the_tool_man

I picked up a gasket and made a block off plate for the EGR. I used a borrowed stud remover to try getting the studs out. But they wouldn't budge. Rather than break them off, I decided to just use the old EGR spacer on top of the block off plate. No change in running, vacuum reading, etc. I found the PCV hose under the intake. But I'll need double jointed elbows to get to the thing. I'll go at it from below on my next foray. But I ran out of time tonight. Sent from my XT1254 using Classic Zcar Club mobile

My methodology at this point is to take the list of possible causes provided by the contributors to this thread, and eliminate them, starting with easiest first. Vacuum leaks seem to be most likely, and with the exception of an intake manifold gasket leak, would seem to be easiest to check. Then I'll test the CSV. Next is a compression test. Then valve lash, timing chain, etc. I chose measuring vacuum at the booster line specifically to isolate possible diaphragm failure. I also tested the check valve while I was there (it's working). Engine RPM was at idle. But I couldn't see the tach while I was doing it. I'd guess 750 RPM. When I revved it, vacuum increased as expected. But I didn't attempt to correlate vacuum with RPM. I didn't mention it because it didn't seem important. But the EGR valve is really dirty. The pintle moves freely under finger pressure. But I can't tell if it seals when closed. I can't really test it until I have a block-off plate made to cover the openings in the intake. Then I can hook it up and visually test it if I want to. If the pintle moves with vacuum, I could attempt to clean it. But the plate will eliminate it as a cause for now. I don't have anything else to report. Between work, family and other obligations (including the death of a friend), I've only had about 30 minutes with the car in the last several weeks. I should get more testing done this week. Plans today include borrowing a stud extractor from a friend, picking up an EGR valve gasket. If time allows this evening, I'll make a block-off plate.

I'm giving serious consideration to stripping down the entire intake and getting rid of all the emissions junk, if for no other reason than to eliminate a bunch of potential problems. But that's for another thread.

Quick update. I used the vacuum line from the brake booster to check idle vacuum. It's below 5" at idle. So I have a big vacuum leak. I've checked all of the hoses for obvious leaks. So I decided that before I start replacing all that mess, I'd pull the EGR valve. It was a welcome relief to break the nuts loose without breaking off the studs. A first, I think! My EGR has a thick cast spacer, necessitating long studs. They're stuck, of course. I plan to pick up a new EGR gasket and make a block-off plate. If this isn't it, I'll just replace all of the vacuum hoses and go from there. Sent from my XT1254 using Classic Zcar Club mobile

I started a new thread for the engine diagnosis. I don't plan to update this one any more. http://www.classiczcars.com/index.php?/topic/56998-Engine-rough-running---at-wits-end EDIT: For the sake of closure, the engine runs now. Turns out I didn't properly seat the #5 fuel injector seal when I replaced it. This caused a huge vacuum leak which was causing most of the issues. See above linked thread for details.

True. I plan to make a block off plate to eliminate that as a cause. Sent from my XT1254 using Classic Zcar Club mobile

I didn't have much time to work on the car tonight. But I had a few minutes to poke around. The EGR/BPT recall has been done on my car (see photo of sticker). I used a mirror and looked under the intake. I didn't see any holes; not even any surface corrosion. I picked up a remote starting switch, too. It'll come in handy for compression testing. Sent from my XT1254 using Classic Zcar Club mobile

What's a BPT tube? Found pics of what you're talking about in your reply to G3BOWSKY's thread on popping noise. Thanks! Sent from my QTAQZ3 using Classic Zcar Club mobile

Not yet. They've probably got about ten minutes of running on them since I installed them. Sent from my XT1254 using Classic Zcar Club mobile

Used from a running car. Sent from my XT1254 using Classic Zcar Club mobile

Early on, the CTS circuit read super high resistance. It may as well have been unplugged. When I corrected it (new sensor and cleaned bullet connectors), it didn't noticably change anything. But I was having fuel delivery issues at the time (bad AFM contacts), so that might have masked the issue. It's something to try. Sent from my XT1254 using Classic Zcar Club mobile

No. That sounds like fun. Sent from my XT1254 using Classic Zcar Club mobile

It's popping in the intake, not out the tailpipe. I double and triple checked the firing order. And when I replaced the plug wires I did them one at a time. Sent from my XT1254 using Classic Zcar Club mobile

I'll swap to aftermarket EFI before I'll swap to carbs, . Sent from my XT1254 using Classic Zcar Club mobile

I adjusted the idle screw. But it didn't really help. It backfires every time I try to rev it, cold or hot. I haven't replaced the CSV or unplugged it. I'm wondering if that's leaking all the time, causing a rich condition that worsens as the engine warms up? If that's the case, I'd need to disconnect it from the fuel line, not unplug it (or maybe that's what you meant). Sent from my XT1254 using Classic Zcar Club mobile

Double post.

Hi all: 1977 280z. Stock with 90k miles. Bought a year ago not running (I know, stupid). It would start, but die immediately. The long version is detailed in my intro thread if you want to read it. http://www.classiczcars.com/index.php?/topic/53262-New-owner-of-'77-280z-from-Upstate-SC The short version. Replaced fuel filter and lines, fuel pressure regulator, injectors, AFM, coil, plugs, plug wires and coolant temp sensor. Cleaned and verified coolant temp circuit function at ECU. Air gap between reluctor and pickup set to 0.012. Timing set to 10 degrees BTDC. All of this was done in response to various symptoms, such as low fuel pressure, misfire, etc. over the past year of off-and-on repairs interrupted by health problems. Now it will idle roughly when cold. If I rev the engine it backfires and then revs okay. But it still runs roughly. Once the engine starts to warm up, it won't stay idling more than 15 seconds or so before sputtering to a stop. New plugs don't read yet. Old ones were sooty, even when fuel pressure was low. I don't know what to do next. Sent from my QTAQZ3 using Classic Zcar Club mobile

Air gap was bigger than spec. Adjusted to 0.012. Spark is consistent at all speeds. Adjusted timing to 10 degrees BTDC. Still won't run smoothly. Now the engine backfires when I rev it off idle. It'll idle roughly when cold. But once it starts to warm up it won't idle for more than about 15 seconds before sputtering to a stop. I think I'll start a new thread. This one's a year old. And almost no one is reading it any more. Sent from my QTAQZ3 using Classic Zcar Club mobile

If you visit the Arduino discussion forum, you can get an idea if the capabilities and issues people are dealing with. Also you can find lots of project ideas on instructables.com. Sent from my XT1254 using Classic Zcar Club mobile

Good point. I haven't delved that deeply into it. But Arduino has several different versions, with different form factors and processors. I can understand having reservations about using it in such a critical system in a car. My other concern would be whether or not the Arduino platform is physically rugged enough to withstand vibration and environmental harshness found in a car under daily use. I recall there is a ruggedized version. But I haven't done much research, to be honest. One use that would be ideal for the architecture, and not "operationally critical" would be to add modern features to an older car. For example, you could use an RF remote control to lock/unlock the doors, or have the reverse lamps come on as courtesy lamps when you exit, etc.. The possibilities are endless. And you can buy the controllers for less than $30. Relay boards are under $15.

I've used both Basic Stamp and Arduino. I've found the Arduino to be quite useful for home automation projects. The free development environment is great, with decent debugging capabilities. I've built a stop light controller and a hot water recirculation pump controller with them. Arduino has tons of aftermarket support for relays, communication modules, wireless technology, motor control and networking. People have used Arduinos to build three-axis CNC machine controllers. I've wondered if it could be used as an open source EFI controller. I'd love for someone to give it a shot. Sent from my XT1254 using Classic Zcar Club mobile

Yes. I'll replace those. I'll also check the ballast resistor (shoulda checked it while I had the coil out). Last resort, I'll test the ignition module. But I don't think that would be intermittent. While I have the cap and button out of the way, I suppose I should check the air gap in the distributor. Any idea what the side play of the distributor shaft should be? I didn't see it in the FSM or the Haynes manual I have. What if the PO hooked the coil primary up backwards? When I changed out the coil, I hooked it up the same way the old one was. The FSM doesn't show the polarity of the primary relative to the wire colors. So I couldn't verify it easily. Another possibility. It could be that my 30 year old, cheap, inductive timing light is malfunctioning, and I'm chasing a problem that doesn't exist. But it sure "feels like" a misfire. And the timing light definitely shows the spark timing being quite irregular.

New coil, plugs and wires. Still misfiring. I'm at a loss. Sent from my XT1254 using Classic Zcar Club mobile

Why not platinum? I picked up my stuff today, and that's all they (O'reilly) had.

Great article, especially the photos. Thanks for sharing. Sent from my QTAQZ3 using Classic Zcar Club mobile