Twerp's '91 Miazda

[Twerp128]

I guess I like the idea of a classic naturally aspirated roadster. But then again I like the idea of power, and the sound of a turbocharger. And kicking my friends V8 arse.

And yes it was the plug wires, knock on wood. Bought some cheapos from Autozone for now and NGKs are in the mail.

[thedguy]

Originally Posted by Nocturnal

Actually

The block is taken from the 323GTR. Essentially, youre looking at a turbo'd engine with the turbo taken off. Hence the compression ratio, and the fact that you can quite literally add a turbo and leave it. You dont need to adjust fuelling (they run rich as standard), or electronics. You can pick up a used GReddy kit here for £600, so I cant imagine how cheaply you could pick one up by hanging around on ClubRoadster.net.

From the GTR? Damn. I know the stock 1.6 and 1.8 miata engines are stronger than any of the turbo b6/bp's sold in the US (we never got the GT-R).

I'm kind of glad I started with an automatic car, they run cams suited for a little more bottom end and .5 less compression, it's just begging to be blown...err boosted.

[Twerp128]

HA, it isn't the plug wires. The fucking Miata was stuttering and missing and stalling all the way to my damn mechanics. Why can't my cars fucking work?

[thedguy]

Wait, is the timing belt fixed?

Might want to make sure the cams are properly aligned or that the CAS is on properly. It's not uncommon to find the cams off by one tooth which will let the engine run, but not well (timing will be off by some 15 degrees for each tooth!) Also the CAS if not properly bolted down might allow the idle to hold but will cause a lot of problems when trying to drive it.

[thedguy]

Any updates?

[Twerp128]

Yep, so I took it to my mechanic, and they couldn't reproduce the problem. If the car sits overnight the problem seems to go away, until the next day. So I came in the next day and drove it in the morning for five hours and only got it to miss three times, couldn't get it to miss consistently like days before. So I talked to the mechanic and he said with new plugs and wires the only thing he could think it to be would be a coil which is $500. He thought if the coil got hotter from driving through out the day it may start to break down and miss more consistently. But then coils rarely go at 130,000 miles especially on a Mazda. So he said it may be just a loose connection or vacuum hose, and take it to a Mazda dealer they may be able to isolate the problem.

So in a last ditch effort I changed the spark plugs. They were new after the belt change, but I figured $9 is a risk I can afford. So I changed those yesterday and drove it for an hour or so with out a missfire, knock on wood. Hopefully it was just a faulty plug but no guarantees yet.

[Twerp128]

aaarrghhhh!

So I thought spark plugs fixed it, I drove it for five days with no problems.

The other day it stalled on me four times and missed another dozen or so. What I have noticed is it only happens after I've been driving for at least a hour or so, it happens when I drive slowly, in traffic or stopped, it goes away if I am cruising and there is plenty of airflow. And even when it is missing to the point I can't drive it, all I need to do is let it sit overnight and the car will start and run like a champ.

I took it to my mechanic and they couldn't recreate the problem. So I drove it and couldn't get it to miss consistently like I have in days before. With what I told my mechanic he thinks it could be the coil heating up throughout the day and as it gets hotter and hotter it starts breaking down.

Could this be a coil, and if so where is a good place to get a good cheap one. I don't much feel like paying $500 for a maybe.

[Punisher Bass]

Try RockAuto.com. They have 4 different coils ranging from $125 to $160. It beats the hell out of $500 for an OEM part.

[thedguy]

Originally Posted by Twerp128

aaarrghhhh!

So I thought spark plugs fixed it, I drove it for five days with no problems.

The other day it stalled on me four times and missed another dozen or so. What I have noticed is it only happens after I've been driving for at least a hour or so, it happens when I drive slowly, in traffic or stopped, it goes away if I am cruising and there is plenty of airflow. And even when it is missing to the point I can't drive it, all I need to do is let it sit overnight and the car will start and run like a champ.

I took it to my mechanic and they couldn't recreate the problem. So I drove it and couldn't get it to miss consistently like I have in days before. With what I told my mechanic he thinks it could be the coil heating up throughout the day and as it gets hotter and hotter it starts breaking down.

Could this be a coil, and if so where is a good place to get a good cheap one. I don't much feel like paying $500 for a maybe.

Have you tried miata.net? I know the coil/ignitors are a notorious problem on all the miata's.

If it is, I'd seriously consider doing the COP (coil on/over plug) conversion, it ends up costing less in the end and provides a mucho stronger spark.

[Twerp128]

OK, finally done with the intermittent electrical problem. Swapped in a new coil and that was it. All I can say is thank God for Ebay because $500 for a new coil is fucking bananas.

[Twerp128]

^Yeah so it wasn't the coil either.

So I've replaced the plugs, wires, coil, and fuel filter. I don't know what else it can be something with the idle maybe, or maybe an alternator? But alternators usually just die. It's weird because whenever I replace something the problem will go away for a week or two and then come back. The dealership and my mechanic can't get it to stutter for them. This is just fuckin' annoying, Mazdas shouldn't do this.

[thedguy]

have you made sure you don't have the notorious grounding problems these cars have?

I used to have a problem with the engine revs dropping way to much when downshifting. come to find out the fix is to turn the diagnostic mode on and adjust the IAC.

Maybe you've got a fuel pump going out or perhaps just a bad relay?

[Twerp128]

So I just did the self diagnostic. Connected the TEN and GND terminals.

The car displayed the check engine light for a second then it went off, then came back four seconds later. I'm not sure if this is displaying fault code one or ten?

If it's one it's the ignition pulse, ten it's the Intake air thermistor in airflow meter. So now what?

[Nocturnal]

Well, you've got two options.

1. Take it back to the garage with what you know, they'll either run another diagnostic, or replace what they think is the problem.

2. Go with the ignition first, then if you still have the issue, go with the AFM.

[Twerp128]

Update!

So as of today I have replaced the entire ignition system, that means plug wires, spark plugs, coil pack assembly, and the ignitor. Still the problem persists.

So today I'm going to replace the valve cover gasket. The folks at Miata.net think the oil may be seeping past the gasket into the spark plug wells and then seeping into the rubber spark plug boot and shorting on the valve cover. And when I got the car the oil was at the full line on the dipstick which makes me think it could have been past full at one point.

I'll let you know how it goes, I have really low hopes at this point.

[boganbusman]

Originally Posted by Twerp128

So today I'm going to replace the valve cover gasket. The folks at Miata.net think the oil may be seeping past the gasket into the spark plug wells and then seeping into the rubber spark plug boot and shorting on the valve cover. And when I got the car the oil was at the full line on the dipstick which makes me think it could have been past full at one point

Umm oil does not conduct electricity, just so you know.

A bad AFM can easily cause the problems you are describing, so I would check that before bothering with the rocker cover gasket. Unless the gasket is actually leaking, in which case you should fix it anyway.

[Punisher Bass]

Originally Posted by Twerp128

Update!

So as of today I have replaced the entire ignition system, that means plug wires, spark plugs, coil pack assembly, and the ignitor. Still the problem persists.

So today I'm going to replace the valve cover gasket. The folks at Miata.net think the oil may be seeping past the gasket into the spark plug wells and then seeping into the rubber spark plug boot and shorting on the valve cover. And when I got the car the oil was at the full line on the dipstick which makes me think it could have been past full at one point.

I'll let you know how it goes, I have really low hopes at this point.

You have my sympathy and I hope you finally nail down the problem before it sends you any deeper into the hole. Also, where did you get the new coil from? I hope you found one cheaper than that $500 OEM one.

[Twerp128]

Originally Posted by boganbusman

Umm oil does not conduct electricity, just so you know.

A bad AFM can easily cause the problems you are describing, so I would check that before bothering with the rocker cover gasket. Unless the gasket is actually leaking, in which case you should fix it anyway.

See that's what I thought, anyways gonna probably try that and the fuel filter next. I know it's probably not the filter, but I figure the filter hasn't been changed in 135,000 miles so it can't hurt.

What's weird is anytime I disconnect the wires, plugs, or ignition stuff the problem goes away for a day then slowly comes back.

[Twerp128]

The Miata is down for the count, wont start today. Think it may have to do with the weather as this is the first truly cold day of the year here.

Gonna check spark and fuel pressure, then tow it to the mechanics, hopefully it has died on account of the misfiring problem. Cross your fingers! I want this thing fixed, to the point where I don't care what it costs.

I'm thinking it's either the MAF or Fuel pump, but I'm most likley wrong. Was thinking my dad may have got water in the MAF when he was washing it earlier this summer?