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noob valve adjusting on 1978 280z


argniest

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There is a check valve on the brake booster hose. Did you remove the brake booster hose where it connects to the intake or at the booster?
I removed it from the larger metal nozzle that sticks out of the back of the intake manifold. Did I boo-boo that? Where are you saying to remove it if not there? I guess I should look in manual tonight to see if I can find whatcha are talking about :-) so many things....

On page BR-15 of the FSM they are talking about this check valve. SO now I think I know where its at. But can you explain where I should have disconnected it? ALso in FSM Fig BR-32, and BR-33 are talking abut this check valve.

The picture below shows a red arrow of where I think this check valve is at. Now I just need to know more about where I should have tested this :)

post-23329-1415081459418_thumb.jpg

VAVLES

Also, I will tackle the valve adjustment as soon as I can. I make be taking some more work days off just to work on Z car a bunch of days in a row. Tommorrow I am going to hook up a noid light and the spark plug tester that has a clamp on it, and sparks in the middle of it, and go one by one from 6,5,4,3,2,1 and check that I have spark, the quantity and intensity of it (as best as I can judge it), and also watch the noid light. Now I have never used one before, but I am hoping the one I saw at harbor frieghts tools will fit first of all and isnt a piece of junk. Their leak down tester from harbor freight looked nice and all, but didnt work. I bought a better one from amazon and it worked exactly like the youtube videos talked about.

So I will hook up noid light to 6,5,4,3,2,1 also, one by one. Im not gonna shock myself either. I will pull off the spark plug boot hook up to tester, hookup noid light, and start car....and watch and learn, and then just stop car, hook up next plug and FI, and just see how it all goes.

FastWoman: I am still mesmurized by the fact that it really seems like 3 cylinders are not working very much at all. I mean you pull that fuel injector connection off from 6,5,4, and it does nothing to sound of engine, but goto 1,2,3 and pull it off, and immeidately slows down a lot, and speeds up to original speed when you put it back on. I mean there has to be something electrical going on here. Its not that I dont think valve adjustment is important, but this 6,5,4 problem, seems a lot more sinister to me. I noticed the dropping resistors control 4 of the injectors and 2 of the injectors. I was hoping to find they would have controlled 1,2,3 and then 4,5,6. I also havent cleaned those particular connections. I know where they are at, but was about the only ones I didnt clean. They are a little hard to get it, but I am gonna pull them apart now, and the squit the old deoxit in there...let em dry a little and stick them back together. And as soon as possible I am going to check FSM for the tests I can do from ECU to those injectors.

You shouldn't think just in terms of the absolute measure -- .001 or .002, but in terms of percent. Your intakes are 1/8th or 12.5% tight and the exhaust somewhere between 20% and 25% loose.

Bit more ominous, isn't it? Chris

Yes that is a good point, it does point out the problem a little more when I think of it that way, But I will still need to warm up car and check the clearances when warm. Just so I know where they are at warm, and cold too.

Edited by argniest
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Yeah, I was thinking about the banking too. It would be "too easy" if it were 1 entire bank. Then you'd almost know where the problem is (that one wire from the ECU feeding the one bank). However, I suspect it's an accumulation of bad connections.

It's a happy coincidence that you're running off of the front half of your engine, because that leaves you with a detonation every other cycle, resulting in a relatively smooth running condition -- at least smoother than any of the alternatives. (The firing order is 153624, as I recall.) Funny, that! ;)

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post-23329-14150814593458_thumb.jpg

If you click that picture, you will see a red line, of where I deteched the brake booster line, from that nozzle. And then I plugged up the nozzle with a short hose and a big bolt in the end of it.

Yeah, I was thinking about the banking too. It would be "too easy" if it were 1 entire bank. Then you'd almost know where the problem is (that one wire from the ECU feeding the one bank). However, I suspect it's an accumulation of bad connections.

It's a happy coincidence that you're running off of the front half of your engine, because that leaves you with a detonation every other cycle, resulting in a relatively smooth running condition -- at least smoother than any of the alternatives. (The firing order is 153624, as I recall.) Funny, that! ;)

ohhh wow, thats a great observation....that would explain what another online friend of mine was saying. He was like, man if it was only running on 3 cylinders, SOMEONE would notice. Yeah I NOTICE, its getting 7 to 8 mpg :)....but seriously he thought wouldnt a local mechanic notice. Well according to what you just said, maybe not. Because the engine wouldnt sound all that bad. THANKS FOR THAT. I think it just contribute more to my thinking that it has to be electrical problems on the FI side. I mean the plugs 6,5,4 are bad news, and probably black because they are lean not rich. And 6 is nada, a zero, not even doing anything. And then the bad gas milage well, the car is only using 3 cylinders to push itself down the road. I mean whats gonna happen??? suck down gas! And then how the FI connectors just have no effect (except #4 for a brief second) when removing and reinstalling on posts.

Oh well. I just need time to tackle all these things one by one.

ieeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

IF this is true, and I am only running off basically 3 cylinders....my gosh whats it gonna feel like when all 6 are working? in my dreams maybe ....I will be flying....I never had a 280Z that worked normally. Been a long long long fight to get here today. But it does seem like maybe there is light at the end of the tunnel. DARE I DREAM? we are narrowing this problem down?

Edited by argniest
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How in the heck does one go about testing the resistance on the dropping resistors? I removed it from the firewall tonight and see there is very little give in the 4 pin and 6 pin connections. I dont think there is anyway to turn them around to easily stick the multimeter probes down in there onto the pins. The 4 pin for cyl #5 and #6 seems doable since I only have to basically check two things in there. But the 6 pin....man I dont know. I definately want to see what kind of readings I am getting from those, according to what the FSM says.

I sprayed some deoxit in both of them, but again, with the 6 pin connector dont know how much really got down in there, because I have to turn can upside down and it doesnt like to spray much in there in that upside down situation. I used a mechanics mirror to look inside of the connector, and it seems like some deoxit got all over in there. BUt I cant say for sure how much. But it did look like each compartment in the connector was wet with dexoit.

I dont know about pulling and of the connectors off their terminals either. Normally, if the plug was accessible, I would have just done it and moved on. But these things are in a very difficult place to do much with, and the clutch cylinder is in the way too. That is not helping at all.

Thanks

Edited by argniest
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Sorry what I meant, was they are in a very difficult to get at place in the car. I have the digital multimeter and wiring diagrams for the car (laminated and colored). Its just that I cant seem to position the 6 pin connector to where it will be accessible to test it very easily at all. I am being very careful with the connectors. If I messed them up,,,,,bad news!

And yup, I have the schematic and troubleshooting pages also from the FSM. So I will test the 4 pin in a few minutes, but I dont know if I can position the probes to get a measurement on the 6 pin connector. Someone else said I could take measurements back at the ECU for the dropping resistors? but how to do that? I was just hoping to measure them at the source of the 4 pin and 6 pin connectors

Thanks!@!

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OK I got the Dropping resistors disconnected. My z parts person told me they are not so sensitive. Just pull the plugs out of there. That was too easy, Im just very careful with everything. Use kid gloves. I just didnt know they came apart like that :) NOW I DO. SO I measured the resistance of each of the pin combinations as suggested in FSM. They all read 6.2 ohms of resistance. So I believe that is within their specs.

Next I looked at the FI bible and they showed nice diagrams of which pin number on the dropping resistor connectoins are related to which fuel injector lead. So then I ohm'd them out (like pin 37 to pin 37 for injector #1). To make sure no broken wires. Each of the 6 wires going from one side of each of the fuel injectors, back to the two seperate dropping resistors (4 and 6 pin connectors) showed 0.001 or 0.002 ohms. Which tells me there is a good path from the Dropping resistors to the fuel injectors. Next I am gonna take the big brute ECU connection off (after disconnection power while I do it) and then hook power back to battery, and then start checking the other fuel injector connectoins in the FI bible. Also they show 4 different grounding connections to check. So I am on a roll I will check those too.

SO at least we know there isnt a problem with the dropping resistors, and no problem with wiring going from the two dropping resistor connectors to the one side of injectors. Hey its a start :)

No smoking gun there. crud. Still wondering how 6,5,4 injectors connections can be pulled off at low idle and high idle speeds with no effect on engine performance. WT!!!

Edited by argniest
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ELECTRICAL TESTING RESULTS

OK so I ran electrical connection tests on various things tonight. After removing the dropping resistors, I was able to clean both sides of the connection with deoxit. They actually looked pretty good anyway, but since I needed to test them. Figured I would just clean them while I could. After cleaning them and testing them I reinstalled them back as they were supposed to be.

DROPPING RESISTOR CONNECTIONS

I referenced the FSM and it showed that between all the various connections

on the 4 pin and 6 pin connections I should get 6 ohms.

Well I got 6.2 on all of them. I will assume that is OK, right?

Also, I referenced the electrical diagrams in FI bible to figure out how to do a continuity check on the wires going from the two connectors for Dropping Resistors to the matching pin number on the fuel injector. All 6 of them tested positive with continuity of like .001 or 002 or 003, but mostly .000/.001.

So that seems to tell me the wiring is just fine between the 4 pin and 6 pin dropping resistor connection and the one side of the fuel injectors. The battery was disconnected during all the above tests.

MY GROUNDING POINT

I always used the same ground for all tests that required a ground. I stuck the (-) black probe on a small screw in the doorway at the bottom that holds that black plate on there.

BATTERY VOLTAGE

My battery, when measured at the battery itself was 12.34v and the also, voltmeter gave it a green light.

FI BIBLE TESTING PROCEDURES

Then I went through most of the FI bible and ran all the tests that I understood.

Here is results. The battery was connected, but car was off for these tests.

TEST #1 - (3a) AIR FLOW METER - RESISTANCE #1 ----> 0.206K (Manual says approx 180 ohms)

TEST #1 - (3b) AIR FLOW METER - RESISTANCE #2 ----> 0.203K (Manual says continuity plus small resistence)

TEST #1 - (3c) AIR FLOW METER - RESISTANCE #3 ----> 115 ohms (Manual says approx 100 ohms)

TEST #1 - (4) AIR TEMPERATURE SENSOR - RESISTANCE ----> 2.81K (Manual says 2250-2750 ohms for 68 degrees)

I dont know exact temperature of coolant. But it was maybe 60 to 65 in the garage tonight. I had heater on for a while.

TEST #1 - (5) AIR FLOW METER FUEL PUMP CONTACTS ----> I dont have a pin #20 in my ECU connector

TEST #1 - (6) WATER TEMPERATURE SENSOR ---> 2.98K (manual says 2250-2750 for coolant temp of 68 degrees

TEST #1 - (7) FUEL PUMP RELAY CIRCUIT ----> I dont have a pin #20 in my ECU connector

PROBLEM????

TEST #1 - (8) AIR REGULATOR AND FUEL PUMP CIRCUIT----> 61.3 (tested several times)

this is just supposed to be continuity

TEST #1 - (9a) CONTROL UNIT GROUND CIRCUIT 1 ----> OK CONTINUITY 0.00

TEST #1 - (9b) CONTROL UNIT GROUND CIRCUIT 2 ----> OK CONTINUITY 0.00

TEST #1 - (9c) CONTROL UNIT GROUND CIRCUIT 3 ----> OK CONTINUITY 0.00

TEST #1 - (9d) CONTROL UNIT GROUND CIRCUIT 4 ----> OK CONTINUITY 0.00

TEST #2 - (1) IGNITION COIL TRIGGER INPUT CIRCUIT ----> 11.5 volts

TEST #2 - (2) CONTROL UNIT POWER INPUT CIRCUIT ----> 11.91 volts

IGNITION ON DURING THESE TESTS, BATTERY CONNECTED

TEST #2 - (3a) #4 INJECTOR CIRCUIT ---> 10.50 volts

TEST #2 - (3b) #1 INJECTOR CIRCUIT ---> 10.48 volts

TEST #2 - (3c) #5 INJECTOR CIRCUIT ---> 10.48 volts

TEST #2 - (3d) #6 INJECTOR CIRCUIT ---> 10.48 volts

TEST #2 - (3e) #3 INJECTOR CIRCUIT ---> 10.47 volts

TEST #2 - (3f) #2 INJECTOR CIRCUIT ---> 10.48 volts

I dont know if that is normal or not???? why it would not be 12.xx volts.

Thats all the tests I did, there was like maybe 5 other ones I didnt do.

Its too late and I dont want to mess with anything else. LIghts are going out upstairs.... X=X

EDIT: TESTS I DIDNT DO YET FROM FI BIBLE

TEST #1 - (1) IDLE THROTTLE SWITCH Page 47

I dont know how I can do this test. how can I probe the ports if the car needs to be running, which would imply that the ECU harness is connected, thereby negating my ability to stick a multimeter probe into ECU connector pins

TEST #1 - (2) FULL THROTTLE SWITCH Page 48

Same issue as previous, I dont understand how I am supposed to do this test

TEST #3 - (1) "START" SIGNAL CIRCUIT

I need to do this when I am awake. Didnt feel like doing this at 2am

But I think I know what to do here

TEST #3 - (2) AIR REGULATOR CIRCUIT

I need to do this when I am awake. Didnt feel like doing this at 2am

But I think I know what to do here

TEST #3 - (3) COLD START SYSTEM CIRCUIT

ummmm...I dont know about this....hmmmmm

I think its basically similar to previous tests

My gosh thats it.

Edited by argniest
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Great presentation of data!

~ 6ohms is normal for dropping resistors

I can't recall the air regulator and fuel pump circuit test details. If the schematic shows this going through relay then the 61.3 ohms is probably carbon on the relay contacts or a corroded connector in the circuit somewhere.

The injector test of 12.5 Volts is not measuring battery voltage. It is measuring the voltage at the ECU which will be applied to the injector harness. The resistance between the battery and and connectors and circuitry within the ECU upstream from your measuring point is causing the drop.

btw a fully charged battery (measured with no load) is ~12.8V and fully depleted is ~ 12.0V (Measure after the battery is "settled" and has not just come from being charged by the alternator (during a ride or idling) or after it was just under load.... first thing in the morning is a good time)... btw battery V sould not be an issue with your problem... seems like bad connectors or bad injectors.

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Great presentation of data!

~ 6ohms is normal for dropping resistors

I can't recall the air regulator and fuel pump circuit test details. If the schematic shows this going through relay then the 61.3 ohms is probably carbon on the relay contacts or a corroded connector in the circuit somewhere.

The injector test of 12.5 Volts is not measuring battery voltage. It is measuring the voltage at the ECU which will be applied to the injector harness. The resistance between the battery and and connectors and circuitry within the ECU upstream from your measuring point is causing the drop.

btw a fully charged battery (measured with no load) is ~12.8V and fully depleted is ~ 12.0V (Measure after the battery is "settled" and has not just come from being charged by the alternator (during a ride or idling) or after it was just under load.... first thing in the morning is a good time)... btw battery V sould not be an issue with your problem... seems like bad connectors or bad injectors.

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