'76 280Z Question on dist/manifold vacuum, dist timing, fuel pressure, brake booster

[Jennys280Z]

I went with whatever cap they gave me at the auto parts store. I don't know the brand. Seemd to work fine. Good fit.

I know my injectors are Standard. There were a few rough spots on the molded electrical connector that I trimmed up, but otherwise everything seemed fine. Still working great. (I was able to get my car out a bit today, if only for a short errand.)

I think 16.5 might be "good enough," but I'd want to be on the rich side of "good enough," rather than the lean side. I think after a while you can end up pitting your cylinder head and cooking your valves with a lean mix.

I agree with Eric, BTW: The valves aren't scary. They're rather easy, and they're actually fun -- way easier than stuff you've already been doing. Enjoy!

Wow that makes me feel better already. :classic:

I think the 3-tooth AFM adjustment has made a difference and set my mixture right. I should be ~0.5 teeth rich right now. I can say for sure that it's running better now than it was with full enrichment on the TPS. Anyhoo on my last test drive, it smelled a bit like gasoline when I drove it but I like that smell. And no grey/black smoke when idling like w/ the TPS jumping.

Some obervations here: At full enrichment my car was idling at 1100RPM and I was getting over 16inHg. With the 3-tooth AFM adjustment I am getting 900RPM which is up from 800RPM before.

I wonder if the higher idle (1100RPM) suggests that I need to be that rich?

I need to see what my vacuum is at this point anyway (I was hoping for 16in!) so I'm making some little hoses for my T-connector at the FPR like cozye said.

Edited January 21, 2011 by Jennys280Z

[Jennys280Z]

I remember reading about that distributor problem on another thread Cozye, and I wonder if the cheaper dist. cap you bought was a defective fit? Or in other words, not "compatible" enough? I wouldn't blame yourself for that, it might not be as much your fault for installing wrong as you think. It makes me want to stay clear of some of the cheap/obscure brands and spend a few dollars more for the best. A 90-day warranty is out of the question and 12-month warranty isn't good either. My rotor is 15 years old.

In part, it's reading stuff like what happened to cozye's distributor cap that makes me scared. Sometimes I'm surprised my car even starts at all after I work on it. But I've had good fortune with everything so far thanks to y'all.

I want one specifically designed to precisely duplicate the OE cap and rotor. Should I buy a Nissan brand cap/rotor ideally? I wonder if Nissan dealers carry these parts? I would think not, due to the many aftermarket choices.

Nissan

Beck Arnley

Bosch

Standard

Daiichi

YEC

And the MSA brand? Wish I knew what brand they are! That kinda puts me off with their website btw, that they don't communicate to people what brands of stuff they're selling. Like with NAPA. Stop telling me it's a NAPA brand thermostat and tell me the truth (that it's a Stant).

[cozye]

I don't remember what brand it was from MSA. The thing about MSA is that they usually wont sell stuff that sucks. All of the parts I've purchased from them have been either Nissan, or high quality japanese replacements. Since they know Z's well and cater to the Z community, I believe they will only offer good quality stuff.

I wouldn't put too much thought into the brand, just buy something. Don't over think it. It's just 10 or 15$

The reason why your idle moves around when adjusting how much fuel you give it, is that the air fuel mixture is off. If it's running lean, and you ad more fuel the idle will come up. If it's running rich and you add more fuel, the idle will come down. Basing your tuning off the idle mixture is not a good idea though, it's much more accurate to base the tune off the way it runs at speed. You are taking in much more air and fuel at speed. At idle there are other factors that do not relate to how the car runs at higher RPM, such as the idle mixture screw, small vacuum leak, dirty air filter, "idle enrichment" algorithm on ECU, etc.. So I guess I'm saying it's ok to kind of try and get it to idle good, get good vacuum etc.. while at idle, but it could be that you may end up with it a little rich at idle but it may run perfectly when driving. That's kind of the nature of the rudementry fuel injetion on this car. It's just not tuneable over a wide range. You kind of have to aim for a good compromise in some cases if you are going to fool the ECU with water temp circuit adjustments or AFM flap adjustments.

I really think you need to throw the tune up parts on, and do the valve adjustment. After that, put the AFM back to stock settings and put some resistance inline with the water temp sensor.

[FastWoman]

^^^ I agree with Eric.

Remember that just because you smell some gas out the exhaust doesn't mean the car is running rich. I don't know how old you are or whether you would remember cars that didn't have catalytic converters. Properly operating cats make our exhaust smell pretty tame. Without them, the exhaust will smell a bit gassy, even when everything is running perfectly -- with a perfect mixture. Go to any antique car show, and you'll smell a lot of stinky exhaust.

[Jennys280Z]

I don't remember what brand it was from MSA. The thing about MSA is that they usually wont sell stuff that sucks. All of the parts I've purchased from them have been either Nissan, or high quality japanese replacements. Since they know Z's well and cater to the Z community, I believe they will only offer good quality stuff.

I wouldn't put too much thought into the brand, just buy something. Don't over think it. It's just 10 or 15$

The reason why your idle moves around when adjusting how much fuel you give it, is that the air fuel mixture is off. If it's running lean, and you ad more fuel the idle will come up. If it's running rich and you add more fuel, the idle will come down. Basing your tuning off the idle mixture is not a good idea though, it's much more accurate to base the tune off the way it runs at speed. You are taking in much more air and fuel at speed. At idle there are other factors that do not relate to how the car runs at higher RPM, such as the idle mixture screw, small vacuum leak, dirty air filter, "idle enrichment" algorithm on ECU, etc.. So I guess I'm saying it's ok to kind of try and get it to idle good, get good vacuum etc.. while at idle, but it could be that you may end up with it a little rich at idle but it may run perfectly when driving. That's kind of the nature of the rudementry fuel injetion on this car. It's just not tuneable over a wide range. You kind of have to aim for a good compromise in some cases if you are going to fool the ECU with water temp circuit adjustments or AFM flap adjustments.

I really think you need to throw the tune up parts on, and do the valve adjustment. After that, put the AFM back to stock settings and put some resistance inline with the water temp sensor.

Well our consensus was that I was running too lean, a little bit.

My car was running too rich with the TPS jumped to full enrichment. But my idle speed was 1100RPM! (up from 800RPM) I wasn't impressed by the performance while driving it like that though and the grey smoke was bad. But you're suggesting that the ideal mixture results in maximum idle speed. So I could have seen 1200RPM with a slightly leaner mix than the full enrichment jumper? In any case I don't want to doctor the idle up too much when driving performance is more important.

My AFM is at the stock setting now. Maybe 0.5 teeth CCW. I have an idle speed readout with my digital timing light so I'll move the AFM flap with my finger again and study the results carefully.

I just put new plugs in today. About 1/2 - 2/3 of a turn past finger-tight with a wrench is all the spark plugs take to tighten. I haven't run the motor yet though. It's cold till Sunday but good driving weather then.

I was going to retard the static advance back to 10 or 11 with the engine off but it is so sensitive to just a little bit of rotation it's best if I just wait till the motor is running and do it with the light.

:bulb:

Edited January 22, 2011 by Jennys280Z

[Jennys280Z]

^^^ I agree with Eric.

Remember that just because you smell some gas out the exhaust doesn't mean the car is running rich. I don't know how old you are or whether you would remember cars that didn't have catalytic converters. Properly operating cats make our exhaust smell pretty tame. Without them, the exhaust will smell a bit gassy, even when everything is running perfectly -- with a perfect mixture. Go to any antique car show, and you'll smell a lot of stinky exhaust.

But when a car smells gassy it smells good hehe

[Jennys280Z]

Really frustrated now. Feel like giving up. I won't give up but I'm feeling like it.

Vacuum is no better than it was....about 15in, if that.

Cold idle is the same as ever. It was almost 50 here this afternoon and I had the opp. to drive the car but I"m just too bummed out. I tightened the AFM boots a few twists of the screwdriver. I pulled the vacuum hose off my Fuel Pressure Regulator. It was dry. Even more convincing, it didn't smell like fuel. Put the hose back on. Another possible culprit eliminated.

I called Motorsport Auto this morning and talked to a customer service rep who told me that their caps and rotors are a Japanese import called Nippon (sp?)

RockAuto has very good prices on Beck Arnley stuff so I'm going to place an order with them for the dist. parts including all my clutch hydraulics.

I verified that my distributor static advance was indeed turned ALL the way over. So 14 (if that) degrees of advance is all that I can get from this distributor. Why is that? Why do others get 17-18 degrees and will my new distributor have this problem?

And I also noticed this. I loosened the bolt on the distributor and turned it back to what I hoped would be about 10 degrees advance. I left the bolt loose on the distributor, walked around the car and checked the timing light and it was sitting on about 10 degrees BTDC. BUT my spark in cylinder #1 became intermittent. (I have observed spark to completely fail in cylinder #1 before cleaning contacts; since then I've replaced plug wires and now, plugs) So the lesson here is either 1) Never leave your distributor loose when checking timing; or 2) Something else is going on here and I wanted to tell the pros here about it. xx

I was going to throw in a fuel pressure regulator and ignition coil because I'm really getting frustrated and ready to start throwing parts at it. I'll do some DD later on how to test my iggie coil.

I just went through all of the repair history of the original owner of my car. He even included quote sheets and the bill of sale when he bought it new in 1976. This was/is my first car when I first got my driver's license. It had about 84,000 miles on it when I got it. 141,000 miles now. I noticed he replaced the master cylinder in 1988. It was still working in 2000 (going bad but hanging on), but failed during the storage period. It was stored for about 9 years from 2000-2008. It was no longer driven in 2000 and garaged for two reasons. One it developed the classic leak under the firewall to the floorpan every time it rained. And two one of the little "heater" hoses on the top of the engine spaghetti developed a leak and started spraying antifreeze up in the air. I knew nothing about cars at the time and was scared. Didn't want to lose the car and couldn't afford to fix it at the time, so into the garage it went.

In 2008 I dropped the tank, had it cleaned, blew out my fuel lines with an air compressor, changed the fuel filter and a few suspect looking pieces of fuel hose in front of the fuel pump and before the fuel rail. Because I couldn't loosen the brake fittings on a slave cylinder I had it towed to a mechanic. I was really upset when I saw one of their mechanics put a vice grip to it and with the flick of his wrist loosen one of the fittings. Something I couldn't do at all. The mechanic at the time told me I did a great job on the fuel system reconditioning based on how well it started up.

So I replaced the master cylinder and both slave cylinders in 2009 however the booster was already about to fail. I had good tight brakes for a couple of weeks (a week) when the new hydraulic parts were too much for the old booster to handle. Coincidentally my car went from running great to running like hell after this "whooshing" leak in the booster became obvious. JUST a coincidence, right?

Another observation, when I drove the car around (after adjusting my AFM and brand new spark plugs) with the timing set back to 10degBTDC, I got some small backfires out the tailpipe when I was driving around.

I don't think my car's problem is fuel/air mixture related because it still "gargled" like this on the street even with TPS at full enrichment belching out thick grey smoke (though the idle and manifold vacuum were higher). The pick-up of the car was no better then than it is now either.

It would seem that the ignition coil on this car is 35 years old.

As well as the alternator. But that's something I can't even replace myself because an unknown mechanic in years past broke a bolt in half that secures the alternator to the front bracket and the tip of the bolt is still inside of the hole. I would need someone to tap it out or dye it out or whatever the right word is...I have zero experience with an electric drill and would need to apprentice with someone before doing that myself. In some cases it's best I know my own limits and humble myself. I'm not suggesting that I'm considering replacing the alternator too...just sharing the unfortunate fact that I couldn't replace it even if I wanted to.

The distributor cap I have on the car right now is a Nissan brand. Can't get those anymore. I hope the Beck Arnley parts are okay. 12 month warranty same as Bosch but I'm more concerned about materials and air gap precision.

Going to adjust my valves soon but I don't think that has anything to do with my problem either for a couple of reasons. 1)They were adjusted 16,000 miles ago according to my repair records (and yes I know I should do it anyway)...and 2) I don't think that a valve mal-adjustment is something that happens all at once. Something...whatever it is...that is wrong with my car happened to it between drives - almost overnight.

In the photos of my spark plugs, you guys can see the extra-long projected tip of these "V-Power" plugs, vs the projected tips of the regular projected NGKs. The shape of the tip has a carved-V shape on it so it doesn't look flat and shouldn't be confused with thinking that there is worn metal on the center electrodes.

The pictures are for all six cylinders, in numerical order from #1-6. I took two photos of cylinder #6 for some reason, hence the 7th unintended photo.

And a theoretical question...I wonder how much advance these projected tips deliver. That is, what is the mathematical translation between length of the tip and degrees of advance. Driving around at 10degBTDC with these new plugs was driving it around more retarded than before, hence perhaps, the tailpipe backfiring that I never got with the old plugs.

Edited January 25, 2011 by Jennys280Z

[Zed Head]

Maybe you should just take it out and beat on it! You'll get your frustrations out, have some fun,and from what I've read and my experience with my own car, it will run better when you get done. Not joking! Your vacuum reading might go up also if you have gunked up piston rings.

You might actually be losing your timing light signal to a different wire or just poor "induction" if you are using one of the clamp-on inductive trigger timing lights. Next time it does that, move the clamp to a new spot, away from the other wires and close to the plug. I've seen the same thing and it wasn't the engine, it was the clamp position.

There is a second adjustment on the bottom of the distributor that would give you more "twist" on the distributor but I wouldn't worry about it right now. Are you still running without vacuum advance?

I see an obsession starting with a number on a gauge (vacuum). How does the car run and drive? That should be your focus (in my opinion). My car was sitting at 16 inches for quite a while but I just lived with it and focused on other things and drove it around (with a few hard "tuning runs" thrown in). Months later, I checked the vacuum, even though I had stopped caring about it, and it was at 20 inches.

There is no relation between spark plug tip shape or length, and ignition timing. It only affects how hot the tip runs. They are specified to run just hot enough to stay carbon free, but not so hot that they cause pre-ignition. Your car is stock so the stock plugs should work fine.

Your thread is looking like you have many objectives in mind - getting a high vacuum reading, getting rid of the exhaust popping, removing the gargling sound, etc.

If it was my car, I would fix my vacuum advance (because without it your engine will still be a little sluggish at part-throttle operation and you suggested that you had poor pickup), set the timing between 10 and 14, and drive it around for while. Take it out, run it through the gears hard a few times, get it nice and warm. Then re-evaluate what single thing you want to improve next and focus on that.

[cozye]

you can rule out running lean, because looking at those plugs that's not your issue.

I definitely would not put a coil in the car. I really doubt that your coil is bad.

Not sure on your distributor issues, if the shaft has play, and your vacuum advance is still broken you may want to just replace that.

I can tell you that I dumped the pickup coil style ignition and went with a crane setup that uses an optical trigger. It is much more precise and phased properly, it did smooth the car out a little and now my distributor has much more "room" to advance since 10' is right about where the center mark is. I don't think this will help you, and it's kind of a pain to install too. I just mentioned it basically because my distributor would max out around 15' too prior to replacing the ignition.

fix the vacuum advance and like zed head says, go drive it some. You still need to do the valve adjust if you have put that many miles on it and never done it. I think the service interval for valves is like 30,000.

Another thing I experienced, I had a small exhaust leak somewhere that caused a little gargling at the tail pipe too, although it didn't really affect how it ran. More reason for you go go drive it some.

[Jennys280Z]

you can rule out running lean, because looking at those plugs that's not your issue.

I definitely would not put a coil in the car. I really doubt that your coil is bad.

Not sure on your distributor issues, if the shaft has play, and your vacuum advance is still broken you may want to just replace that.

I can tell you that I dumped the pickup coil style ignition and went with a crane setup that uses an optical trigger. It is much more precise and phased properly, it did smooth the car out a little and now my distributor has much more "room" to advance since 10' is right about where the center mark is. I don't think this will help you, and it's kind of a pain to install too. I just mentioned it basically because my distributor would max out around 15' too prior to replacing the ignition.

fix the vacuum advance and like zed head says, go drive it some. You still need to do the valve adjust if you have put that many miles on it and never done it. I think the service interval for valves is like 30,000.

Another thing I experienced, I had a small exhaust leak somewhere that caused a little gargling at the tail pipe too, although it didn't really affect how it ran. More reason for you go go drive it some.

Noooooo...Valves were done 16,000 miles ago according to my repairs paperwork.

Someone already told me to take it out on the highway. A 10-mile jog at 60mph and stretch its legs for the first time since ummm...Bill Clinton was President So this makes three of you saying that.

Hey oh yeah, RockAuto has a thing I can buy where I pay $108 plus $5.00 handling fee and I take my dist off and send it to them and A1 Cardone will rebuild it for me. Another option to consider. I've also considered just buying a used one on Ebay for $20-30 and practicing taking it apart, cleaning/rebuilding it.

I haven't ran vacuum advance on this car since maybe ever. So I'm just comparing how it ran without it before (at all throttles) to how it's running now. It's capable of running awesome without it so it keeps me motivated knowing its potential.

But driving it is on the agenda....hey something really fun. xxx

Thanks for helping me

Edited January 25, 2011 by Jennys280Z

[Jennys280Z]

Maybe you should just take it out and beat on it! You'll get your frustrations out, have some fun,and from what I've read and my experience with my own car, it will run better when you get done. Not joking! Your vacuum reading might go up also if you have gunked up piston rings.

You might actually be losing your timing light signal to a different wire or just poor "induction" if you are using one of the clamp-on inductive trigger timing lights. Next time it does that, move the clamp to a new spot, away from the other wires and close to the plug. I've seen the same thing and it wasn't the engine, it was the clamp position.

There is a second adjustment on the bottom of the distributor that would give you more "twist" on the distributor but I wouldn't worry about it right now. Are you still running without vacuum advance?

I see an obsession starting with a number on a gauge (vacuum). How does the car run and drive? That should be your focus (in my opinion). My car was sitting at 16 inches for quite a while but I just lived with it and focused on other things and drove it around (with a few hard "tuning runs" thrown in). Months later, I checked the vacuum, even though I had stopped caring about it, and it was at 20 inches.

There is no relation between spark plug tip shape or length, and ignition timing. It only affects how hot the tip runs. They are specified to run just hot enough to stay carbon free, but not so hot that they cause pre-ignition. Your car is stock so the stock plugs should work fine.

Your thread is looking like you have many objectives in mind - getting a high vacuum reading, getting rid of the exhaust popping, removing the gargling sound, etc.

If it was my car, I would fix my vacuum advance (because without it your engine will still be a little sluggish at part-throttle operation and you suggested that you had poor pickup), set the timing between 10 and 14, and drive it around for while. Take it out, run it through the gears hard a few times, get it nice and warm. Then re-evaluate what single thing you want to improve next and focus on that.

Wow excellent advice Zed Head. I will watch out for the induction which is the clamp-on kind (I had it clamped on the #1 wire about six inches from the plug. It was kinda touching my fuel gauge installed near there.

I'm focused on vacuum because I like the feedback I get from what I've done to the car so far. A barometer of sorts, but I see what you mean, I am excessively focused on it. Also it was the way the car ran (which is my true focus!) which brought me to the vacuum gauge.

Oh yeah, and I'm timed right at 12deg where I'll leave it at. Rotor and Cap will be on the way tomorrow.

Edited January 25, 2011 by Jennys280Z

[Jennys280Z]

Cozye, it's big news that I'm not running lean....then why the 17in of vacuum and 1100RPM idle at full enrichment?

I guess this invokes Zed Head's larger point, which is, I was obsessing over a vacuum gauge

Edited January 25, 2011 by Jennys280Z