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

[Cyrillink]

12 minutes ago, siteunseen said:

I would loosen the distributor and have someone crank it over while you turn the distributor. It should get better one way and worse the other.

You say it cranked but now it won't. Check the simple stuff. Coil wire, rotor button, etc.

Doing that now.

[Zed Head]

4 hours ago, Cyrillink said:

Timing light is firing about 15 degrees of TDC on crank. Car wont start (facepalm). Distributor is set to factory marking. not sure what da hell is going on.

You might be getting cam timing confused with ignition timing.  It's a common misconception.  You groove and notch have nothing to do with ignition timing.

You should confirm that the ignition timing mark is at zero when the #1 piston is at TDC of the compression stroke.  That's the starting point for ignition timing. Not uncommon for the marks on the damper to be in the wrong place.  Could be a bad damper.

Edited January 12, 2020 by Zed Head

[Cyrillink]

1 hour ago, Zed Head said:

You might be getting cam timing confused with ignition timing.  It's a common misconception.  You groove and notch have nothing to do with ignition timing.

You should confirm that the ignition timing mark is at zero when the #1 piston is at TDC of the compression stroke.  That's the starting point for ignition timing. Not uncommon for the marks on the damper to be in the wrong place.  Could be a bad damper.

I will send pictures first thing tomorrow morning with piston #1 at TDC, I am taking a break. busted my hand on the radiator pretty badly while cranking the motor setting to TDC

[Zed Head]

Ouch.  You can move the crankshaft by putting the car in high gear and rolling it.  Future reference...  

[Cyrillink]

3 minutes ago, Zed Head said:

Ouch.  You can move the crankshaft by putting the car in high gear and rolling it.  Future reference...  

Will try tomorrow. 

Thanks for the heads up!

[siteunseen]

That hurts like hell, like a hundred papercuts.  If you have the valve cover off you can use the cam sprocket bolt too.  You don't want slack on the driver's side of the chain so if you go past the mark don't roll the car backwards.

[Cyrillink]

On 1/11/2020 at 8:38 PM, Zed Head said:

You might be getting cam timing confused with ignition timing.  It's a common misconception.  You groove and notch have nothing to do with ignition timing.

You should confirm that the ignition timing mark is at zero when the #1 piston is at TDC of the compression stroke.  That's the starting point for ignition timing. Not uncommon for the marks on the damper to be in the wrong place.  Could be a bad damper.

On 1/11/2020 at 4:03 PM, siteunseen said:

I would loosen the distributor and have someone crank it over while you turn the distributor. It should get better one way and worse the other.

You say it cranked but now it won't. Check the simple stuff. Coil wire, rotor button, etc.

Ok, Hit another brick wall today. Hahaha

Well,  Car is together. My Knuckle healed up.  

So my previous post was a none starting issue.. FIXED - Wet Spark PLUGS.. So, went out and exchanged the spark plugs, Installed. Car started. YEY

I adjusted the Ignition timing using distributor cap to 10 to degrees of TDC at 800RPM . The car idles more or less okish at 600 - 700rmp. The throttle screw - 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. One turn on the throttle body Idle Screw counter clockwise and the car starts idles rough same way at 600 700rpm.

So, I was reading some guys had clogged injector, pulled the system CLEANED EVERYTHING. Put it together - same issue but the car is running rougher. Pulled the plugs WET again. Decided to run the car a bit to see if she runs better. NOPE Nada. same issue rough idle tons of smoke.

Started messing with the Idle A/F Ratio but i don't have a A/F Ratio meter,

Going to see if i can make A/F Ratio Meter using an old gauge laying around. The 280z does not have any O2 connected to it, with after market pipe it has on it. Might need to make a hole in the exhaust  or just buy EZ Clamp-On Tailpipe to attache the o2 sensor for tuning.

Thanks guys.

[Zed Head]

Wet plugs is too much fuel not clogged fuel supply.  The A/F ratio screw is for small adjustments.

Wet plugs are a gross A/F ratio problem.  Wrong injectors or bad readings from the coolant temp sensor, or maladjustment of the AFM.

Edited January 21, 2020 by Zed Head

[Reptoid Overlords]

Is the PCV system connected in the stock configuration?  Crankcase breather tube to PCV valve on bottom of intake manifold/ Valve cover breather to throttle body. 

[Dave WM]

Don't know if this has been mentioned but wet plugs..

leaking fuel pressure regulator thru the vac holes /regulator not working. check for fuel at the vac hose/ use a pressure tester for fuel pressure test.

stuck open cold start valve

CTS (temp sensor) or wiring from it.

throttle  position working correct.

leaking injectors, check with bleed down test how long does the fuel pressure hold after engine off.

fouled up AFM (test with a voltmeter and battery for function, not a test for calibration but at least checks for gross function) hope its not been fooled with on the big main spring.

ECU, not sure how to test. I have though about doing a scope test in a controlled environment to see the waveform generated when operating normally under stated parameters (heat rpm throttle position sensor). That would give a base like results to be compared with on problem engines. What would be great is a test stand that you could plug in a ECU and feed it inputs then scope the output under an inductive load to simulate the injectors. sounds like a Capt. Obvious  project to me...

 

 

 

[siteunseen]

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

 

 

[Dave WM]

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.