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Sunday, September 24 2017 @ 08:00 AM EDT
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 No Power To Accelerate - 1990 Miata
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BAMiata
By: BAMiata (offline)  Tuesday, August 29 2017 @ 07:57 PM EDT (Read 211 times)  
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Registered: 08/17/17
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It's been a long time since I've posted here; long enough that I lost my post count. 

 

Over the past 2 years, I've only been able to put about 200 miles on my 1990 Miata. When I drove it to work for the first time this year, it ran fine. At lunch that day, I got caught in traffic and it stalled a couple times. During the ride home, it stalled every time I put the clutch in and got off the gas. The next time I drove it, I had no power over 4000 RPM (the engine would stutter). Then the next time, the stutter started at 1500-2000 RPM. Virtually no power.

 

I had it towed to Young Mazda. They charged me $280 to diagnose that the O2 sensor was cross-threaded, leaking and not working. They wanted to replace the O2 sensor and the whole manifold since they couldn't get the sensor out. 

 

I feathered it home, short-shifting to get it up to speed. I maxed out at 40 MPH in 5th. I removed the O2 sensor with a box wrench with no problem. It was not cross-threaded at all. I installed a new sensor anyway. The problem is worse, though it could be the cold engine. 

 

Does anyone have any thoughts? Can someone recommend a mechanic? Young Mazda has never done me right. 

 

Thanks!

Bo

 

PS My Miata is for sale in Trader Paul's. I'll discount the price if you can fix the problem. 

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Davef
By: Davef (offline)  Tuesday, August 29 2017 @ 08:06 PM EDT  
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Sounds like a clogged cat is a possibility. Remove the O2 sensor and take it for a spin. If it is a clogged cat, removing that sensor will give the exhaust a way to escape and improve the power. Running without the sensor isn't the solution but it should help you determine if it is the cat. .

.

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Alan Alan Alan
By: Alan Alan Alan (offline)  Tuesday, August 29 2017 @ 08:31 PM EDT  
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I had a similar problem with my 1991 at around 200,000 miles.  Whenever I accelerated the car would sputter and sometimes stall.  Older Guy diagnosed the Mass Air Flow Meter.  In the early Miatas the MAFM was of a design with a door that would swing.  The door was connected to a needle that would sweep a contact across a circuit board to increase the output of the fuel pump.  In my case the needle lost contact when the throttle was pushed, causing the fuel pump to fail to meet the increased demand.

 

swapping out the MAFM immediately fixed the problem.

 

 

ZOOMBIE & ZOOM B ... Could it get any better?


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BAMiata
By: BAMiata (offline)  Tuesday, August 29 2017 @ 08:44 PM EDT  
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Is there a way to diagnose the MAFS?

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Alan Alan Alan
By: Alan Alan Alan (offline)  Tuesday, August 29 2017 @ 09:04 PM EDT  
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Not really sure.  The circuit board and needle are in a sealed compartment at the top of the MAFM (or MAFS).  You can open that compartment, but you will have to reseal it again to keep moisture and dirt out.

 

I was headed to Older Guy's house to swap out the MAF unit, but the car got particularly cranky.  The drive was about 50 miles away, but I couldn't go faster than 5mph.  I found a temporary solution, though. I opened the hood and took out my 14mm box wrench.  (A12mm wrench wouldn't do.).  Now, this next step is critical:  I identified the top of the MAF unit and beat it six times with the wrench in total frustration.  (I figured anything less wouldn't be enough.). I closed the hood, started the car and drove at about 70mph to Older Guy's home.  Once there we swapped out the MAF unit and the problem hasn't recurred.

I don't really recommend this beating technique but it did work for me... so much so that I got a speeding ticket just before I got to Older Guy's home.  Figures!

ZOOMBIE & ZOOM B ... Could it get any better?


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BAMiata
By: BAMiata (offline)  Sunday, September 03 2017 @ 05:38 PM EDT  
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I pulled the entire cat out to see if that was the problem.  1) The cat seems to be in good shape, no rattles, can see light through it.  2) While extremely loud as expected, there is still no power under throttle.  If fact when I hit the gas hard, it tries to stall first like it's choking out.

 

While hitting things witha hammer sounds like fun, I've got to imagine there's a better way to troubleshoot this problem.

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Alan Alan Alan
By: Alan Alan Alan (offline)  Sunday, September 03 2017 @ 07:17 PM EDT  
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Of course, but try a new MAF if you can.

ZOOMBIE & ZOOM B ... Could it get any better?


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Ken Hill
By: Ken Hill (offline)  Saturday, September 09 2017 @ 12:46 AM EDT  
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Registered: 04/18/09
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Reading, PA

I suspect ignition coil or spark plug wires.  The only way to test is to substitue new parts.  Do you have a friend with an NA Miata who can sepnd a few hours at your house one day swapping parts from one car ot the other to test?

 

Otherwise, contact Mike at Moto-East in Easton.  He is a great mechanic who should be able to help you.  http://www.moto-east.com/store/

 

 

Ken Hill
2002 LS
HZ Yellow


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