eec564

I would also mention that while my ZX 2+2 is fine on the straights and mild curves at 100+, cross winds seem to hit it really hard. That could just be kinda worn out/ancient suspension parts, but if I can see the trees on the side of the road blowing around hard, I keep my foot out of it.

Anyone notise how old this thread is? I've hit 117 (gps checked, damn 85mph speedo) in my 82 2+2 N/A, felt stable, but I need far better brakes if I'm going to do that again. 205/70/14 speed rated tires.

Absolutely. That's something I also like about my Z. I can easily do all the work on it, and the various systems are seperate, so they're easy to troubleshoot and repair. Even the EFI system is independant of the rest of the car, and dosen't use fancy and obscure parts to run.

The megasquirt actually runs off of 5 volts, not the 12-14 you have in the car. The LM2937 converts anywhere from 26 volts to 5.5 volts directly to 5 volts, with very high accuacy. A capacitor in the input circuit effectively takes care of any spikes and the regulated 5 volts out is very stable. Since the megasquirt outputs switch a ground signal, and the ground is common for the 5 volt and 12 volt circuits, so a drifting 12 volt signal dosen't really matter. The only wires that a decent amount of current flows through on the megasquirt are the ground wires, for turning on the injectors and firing the coil. There is very little reliance on the 12 volt supply for anything, and it is very well protected. Plus, your car dosen't run off of exactly 12 volts. The battery has a full charge voltage of anywhere from 11.5 to 12.5 volts, which drops to 10-ish when cranking, and 14.5-ish once the alternator kicks in. It makes a bigger difference with car stereos, because they draw far more power, and use the 12 volts directly to run an amplifier which you can hear the output of. If you're getting spikes for more than a few milliseconds up to 50+ volts, there is something majorly wrong with your car, and you'd blow up any OEM engine computer. Megasquirt would be more likely to survive, as you'd blow out a power regulator and maybe a capacitor or two, and be able to relace them with over the counter parts.

So, I finally got a chance to check under my hood right after driving fairly hard. Up until now, everywhere I went had a bunch of slow city street traffic that let my engine cool off. My manifold still has a slight glow to it, and my engine temp is now back where it was when I bought the car. In the mid-40s weather we had the other night here, I never did get the car fully warmed up to get anything decent out of the heater when I drove my girlfriend home. I also checked my spark plugs, and they have a slight dark brown spot on one side of the ceramic (after 300 miles on the new set) and the electrode (not the tip, but the part you move when you gap them) is black, but with a slightly white coating (that doesn't rub off by hand) on the top. That is, with the top as seen with you holding the plug upside down, looking into it, the side that sticks farthest into the engine. I can get my hands on a digital camera and post a picture if you all think it would be helpful. Thanks again for all the advice.

Here's what's new on the car: Plugs (few hundred miles), cap, rotor, O2 sensor (those have 14K miles on them, in 8 months). I've checked the resistance of the CHT and IAT (at the ECU), fuel pressure is 36, timing is at 10.5 degrees. The engine runs FAR better with a bit more advance on it. I know my cat isn't clogged, as I've recently had it off the car. In fact, it has a hole burned through it. I have no idea how it passed smog like that, but it did. I've also scoped my ignition coil and the output looks good, and ran a DAC in the car with me tapped into my O2 sensor wire, and it cycles between rich and lean very quickly, exactly within the range it should. I've also had the exaust off the car for some welding, and I checked it for obstructions, but there are none. I'm still fairly stumped. After driving it back from davis, and it starting to run better, things are marginally okay. It still runs hot (starts to overheat, but I don't let it) if I run at over 90mph for extended periods of time, or make a 5 mile run at WOT. I'll check back in once I get a chance to pull my new plugs and see what they look like.

Well, something changed. Sunday, while driving back from Davis to the bay area, I felt some change in the way the car ran. The temp gauge still stands straight up while cruising, but I can cruise up to 85 without overheating. Much more than that and it starts to creep back up. My manifold still glows when I'm driving hard. I've no clue what or why. Anyone ever see something like this? Comes on and changes randomly with no changes made to the engine at all.

So what are the side-splitting names of your other cars?

Where is that yard? I need a new transmission.

I'm still thinking. There has to be something wrong with either the romulator or the ECU that's been worked on.

I checked the AFR on a smog machine, and the setting the AFM is on now is where it passed smog easily. The CO was high when I first bought it, before I leaned it out. The car ran great and then all of a suddon started doing this, with no changed made within a month or more.

Long story, just because I'm trying to provide detail and history. The current tune on the car is: Base timing: 12 degrees. AFM leaned out about three teeth. O2 sensor dissconnected (last week, all it did was improve MPG by 2). Aux air regulator blocked off as it made noise. It passed its last smog test with average (for the vehicle catagory) NOx at 15 and 25, and very low CO, took a total of 1min, 30sec to pass on the dyno, for both speeds, I timed my ignition to 10 degrees for the test. Otherwise stock engine. New cap and rotor (napa). 14 city, 19-20 highway MPG, and I drive not-so-gently. The story: A little bit ago, I notised my Z (82 N/A, 5psd, basically stock) was running hot. The temp gauge would creep up to the center while cruising at 70, and even higher while cruising at 80. If I floored it and cruised at 110+, the car would start to overheat. Shortly thereafter I notised my exaust maifold had a cherry red glow to it after I drove it hard. I figured this out when I popped the hood at a gas station to check my oil while I was filling up. Not good, and high EGTs would explain why the car was running hot. Before this started, my CHT would stay down to where my thermostat would start to close. If I slow down to 55, my CHT drops back to just below half way on the temp gauge driving in 85 degree weather. I thought that the problem could have been related to some exaust work I had done to the car. Upon examining the work, I found my 2-1 collector was partially restricted. I got myself a nice (read: cheap) little welder and took last weekend to fabricate myself a new piece. Didn't help one bit, and while I had the exaust off my car, I notised I've managed to melt my catalytic converter. Well, just the inside. Luckily, I don't have to pass smog until december of 08. I've pulled my plugs, and they show signs of running rich (before I changed my AFM, I'm presuming) and signs of running lean, which look more recent. I'm going to pick up another set of NGKs when I have a short break from school and clean my room for spare change. So anyone have any advice, questions, or want to point out something stupid I'm doing or haven't done?

Try unhooking the romulator, and taking your engine back to the original injectors and chip. After making sure the engine is running perfectly, plug the romulator back in, with an un-edited rom, exactly the same as what runs fine in your car, on the original chip. If it dosen't run, then your romulator has problems. Next, try editing your injector sizing by around half a pound or something, still using the stock injectors. It won't run well, but shouldn't hurt anything, and it will verify that the editing is doing what it should. Verify the engine runs as your configured it. Then set everything back to stock, with the romulator. If everything has worked so far, now you are ready to swap injectors, and edit the rom. Troubleshooting 101 - only change one thing at a time and test at each step. You'll figure out what works, and exactly what gets you caught up. Hope this helps. Edit: I just read the post you linked to. Tips to check your soldering job: Verify no two pins next to eachother are shorted together. Use a quality meter, I have a 40$ Metex that has proven to be EXTREMELY accurate, reliable, and high quality. Next, test to make sure that each pin on the socket connects to where it should. Using good light, visually trace the circuit paths on the circuit board, and test to make certain the pins connect to the other points on the board they should. If they don't, solder a small jumper wire to make the connection. Be very careful not to solder a wire where it shouldn't be, and always check to make sure you didn't make any connections you didn't mean to. If you need help soldering or seeing small paths on the circuit board, ask for help. Soldering is difficult and there is an art to it.

That's an interesting place to mount injectors on that honda manifold. A design like that would have physics (kinda) similar to tripple TBs on our Zs. For our single TBs, mounted at one end of the intake, I think Paul's #1 point is the one that qualifies. Another point I would add is this: 3) Engine Control An oversized TB resulting in full power applied at 50% throttle can make an engine overly sensitive. Properly sized intake components will allow better modulation of engine power, and far better vehicle control. Exception: I've thought about a design where the engine stays at 17:1 AFR until the manifold is at 0" Hg, around 50% throttle, then increases the fuel to 12:1 afr to increase power. One day I may get around to calculating if this could actually save some fuel even while cruising under a decently high load, such as gentle acceleration going up hill on the highway.

In terms of high gas velocity, our small runners on the intake would keep things moving fast. At that point, port missmatch from the intake to the head could be a bigger problem. The exaust on my 82 N/A isn't all that bad, until you hit the cat. It's 3-2-1, then 2" OD piping, with a a crush bent (not good, soon to be mandrel) section leading under the car and into the cat. Everything after that should have less restriction than the cat, so it won't make much a huge difference. I figure 2" OD exaust piping would result in fairly high exaust velocities, and help conduct heat away from the engine.

I think this would be just perfect. http://forums.hybridz.org/showthread.php?t=117607

1. People think bigger is better. 2. People think their engines make more power. It's just that they reach full throttle (as far as the motor and intake are concerned) when barely touching the pedal. They just neglect to notise that the second 50% of their pedal travel dosen't do anything any more. 3. People do things that don't make sense. I've seen someone take their backseat out to lower the weight of their car and make them go faster. They also had a rather large speaker box with 2 15"s in their trunk.

That Z brings a tear to my eye. That is exactly the way the ZX's engine bay should have been from the factory. Even the A/C and power steering don't clutter the engine at all. Truely a work of art.

My dream would be a gas tank that never needs to be filled. But in lew of that, I'd settle for rear window louvers that will fit the ZX 2+2 and clear the rear wiper.

I've always wanted a 1980s Mercedes 300SD with a big block in it. A VERY big block. Nice, big cruising car, 126 body, very comfortable. Largest engine they came with was 5 liters, and something mean under the hood with that "Turbo Diesel" badge on the back would be great. I'll see if I can dig up pictures of my old 83 300SD.

I'd say small engine, light car, and a very good tune will give you the best milage. Even in a junk car, a good tune makes a huge difference. Here are a few of the more fuel stingy cars I have in my database. EPA Estimated MPG, combined driving. Here's a link to a text file I generated with the EPA data in it, I'll leave it up until someone yells at me for using the work webserver to host personal data again. heh http://www.defyconvention.net/computing/eec/milage.txt ROCKET 1992 45.2 CHEVROLET SPRINT 1987 44.4 GEO METRO 1992 44.4 HONDA CIVIC 1986 41.2 GEO METRO LSI 1995 39.7 FORD FESTIVA GL 1992 39.2 YUGO GV 1987 39.0 SUZUKI SWIFT GTI 1989 38.8 MITSUBISHI MIRAGE 1986 38.7 SUBARU JUSTY GL 1992 38.2 HONDA CIVIC CX 1992 37.8 TOYOTA TERCEL 1992 37.0 TOYOTA TERCEL 1986 36.6 SUBARU HATCHBACK 1986 35.8

That would it it all right. Changing the fuel filter can't hurt either, it's often overlooked. When I got my Z, the air filter had a DENT in it. The metal on one side was pushed way down. The housing was fine, so who knows how it happened. I just undented it and drove it that way until the local nissan dealership sent me a flyer with a coupon in it for 7.99 for any air filter. I was really happy to have the coupon when I ordered it at the parts counter, and the guy behind the desk couldn't figure out why, talking about how that's not much of a discount, until he saw the normal price - $33 and something cents. All he said was "Wow, you made out like a bandit."

Ahh okay, very good to know. Thank you.

Ahh, now you sound like the rest (most, anyways) of us. I'm certainly in that boat.

That's a beautiful car fit for a queen! I've always loved that color, and to see it on a 300ZX makes me happy. Especially without a spoiler and with stock wheels. How well was the re-spray done? It looks excelent from the pictures, with clean lines in the engine bay and no bubbles around the door sills. My vote is drive it as-is and keep it looking clean and smooth.