A few Questions about AFM

[240260280z]

You can momentarily hit the injector's pins with +12V or +9V battery to fire them. The click from the solenoid in each injector should be the same.

You can also flow a fluid through the injectors at a fixed pressure and open the injector for 10sec and measure the flow in a graduated cylinder.... or just swap your injectors from 123456 yo 654321 and then re-read the plugs after a few miles to see if the problem moves.

[conedodger]

Your compression numbers aren't all that bad. Check the resistance of your spark plug wires. What are their condition?

Just from some of the things you're saying it sounds like you're using a rather expensive method of fixing a problem. One that eventually works but costs lots of necessary money. Figure out what's wrong, then buy the parts. Don't throw parts at it until something works. I am also a bit worried about your mechanics. A valve adjustment comes before any tuning. Otherwise, you are tuning out the problems caused by the poor valve adjustment. And spending money you will have to spend again once they are adjusted.

I suspect you have an electrical problem. Someone above mentioned pulling plug wires one at a time and listening to the engine. No change? Probably no spark. Another way is to check with a multimeter to see what the resistance on the plug wires are. If you're feeling frisky, there are resistance readings in the manual for all portions of the EFI harness. Check all that before you spend more money.

[240260280z]

If you have a spark problem, be sure to check distributor rotor and cap too.

[FastWoman]

Argneist, you've definitely made a breakthrough! It sounds like you're running on 3 cylinders. I agree with everything everyone has said above.

Here's where we get back to basics. Here's what you need for fire in your cylinders:

fuel -- to be determined

air -- yes

compression -- confirmed

spark -- to be determined

You can check spark one of a few ways. Probably the easiest is to put your timing light on each spark plug wire. If the timing light flashes, you've got spark -- barring any short, of course. Those look like possibly older NGK blues. Those have a really good lifespan, but you never know. If the cups on the ends are dirty enough, your spark could be shorting to ground, which I suppose would still trigger your timing light. Here's a trick: Start your car up at night, and run the engine in the dark. If your spark is shorting anywhere, you'll see it. You can also check for spark by jumping a spark from each unplugged wire to ground.

I'm actually placing my bets on your injector wiring being bad. Here are my thoughts: Your #6 cylinder seems not to be firing at all, which could be attributable to multiple causes. Your 4 and 5 cylinders, however, are extremely sooty. Ordinarily that might appear to be from really rich running, but it can also be due to such lean running that you get only partial detonations (and lots of unburnt hydrocarbons). So I'm thinking your 4 and 5 wiring might be weak and might trigger the injectors very weakly, only delivering a partial charge of fuel.

So here's how you test your injectors: Are your christmas lights still close at hand? If so, pull out one of those little bulbs from the string, and straighten its wires. Plug the wires into the injector connector, and run the engine. You should see the bulb flashing once with every engine revolution. I'm betting you won't see much on 4, 5, and 6.

I don't think it would be time wasted at this point to go ahead and REPLACE THOSE CRUSTY CONNECTORS! That might clear up your problem instantly. At least you won't be trying to do tests on questionable and possibly irratic electrical connectors that have long outlived their usefulness!

[Zed Head]

Regarding injector wiring and injector testing - don't forget that the Zs are batch fired. All of the injectors fire at the same time so you can move your injector plugs to any injector you'd like (if the harness will stretch that far). So if you know that 3 is firing, you could move it over to 4 or 5 to see what happens, or vice versa.

If your plugs are fouled it might not tell much about the 4, 5 and 6 cylinders, but if you put 5 on 3 and it runs the same (when removing 3 causes stumbling), you could be confident that the #5 wire was putting out an injection pulse.

Just another angle (if you don't have the Christmas tree lights, although I do like the idea).

[argniest]

Man you all have such wonderful advice. I am so lucky to have you out there!!!!!!! I just feel over my head sometimes, I guess even depressed a little sometimes. I dont mind spending money to replace all the equipment I mentioned in the book I am compiling here in cyberspace on my Z car. I planned on replacing the equipment, saved for it, etc. But this is such a roller coaster of emotions. I love this car, and want it to run so bad. SOmetimes I feel close, and then as far as way as pluto, its quite maddening sometimes, and so rewarding on another day!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I spend most of my free nights and weekends trying all these things, learning, doing, reading, posting, and here we are 6 months later. I think I wanna bash my head into the wall about right now!!!!!!!!!!!!! UUUUUUUUUUUGHGHGHGHG

OK SORRY, DONE VENTING, FOR NOW

One day I think I find a smoking gun (like last night when I removed the HVAC and brake booster hoses from the vacuum loop of the engine, and then nada. Apparent dead end. Nothing was different. I really thought after reading on this forum, that if I removed those systems, I was gonna find or eliminate a vacuum leak that I wasnt aware of. But you know, it effecting things exactly zero.

But it always leads to something else...just like yesterday doing something as simple as pulling those stupid fuel injector connectors and retesting again this morning. Same results. Repatable problems are good ones. I know from working on writing software about limiting down the scope of the problem.

So this morning, while playing with idle on car to speed it up, and try it again, I pulled off 6,5, and 4 and it MAKES NO EFFECT on the sound of the running engine. Whether at 900 rpm's or 1500 rpm's or even when I pushed down the throttle a ways, and at same time pulled off those connectors. I just never hearing it making a difference. I MEAN IT HAS TO RIGHT?????????? There is just no way on gods green earth that pulling those 6,5,4 connectors off there should not make a difference.

I mean 1,2,3 make an immediate differnce. I also cant really believe that my timing is so far off, that it would cause 6,5,4 to be that way???? right? I mean setting timing is just too much for me to comprehend right now, and even in 3 months, I know my limits and that is one of them. But I have had 3 different mechanics play with it. But the latest guys had a previous Z owner there, and he really did seem to know what he was doing. ANd said he set it as good as he could, because of low vacuum in engine, I think was why he said he couldnt do any more with it.

Well yes, I have xmas lights too, and I was gonna buy some noid lights. I was thinking if they sold them in packs of 6, then I could hook them all up inline, and see how they are looking. I dont know much abuot them, but some another online friend of mine mentioned to use them. I just need to try to find some locally if possible that will fit the car.

I will really try to do everything you said in the last few posts here in this thread, and see what happens. If you have time read over this monster reply and let me know what you think about what I said here. Thanks again all you super nice z friends ))))))))))))))))

PS One other thing, wont I get a 20000 or 50000 volt shock if I touch my spark plug wires. And look, spark plug wires are so cheap I can just buy new ones anyway. I know I know...throwing money away, but if it saves me from spending so much time learning how to troubleshoot the problem, I would rather skip anything I can, and buy new parts. I know some of yu wanna sock me for saying that

Zed Head: I dont understand what you said about injectors all firing at the same time. I mean it seems like they all have to fire at different times because the pistons are always in a different position as the engine runs. And they hit their compression stroke at different times...what I am not understand about what you said. I mentioned what you said to a mechanic BTW, and he was like naaaaaaaaaaaaaaaaaaaa you CANT do that. It wont work. Personally, it sounds like a great idea. But also, I dont know how far those connectors are gonna reach anyway, since its 1,2,3 and then 4,5,6 that are at opposing sides of the engine. I dont know if there is enough extra wire to move them as you said.

Blue: Im sorry but I dont know diddly squat about distributor yet Each day it seems I have to keep learning about something new. Its all good, but learning how and where to unplug HVAC hoses to eliminate that system from the vacuum loop in the engine, is a whole lot easier for me to understand, than the distributor. Im not saying I cant learn, but I am already up to eyeballs with so many other things to do. I wish I had a local mechanic that could really help me with some of this stuff. But they all seem to be operating on different wavelengths.

Edited April 19, 2011 by argniest

[conedodger]

LJet which is the system on the early EFI Z and many other cars of that period were 'batch fired' in other words, the injectors fired at the same time in groups irregardless of what position the piston was in. It really didn't matter that much because the real magic happens when the spark comes and the spark fires individually for each cylinder. What Zed Head is saying is that if the problem is the injector harness, you obviously have some injector wires that are good. If you switch the leads between the cylinders you will fire the injector that wasn't previously firing. It really comes down to checking the resistance of each lead. There is a sequence for this in the FSM. It will tell you to touch one end of the multimeter to a numbered position at the ECU plug and at the plug end of a particular sensor or injector. It will tell you a range of resistance that the factory considers 'serviceable'. You can put a set of plug wires on if you wish. They are as you said, cheap.

[argniest]

Argneist, you've definitely made a breakthrough! It sounds like you're running on 3 cylinders. I agree with everything everyone has said above.

I do feel like this was something important to find out. Too bad I didnt try that weeks ago. But you know, I am just a puppy learning how to walk around. AND Yup, I could believe its only running on 3, or maybe 3.5 or 4 cylinders. I couldnt put it into words exactly but you did below. I was thinking if the wiring, or the dropping resistors or the ECU...any of those things were not getting a proper or strong enough signal to injectors 6,5,4, that therefore they are not getting enough fuel or not delivering it correctly. Resulting in the condition of the spark plugs that we have seen, the lack of power, and because of that the engine is pushing itself around on 3 or 4 cylinders, hence giving me horrible gas mileage.

I think the black plugs are because of a lean or incomplete burn because of things you have said, and things I was somewhat thinking about last night too.

I just know this car must be capable of hauling at least some A$$, so if you combined the partial explosion power of 5 and 4, you might get the equivalent of a .5 or 1 more cylinder. So the end result is that I have 1,2,3 working probably OK, and the other 6,5,4 combined are only giving a little extra power. I still think I hear a put put sound, or a chug chug sound when idling, and driving. But who the heck knows for sure. I have never heard a good running old Z car so I have nothing to base it on. Except the data I am giving you all.

You can check spark one of a few ways. Probably the easiest is to put your timing light on each spark plug wire. If the timing light flashes, you've got spark -- barring any short, of course. Those look like possibly older NGK blues. Those have a really good lifespan, but you never know. If the cups on the ends are dirty enough, your spark could be shorting to ground, which I suppose would still trigger your timing light. Here's a trick: Start your car up at night, and run the engine in the dark. If your spark is shorting anywhere, you'll see it. You can also check for spark by jumping a spark from each unplugged wire to ground.

I should just buy news ones, and try those. If I had to guess based on all data I have collected so far, it seems like I have spark power. I also have a timing light, and 3 kinds of spark plug testers. One you lay on the outside of the wire and it lights up, one you have to connect inline, and one you connect to the end, and then set near a metal grounding point. Those local mechanics showed me how it worked on my Z car. We hooked it up to #6, and it was buzzing and zappping away. It has a clip on one side to connect to the car, and a port to put the plug wire into.

CAN ANYONE TELL ME WHERE I MIGHT FIND GOOD PLUG WIRES LOCALLY? I HAVE NAPA, AUTOZONE, ORIELLY'S, CARQUEST AND AN IMPORT CAR PARTS STORE THAT HAS HAD A FEW PARTS FOR MY Z CAR.

I'm actually placing my bets on your injector wiring being bad. Here are my thoughts: Your #6 cylinder seems not to be firing at all, which could be attributable to multiple causes. Your 4 and 5 cylinders, however, are extremely sooty. Ordinarily that might appear to be from really rich running, but it can also be due to such lean running that you get only partial detonations (and lots of unburnt hydrocarbons). So I'm thinking your 4 and 5 wiring might be weak and might trigger the injectors very weakly, only delivering a partial charge of fuel.

This is what I was envisioning last night once I saw how 6,5,4 made no difference to how engine runs (well except a little poof with #4 as I metioned). That is has something to do with the clips, the wiring, the dropping resistors, or the ECU. I mean I know thats a LOT of stuff, but to see how 1,2,3 work great, and 4,5,6 nada...it really does seem like an electrical failure somewhere between ECU and injector connections

So here's how you test your injectors: Are your christmas lights still close at hand? If so, pull out one of those little bulbs from the string, and straighten its wires. Plug the wires into the injector connector, and run the engine. You should see the bulb flashing once with every engine revolution. I'm betting you won't see much on 4, 5, and 6.

I don't think it would be time wasted at this point to go ahead and REPLACE THOSE CRUSTY CONNECTORS! That might clear up your problem instantly. At least you won't be trying to do tests on questionable and possibly irratic electrical connectors that have long outlived their usefulness!

I will think this through in next few days and take action as soon as I can.

:bulb:PS

One other thing, if 3 of my injectors are not working correctly, I suppose there is a direct relation to engine vacuum or lack of it. Figure 10 or 11 IN of vacuum with 3 to 4 cylinders working, and if 6,5,4 would all kindly get their A$$ in gear and start working again, then engine vacuum could come back to 17 or 18 IN, no?

Goodnight all your crazy z finatics!

THANKS AGAIN!

Edited April 19, 2011 by argniest

[FastWoman]

Quick answer to your question in red: I would think if you only have 3 working cylinders, restoring the remaining 3 would bring your vacuum up A WHOLE LOT. Whether that takes you to 17 or 18 is anyone's guess, but I bet you get close.

[argniest]

Just kinda of an off the wall question, but how fast would a good running Z car from 1970's compare to a similar corvette of the time? Im just wondering how fast/powerful this car is supposed to be???? Because right now a 1949 VW beetle is faster than my Z. I know its sick car right now...but hey, Im working on making it all good again

When I think of corvettes I think of fast and raw power. When I think of Z's....well I dont know what to think or dream of....because mine car is in the hospital right now not quite on life support but if its only running on 3 cylinders OMG!

Edited April 21, 2011 by argniest

[FastWoman]

Well, a stock Z's acceleration might be slightly disappointing by today's standards. After all, there are now stock configurations of automobiles that boast 500+ hp! The modern-day hunger for power is insane, even by 50's and 60's standards. That said, a Z isn't meant to race Corvettes. A Corvette can easily take a Z on a straight road. Top-end speed might be different, though. I think A Z can top 150 or 160 mph. I don't know what a vette will do.

Where the Z will take the vette is on twisty/curvy roads. The vette has a very light body and a very heavy engine, with most of its weight on the front wheels. It's not a particularly nimble machine. The Z is VERY nimble, by comparison.

I think a Z should EASILY take a '49 bug under any driving conditions, perhaps with the exception of fording a river. (Bugs float.) What sort of performance should you expect? Well, I like to do a brief Italian tuneup on my Z everytime I take it out -- one quick, WOT acceleration from stop to some reasonably fast speed, revving the engine somewhat high-ish (e.g. 5k). I do this just to blow the cobwebs out. When I do this, my SO says it's like being in a rocket ship. It's not as fast as our BMW Z3 was, but it's faster than our Miata. You should get around 160 hp from your engine, give or take. A bug, by comparison, has around a 50 hp engine and about 2/3 the weight. At the Z's weight, it would be matched to the bug in horsepower if it had 75 hp under the hood -- or if it were running on about 3 cylinders.

[argniest]

thanks for that info :-) was just wondering. I have an road and track from 1978 I found on ebay (havent read it yet) they talk about the corvette and the Z car. Saving it for a day when I am not so busy. Headed back out there now...