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I recently purchased a z-car project, '76 280z. It ran rough when I purchased it. I replaced plugs, plug wires, cap, and rotor. This cleaned up the performance, but I still experienced popping and sluggishness under acceleration. I was also unable to get the car through DEQ. I replaced the air flow meter and that took care of the popping under acceleration, but still didn't get it through DEQ. I found a fuel leak at the filter and replaced a couple of hoses. This cut the hydrocarbon count in half, but was still too much to pass DEQ.

Just when I thought I was getting close, the car developed an alter ego. Now, it runs good when cold but has no power when warm. It has a heavy fuel small (very rich) and exhausts black smoke when it's performing this way. Also, when I turn the car off it won't resart until it cools down. Following the manual, I checked the throttle position sensor and found it to be in working order. I notice some small gas drops on the ground around the fuel pump, but can't find a leak.

I hate trying to diagnose the problem by throwing $50 - $100 parts at it until it gets better. I would be very appreciative of any advice.
 

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> I recently purchased a z-car project, '76
> 280z. It ran rough when I purchased it. I
> replaced plugs, plug wires, cap, and rotor.
> This cleaned up the performance, but I still
> experienced popping and sluggishness under
> acceleration. I was also unable to get the
> car through DEQ. I replaced the air flow
> meter and that took care of the popping
> under acceleration, but still didn't get it
> through DEQ. I found a fuel leak at the
> filter and replaced a couple of hoses. This
> cut the hydrocarbon count in half, but was
> still too much to pass DEQ.

> Just when I thought I was getting close, the
> car developed an alter ego. Now, it runs
> good when cold but has no power when warm.
> It has a heavy fuel small (very rich) and
> exhausts black smoke when it's performing
> this way. Also, when I turn the car off it
> won't resart until it cools down. Following
> the manual, I checked the throttle position
> sensor and found it to be in working order.
> I notice some small gas drops on the ground
> around the fuel pump, but can't find a leak.

> I hate trying to diagnose the problem by
> throwing $50 - $100 parts at it until it
> gets better. I would be very appreciative of
> any advice.
your problem could be a resistor in the wiring from your water temperature sending unit. when the resistor gets old, it goes bad and causes the computer to think the car is running cold all the time, thus the rich mixture when warm. the actual piece is located in the wire that leads from your temp sensor at the front of the head on the intake side of the motor. if you strip away the cover on the wire, you'll see it spliced into the wire with solder. it needs to be cut out and replaced. the only thing i can't remember is the proper resistance is for the replacement. hopefully someone will know and post it.
hope this helps
andy [email protected]
 
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