Chickenman

Some good suggestion have already been made above. You're going to have to do your best Sherlock Holmes impression and hunt this down systematically. Regarding your intermittent running problem. I suspect a poor electrical connection could be your issue. This often happens on Vintage cars and occurs randonly when the car hits some bumps or pot holes in the road. One way of checking for this is to run the car over a rough railway crossing a few times. Make DARNED sure that you have enough speed to clear the crossing if the engine conks out!!! Start checking ALL of your grounds and pull apart all of the connections in the engine bay and clean them with DeOxit or a similar purpose made electrical cleaner ( Weicon is amazing ). Look for frayed and loose connections. Pay particular attention to the ignition circuit. Don't forget the relays hidden under the passenger side relay cover. I'd carry a test light and a Volt Ohm Meter with you at all times to check for voltages and continuity when the thing eventually conks out. Might be a good idea to replace the ignition switch with a new one just to be on the safe side. These get a lot of use and are often over looked.

Thes cars use a LOT of bullet style connectors that get corroded over time. Go buy yourself some good electrical contact cleaner like DeOxit and start pulling apart and cleaning connections. The headlight connectors are in a bad location ( in front of radiator support ) and get exposed to a lot of road grime and moisture. On my 280z I saw a dramatic increase in headlight brightness when I took the headlight connections apart and used an Electrical contact cleaner. Same with my windshield wiper connection. A few minutes with a Good Electrical contact cleaner and the wiper speed increased significantly. After that I started pulling apart every single connection in the engine bay and sparying them with contact cleaner. Including bullet connectors for the fuel injection, all of the snsors including the water temperature sensor. It is amazing how much better the car runs and how accurate the instruments are. It is important to buy a GOOD industrial contact cleaner made specifically for the job. WD-40, while it will work, is not a good as chemicals made specifically for the job. I use a German product ( which I can't remember the name of at 5:07 AM ) that worked amazing. Dull oxidized terminals turned bright and shiny after only a 5 minute application. You just spray the stuff on, wait 5 minutes and then re assemble connection. I'll look up the name later today. Edit: Here it is. Weicon Electro Contact Cleaner. WEICON Electro Contact Cleaner (Spray)

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.

^ ^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... . 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.

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 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.

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.

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

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

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.

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.

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.