280z 280z 78 Wont idle, Running Rich, out of ideas.

[Zed Head]

On 1/20/2020 at 8:27 PM, Cyrillink said:

completely useless does not do anything when i adjust it counter clock wise, but when i shut it all the way the car stop running.

The fact that you can kill the engine with the idle adjustment screw is a sign that any vacuum leaks are small.  You're cutting off the air supply.  If there was a vacuum leak it would most likely keep running.

The blown FPR diaphragm is an easy one to check.  Pull that vacuum hose and check for fuel.  Run the fuel pump while it's off, if it's blown fuel will drip from the FPR.

[Cyrillink]

On 1/22/2020 at 2:07 PM, Zed Head said:

The fact that you can kill the engine with the idle adjustment screw is a sign that any vacuum leaks are small.  You're cutting off the air supply.  If there was a vacuum leak it would most likely keep running.

The blown FPR diaphragm is an easy one to check.  Pull that vacuum hose and check for fuel.  Run the fuel pump while it's off, if it's blown fuel will drip from the FPR.

 

On 1/22/2020 at 9:41 AM, Dave WM said:

if you think you have a vacuum leak a smoke test will help locate it. blow smoke into the brake booster port and look for leaks. You need to cap off the AFM with a stryofoam cup. You should feel some resistance when blowing the smoke in. vacuum leaks are a common problem anytime you have poor running issues.

 

Vacuum leaks, rust in fuel lines and bad electrical connections are a frequent issues that are easy to overlook.

 

Spend another few hours working on this clunker  ? ( as you can see from my tone about one of my favorite cars of all time)

Today tasks,

Cleaned all the spark plugs again,

Started her up ran well no idle still.  Did find a small hex to adjust the butterfly but what i gather dont mess with it. wrong way to get a good idle.

Had the A/F Ratio gauge hooked up and was right super super rich. 

Now, the AFM is brand new (re-manufactured by whom unknown)  (maybe an issue why the car has so many problems)

Replaced FPR (it was not working at all leaky)

Put the car together a 100% and then started working with AFM. 

AFM - Idle A/F Ratio did nothing. Rich AF (not in the good way)

I hooked up my leak tester and noticed that there was a bit of smoke coming F.I.C.D. solenoid. (i think that's what it is called.) It was minor but  I am still going to take all the accessory hoses and zip tie them shut. Connect my vacuum gauge and really see whats up.

Going to use this is a reference, http://www.atlanticz.ca/zclub/techtips/vacuum/

Will keep you posted, thanks for joining me on this fun journey, learning a ton!

 

 

[Dave WM]

The only problem with using a vacuum reading to diagnose is its going to have poor vacuum since its running badly, I use vacuum gages for checking sticking valves or other minor issues on a engine that otherwise seems running pretty well. The idle mixture control is very limited in range, so if you have other issues like a poorly calibrated AFM, then its not going to be of any help. I presume you are in a cold environment, my guess is still the temp sensor, any excessive resistance is going to make things worse. You must make sure you are getting the correct resistance AT THE ECU 36 pin connector. Of course the new/rebuilt AFM is always going to be a nagging thought. If I was sure the rest of the system checks out I would be tempted to remove the rubber elbow from the air cleaner to the afm so I could get at the flap, then try to get some way of manipulating that flap while doing all this testing. The only problem I have with this is its so typical that anytime there is a problem the go to solution (generally incorrect) is to suspect the AFM, BUT if its not OE or been messed with then all bets off.

Edited January 26, 2020 by Dave WM

[Dave WM]

I cant recall did you try removing the oil filler cap while it was running? if so did it have any effect?

[Zed Head]

3 hours ago, Dave WM said:

You must make sure you are getting the correct resistance AT THE ECU 36 pin connector.

Agree with Dave here.  I don't see any electrical measurements.  The 280Z EFI system is all about the electrical system.  Almost pointless to try working on it without a meter and knowledge of how the system works.  Use the 1980 EFI Guidebook.

 

[Cyrillink]

On 1/26/2020 at 3:12 PM, Zed Head said:

Agree with Dave here.  I don't see any electrical measurements.  The 280Z EFI system is all about the electrical system.  Almost pointless to try working on it without a meter and knowledge of how the system works.  Use the 1980 EFI Guidebook.

 

 

On 1/26/2020 at 11:52 AM, Dave WM said:

I cant recall did you try removing the oil filler cap while it was running? if so did it have any effect?

 

On 1/21/2020 at 3:59 PM, siteunseen said:

Let me play! 

If idle adjustment does nothing I'd say you have a vacuum leak. Borrow a gauge from a local parts chain and tell us the numbers.

https://images.app.goo.gl/Y2DgmnNPhL95LTdg8

 

 

Hey Team,

Had a few more hours going at the 280z last night i was still sure i am leaking from somewhere and was right. 

So here is the quick update.

Took of the throttle body and made a block off plate and ran a vacuum test of the whole system again just to be a 100% sure it was sealed. With about 30-40psi on the smoke machine.

Saw i was leaking vaccum leak from Engine Cap, Cold Start Valve, Charcoal Canister, and few places on the throttle body (secondary air pump). ANYWAY. got really annoyed bought every possible hose under the sun and replaced. Some of them were loose. tightened everything up.

Starting to check the wires and resistance. Notices an intermittent issue with fuel pump. replacing wires.

Still checking and hoping with the new vacuums plugged up.

I saw a FAST efi for the datsun thinking of making the recommendation of installing it. 

[siteunseen]

I use a big Oring under my oil cap. I think there's a flimsy gasket under the cold start valve. You could make one from an old cereal box or buy some gasket paper at the parts store. 

Progress!

[Zed Head]

35 minutes ago, Cyrillink said:

Took of the throttle body and made a block off plate and ran a vacuum test of the whole system again just to be a 100% sure it was sealed. With about 30-40psi on the smoke machine.

Saw i was leaking vaccum leak from Engine Cap, Cold Start Valve, Charcoal Canister, and few places on the throttle body (secondary air pump). ANYWAY. got really annoyed bought every possible hose under the sun and replaced. Some of them were loose. tightened everything up.

I saw a FAST efi for the datsun thinking of making the recommendation of installing it. 

There are always at least two valves open in the engine.  I've never been a big fan of that kind of test although it can be informative.  You'll blow smoke through an open intake valve and can get leakage past the rings.  Plus the PCV valve.  Have you checked the PV valve?

Don't forget that the FAST system is basically the same as the stock Nissan system.  Same sensors, same responses.  Tuneability to cover mistakes is better but you'll just be covering up problems.

Still looks like you haven't really absorbed what we were saying - rich, wet, plugs is not typical of a vacuum leak.  Not sure why you're looking for leaks.

[siteunseen]

Speaking of valves. You should check yours to see if they're in spec. cold.  And try leaving the cold start valve unplugged, they get stuck open and dump fuel in the intake. I guess plugging the fuel hose would be best if it's stuck open. 

Did you replace the fpr? Seems like you said it was dripping fuel. 

Good luck.

Edited February 1, 2020 by siteunseen

[Dave WM]

maybe something in this will help. I have a spare ECU that I will test on this rig later. Maybe look into see if there is a way to hookup a 02 sensor for some closed up checks. I think its pin 24/23, if those pins go somewhere on my spare ECU, perhaps I can hook up and see what happens with a variable voltage supply...

 

Edited February 1, 2020 by Dave WM

[Cyrillink]

13 hours ago, siteunseen said:

Speaking of valves. You should check yours to see if they're in spec. cold.  And try leaving the cold start valve unplugged, they get stuck open and dump fuel in the intake. I guess plugging the fuel hose would be best if it's stuck open. 

Did you replace the fpr? Seems like you said it was dripping fuel. 

Good luck.

Yes replaced the regulator.

Sorry actually working on this car now.

4 hours ago, Dave WM said:

maybe something in this will help. I have a spare ECU that I will test on this rig later. Maybe look into see if there is a way to hookup a 02 sensor for some closed up checks. I think its pin 24/23, if those pins go somewhere on my spare ECU, perhaps I can hook up and see what happens with a variable voltage supply...

 

I will test it. now.

[Cyrillink]

6 hours ago, Cyrillink said:

Yes replaced the regulator.

Sorry actually working on this car now.

I will test it. now.

So i was working on the car today and checking resistance and connections i noticed that the Air Regulator was not working and the sensor was almost broken off. Do we think it might have been an issue first of all that was causing the bad idle? 

was thinking of ordering this part as a replacement : 22660-45P00 according to Chickenman's recommendation.

So just as a safety measure i replaced the fuel pump.

OK, newest update this was kinda cool first time i seen the car running well.

I was working and testing the car had the AFM connected electricly but the boot was off by about an 1"  enough to see that there was an opening.

I started the car up she ran at about 1k rpm REALLY NICELY! i mean i was thrilled to see her run. once i put everything together she was wabbleing again. which lead me to my earlier discovery.

Also i am going to block off the cold injector to test if its leaking into the motor which is causing to go super rich. had to clean the plugs again twice. and yes i will be on my 6th replacement set. HAVING a blast.

BUT WHAT I FEELING TO SEEING HER RUN!