This is related to my previous post. I just disconnected the vacuum to the sensor inside the air intake ( 85 Caprice 305 Roch qjet)... becasue it was ALWAYS sucking in hot air. But maybe it is SUPPOSED to if the air temp is below xx degrees. Now it is always sucking in cold air, but now I am stalling sometimes at partial warmup. I am going to reconnect the vacuum to the sensor and see if it stops my stalling.

Anyone know if it's normal for the air intake to be taking in only heated air, even after engine has warmed up ?? Maybe if the air temp is below a certain temp ?


Thanks

 

The air temp sensor is located in the air cleaner housing, in between the carb vacuum and the vacuum motor on the snorkel. If that sensor is bad, the motor could be closing the snorkel flap all the time. It typically opens when the engine is warm, even if the outside temp is cold. I believe the sensor is looking for ~110 degrees inside the air cleaner.

Not being connected could very well cause the problems you describe in the other post.

Try replacing the sensor and see if that makes any difference.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/LB9 block, ZZ3 cam and intake, WP 305 heads ported & polished, Hooker headers & y-pipe, hi-flow cat).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & shift kit, 3.08 10-bolt, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.

 

Definently. All that stupid thermac system is designed to do is aid warm-up performance. Stick the carb preheater tube back on. The air cleaner sensor is kinda hard to find so it may cost $20+.

I can't wait for spring when i'm getting an open element air cleaner...
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--Steve S--
1984 Trans Am 305 LG4, 5 speed
RPO codes point to Recaro version
Daily Driver, Flowmaster 80 Series

[This message has been edited by 84TransAm (edited January 31, 2001).]

 

Well, the intent was to give the carb a fairly consistent air temperature over a wide range of operating conditions, so the "calibration" would stay consistent as well. The biggest aid comes with cold running, but a slight off-idle stumble can also result if it isn't getting the warm air it expects.

Anyway, try getting a sensor (should be able to find one from most any GM carb'd application) and see if that solves your problem.

 

57kid and 84 transam, Thanks for the replies. Just to make things more uncertain, the sensor has now decided to open the snorkel flap SOMETIMES. This morninng, after I reconnected the heat tube, I took it out on the highway for 15 minutes, pulled over and checked. The flap was closed( letting only heasted air in), but as I watched, it opened all the way as the engine idled. Took about 1 minute to open fully.

Apparently I am breathing hot air while driving, and cold air at idle. Temp was 41 degrees this morning. I did NOT stalll out this morning, which is good.

I am running a 180 stat instead of the stock 195. Could the 15 degree colder engine temp be affecting the operation of the sensor ? Less radiant heat from engine ?

I did find a sensor at AutoZone for only $11.95 on their website (but the store clerk said it was really $17.99). Strauss had one for $24.99 ouch.

The sensor seems to be working, inasmuch as it opens the flap at hot idle, when the air is moving slower, and is able to get hotter than while driving.

 

that sounds odd. Maybe the vacuum line leading to the flap has a leak, or the vacuum hose to the air cleaner was hooked up to the wrong port on the carb? good thing u didn't stall out. What u could do is buy that sensor, c if that does anything, if not return it [make sure to make it seem unopened]. They aren't cheap parts cuz they rarely go bad. Definently get a new one though, who knows when u might have this problem again w/ 1 from a junkyard, plus it is bound to be under warranty for at least a year.

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--Steve S--
1984 Trans Am 305 LG4, 5 speed
RPO codes point to Recaro version
Daily Driver, Flowmaster 80 Series