madkaw Posted March 8, 2011 Share Posted March 8, 2011 I've tried searching this several times, but haven't found someone with a similiar experience on their 81ZXT. Engine performs great under all conditions except when a selection on the auto climate control demands the use of the A/C compressor,i.e. defrost mode or a/c. If I have any selection on the climate control other than economy, the engine will stumble badly around 3000rpm. I have checked all the vacuum lines that I can see and replaced all that I can get a hold of. The only ones that would be question would be in the dash. The second I turn the climate control off, the engine smooths out. Is this a vacuum problem or electrical I wonder. Anyone dealt with this issue? Another member is trouble shooting the same issue and has replaced his AAC valve, but has yet tested this. I have removed this valve along with the EGR on my car. Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted March 10, 2011 Share Posted March 10, 2011 Lucky that yours works. Mine didn't work when I got the car, so I trashed it. Problem solved haha. Quote Link to comment Share on other sites More sharing options...
83zxt_Japan Posted March 11, 2011 Share Posted March 11, 2011 It seems that "idling-up" function doesn't operate properly. Possible culprit would be one of these. 1. AC switch (It tells status of the AC compressor =ON or OFF= to ECU.) 2. AAC valve (It controls idling speed by the output from ECU.) Anyway, I think the AAC valve shouldn't be removed as long as your car's engine management is in original condition. Quote Link to comment Share on other sites More sharing options...
calvin280zxt Posted March 14, 2011 Share Posted March 14, 2011 i was just looking at the classifieds on here and the guy said his car studders at 3200 when the ac is on Quote Link to comment Share on other sites More sharing options...
madkaw Posted March 14, 2011 Author Share Posted March 14, 2011 UUMMMMMMM, that car for sale is mine Interesting what the AC switch directs the ecu to do when it's on. I don't really have an idling issue, it's just at the higher rpm around 3000rpm. Quote Link to comment Share on other sites More sharing options...
kj280z Posted March 14, 2011 Share Posted March 14, 2011 UUMMMMMMM, that car for sale is mine Interesting what the AC switch directs the ecu to do when it's on. I don't really have an idling issue, it's just at the higher rpm around 3000rpm. I suspect one of the vacuum pots under the dash or a one of the vacuum lines running to/from them under the dash Quote Link to comment Share on other sites More sharing options...
calvin280zxt Posted March 15, 2011 Share Posted March 15, 2011 that makes sense, probably should have looked Quote Link to comment Share on other sites More sharing options...
signal34 Posted March 22, 2011 Share Posted March 22, 2011 (edited) Another member is trouble shooting the same issue and has replaced his AAC valve, but has yet tested this. I have removed this valve along with the EGR on my car. I was having a problem similar to madkaws. My 81 280ZXT lost power badly and stumbled upon acceleration especially above 3K RPM with the AC on. After hours of searching on this site and others I found threads that pointed to the AAC. I've replaced the AAC and I finally had a nice day to get her out of the garage and test my repair. I was pleased to find that in my case the AAC seems to have been the culprit. The loss of power and stumbling are no longer present with the AC engaged. Edited March 22, 2011 by signal34 Quote Link to comment Share on other sites More sharing options...
madkaw Posted March 23, 2011 Author Share Posted March 23, 2011 Thanks for the update, I will definitely check that out. That beats tearing out the dash to find leaky vacuum hoses. Quote Link to comment Share on other sites More sharing options...
81 ZXT Posted August 9, 2011 Share Posted August 9, 2011 I am having the exact same problem on my 81 Turbo. I have looked but can not find anything in the FSM about an "AAC". Where is it and how do you check it? Quote Link to comment Share on other sites More sharing options...
madkaw Posted August 9, 2011 Author Share Posted August 9, 2011 The ACC valve is right on top of the intake. In the picture below it is the tallest diaphram in the pic with the vacuum plug on it. You need to have that and a good working VCM( sits under the mass air sensor) Quote Link to comment Share on other sites More sharing options...
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