Code 23

I have a 1985 Z-28 305 4-bbl. H model Camaro. I am getting a engine code 23 from the ECU. My question is, I read that the code 23 is for a 'Manifold Air
Temperature Sensor. As far as I can find is that my carbureted engine doesn't have that sensor -- or does it? Does anybody know what his error code may be indicating? Could it be the 'Throttle Position Indicator' on the carb? BTW, I just fixed a bad vacuum leak but the car still seems to be running lean. Also I am getting a steady vacuum reading around 18 PSI.
Thanks, AA
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Haynes Techbook says the following for Chev/GM '86 to '92 (yeah I know... but let's just look)
Code 23 Probable Causes
(23) Open or Grounded M/C solenoid (feedback carburetors)
OR
(23) IAT or MAT (intake or manifold air temperature) sensor out of range, or low temperature indicated... (Buick and Oldsmobile)
OR
(23) EST or IC circuit fault... but that's supposed to be for Cadillac DFI.
Anyway, these code definitions are not specifically for an 85, but doubt there was much diff from 85 to 86, especially where what you've already read is the second in it's list of causes. I'd look into the first one there... what do you have to loose, eh?
Vaccuum leaks are the worst......
Take care.
-Merius.
'89 Firebird 2.8L MPFI (red)

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I read the MAP sensor with a Dwell/Tach/DMM and as far as I could see it was bad -- voltage read .5 volt. Replaced it but didn't help at all, I hate when I do that! I am going to test the M/C solenoid next and see what is going on there. I'm about sick of this problem so I ordered a ALDL connector for my laptop. This type computer thing has happens so many times I just decided to see if that will help detect my engine problems faster. It should come in handy for the future too. I'll let you know if I find the problem and what is was. Thanks for the info!
I might as well get a Haynes manual too, I got all the other ones anyway! Worthless as some of them are. :)
AA

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