewhere (even on other makes and models of cars). If/when you find one that functions the same way you could use that. If it doesn't mount the same you could wire tie it up or just let it dangle from the wires/vacuum hoses. Tim



Per tims suggestion I tested my idle up vsv (with the broken nipple). This vsv appears to be normally closed. Unfortunately, the 90910-12003 I got from a junkyard did not work with TimÂ’s 12v test. No air passed when hooked up to 12v. Same was the case for 90910-12005. Appeared to be normally closed, hooked it up to 12v no air blew through.

At this point wether 90910-12005 will work, looks likely but still inconclusive. However, I did learn 90910-12003 is normally closed.

If im pulling my air conditioning, would there be a way to “loop” the vacuum so I didn’t need this VSV and my idle would return to normal?

If not, anyone with an idle up vsv, IÂ’m on the hunt. Willing to buy. I pay promptly.

[timsrv]

To keep it simple I only mentioned the most common VSV's functions. There are also other more complicated ones. Some have more than 2 nipples and some will perform multiple functions. Another common function is to vent/seal depending on their intended purpose. If you see one with a round cylinder thing on one side, chances are it's meant to vent to atmosphere. Like the pressure-up VSV, when it's activated it will close the vacuum side while opening the fuel pressure regulator side and venting the FPR to atmosphere. All I'm saying is that when you are testing these it's important to understand intended function. If you don't know, then be sure to blow in both sides while testing. If nothing else it may help you understand function better. Tim

[whatvan]

Gotcha, thanks Tim.

[nickgorey]

Anyway to know if the idle-up diaphragm is bad? My AC idle-up VSV seems to be working; it lets air through when provided power–but nothing happens when I adjust the nylon screw on the diaphragm. I also just redid all of my vacuum hosing, hoping that would help, but when I throw the AC on I lose ~250rpm, from 750 to 500. The car still cycles through idle increase momentarily while the AC is on, kicking it up to about 800rpm, but then drops back down to 500. My understanding is the AC idle-up VSV should kick the rpms back up to 750, should it not?

[nickgorey]

So I got my OEM idle-up diaphragm from the dealership, threw it in and, unlike the old one, when I adjust the nylon screw it effects the idle speed. Now, following Tim’s advice on setting idle speed and the diaphragm, I set the idle speed with the screw on the throttle, put the AC on, then adjusted the diaphragm to match the speed. The only issue is that when I turn the AC off, the diaphragm still seems to be activated and kicks the rpms up. So, it would seem as though my idle-up is always being engaged. My idle-up VSV seems to be functioning properly, so does that just leave the air control valve on the power steering as my only culprit? Could it be stuck open?

[nickgorey]

Welp, I went back at it, and after perusing an AC thread, I decided to undo the grounding of my coolant temp switch, and voila! My idle-up diaphragm only kicks in when I’ve got my AC on :). Seems like grounding the CTS caused the idle-up diaphragm to always be active.

[Ian R.]

Welp, I went back at it, and after perusing an AC thread, I decided to undo the grounding of my coolant temp switch, and voila! My idle-up diaphragm only kicks in when I’ve got my AC on :). Seems like grounding the CTS caused the idle-up diaphragm to always be active.

This is exactly the answer I need for an issue I have been struggling with.

I had a failed air idleup diaphragm. It was basically routing unmetered air through the large port, through the diaphragm activation port, through the vsv, then back through the manifold side port of the diaphragm (if that makes sense). This cause the engine to idle about 200 rpm higher. When I installed a new idle up diaphragm it did not seem to fix the idle issue. Then I notice that when I turned the spring retain screw on the idle up diaphragm it change the idle. It did not make any sense at first. Why was the VSV activated when there was no load from the PS or A/C? THE COOLENT TEMP SENSOR WAS GROUNDED TO THE ENGINE BLOCK! I would have never figured that out on my own. I removed the coolent temp switch wire from ground and the problem resolved. Thanks for this!