Sputtering and missing when cold...

My '93 (1.6l) will sputter and act like it's not getting gas when the engine is cold. Only happens when accelerating from a full stop, but sometimes it will carry a little hesitation into 2nd gear.

Every once in awhile it will have a mild backfire. New plugs and wires did not solve it. Any ideas?

Motor is shot. ;-)

^Tired, yes. Shot, no.

Any codes -> http://www.miata.net/garage/isc.html

Don't think so but I'll check tomorrow.

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Originally Posted by sammm

Don't think so but I'll check tomorrow.

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and?....

Run some Techron Injector Cleaner or Seafoam. May be just dirty fuel system or they change to "winter gas". My 06 was idle rough and lost power. It got better with each tank with Techron. I just finished the 3rd tank. It is getting better each time I drive it. My plan is to run 4 tanks.

Did you sell the car or what?

Would a flaky AFM produce these symptoms?

Mine does this somewhat when cold, too. Let me know what you find.

Looking more and more like the AFM. Car died this afternoon after I got home from work and wouldn't start. Disconnected the AFM and it would start, but die as soon as I gave it some gas.

Replaced the AFM. The car is running well again, but still sputtering when it's cold.

Thermo sensor on back of block? Got a spare stock ecu if you want to check that.

Thanks Steve, I may take you up on the ecu. I did check codes again and had a '1' in there.

Perhaps a dumb question, but have you checked for vacuum leaks?

^Not dumb and I have. I am starting to suspect the corrugated section of the intake cross-over tube.

When was the throttle body and butterfly cleaned?

^Last week....wasn't that dirty, but I cleaned it anyway.

It might not what you have. I just know the wire to the plug of the MAF is very sensitive. My NB didn't even start after I messed around. I than wiggled the wires and pushed them into the plug and wraped it w electrical tape. Problem fixed!

The 1.6 doesn't have a MAF, it has an AFM (air-flow meter).

Sounds like your MAF is toast. Practically disintegrated!

I may have found the problem....check engine light came on today.

Fault code-9 ( Water thermistor open or short circuit) which would cause the weird idle issues I've seen. Now to figure out how to fix it.

Think I found the problem. 😏http://tapatalk.imageshack.com/v2/14...b5bdc2c0cf.jpg

Check your car's warranty.

JB Weld.

Vatozone had it in stock. $16

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Originally Posted by jrj512

Check your car's warranty.

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+1! This is what happens when you don't take the car to a Reputable Miata Shop to give it the once over before you buy it!! ;-)

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Originally Posted by POS Racing

+1! This is what happens when you don't take the car to a Reputable Miata Shop to give it the once over before you buy it!! ;-)

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I second that! Nothing has been covered by Barney's warranty!

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Originally Posted by wrx74

I second that! Nothing has been covered by Barney's warranty!

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:clap:

Still chasing the problem....replaced the throttle body/ISCV and now it's idling high (1700 RPM or so). Idle adjust screw is closed all the way. It threw a '17' fault code, so I replaced the O2 sensor, still no joy.

So this morning I started chasing vacuum leaks by spraying throttle body cleaner around the intake side of the engine. Sprayed down by the fuel injectors and got a stumble. Took off the fuel-rail and injectors and
suspect the bottom seal on one of them is sucking air. Just ordered a set of 4 since I couldn't find any locally. Here's the part I'm talking about.

Part # - JE06-13-257
http://parts.arlingtonmazda.com/prod...58496_zoom.jpg

Update...I know y'all are on the edge of your seats! :rolleyes:

Put my original throttle body/ISCV back on. Car is idling lower (around 1000) with the idle screw all the way closed. I'm stumped....could a bad ECU cause this?

The other weird thing (that it's been doing from the start of this adventure)...when you jump TEN/GND it actually idles up, instead of down.

If you could provide more details and photos, it might make things clearer for us. Like this:

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Originally Posted by Fair!

(continued from above)



http://vorshlag.smugmug.com/Projects...1DSC1731-S.jpg http://vorshlag.smugmug.com/Projects.../DSC1746-S.jpg
Left: Miata "BP" 1.8L engine weighs 348 lbs. Right: Miata 5-spd manual transmission weighs 85 lbs

Some of the weights involved are shown above and below, from weights we have taken. Looks like the 1.8L Miata motor and 5-spd trans together weigh 433 lbs, with accessories. Not bad for an iron block 4 cylinder. By comparison the BMW E36 chassis' 4 cylinder M42 DOHC 4 and Getrag 5-spd are 429 lbs, which is almost identical. The big 5.7L LS1 V8 weighs 457 lbs soaking wet, with all accessories (and has more than triple the displacement and triple the power of the Miata 1.8L). The 6 speed Tremec T56 (from the 1998-2001 Camaro) itself is a portly 125 lbs, but it's a big strong transmission with two overdrives. That should give us a 582 lb drivetrain, if we stick with the T56, or an extra 149 lbs over stock. The combined "609 lb" weight shown below was indeed for an LS1 and T56 drivetrain with accessories, but also included a stock Camaro engine harness, MAF sensor, and engine computer.

http://vorshlag.smugmug.com/Projects..._w3v4X-S-1.jpg http://vorshlag.smugmug.com/Projects...57_YfRmL-S.jpg
Left: The M42 1.8L DOHC 4-cylinder and Getrag 5-spd is 427 lbs. Right: A fully dressed 5.7L LS1 + T56 at 609 lbs (click to enlarge)

Why do we love the LS1 V8 so much? Well, there are several reasons. It is a compact and light engine, as I mentioned before. It has been used in literally millions of cars and trucks worldwide since 1997, in so many variants - iron and aluminum blocks, and factory displacements that include 4.8L, 5.3L, 5.7L, 6.0L, 6.2L, 7.0L - that are all dimensionally identical. With aftermarket support that dwarfs almost every motor in existence, there are essentially no limits on power goals, which aftermarket engines that can make 8.5L and boosted engines pumping out 2500 hp. A common build is to use a nearly stock aluminum 5.7-6.2L LS1 series engine and make 350-450 whp, with a mild camshaft, good street manners, and great power under the curve. Even "only" 350 whp in a 2500 pound package can be a total blast at an autocross or track event. A little more displacement and/or compression+camshaft can get you to 500 whp, which is a LOT of fun.

Our first steps included finding a willing Alpha customer, which we found in Jason Toth. He was eager to become our first test customer and on his own he rounded up this highly optioned, 1999, silver 5-spd Miata that needed a little help and wasn't anything super rare, so it will make a great swap candidate. Once the car was here, we took a ton of measurements and fixed a few little things on the chassis that were going to stay. Then the OEM drivetrain was pulled out so we could take a closer look.

http://vorshlag.smugmug.com/Projects.../DSC4026-S.jpg http://vorshlag.smugmug.com/Projects.../DSC4137-S.jpg

The car was coated in oil underneath from a leaky front seal, so we gave it the full pressure wash treatment under the hood and on the bottom. Once the car was in the air I noticed the relatively large transmission tunnel, so I was pretty confident we could make the Tremec T56 or something like it fit without too much trouble. We might go another direction with the transmission, with two other possible gear box candidates, but I will share more on that soon.

http://vorshlag.smugmug.com/Projects.../DSC1783-S.jpg http://vorshlag.smugmug.com/Projects.../DSC4141-S.jpg
First test fit of our mock-up LS1 and T56 transmission

Once the stock drivetrain was out, we shoved our "mock-up" LS1 engine and T56 into the little car. The initial fit wasn't half bad, but there are two corners in the firewall that really limit rearward movement of the V8 engine's cylinder heads. Our guys cut some small notches back there (which will be covered in steel when the final engine placement is locked down) and re-installed the LS1/T56 drivetrain farther back, and now it looked much better.

http://vorshlag.smugmug.com/Projects.../DSC4138-S.jpg http://vorshlag.smugmug.com/Projects.../DSC4139-S.jpg
Well we're committed now! You can see the corners we trimmed to make the LS1 fit farther back, which lines up the shifter nicely, too.

After seeing this second test fit's engine placement, we were happier and now know which oil pan should work perfectly. We've also got a good idea on how we want to build the new front crossmember, which will be a custom tubular design utilizing mostly stock suspension geometry. Definitely some weight to be lost there. The rear differential was also mocked up with an aluminum Ford 8.8" 31-spline differential carrier from a 2003-04 Cobra. This will need another custom subframe to mount this diff carrier, plus some other parts we will discuss later.

(continued below)

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Originally Posted by OZMDD

If you could provide more details and photos, it might make things clearer for us. Like this:

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http://www.weirdohead.com/wp-content...1ed8404e12.jpg

:clap:

If the ECU was fubar would the car even run??

Have you tested the TPS? (Throttle Position Sensor)

Good stuff here - http://www.justanswer.com/mazda/46ox...st-bought.html

http://ww2.justanswer.com/uploads/su...040302_tps.gif

I haven't tested the TPS, but since it acted the same with 2 different throttle bodies it seems unlikely. Good question about the ECU...don't know the answer.

I have 2 93's right now, including the LE. You are welcome to come over and do some side-by side troubleshooting and parts swapping if you still can't figure it out after the first.

Thanks Mike, I may do that.

We are going to Big Bend tomorrow, but Will be back in a few days.

No problem... I have to return that throttle body to Rogue and he may have an ecu laying around I can test with.

Still have one you can use. Headin to Ks tomorrow to drop some diffs for rebuilds. Be back.monday

Steve