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Discussion Starter #1
First off, it's a 1977 280Z. Like any old car it doesn't like cold starts. Once it's warmed up, it runs okay, but not really good. If I shut it off, and start it up while it's still warm, it'll run perfectly for about 5 seconds. No missing, no pinging, nothing. After those 5 seconds, it slowly progresses back to the running like crap stage. It keeps getting worse until about a minute has passed then it stays there. When I watch the RPM's, start is about 950, then 900, and down to about 800. It doesn't have much throttle response but it does have some. When I gun it, (full throttle,) it backfires some and has troubles getting the RPM's up. It then stops going up in RPMs at about 4500-5000, and goes back to idle. Sometimes it goes up to 5000, then drops to 1500 and stays for a second, and goes back to 5000.

Please help me out guys!

Tony
 

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yes too rich.

Clean plugs then check to see that wires and connector to water temp sensor in front of thermostat housing are fastened well and clean.
 

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Discussion Starter #5
Yes the connector and wires are just fine. Could it possibly be that there's too much stuff in the gas? I dumped in a bottle of Fuel Injector cleaner, (for 21 gals,) into 5 gallons of gas, as well as HEET. Could that be the problem also?

Tony
 

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it sounds like you are starting off the cold start valve which is really a 7th injector sending fuel into the intake upstream. What does your exhaust smell like? If it is that rich you may smell unburned gas .that would also explain the backfires. otherwise a fuel injected engine shouldnt backfire
 

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Yes, that is major overkill putting all that you listed into the fuel tank especially with only 5 gallons. Possibly all that stuff you put into the tank loosened up any crap in the tank and went through the system clogging up the filters lines ect... Did it do this before you dumped those additives in the tank???

 

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Discussion Starter #10
I hadnt had it running before now. When I first started it, it ran real bad and the injectors were all gummed up. That's why I dumped all the stuff in. I cleaned out the tank prior to running it, hence the HEET. I'm going to go get a cap and rotor, so we'll see if any of this smooths over.

Tony
 

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Discussion Starter #14
The plugs are brand new. Autolite copper cores, not platinums. The plugs were yellowish when I first had it running, but are now just black and sooty.
 

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Air/fuel problem

usually caused by:

water temp sensor connection problem
fuel pressure regulator problem or restriction in return line
wrong size injectors
afm set wrong
air temp sensor connection problem
ecu problem
 
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