Problem with Acceleration - Miata Forumz - Mazda Miata Chat Forums
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NA (1989-1997) NA Miata discussion within. The MX5's first generation, the NA, sold over 400,000 units from 1989 to 1997.

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Old 06-15-2012, 12:20 AM   #1  
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Default Problem with Acceleration

Hey everyone, I'm having some problems with my 92. When I start moving from a complete stop its almost as if I have no throttle response. It bogs down and won't accelerate until I hit about 3,000 rpm then its fine. Also, when I have the AC on its compleatly gutless. I've done the timing, even adjusted it advancing it 10 degrees. It fixed the problem for a few days, but now its coming back. I have some ideas of what it might be, but I need some help to confirm or point me in the right direction. Last weekend I was removing the valve cover and I broke the PCV valve, so I've ordered a replacement. Do you think that's the problem? Or could it be the air flow sensor? Any knowledge on this issue would help. Thank you for your time.
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Old 06-16-2012, 06:50 PM   #2  
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A broken PCV valve or any vacuum leak will cause the fuel/air mixture to be incorrect and will kill power. As the engine spins faster this imbalance will likely be reduced in noticeability.
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Old 06-16-2012, 11:52 PM   #3  
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so I relaced the valve today. its still having problems. after I changed it out I took It for a drive and the power doesnt kick in until 3000 RPMS
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Old 06-17-2012, 11:14 AM   #4  
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Check timing belt, if all is good change to 12-14 base timing.
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Old 08-04-2012, 06:52 PM   #5  
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Older stock N/A's are great until you turn on the A/C. My totally stock '91 N/A, has great torque in low ends gears and still has some left from 75-90mph. Honestly the car drives the best at 80mph. The Japense engineer that designed the N/A sure knew what he was doing, in the design of the little roadster. Others have come and gone but for the price, still the best roadster for just plain driving pleasure.
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Old 08-06-2012, 08:03 AM   #6  
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It sounds just like the symptoms of the timing belt being off by a tooth. But it could be other things as well. What has been changed between it running well and now.
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Old 12-16-2013, 02:06 PM   #7  
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I just bought a 1990 Miata, the engine runs but there is no throttle response. Changed the MAF sensor and TPs-no change. disconnected exhaust-no change. any ideas as to what could be the problem?
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Old 12-16-2013, 02:23 PM   #8  
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What do you mean; no throttle response. Tell us what happens
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Old 12-16-2013, 03:08 PM   #9  
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What is happening is when I push accelerator nothing happens- engine does not rev at all. When car gets to operating temp I can get it to go up to 3500 rpm briefly but after that it will only idle. The is not miss and no check engine light. Not sure where to go from here.
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Old 12-17-2013, 08:51 AM   #10  
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If the throttle cable is opening the flapper, the next thing to check or replace with a known good unit is the AFM. After that, switch in a known good ECU.

Last edited by olderguy; 12-17-2013 at 08:53 AM.
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