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Idle woes. . bucking . . and stalling engine with Behr AC


sealions518
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I have a 72 tii with a Behr AC system in it. I have not been able to run the AC when it's hot outside. The car tends to run slightly differently when it's hot (SoCal high 80s) and I know that if I try to run the AC the car is going to die as soon as I'm off the accelerator and the rpms drop down to idle. With LA traffic you can imagine how many times that happens :/ 

 

Last night I followed the fuel pump manual from the tii registry to make sure all of that was in order (my tii has the newer tuna can). I do notice that if I make the car run leaner by turning in the screw then the AC can be run without the car dying but it also causing some slight bucking when driving (more so when the ac is off). If I make it run richer then the AC will surely cause the car to die but it's a smoother ride.

 

Now I know it's a 45 year old car and they don't have the modern systems to account for AC on/off but I have heard of others on the forum using these cars in my home state of AZ with AC.

 

Is this fixable?

 

Thank you,

 

Josh

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I don't know if it can be rigged on a tii, but on carbureted 2002s it's possible to install an "A/C idle speed booster."  This is a small solenoid that's wired in parallel with the compressor clutch so that when the A/C is on, it prevents the idle from dropping to its normal point.  This prevents too-low idle resulting from the compressor's drag on the engine and subsequent stalling.  I rigged one up on my '73 by placing the solenoid where the decelerator diaphragm used to live, but I don't know if there's a similar location on a tii's accelerator linkage that would work.  

 

Unfortunately the solenoid I had died several years ago so I removed it or I'd post a picture.

 

Feel free to chime in here, tii owners... 

 

mike

Edited by mike
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First..what screw are you talking about?  Take a look at the picture...the screw for idle is access from the outside...the one inside is for mixture. You need to get timing, mixture, plugs, points, coil ....all in order.  Once you do that you can mess around with the idle.  There is no reason why your idle can not be set when the engine is warm at 950 rpm and when you turn on the A/C  it may drop down by 100rpm ...sound different but it SHOULD NOT DIE on you. 

I too have a 2002tii and if it is tune ...all should work just fine if the car is in tune.

 

Abe

ccs-32029-0-69792300-1429556353.png

Edited by abe2002tii
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Thanks for the responses. Yeah I'm talking about the mixture screw . . As far as I know timing, points, and coil are all in order. The rebuilt motor only has about 7k on it and all of that was taken care before I purchased it (car has Pertronix). I replaced the plugs not too long ago and I attempted to do the mixture myself yesterday. I referenced the article from Jim Rowe and Jim Brenton and I think I did it correctly but I am a newbie for sure. The car will idle just fine with the AC on its just when it goes from a higher RPM back down to an idle it usually dips below what would be the idle before settling back up there (about 900-1000 rpms). This dip down is where the stalling occurs. I am all for learning on the job to do this myself (one of the reasons I wanted to get into these cool cars) but it's sometimes difficult to know where to start.

 

Josh

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1 hour ago, sealions518 said:

I do not have a CO reader or gauge :/ perhaps it's time to take it in to get properly adjusted? I was really hoping I could tackle this myself but I think I have much more to learn. How much should I expect for that type of work?

Analog AEM brand Wideband o2 sensor gauge kit from  Jeg's isn't that much, but very helpful in tuning both a tii and carbureted 02.  Welding the 02 sensor bung is the hardest part.  You are just guessing by making adjustments that may or may not make improvements to the performance of the car.

 

Did you try downloading the Behr a/c instructions manuals from the tii registry website?  

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