Connor280ZX

I understand. Thank you for your help. I will replace the faulty components in the carb before I attempt to tune it further,

Ok, I've gone through the FSM/tuning pages and I have all the screws and knobs adjusted to factory settings. Can't narrow it down too much because my flow meter hasn't arrived yet. BUT! I discovered something interesting. Every time I give the engine around 2/3 throttle or more, the rear carb piston gets stuck up. I pulled down the piston with my finger and the engine started to idle much smoother. I believe I need to replace the needle and needle seat in the carb to fix this. Correct me if I'm wrong.

On the way. In the mean time, I'd like to know how to at least get the car driveable/running on all 6. I left them all the way unscrewed, and for like 5 miles the car ran much better. Still idled very rich, but would run great above 3k rpm. Next day the car would barely start... Screwed the knobs in all the way this time, and car still runs like shit, but now backfires flames out of the exhaust when I try to gas it off of idle occasionally.

Car supposedly ran "perfect" last time it drove 3 months ago according to the P.O... Got the car yesterday with it running super rich. It would only idle on 4-5 cylinders and puff out black smoke, and when throttle was applied, huge pops out of the carbs and the engine would cut down to maybe 2-3 cyl. Today, I unscrewed the mixture adjustment knobs all the way, cleaned the needles and pistons in the carbs (Weren't gummed up much at all) set the timing to 10BTDC, checked fuel pressure (4 psi), ran a compression check (175-185psi on all 6) and verified that the chokes aren't sticking. The car runs much better, but still runs stupid rich, sputters and wants to die out below half throttle. Carb backfire is no longer present however. When I put my foot in it, the engine clears out and pulls good on all 6. Other than that, still having issues. Could this may be related to the carb floats being stuck or something? I'm kind of new to the carburetion game...

I mentioned that when holding the engine speed at 2000 RPM, that the ECU light does not blink, or come on at all for that matter. I've been corresponding with a local shop that specializes is classic Datsun/Nissan cars, and the owner advised that I put a multimeter to the o2 sensor connector and read voltage at 2000 rpm. He told me that the voltage should fluctuate between 0.01-1.4v constantly at that rpm and should not remain steady. The lower the voltage, the more the ECU is trying to enrichen the mixture, and the higher the voltage, the more lean. I'm getting a rock steady 0.021v throughout ALL rpm ranges including idle and 2000 Rpm, which means the ECU is trying to enrichen the mixture. HOWEVER, no matter what I do to change the mixture (pinching off return line, introducing vacuum leaks, unplugging CHTS etc) I cannot get a different voltage result. Tried 3 different o2 sensors and swapped ECU'S but the results stay the same! I'm at a total loss... May the Z gods have mercy on my soul.

Any thoughts? Still having issues

Ok, with the infrared laser thermometer I got 202-206F in front of the cat, and 297-301F after the cat. This was after an 8 mile spirited drive.

Is there anything else besides the CAT temp that I should check before I go back in to smog it?

I'm also getting 21 in/hg of vacuum from the manifold.

Got the valves adjusted, and the car idled smoother for sure. There's hardly any fluctuation in the tech needle now. When I got the car, the o2 sensor wire was severed, and I attempted to reconnect it with a splice connector along with a new sensor. There seemed to be two layers of copper inside the wire, and they may be contacting each other with the way I spliced them together. Not sure if that matters though.

Checked my valve clearances. .007-.009mm cold. Should be. 017mm cold according to the Haynes repair manual. Couldn't adjust them due to the lock it's being way too tight and starting to round off when I turned them. Will have to take it in to get them adjusted.

Are you talking about the teeth being worn? I pulled the oil pump to see if the shaft was lined up correctly (which it was) and the teeth looked fine to me.

Swapped ECU's with one from an '83 Turbo. Green light comes on with key on, but still nothing at 2000 rpm. I also can't get the timing under 22, the dist is turned all the way ccw and that's as far down as it'll go.

I have done resistance tests per FSM at the sensors themselves, and at the harnesses. Both yielded results in acceptable resistance range. There's a receipt in the glove compartment of a work order to replace the AFM and TPS with new units. This was from 2008. I can assume that the AFM is a rebuilt one. In that case, I will re adjust timing before next test. I also found that the inspection light from the ECU is not coming on. Not at they key ON position, or at 2000 RPM.

Car is also bone stock.