Finally

mattslope · 07-21-2007, 11:33 PM

That looks like a clean little rocket. Do I see an Alpine in the radio hole?

Shredcheddar · 07-22-2007, 07:08 AM

Yep, that's an Alpine.

Shredcheddar · 07-22-2007, 11:25 PM

Update on the clutch...

I got a chance to drive it tonight (got back from Colorado) and with the clutch in and in first gear I got it up to 5500 RPM and the car didn't budge. The clutch didn't feel like it was slipping though I did feel the car starting to vibrate around 4000 RPM, but it was through both pedals and the steering wheel, leading me to believe it was just the firewall vibrating.

So I'm not going to worry about it. I put some fuel injector cleaner in and am going to take gradual steps to see if anything fixes the problem. If not, I'm prepared to live with it. But I'd rather not.

mattslope · 07-23-2007, 12:33 AM

So, with the car sitting still and the motor revving to 4000 rpm, the pedals and wheel shake? My immediate thought is motor mounts. Does your engine have balance shafts? I'm sadly in the dark on this car, but I really want to learn about it.

Shredcheddar · 07-23-2007, 10:49 AM

Yeah, they vibrate noticeably though I honestly didn't react to it as it if were problematic.

About motor mounts... why should I care (are there potentially severe consequences)? Are they difficult to replace? I think I know what front mounts generally look like and they seem relatively easy to do (e.g. don't have to remove the engine, right?). All I know is I watched a mechanic replace a short cast-metal beam that held up the front of a PT Cruiser engine.

I can't believe it but I don't know about the balance shafts. It's only a 1.6L so I suppose it may not need them because I can't find anything about them, even exhausting Miata.net for info. I'll ask a Miata buddy of mine today, he should know.

I guess there's no hurt in bleeding the clutch system anyways. No matter what that test tells me there has to be a correlation between putting it in gear and the RPMs changing.

Shredcheddar · 07-23-2007, 01:21 PM

After checking with Miata buddy:

- No balancer shafts which partially explains the vibrations. It's still a good bet that the motor mounts aren't great and if the motor is ever out (God forbid) they should be replaced.

- The idle problem stems from improper calibration of the idle air valve. Also, the computer has different fuel delivery settings depending on whether the clutch is depressed or not. This should explain the idle drop when putting the engine in gear. Either way, it's a relatively simple adjustment that needs to be fiddled with every so often. It's liveable.

O'Reilly is out of gear oil and doesn't have white lithium grease. I'm going to be doing standard maintainence this week so I'll get a chance to take a few pictures inside the engine bay and under the car for you guys.

Oh and if I can get off work I'm getting track time at MSR Houston next Thursday and then autocrossing Sunday. I'm excited!

mattslope · 07-23-2007, 07:45 PM

Balance shafts could be the culprit of the shake, though I've ridden (too long in leg to drive) in quite a few 1g Miatas and never heard or experienced any vibration at 4k.

bobthecockroach · 07-23-2007, 07:48 PM

Quote:

Originally Posted by Shredcheddar

I do have one problem.

When the car sits overnight and cools down to "room temperature," when I start the car it will want to stall if I just let it idle. This is precipitated by an unstable idle (only when cold). After a few minutes around the block the idle stabilizes at around 800 RPM.

I can make the engine idle even lower and start to sputter by putting the clutch in and putting the shift lever in gear. For some reason this makes it idle worse!?

What is the problem here? Keep in mind this car is entirely driveable: all I have to do is give it a tiny bit of gas so it is stable until the engine warms. What gives and how do I fix it?

Heh, couldn't say. I've had practically the same problem with my car for 3 years.

Shredcheddar · 07-23-2007, 11:03 PM

Quote:

Originally Posted by Mattslope

Balance shafts could be the culprit of the shake, though I've ridden (too long in leg to drive) in quite a few 1g Miatas and never heard or experienced any vibration at 4k.

Well, under load it's smoother and less noticeable, probably because the whole car is moving. It's a gentle, gradual vibration that I wouldn't have noticed otherwise.

I know what you mean about the long-legged thing... I'm only 6-foot and I have a hard time with heel-and-toe unless I'm wearing the driving shoes due to how close the pedal is to the transmission tunnel.

Yeah, hopefully I can find some info to fix the engine deal. It stalled very quickly a couple of times tonight. I guess I'd just rather have the behavior be consistent.

I wish I could stop being paranoid and forget about it.

el cabong · 07-23-2007, 11:06 PM

Quote:

Originally Posted by Shredcheddar

I wish I could stop being paranoid and forget about it.

Good luck.

Some of my friends think I'm crazy because I'll turn down the radio repeatedly while I drive to listen to my car.