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New member here, so I don't know if this has been covered before.

I've found a replacement for the original 280Z 280ZX AAR that works much better, is relatively cheap and best of all it's from Nissan. No more Toyota Cressida valves!!

Nissan part # 22660-45P00. These are off a Z32 300zx/early Infiniti J30 and will bolt right on to any 280Z or ZX. One slight modification is that the terminal locating tab on the electrical connection is slightly offset from the original. It's not needed. 5 minutes work with an X-Acto knife or file to remove it and you're done.

This is a new style " Rectangular " model that can be easily disassembled for cleaning and has a composite slide plate that resists sticking. A much better valve than the earlier " round " style. Bolt pattern and hose size is exactly the same as the original 280Z AAR.

I've found new OEM Nissan ones online from about $75 - $80. I lucked out and found a BNIB 22660-45P00 for $29.95 on E-Bay. Good used ones are plentiful as well as are aftermarket. Standard Motor Products carries them as Part number AC366. Rock Auto stocks them.

Measured resistance is 75 ohms.

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Edited by Chickenman

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Since my car is a 1976, I was going to update the PCV hose routing to the later 1978 style. This to reduce some of the oil contamination issues of the AAR. Then I decided to clean things up further and simply feed the AAR inlet through a small K&N breather vent. K&N Part # 62-1330 with a 1/2" id neck.

I'll take some pictures of the completed install a bit later.

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Not sure how it can work "better". I have an original style and it works correctly. Junk yard $2 find.

As Capt said, wont work right the way you want to install it.

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That won't work right. The AFM won't know about the air being supplied by the AAR and you'll run lean until the AAR closes.

Just to clarify why it won't work, the AAR is an air bypass to the throttle blade, which affects (increases) idle speed when the engine is cold, but ALL air going to the engine must pass throught the AFM or it cannot set the fuel mix correctly. That little filter will pull air from atmosphere that cannot pass through the AFM.

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That won't work right. The AFM won't know about the air being supplied by the AAR and you'll run lean until the AAR closes.

That was my initial thought as well and you are probably correct... but I was thinking that as the AAR connects from the Valve cover and then connects ahead of the TB and after the AFM, that it would be OK. On second thought it may not be....

However, it may not affect the system all that much. Airflow values on the factory AAR valves are pretty low...around 5 cfm at 70 F. I'll test it out and let you know the results. It may help my particular car as it has a big cam and tends to idle rich with the TPS setup " properly "

My car has always idled too rich with the TPS adjusted properly, it actually idles better with the TPS adjusted so that the idle contacts are open at idle speed. This is true with either the stock cam or the 280 degree cam. ( and yes EVERYTHING has been checked, TPS operation, AFM mixture bypass on AFM has been adjusted to best vacuum reading " Lean Best Idle " , AFM calibration is spot on ..confirmed with DVM and 4 gas analyzer, brand new ECU CTS ) .

Even when fully warmed up my car idles better with TPS idle contacts setup " wrong " ( Contacts open at idle ).

According to the Nissan EFI Bible, when the TPS idle contacts are closed the ECU compensates by enrichening the mixture slightly. That makes sense as Idle mixtures are typically richer than Stoich. Combine that with low compression ratio's , retarded timing values ( relative to ideal non-emmission timing ) and sometimes EGR and it all adds up. However, my car now has 10-1 CR and lots of advance at idle. It doesn't seem to need the extra fuel at idle... on my particular car. Weird that the big cam doesn't like the extra fuel at idle though. I'm suspecting that ECU may be getting some " drift ".

That problem should be solved next year as engine will be getting a Mega Squirt 2 or 3.

Edited by Chickenman

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My car has always idled too rich with the TPS adjusted properly,

AFM calibration is spot on ..confirmed with DVM and 4 gas analyzer,

The stock EFI system is a collection of parts that were all designed to work together. So, with the cam, you're out of spec. anyway.

I can't help but point out the contradiction in the above statements though. What you're really saying is that the gas analyzer specifications are too rich. For your nose, I assume.

Good luck with the tuning. Not sure why you want to remove the PCV anyway, since it actually cleans combustion byproducts from the crankcase, leading to a cleaner engine. Unless you're looking for that little bit extra of clean air and power that the PCV gases are taking up in the intake air supply at full throttle.

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Not sure how it can work "better". I have an original style and it works correctly. Junk yard $2 find.

As Capt said, wont work right the way you want to install it.

Well that's all fine and good if you can find a Junkyard AAR. Then it's a crap shoot to see if the 35+ year old part still works. And you can't buy a new S30 AAR anywhere. They're just about extinct.

I've worked ( many hours ) on my 37 year old AAR valve trying to get it working properly and I'm just not satisfied. After much cleaning, adjusting and trying to get the heater coil " clocked " just right, the original valve still closes hit and miss. Not good enough for me. I have a new Cressida AAR valve and this new Nissan AAR valve. Both have composite slides..both are BRAND SPANKING new and both operate as smooth as a hot knife through butter. That to me is " Better "

As far as better? Yes they are better than the originals. Composite slider resists oil contamination better than stock, you can easily take them apart with 4 screws for cleaning or adjustment... and they aren't 35+ years old :beer:

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The stock EFI system is a collection of parts that were all designed to work together. So, with the cam, you're out of spec. anyway.

I can't help but point out the contradiction in the above statements though. What you're really saying is that the gas analyzer specifications are too rich. For your nose, I assume.

Good luck with the tuning. Not sure why you want to remove the PCV anyway, since it actually cleans combustion byproducts from the crankcase, leading to a cleaner engine. Unless you're looking for that little bit extra of clean air and power that the PCV gases are taking up in the intake air supply at full throttle.

You know what they say when you arse-U-me... LOL

Who said I was removing the PCV? Not me. I know the benefits of running a PCV and it is fully operational.

And yes the car was checked and setup confirmed with a Sun Allen 4 gas analyzer at Bills Datsun Shoppe in Claakamas Oregon ( One of the top Datsun specialists in the PNW. 37+ years in Business. The guys sharp ) ). And I'm no noobie to Datsuns or Race car/Street Car tuning. Have built and raced them since the mid 1970's. Not my first rodeo. I'm one of those old timers who can still setup a car with a timing light, vacuum gauge and my nose and ears. That's what we had to work with back then and these days there are few of us left. And my tunes all come out BANG on the money when the checked with WideBands, Emmissions Testing, Chassis Dynos etc. I'm no stranger to modern equipment either, but a good set of ears and nostrils can still give you an initial heads up to a problem.

You'll typically find me at the track tuning some one else's car. I actually do a nice little side business tuning Vintage cars and Hot Rods. I've got years of experience tuning Webers, Dellorto's, Mikuni's, SU's, Hitachi's, Holley's, Quadrajets, Rochesters and just about every carbed car under the sun. Mainly a Carb guy, but am gaining more and more EFI experience every day. Have been studying and Tuning Bosch Motec series for the past few years, both WB and NB.

I'm not bragging...just introducing myself as I'm new here...but not new to Datsuns :beer:

Edit: PS also have 17.5 years under my belt as a Certified Nissan Partsman.. just as an introduction. Did I mention I was an old Fart? ;)

Edited by Chickenman

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I didn't say the gases weren't checked. I'm just wondering what you meant when you said that it's still too rich. It doesn't matter how many modifications you make if you keep tuning those modifications to the gas analyzer, and the gas analyzer specs. are too rich for your nose. You can tune to the analyzer, or tune to your nose.

And, no offense intended, but you should have seen the questions coming about the bypassing the AFM, with all of your experience. "All air must pass through the AFM" is one of the fundamentals of the EFI system.

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Hmm....I never had to do anything to my AAR. It works perfect, period. Junk yard find was probably 15 years ago so it is original equipment. Besides the fact I have an extra original one in the garage. Thats the one I compared it to when I got it from the junk yard, salvage yard, what ever they are called these days.

Thats how I tune my Z...vacuum gauge, and timing light. And my dwell/tach for rpms.

Go ahead and brag man. We can use another well rounded mechanic here. Welcome to the club, BTW.

As you probably know already its tough to do tuning or performance engine upgrades due to CA emissions laws. Not sure what it is in Oregon, must be lenient there? I am curious on the results of the AAR you have so please post results.

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To the basics of the original post - I like the find on the alternative AAR. I've seen the newer designs and pondered if they could be adapted. I'd probably get one from a wrecking yard if I went that way, but the one I have works fine, and I have two more that I've cleaned up and are ready for use if needed.

Nissan changed the PCV hose routing in 1977, because of AAR and throttle blade fouling. The newer AAR could have the same problem if the 76 hose configuration is still in place.

rcb, the OP is in Canada. In Oregon, I only have to pass idle emissions. All of my AAR's are stock 70's time-frame.

Edited by Zed Head

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And my Z has that "new routing". I believe it was changed in 4/77 and mine is a 5/77. I never have any "clogging" issues or anything interfering with operations.

Ah yes, I see Canada now, thanks.

Although when I owned a 76 about 18 years ago I had the problem with the throttle blade and AAR fouling, IIRC.

Edited by rcb280z

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Yep... the original post was just an FYI for an alternate part to the original 280z and 280ZX AAR valve. The part about mixtures etc wasn't really a concern of mine. If it does affect my idle in a negative way then I can easily connect the AAR valve up the correct way in 5 minutes. I do appreciate the heads up though...

The later revision on the 280Z's AAR hose was in response to oil contamination as mentioned. I was working for Nissan at the Time and remember the TSB's from " Datsun " at that time to modify the 1975 and 1976 models. If I do have to revert to using the factory routing, I'll upgrade to the later style method or add a closed catch can.

As I mentioned, I suspect my particular ECU has a bit of " drift " at idle causing a mixture that is richer than it needs to be. Even with the stock camshaft I had to lean the AFM mixture screw ( not the TB idle screw ) much more than necessary when the TPS idle contacts were closed. And I know that's not correct.

I'm not 100% convinced that the AFM does compensate for increased idle air going though the AAR. After extensive reading on the EFI Bible and the FSM's, it looks like idle enrichment may be a purely calculated Mapping that only varies with engine RPM and TPS contact position. Based partly on the fact that ALL Nissan AFM's have a hidden idle mixture trim adjustment on the AFM and the TPS has to mechanically tell ECU that engine is at idle. I don't think the AFM has enough sensitivity at idle to self correct for small deviations in air flow, and that is why you have the " hidden " Idle mixture screw and TPS idle contact signal. I could be totally wrong though...

I could be totally wrong, and it won't be the first time... but it does bear further investigation. TPS idle contact affects idle enrichment ( adds fuel at idle ) and also allows fuel cut between, 3,200 rpm and 2,800 rpm on Decel. Other than that, the TPS idle contact, open or closed has no bearing on fuel curve.

Once I get the new AAR installed I'll do some simple comparison runs. and report back. Sorry...no 4 gas analyzer this time. Car's unlicensed for winter. Nose, tachometer and vacuum gauge is gonna have to suffice :)

PS: Car pulled 28.6 mpg on a recent long run ( with stock cam and 5 speed ) ..so fueling and tune are pretty danged good.

Edited by Chickenman

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Post #6 you state the car has a "big" cam in it. And that it idles rich.

Post #14 says you are running stock cam.

What am I missing?

That the " Old " motor, with the stock cam, blew up just outside of Portland back in August, while on the way to the Monterrey Historic races at Laguna Seca. Ruined my whole freakin' vacation banghead.gif

Then I had a brand new motor built from the ground up at Bills Datsun Shoppe in Clackamas Oregon. That's when we put the " bigger " cam in. Intake system, and AFM settings were all the same. It was a very long Tow back to Vancouver, BC and it worked out cheaper having it done there than back home. Very pleased with new engine.

Actually, we adjusted the AFM a few " clicks " as it had a lean spot at around 3,000 to 3,500 RPM's when the new cam was installed.

Edited by Chickenman

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There's good info on the AAR in this thread:

http://www.classiczcars.com/forums/fuel-injection-s30/47447-help-me-understand-aar-please.html

About a third of the way down, there is some discussion about the screw together AAR versions (Look for TomoHawks posts) . Some with two tubes like you posted above and some like one I nabbed off a Pathfinder that has one tube and a hole in the mounting face that ports air right into the intake manifold.

I assume you searched around for aar stuff and that thread didn't show up. I couldn't find it with the search function... I'm guessing that "AAR" is too short of a keyword and it doesn't work?

So about the mixture running lean if the AAR is ported to atmosphere... If you're running too rich for some reason, then having the AAR artificially lean the mixture will be a positive, right? At least until the AAR heats up and closes. And then you're back to your original rich running anyway.

So what was your original AAR doing (or not doing)?

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^ ^Yep... have read all through that thread and researched several others. Pathfinder and Toyota Cressida AAR valves are close, but the have holes in bottom etc. 22660-45P00 is a direct bolt on for our cars. Bolt holes, hose sizes etc all match up. The only thing you have to do is file down that one locating tab on the electrical terminal. Easy Peasy.

My original AAR was just tired and gunked up. Thoroughly cleaned it with Brake cleaner, but heater element had came loose. Re-clocked it and epoxied in place, but sliding disc was still " sketchy " in operation. I wasn't getting repeatable results. Hell..it was simply old and tired. Did some more searching and found the Z32 AAR was an exact bolt on.

As mentioned it has the new style Composite ( Graphite? coated ) slider that works much better than the old Brass sliders. The Brass ones seem to gall with age. And the cover easily comes off with four Phillips screws if you ever need to fiddle with it.

Richness at idle can be eliminated just by adjusting the TPS so that the idle contacts are open at idle. I'm pretty sure that there's something fishy with my ECU ( probably ECU drift as FastWomen has experienced ) but at least I can work around it.

Other than that, the ECU works pretty damned good as car pulls super hard to 7,000 rpm with the bigger Cam. Haven't run fuel mileage tests on the new motor yet, but the old motor with same specs, but with a stock cam, was pulling excellent fuel mileage numbers ( 26 to 28 MPG Highway ) and ran really sweet. The old Analog dog can't be that bad... LOL.

Edit: PS. I've been lurking for several months at this site and others..... gathering Intell... Been super busy on my Audi forums but will be posting more often here now that I have a bit more free time.

Edited by Chickenman

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Gotcha. My original AAR didn't work right either. It was mechanically fine, but electrically intermittent.

Anyway, welcome aboard and glad you got your car running well. Here's hoping you get to the bottom of the rest of the running rich issues.

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I did some bench testing on this AAR valve, a new Toyota Cressida valve and my 38 year old valve. Use an ATX power supply and spare terminals. New valves opened and closed as smoooooth as a hot knife through butter. Old valve opened and closed in fits and starts. Even after a thorough cleaning and a light spray with WD-40.

I think that the fact that these AAR valves were brand spanking new had a lot to do with it. ;)

PS: Don't bother with Toyota Cressida valves. The bolt spacing and hose size is off. The 22660-45P00 fits a 280Z/ZX perfect.

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Okay got it in yesterday. First thing I did was open it up for a peek. Same principle as the stock one. Except for operation. When I had it open I saw a very clean AAR interior. So I put it back together and installed it on my car and started it up (cold engine). She idled about 900 rpms (400 less than stock one) and within 2 minutes I was shutting down the car. It was running very rich. The car was cold when I installed it. I re-installed my stock one and she ran the way she is supposed to (1200-1300 rpm's). So this requires a little more looking into. I did get it used off ebay. But from a reliable source. Just my 2 cents.

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^^ Sounds like the slide stop needs to be opened up a bit.

 

Or you could re-adjust the air bypass screw on the AFM ( Mixture adjustment ). The slide opening and AFM mixture setting have to be matched during warmup. If the CFM flow of one AAR is different from another then the idle mixture adjsutment on the AFM has to be adjusted.

 

 FYI:  FSM says idle mixture on 75 and 76 models cannot be adjusted...but that's not 100% true. Depending on Model of AFM it may have an aluminium plug in it ( " Tamper proof plug ) .. but it can be easily drilled out and  removed. Later models, with Catalytic convertors, had no plug or a rubber plug covering the idle mixture bypass screw.

Edited by Chickenman

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