Captain Obvious

Great pics. One thing that was amazing was the amount of mirror image they did for the RHD cars. Two completely different cars from the dash forward. One thing that caught my eye, however, was that they did NOT redesign the center console. They used the same center console and ebrake assy on both RHD and LHD versions.

Another tip. Make sure you take the gas cap off and release any pressure in the fuel tank before you go opening the system. If you don't you might run into a situation where fuel seemingly defies the laws of physics runs uphill for no explainable reason. Well there is a reason... The fuel vapor pressure in the tank is pushing fuel up that hill. Not that this took me two hours to figure out or anything... :stupid:

Gotcha. On the good side, the fact that the problem persists makes it easier to find. So with what you have described, it could be a huge scope of things. Could be fuel or spark. Anything from an intermittent electrical connection inside the ignition module to crud in the fuel tank blocking the pickup screen. Next time it happens, check for spark. That could narrow the scope significantly. Like zKars described it's a hunt, but the hope is to narrow the hunt as quickly as possible.

My first blush advice would be to start simple. Attempt to determine if the problem is spark or fuel. When the problem is occurring, pull the coil wire and see if you have spark. I couldn't tell from your description... When the engine dies, does it restart or does it just crank and crank and not start?

Probably not directly applicable, but here's some info on how the temperature switch works and it's affect on timing, etc. Might be some stuff in here that helps. http://www.classiczcars.com/forums/electrical-s30/46647-water-temp-switch-what-does.html

Sounds like you've got a lot of air going through that valve cover vent hose and into the throttle body nipple without going through the AFM first. That will cause a lean condition. So, where is that air coming from? Some things to look at: Make sure that the PCV valve and it's hose are in good shape and properly connected. (The PCV and hose are located on the underside of the intake manifold right behind the throttle body.) Make sure you've got the oil cap installed and snug. Make sure you've got the dipstick installed and pushed all the way home.

I'm no expert on the topic of idle air valves, but I believe it goes like this: If the valve has two wires, it's a PWM control with one field coil fighting against a spring. Simplest, but not the fastest response time. If the valve has three wires, it's a PWM balancing between two field coils. More complicated, but faster response. If the valve has four wires, there's a stepper motor inside. More complicated, but stays positively where you left it with no input signals. Example is GM. I thought about the concept of just having two idle speeds "cold" and "normal" and just using a small simple solenoid valve to open up a bypass around the throttle plate. I've seen some really nice small solenoid valves used for EVAP can purge functions on cars. Maybe I'll grab one of those and mess around.

I think a trip to the junkyard is in order. I'll have to make sure I take a ruler along...

I'm not sure I know what you mean when you say that you can't get the idle "back to where it should be". Are you talking quality or quantity? By that, I mean... Are you saying that the idle quality is poor (stumbles, runs rough, etc) or are you saying that the idle quality is OK, but it simply idles at too high of an RPM?

Well I surely wouldn't claim to be either a Z or an EFI expert, but I'd be happy to lend a hand if I weren't on the other coast. Good luck on the endeavor and if there's anything that can be done remotely, make sure the forum is on call at the time?

Hmmm... I've got my AAR adjusted such that I don't get much of an idle boost when first started, but I don't think my engine would idle stone cold without it. My idle settles out to 700-800 once warmed up, but I think if I cut it out completely, I'd have to sit there with my foot on the pedal for the first minute to keep it from stalling. Maybe I'll try that and see what happens.

I find the whole thing very unpleasant. I understand the frustration of fielding questions who's answer is pretty easily found in the manuals, but I don't believe that the solution is to post non-helpful sarcastic responses to virtually every post. What's my recommendation? Move on. Don't want to answer the question? Then just don't. I sure don't believe the solution is to post stupid non-technical pictures of "loosely related"? situations simply in order to make a point. on. every. thread. :sick:

Thanks all for the additional input. I understand that there won't be any performance gains to be had by switching to a different throttle body. That's not the intent. As a matter of fact, that's why I would really like to find one similar in bore to stock. I don't want to change the flow characteristics. I just wanted to consolidate the function of the AAR into the throttle body like newer vehicles. Incorporating the BCDD function would be a little more difficult because the control would have to be vacuum based as well as temperature based. Currently, the AAR is temp only, and the BCDD is vacuum differential only. If you use the same IACV for both functions, you'd need to control it based on both temp and vacuum and set the valve based on either. Problem is... No other throttle body is going to have anything like the BCDD. The thought of moving it to the underside of the intake like Zed mentioned is interesting.

My original leakdown was like yours... Instant. I traced the majority to a bad check valve back at the fuel pump and a minor leak in one of the lines in the engine compartment. I replaced the check valve (story there that I'll get to hopefully soon) and repaired the leak in the line. That got me to an hour. Prior to that work, I was boiling the fuel in the rail on very hot shutdowns and creating a bubble that needed to pump out before pressure would build in the lines. That resulted in a long cranking time and embarrassment in the parking lot. Now that I've got the leakdown to an hour, I don't have that problem anymore because an hour is long enough to get me past the temperature crest on the hot shutdowns. So my hot restart issues are conquered, but I'm with ya on the junkyard cars... I've split the fuel line on countless cars in junkyards over the past year and most of them still have plenty of pressure. Some of these cars I know for a fact have been there for months. That tells me that it's certainly possible. And even though I don't really NEED it, since I know it's possible, I want it. So my FPR isn't anywhere near as bad as your aftermarket Aeromotive, but I know from clamping off the return line that my FPR is the next largest contributor to my leakdown. I get up to maybe ten hours of line pressure with the FPR blocked off. Beyond that, I'll probably go with a fuel pump prime as Lenny mentioned.

I lost track a long time ago the number of things I've opened up that were never intended to be worked on. I know that I spend waaaaaaaay more labor value than the parts are worth, but I just keep doing it anyway! :stupid: The best part is (as you now have in your case) a unit that is serviceable in the future. The time you invested this once will allow for simple and easy future repairs if necessary. Awesome!

That's awesome!

I wasn't trying to send a reminder. I was just trying to help out with the thread. One of the other forums is currently in a tailspin with noobs on one wing asking typical noob questions and longer standing members who have become bitter about answering such questions on the other wing. It isn't pretty. :sick: So you bailed on the AAR completely? I considered this as well but haven't pulled the trigger...

Thanks for that pic. That's a cool shot. The only one of these I have is the one on my car or I would have dissected one. Thanks for taking care of this. I've been working on a fuel presure leakdown issue with my 280 and after fixing a few things I've got it to the point now that it takes about an hour to drop to zero. I've traced most of the remaining leakdown to my FPR and I haven't decided if it's worth trying to make it any better. All I have to do is outlast the temp crest on a hot shutdown day and I think I already have that beat at an hour. Still bugs me though...

Yeah, it would suck to buy a whole regulator assembly just for that stupid washer. Think about it this way... If the only other option is to buy a whole new one, then there's nothing to lose by trying other ummm "creative" methods first, right? And you know where to find me if you want to send me the assy, right? No? You don't? Awwwww. :laugh:

Wait... So if I drink more, I'll forget stuff? Can I decide what goes and what stays? That would be very valuable.

Haha! Note that I've not performed this specific repair. Just looks possible from the pics. Proof is left to the attempter.....

Yup. With the 78 configuration, there will still be junk in the throttle body and intake manifold, but the AAR should be cleaner. Bunch of discussion about such things in this thread: http://www.classiczcars.com/forums/fuel-injection-s30/47309-valve-cover-hose-question.html

Whaaaa? "Permanent?" What is the meaning of this word "permanent"? Carbide burr on a Dremel. Drill and tap the remaining stub and use a small screw and a washer to retain a new wheel.

Making an adapter plate is something I could definitely handle. I'm mostly concerned with getting something that has the same or close to the same bore diameter and already has an air control mechanism installed. I've looked over the stock TB for a location to mount such a device, but I've come up blank. That BCDD takes up the entire bottom side. If it weren't for that... So there's a question for the collective... Every year from 70 all the way through 78 had some sort of vacuum controlled air bleed into the intake manifold. The carbureted years called it the throttle opener, and the FI years called it the BCDD. Did that continue into the ZX years? Did the ZX cars have a BCDD or similar device?

Cool. Sounds like good progress. 78 used alternator output AND oil pressure switch to control the fuel pump. Unless the key is in START, the alternator needs to be spinning AND there needs to be enough oil pressure to close the switch in the oil pressure sender unit. If those two conditions (spinning alternator and oil pressure exists), then the fuel pump relay should close and send power to the fuel pump. The fuel pump relay is located on the relay bracket up in the engine compartment near the battery. It has four wires going to it... Black, white/black, and two green/blue wires. If you separate the connector and the relay and then short the two green/blue wires together at the connector, the fuel pump should run. If shorting the two G/L together doesn't cause the fuel pump to run, then the problem is between that relay and the pump. If the pump runs, then your issue is upstream of that point and could be a bunch of things. Doesn't matter what position the key is in. You can do this test with the key in your pocket. Give that a try and see what happens?