240260280z

Hi Mike, Maybe we should all step back and look at some other areas. A picture of all 6 plugs side-by-side would help determine if it is a broad over-fuel issue or localized to a few cylinders. Have you conducted a pressure test recently? if so the results would be interesting. Have you checked the valve lash recently? How is it?

There is an old post about the EGR rotting through and polluting the intake with too much exhaust. It is worth a check.

A friend just bought a new Cannon with linkage on Ebay for ~ $300.

Mike, I find the 7902 seems to link to: 1991-1992 Mitsubishi Galant Fuel Injector - Fuel Injection ... www.partsgeek.com/gbproducts/WC/7083-01011314.html Fuel Injector, Fuel Injection Corp. Injector SKU: 7092-01011314 R Another injector for the 91-92 N/A 2L Gallant is Part No. 155-0213 Flow Rating: 12 - 24 lbs/hr Fuel Pressure Rating: 43.5 PSI Hardware Included: No Line Repair Kit: No New Or Remanufactured: Remanufactured OE Replacement: Yes Pressure Rating: 43.5 PSI Seals Included: Yes The data is not specific enough. Stock Z EFI injector is ~18lbs/hr

I have heard about this "4500" limit but don't think a 4500 rpm limit exists until someone shows me the circuit and its purpose. I can rev to 4500 out-of-gear with very little air by hand reving or I can cruise down the highway in 3rd and hold at 4500 or I rev to 4500 WOT in 5th tearing down a straight at Bonneville. The CFM of air entering the engine is different for each 4500 and the AFM Vane will be in different locations. It is a bit of circuit de-constructing that is required to figure it out for ourselves. Even the Nissan EFI fuel table (below) does not show the AFM contribution! So there are a lot of unknowns.

One plug looks much richer than the other. I wonder if something else is going on?

The analog nature of the 280z ECU would require a frequency reference or frequency to voltage reference and a comparator tuned to flip at 4500 rpm for the input from the AFM flap. It would be interesting to see if this exists in the circuitry.

I think you just have to lean the AFM (just tighten the spring)! I missed that you were 1 mile high. The AFM calibration procedure using the water is for sea level. My friend bought a 510 from Colorado and we picked it up in Boston. It ran like crap until we enriched the mixture. I think your problem would be the reverse. For completeness if you could read the part number on the plastic edge of the injector that would help us help you!

The unisync fits in tighter spots and fits on more carbs. It can measure a larger range of airflows. It is also very tough (metal) and can live in a tool box. The STE (Modles SK and BK) is designed for airflows where 1 barrel feeds 1 cylinder. It has a more precise gauge and is easier to read. It is big and made of plastic so it is difficult to fit on some carbs. Adapters are made that can help. I like using the Unisync on twin SU's and STE's on triple webers.

http://www.reuters.com/article/2015/03/22/us-pirelli-chemchina-idUSKBN0MI0PQ20150322

If all plugs are sooty then problem will be common to all.

Don't chute me Mr. Policeman! http://www.speedhunters.com/2012/10/a-9-second-700hp-street-legal-datsun-510/

Hi Mike, The graph's bottom layers (coolant temp sensor and air temp sensor) seem to affect the richness the most. I had a coolant temp connector come off once and my car lasted about 10min before the plugs fouled black. I have never had a chance to "play" with an EFI Z and my A/F sensor but hopefully I will this summer and I can map what the A/F changes are. I'll finally be able to quantify the EFI components. For your car if you tighten the AFM spring it should eventually start leaning out the overall mixture to get you out of the deep end.

Reminds me of being a kid again! Great price for all that metal.

We are all in the same boat. I'll have mine on a motor later this iceage I mean spring.

This should help: http://atlanticz.ca/zclub/techtips/efisystem/overview.html and the picture below: #1 only occurs when you crank and when it is cold outside. It is the Cold Start Valve. #2 is your idle enrichment and it continues while the car warms up and when it is warm until you press the pedal and cause the TVS to move. #3 is extra fuel added by 6 injectors when cranking #4 is extra fuel added by 6 injectors when cranking and while the car warms up at idle #5 is a blip of extra fuel when coming off idle. it will blip when you change gears too and take your foot off the gas for a moment. #6 is the TVS at WOT position. So your TVS controls the adding of extra fuel at idle, at WOT, and when you come off idle (blip).

And they drove happily ever after. --- The End --

They could have been set tighter before you measured or the valves could have seated more (worn in) and risen the difference from nominal. Nothing to worry about. You can do a compression test to see how well they are seating.

AFM and temp sensor measurements are fine!

I measured 6 to be at or near ground so the resistor array and the temp sensor seem to be in series from the diagram but are not.

yes you will hear more tap by opening the lash. FYI the oil passage to the head from the block is between 3 and 4 on the passenger side

DIY rod balancing. Warmup your grinder or belt sander!

Maybe bending the wiper so that it touches a different part of the trace (where it is not worn) will help. Prayers for your son this week at church.

Just a thought: We set "valve clearance" but we actually set cam-to-rocker clearance. The real valve clearance is ~ 1.5X greater. No worries, I checked the FSM and the EM picture shows measurement at the rocker... not the lash pad (where it is more accurate)

FW I was lazy and never probed the AFM circuit board with the carbon trace enough to tell how much resistance it adds to the chain of surface deposited carbon resistors (dark rectangles) I am guessing the carbon trace has some resistance like a regular "pot". Especially when looking at the funky sawtooth traces