Just got an 84 300zx turbo yesterday, drove it from Danbury to Meriden and it ran mint. I stopped at a store and when I started the car it started up fine but then in a few seconds the idle started to drop and it bogged out and died. Had it towed home and was checking over everything today and ran it for codes and got 23..idle switch circuit and 31 load signal circuit or ECU. Started it again and when the revs would start to drop i gave it some gas and then it smelled like gas really bad inside but not under the hood. Anybody have any ideas of what could be the problem? Any help is appreciated.

It sounds like a gummed up Idle air control. Just a guess as Im not familiar with the set up in that particular car.

I know it can't be......but it sounds like the plain old-fashioned vapor lock of the 1973 flat-top carb carz.

After running awhile, you shut it off and the engine heats up (the fan is off and the water pump isn't circulating any coolant). That heat affects the fuel line, causing slight percolation, which allows air bubbles in the fuel line. Fuel pumps can't pump air, so the carbs starve at anything above an idle.

That was all cured by electric pumps at the tank, insulated fuel lines and fuel injection.

So it can't be. Anything with a computer is out of my league.

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1970 240Z

I checked the auxillary air control valve...if thats the same thing..and it looks brand new. I hear ya Frank, anything to do with the computer system and wiring is all too complicated for me Which leads to my next question..Would it matter if it has an ecu from an AE? Just trying to rule out any possible causes.

Well, I would *think* so ~ the brain telling the wrong signals to different equipment? Maybe.....

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1970 240Z

I got an old ecu from an 85 turbo layin around so I'll pop it in tomorrow and see if it does the trick...fingers crossed

Try cleaning the harness connectors to the ECU with some electrical spray cleaner. Plug and unplug the connectors several times to clean off any corrosion. I have to go through that process a few times a year with my 280zxt. Clears it up every time!

Since you just purchased the car you may want to go through all the fluids including changing out the fuel filter. Had the car been sitting for a while? There may be some rust in the gas tank that worked itself loose during your first drive and has clogged the fuel filter.

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Phil
1981 280zxt - Now in the care my son!
2014 370Z Sports Touring Roadster

Glance around for vacuum leaks while you're at it. Any split vacuum hose might cause most of those problems (except the fuel smell).

I actually like Phil's filter suggestion. If your fuel filter is clogged, the fuel smell might be the fuel which couldn't make it thru the clogged filter returning to the tank under pressure. Insufficient fuel would make it idle poorly and stumble when you opened the throttle, too.

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1970 240Z

Putting in another ecu did not help and the the connecttors are corrosion free. The car was sitting for 3 weeks but has all new fluids but...the fuel filter has little bits of something all over it so I'm gonna replace that a little later and go over every vacuum line.

So I did some research on the ecu code 23 (idle ciruict switch) and it said to check the tps so I just put on another one and it helped It doesnt die on me now but the idle still bounces around alot. So now I just have to find the reason for that..but I'll wait until tonight to do that..it's way too hot today!

A "rolling" idle (hi-lo-hi-lo) is either electrical or fuel related. A vacuum leak would be considered "fuel related".

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1970 240Z

with my 280 a wavy idle means a fuse got wet. so i pull them out dry them and bam problem solved. so it's other a bad electrical connection somewhere. check your connectors. or vacuum leak.

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Mike Tubiak
1978 Datsun 280Z - HLS30-438694

Also indicative of what we used to call a "lean surge"--
at least up to and including the 280Zs......
FWIW,.........~Rick~

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All Z Best,.......Kathy & Rick

1969 Z.CAR (#00013 10/69) 8/30/76
1969 ITSA.Z (#00171 11/69) 8/24/73
1970 OLD.Z (#06289 6/70) original owner
1971 510 2dr since 12/31/75
1969 1600 rdstr (our 160-Z)
1971 (#19851 1/71) sold
1975 75.Z (#01343 1/75)

She seems to be running fine now...but now theres a loud kind of tapping sound coming from the middle of the dashboard. I just dont understand where all these problems are coming from I appreciate all the help and suggestions though.

Check for leaves (or mouse nests) in your vent system. As hot as it's been lately, I just KNOW you're running the AC. Something might be touching the fan barrel in your vent. Run the fan at different speeds to see if the tapping changes.

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1970 240Z