This is going to be long, but I know you guys/gals like data, so I am trying to preempt most questions. :cool:Well this winter I have been busy. I removed fuel sending unit, which showed me I had 1/2" of rust in laying some places on bottom of gas tank. And the fuel filter was filled up with a lot of rust too (I cut it open of course -and most if it got stuck right to a magnet I put near the pile of rust). So I figured out how to remove the tank (it got cleaned and restored by a pro who does that kind of stuff - washed out, boiled out, acid, and then 2 coats sealer and now its awesome), all the hoses, the fuel pump replaced (put on new original connectors for the new bosch fuel pump), damper assembly cleaned, fuel filter repalced, fuel rail removed and cleaned with carb cleaner, removed and replaced fuel injectors with new good ones (and all the orings too), changed fuel pressure regulator. I replace with all new parts, and all new fuel injection hoses and/or fuel hoses where needed, i cleaned out the long metal fuel rails under car with carb cleaner too, it helped somewhat. Also new air filter, new boots on the AFM both sides....

Oh yes, also changed oil with castrol 10W40, and put in the datsun/nissan big blue oil filter, and it has new NGK wires, NGK B6ES-11 plugs (gapped to .40)

Of course, the car runs better now, better than ever before (too long to explain) but its still only getting 10IN of vacuum. :-( at idle.

Both myself and some local mechanics, used carb cleaner around injectors and intake manifold, and nothing changed. We were thinking maybeI foo-barred some of the orings in injectors, but the engine did not budge one bit with any carb cleaner around intake manifold, or injectors. So it just seems to confirm even more, I dont have any foo-barred orings or intake leaks. I have new quick disconnect electrical connections for the new injectors, just havent had time to install them yet.

I found a local garage with a smoke machine, and no intake leaks were seen anywhere (and they had an oscilliscope/computer system they clamped onto the main ignition/coil wire). They also said secondary ignition system was looking good on the oscilliscope, firing pattern and burn time looking good/normal. I myself found many little cracked vacuum/pcv hoses and replaced all of them over past month while doing all this other work.

I cleaned all electrical connections and sensor connections in the engine area, cleaned grounding points in engine compatment where all the ground wires connect to, cleaned fuse box, replaced all fuses. Oh yeah replaced PCV valve, replaced thermotime sensor, replaced water temp sensor, AFM (air temp sensor was bad), replaced thermostat (it was running too cold and now its hot like it should be). I installed a new clear see thru G3 fuel filter after gas tank, after installing new tank back on car. I have a fuel pressure guage currently connected after fuel filter in engine compartment. So I can check it when needed.

My fuel pressure looks good when starting up, idling, and revving engine. Seems normal to me. Right around 36 psi.

I probably left some stuff out. But after all this work, the engine is running better then it ever had before, however, I really feel its holding back. I still smell some exhaust even with downward tip extenders (I think those reallllllllly helped a whole lot and only cost 10$)...And lets see, Im getting 7 to 8 mpg in town driving , yes really that bad, and my AFR's from the innovate meter are showing my idling at very lean conditions like 18 AFR or a little higher when sitting at stop sign, and WOT is 10.1 to 10.3, and crusing is around 12.5 average, sometimes almost 13 if I am going in a straight line and barely touching the gas pedal. I drove for 44 minutes and recorded all the data on the AFR meter and played it back on my PC. Several times now.

The local mechanics checked timing(and changed it as much as they say they could-because of the 10IN of vacuum the engine was only producing), they also played around with the idle adj screw and AFM bypass screw a little bit.

The also said distributor cap looked good and clean inside, and the distributor itself (what you can see by popping the top off anyway, basically looked OK - but they suggested a removal/inspection/and possible replacement of its 'guts', if needed)

After all this information I gave them, and the tests they did, they say I need valve adjustment. I have heard that before earlier in this project, but I have wanted to restore car to as much new stuff as I could....and also do as much of it myself. So I have learned a lot over the winter time, and thanks to many people on here to encourge me to do all this stuff.

However now to the meat of the meal, adjusting valves scares me somewhat that I could royally foo-bad something. I will be careful of course but still....So I was wondering if someone can offer some tips faq watchout problems etc. I saw bits and pieces of information about valve adjustment, but it seemed like they were for older z cars. Dont know how much it applies to my 1978. I have read about doing it hot and cold, and I would plan on doing it cold the first time. And I suppose first of all, I just need to remove rocker cover, and just inspect them in the first place and see whats what. And what their clearances are now.

!Oh yeah!, I learned how to do compression tests (was about 150 psi on average across all cylinders), but I did it with cold engine and didnt open the throttle (didnt know about it then, and still honestly dont know how to do that exactly), so I read on this site, that doing the tests warm, and opening throttle could add anywhere from 5 to 20 psi. So my compression could even be higher 155 160 170?

I also learned how to do leak down tests, on average it was 15 to 19% (mostly towards the 19% side) and one cylinder I could only get down to 23%, which all that seems OK to me from what I have been reading. According to the guage up to 40% is in the green, of course I dont really beleive you want to be around 40%, around 20% seems a lot better to me. And I was told that 15% is about normal for any average new(er) car. Ohhh I am sure I left some things out. And I realize just beacuse I replaced all this stuff doesnt mean its all working. But I am gonig to choose to believe it is all working for now. It really seems that if I have some valves that are tired and not set correctly, that my gas mileage will suffer, could smell wierd exhaust problems because of incomplete combustion, and not have the power I believe the car is missing right now. So I am reallly hoping a valve job can bring it back to even have more power and fun!

Edited April 15, 201113 yr by argniest

Argniest I love your attitude, perseverance, and very clear, concise and well formatted posts! Also your logic and careful approach to tackling problems is superb... keep it up!

Thanks I really appreciate that comment :-) I use similar skills in my years of designing software, debugging it, and fixing all kinds of problems with software, hardware, firewalls, routers, computers, virus removal etc ITS A step by step, bit by bit approach to limit scope of problems. I know there is a 1000 different ways to go about it. I have gone down my path to Z enlightment, slowly but surely.

Stick with the NGK plugs and wires and you should have no problems.

I got NGK plugs, I should have ordered new NGK wires a LONG time ago. I had my finger on the trigger many times, just didnt do. I am sorry now. Because I want new NGK's like right now.

An easy way to check spark is simply to idle the car then pull one plug at a time. You can feel the spark with your hand on the boot and you can notice how far off the plug that you can hold the boot away before the spark won't jump. It should be the same for all plugs.

OK, not to sound like a broken record, but I believe the 3 tests I did today, and one last night using those special spark testers, has beyond a shadow of a doubt proved that all my cylinders are not getting spark all the time. Some are much worse off than others. As I mentioned, 5 and 4 are the worst looking spark, missing for several seconds. I mean its like someone just turned them off. ANd then they come back on, and spark some, and then back off....etc 6 also misses sometimes, but doesnt go dark like 5 and 4. ANd well 3 is kinda like 6, but a little worse, and 2 is like worse then 3, but not as bad as 5 and 4. ANd well, 1, doesnt seem to miss very much. But I think I did see it miss a few times.

So all I am saying is that I dont know if I need to prove anymore that I have a spark problem, right? It seems I have spark problems on all of them, and much more severe on some. Just my 2 cents

I just wish I knew which part of the system is causing this spark problem, so I could just fix it and move on. If my local store has those 4 parts, I will replace all the easy ones, tomorrow morning, and see if it makes any difference. I will keep hoping it will. ANd I dont have to dig deeper.

Edited April 23, 201113 yr by argniest

My only thought on the spark problem theory causing uneven fuel burning in some cylinders is that the photo you showed of the plugs had 6 lean and 4&5 rich with 123 similar and almost normal.

If you had a coil or ignition problem then it would affect all cylinders equally as it is upstream from the "distributor" (which evenly distributes the spark). This would affect all cylinders evenly. Since you have problems with 6 5&4 there is asymmetry and variance of the symptoms. This leads me to think if it is a spark problem it has to be distributor, or wires. However, it could even be an obstruction in the fuel rail on 6 and a common partial obstruction on 123 (but this is uncommon).

EFI flow would be another area to confirm. Bad injectors are not uncommon.

It could also be oil getting into 4&5 cylinders that blackens the plugs rather than fuel.

Still a lot of possibilities.

Well because those parts were readily available this morning, I changed them. I used the BWD cap rotor and ignition coil. NO DIFFERENCE. The spark problems, misfires, seem to actually be worse. I mean longer delays when spark diappears to when it comes back, when I had all 3 of those new parts on there. SO I one by one, tried each of them. ANd the spark problems I have described all remain.

I will have new NGK wires in a few days. Still wondering about the distributor and that transistor ignition unit. I dont have an osicilliscope so I cant test it that way according to the FSM

I also retested using two different kinds of spark testers. It really seems like all 6 of them are having spark issues. The more I watch them. I used a tester that you lay on the wire, and it lights up orange. Well it was coming in and going out too. So that to me validates that all 6 are having spark issues, for whatever the true reason is. Of course, during those tests I left the new ignition coil on there. Just to see.

Edited April 23, 201113 yr by argniest

Blue, I agree with you that there could be a fuel delivery/metering issue, but there's definitely also an ignition problem. That's the first thing to correct. Once the engine is firing on all 6, we'll be able to determine more. I'm somewhat surprised that 6 is getting spark and power to the injector, because the plug looks like there hasn't been any fire in the cylinder. I also suspect 4 and 5 COULD appear sooty from extremely lean running. Although it's a counterintuitive interpretation, an extremely lean can lead to a slow and incomplete burn, thus generating lots of unburnt hydrocarbons. I only know this because my own engine was running extremely lean and had similarly appearing plugs. Imagine how confusing that was!

Anyway, I'm anxious to see what happens when the ignition is straigtened out. I don't think that will be the end of the problems, but I think Argneist will achieve a quantum leap in engine performance. I think once the engine fires on all 6, then a 100-200 mi drive is in order to give a new set of plugs a read. Then if the plugs aren't consistent with each other, it's probably time to pull the fuel rail again (sorry, Argneist!) and spray some fuel into 6 juice glasses.

BTW, Argneist, the plug read will be a lot more meaningful if you ADJUST YOUR VALVES! You can do that while waiting for ignition parts to come in!

Edited April 24, 201113 yr by FastWoman

I have a little new information to report today. According to another friend of mine, I was using the spark plug tester for newer cars and not a standard one for something like the Z car. I guess if I think about it, that makes sense. I mean if you walk into a car parts store they are going to have components for recent cars, not something that is 3 or 4 generations old.

What I was told is that I need something for standard ignition systems, not a spark tester for high output ignition systems. On the tester itself I mainly used, it said HEI. Which supposedly means for higher output systems. The interesting thing is that the HEI one that I am using, looks very similar to the one below...except the one below has a metal post in the middle of it...kinda of like a spark plug.

This is what I was told to get

http://www.denlorstools.com/home/dt1/search?keywords=kd+2757

I guess the one I was using was made for modern cars, and has a larger (air gap) for the spark to jump across, which therefore could be the reason I was seeing such craziness when testing the Z car with the modern tester, when I need a tester for standard ignition.

Oh well, I am going to get this one, and retest. Since right now, I have the entire EGR system blocked off (one of my tests for eliminating vacuum problems), and the new ignition coil in there, and also the vacuum lines for HVAC system are disconnected. I decided to take car for drive. It still is hesitating. I think I am starting to learn what it feels like to have the car missing.

Even tho I was using the wrong spark tester, I am starting to believe what I am feeling in the engine is in fact misses in the spark, and there for causing inconsistent accelaration. SO even tho the spark tester I used may not have given completely accurate results, I still think I have a spark problem.

Once I get the new tester, and new pickup coil next week, and new NGK plugs next week, and also am doing some other tests with distributor....I should have more information to post.

Thanks again to everyone for helping me. Unfortunately the new ignition coil hasnt seem to make much difference, nor did the new rotor or dist cap. But I just need to learn to change one thing at a time. And retest.

And oh yeah I am also trying to get my hands on a transistor ignition unit to replace mine. It could be a week or more I suppose before I have that. And I got a loaner ECU from a friend, so if needed I can always try that too. have lots of things inbound in the next week or 10 days. Then will have lots more parts and testing to do.

PS

My cousin who restores cars, agreed to help me get started on valve adjust. I just need to take a day off work and go up there to see him. I mainly just asked if he can show me the first one, and watch me do the rest. He wants to do it cold tho. I didnt want to get into a long discussion with him. He works on very high end cars for 30+ years. I have seen cars worth 500,000$ and more at his shop. He does nationwide work. So if he says he wants to do them cold....welllllllllllll how can a noob like me argue. but I am going to bring 1 page of notes from everyone who has told me to do them hot. And see what he says. But regardless, I hope to get this done also within the next week.

Edited April 24, 201113 yr by argniest

OK, so since last posting I got to meet with my relative Steve who restores cars (mercedes, jag's, bmw's) for a living for 30 years now professionally in his own business, he has customers from all over the nation too. He is VERY good! I am very lucky to have him available when I get into over my head.

Well anyway, I told him what has been done to the car since he saw it last october. He said its good I have eliminated some possible problems. I also re-ran spark tests with two different kinds of testers. And this time the spark looked fine. No misses that I could see. The spark for all 6 was consistent at idle and revving. Those other testers DEFINATELY were not for a Z kind of a car.

Steve also confirmed good spark the old fashioned way. He pulled wires off one by one and left them a little off the top of the plug...we could hear them all buzzing, and he said sometimes when you do that, because it produces a more powerful spark, that it can light up the cylinders again. but it had no effect. But he did say he really felt the spark sounded good, and of course I mentioned again about both my rounds of testing.

I spent 2.5 hours with him, and we talked about a lot of stuff, he tinkered and tested stuff, based on his hands on approach from working with cars for like 45 years now, since he was a teenager. Next weekend I am going back and this time he is going to hook up his computer and oscilliscope and ...he says, many many times that computer has shown him problems to fix. So we are both hopeful he will find something. He talked on and on about some possible problems that are causing my 6,5,4 to basically not be working. Things like a problem with the head gasket and it letting air pass between the fire ring, and other issues with valves not closing, cam timing...but of course he doesnt know for sure yet, without digging into things further. He is trying to help me do everything I can to avoid cracking the engine open. He knows that is THE last resort.

He was kind of surprised, when I told him to pull off 6,5,4 injectors and spark plugs...and then he saw what I meant!!!!!!!!!! He was like what THE???? There is NO difference in how the engine runs. but as soon as he did that on 1,2,3 it was immediately noticable both by removing plug wire and fuel injector connector.

He also squirted carb cleaner all over, and NO difference anywhere. I have temporarily blocked off the egr system, also removed vacuum lines from hvac system(and plugged them off of course) to eliminate any possible vacuum degradation from those systems. He thought that was good idea to do those things to remove other possible vacuum problems.

I told him how I removed brake booster line too, capped it off, and NO difference in engine running sounds. He really felt after all that, and the smoke test I had done, etc etc that we really are not looking at an intake/vacuum leak anywhere.

He also pulled the little vacuum hose that I had plugging off the small nozzle that normally feeds the hvac system...and squirted carb cleaner into intake runners which is down by 6, 5 and 4. NO difference!!! Number 6,5,4 was like they were dead. They didnt care we shot carb cleaner in there. Now that realllllly surprised me, I thought for sure when he did that the engine should have picked up even a little. But nope, the lights are on but nobody's home.

So lets review some things we know, and what Steve confirmed....noid lights are lighting on all 6, using screwdriver or stethescope you can hear all injectors clicking, spark really seems good form numerous tests on all 6, no missing noticed, fuel pressure is 32 at idle, I ran all those EFI bible ECU tests, and dropping resistor tests...all came back good. I mean I can list other stuff too. But it really seems like we have good spark, and fuel injectors seem to be working, and its using a LOT of gas...8mpg now :-( which makes me believe all 6 injectors are in fact squirting gas. Of course driving down the road on 3 cylinders would also cut gas mileage down drastically.

Steve has a way to test fuel injectors, its a system he devised himself. So we both agreed, at some point, we will need to verify they are all working. And I also gonna give him my old ones...and see what they look like.

I could go on an on....we talked for 2 and a half hours about a lot of stuff. He also told me that the valve clearances I reported would not be causing this kind of a problem. I do believe him, seeing as how many cars he has worked on for 45 years. Including some Z's back in the day. He will help me with the valves soon, but first some of these other things.

First, I want to have him run his computer diagnostics on the ignition system, and lots of other things he said he can tell by that. He agreed its not a bad idea to do that next. Because if there ARE certain problems with it, it could totally hose us over. Like what we are seeing. I REALLLLLLLLLLLLLLLLLY hope he sees something.

I will also be putting in a different ECU that a friend of mine lent me...and see if that has any effect. If not, I will put the old one back in. Then I have a replacement Transistor Iginition unit sitting here...to try right after that. And a new rotor and cap that are the "good stuff", best quality parts. I will try those following the ECU and TIU. And I have a new pickup coil to put on there too, but Steve will have to help me with that. He was talking over my head about what he was gonna do with the distributor. But basically taking it out, inspecting it, cleaning it, tightening things up??? is what I think he meant.

He did say the distributor seemed a little loose, and something about how the rotor was turning or moving when it shouldnt be. So that is something he wants to look into more detail next weekend. Im not messing with that distributor, I am going to let him do it. I want a pro to do some of this stuff. I just think its wise to use Steve when I feel the need.

Oh well... sorry for a lot of rambling. Its just a hodge podge of information. Steve is my ace in the pocket. I really look forward to next weekend. At a minimum he will evaluate the ignition system with his computers and we will have a final proof one way or the other about a lot of things related to that, and hopefully we will replace pickup coil, and he is going to help me put on the new FI connectors, since the current ones barely even stay on there. He wanted to do that soon. If I get lucky, we will do the valve adjustment too. but I think that may have to wait until the next weekend, since he didnt feel it was part of the main problem here. I only want to attack the problems that seem mostly likely to be causing this problem. So he agreed that could wait just a little longer.

So between me swapping out those important components this weekend, and what we will do next weekend, I think we will know a lot more than now. And will set the stage for the next set of testing.

I left out more discussions, but I have already bored you to death. You get a cookie if you made it this far :-)

Edited April 30, 201113 yr by argniest

Yum! Me love cookies! (... Cookie Monster)

It sounds like you're on the right track. I'm guessing what you'll find is that the 4-6 injectors aren't spraying -- perhaps defective, stuck, or clogged somehow.

I look forward to hearing back from you about how easy and strangely enjoyable the valve adjustments were. That's my favorite part of the engine.

Ok anyone watching. Check out the pictures. I went to see my cousin this weekend who restores cars. We spent hours going over my case history, and then he hooked up some big humongous old Sun computer osicilliscope testing machine on wheels. He checked the primary and second ignition and said it looked good. Although, he could see how #6,5,4 were giving irrational readings. It was cool to watch and learn about those wave forms.

But basically, I got a thumbs up on the primary and secondary ig systems. Especially after what we found next. I have so much to write but will keep this short.

I got several new replacement pieces since my last post here, on the car (AND NONE OF THEM HELPED THE SOLVE THE PROBLEM, BUT YOU WILL KNOW WHY IN A MINUTE) So I got good quality YEC parts for cap and rotor, and new igntion module, a known working ECU, and a replacement transistor ignition unit.

I also have a replacement pickup coil (but now I wont need it), and I have good quality replacement fuel injector connectors from bosch.

I did more testing with the new spark plug testers, etc etc etc but got NO WHERE with that. Planned a drive to see my cosuin yesterday, and boy oy boy did we hit a pot of gold!!!!

WELL ANYWAY, NONE OF THAT MATTERS. WHAT MATTERS IS NEXT

So as we talked and looked over stuff, we worked our way around to the EGR system. I had made a gasket to block it off from the rest of the car, to eliminate any possible intake leaks from the whole EGR system. But that didnt help either.

Well, we took the EGR valve off, and started poking around down there. As you know there two sides to the EGR housing. They are supposed to be separated. WELL GUESS WHAT????? Probably 10 or 15 years ago??? the firewall between those two ports got eaten away. So exhaust has been eating it away for a long long time. And exhaust is pretty acidic anyway.

Normally the EGR valve is supposed to meter or measure how much exhaust gets moved in there. But a GAPING HOLE!!!!!!!!!!!!! sucking it directly into the intake???? WHOA!

You will see in the pictures how I stuck a wire right through it. You can see how the white wire runs right over into the intake manifold. That means all that exhaust and air too is going over into the intake manifold to totally screw with 6,5, and 4 cylinders combustion process.

So that mean I am currently getting a LOT of exhaust/air directly sucked into the 6,5,4, and especially #6, since its closest to it. The more I have tested things, the more I wanted to really believe this was an intake leak/vacuum leak. but no one could find any vacuum leak externally, anywhere on the car.

However, had I completly understood how this EGR system and the EGR housing underneath were designed, I would have looked there a long time ago. And I could have found this problem. Of course now its seems like a no brainer. Actually, I DID LOOK IN THERE SEVERAL TIMES, but before I didnt comprehend that something like this could be happening.

We have a plan to band-aid it for this season, because I want my car back to be running good and start driving it a lot more and further way too. And eventually I will be buying a modified throttle body from my Z wizard of the northwest. And fix it permenently.

I believe immediately after fixing this, a lot of things will happen. Incredible amount more power, smooth idle, normal 18IN of vacuum and not 10-11In like now, normal gas milage, non stinky exhaust, clean burning spark plugs (remember 1,2,3 have been mostly burning OK - and my cousin confirmed he thought my plugs from 1,2,3 were OK).

I have done so much to this car, it should be like brand new, and even better in some areas because of performance addins like shocks and polyurethene bushings and all new suspension pieces, and you know all the other things that have been done.

My cousin kept saying he thought it felt like something stupid, but we were both like WHAT!!! WHERE???? Where could this be.

Well I will post back once he fixes this situation for me. And let you know how it goes. It should be tuesday this week or wednesday if plan goes accordingly.

ALSO, if you look closely at the picture of the topside of the EGR housing, notice how bad it looks. The hole isnt even round anymore. Its been eating all of that away for who knows how long, and ate a frigging hole RIGHT THRU the firewall between them.

Edited May 9, 201113 yr by argniest

eureka! way to go sleuth

Definitely great work in digging into the system. It helps to have good diagnostics tools, too.

That's for sure a new one. Have to remember this for future people with "low intake vacuum" problems. I wonder how many other corroded EGRs are out there.

I got curious and just went out to the garage to take apart a 1978 parts intake I have. The EGR channel was totally choked full of caked carbon residue. Interesting that your was the opposite and apparently still letting exhaust gas through, although in excess.

Fascinating! Another mystery solved. Great job!

I just have to say, though...

YOGURT CUP TEST

Such an easy thing to do, and it would have revealed your leak. It might have been hell tracing it down, but it would have revealed to you that somewhere in the recesses of the engine... somewhere in that thing... there was a leak. In this case, a leak directly from the exhaust to the intake, bypassing the EGR valve.

Anyway, you found the problem, and that's what's important. Soon you'll be be taunted no more by the drivers of those VW bugs!

Edited May 9, 201113 yr by FastWoman