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Old 09-16-2008, 11:54 AM   #1
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Default Engine misfiring and stalling, help (with video)

So i'm just finishing up my engine swap, and the ending starts, but it runs below 1500rpm really rough and always stalls. I think its misfiring.
This is the longest the engine has run on its own yet.

http://www.youtube.com/watch?v=13IUsndnPO0

Any ideas whats wrong with it?
Its a 2000 motor (21k) replacing a 96 (176k) that i blew a headgasket on.
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Old 09-16-2008, 05:06 PM   #2
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Are the cams correctly aligned? Did you check timing?
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Old 09-16-2008, 07:19 PM   #3
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I have no idea, how do I check that?

I just replaced the plugs and wires and now its smooth above 1k rmp. below that it shutters alot and bounces from 500-1k a bit, and eventually stalls.
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Old 09-16-2008, 07:27 PM   #4
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Quote:
Originally Posted by crazzy View Post
I have no idea, how do I check that?
You can tackle the job of swapping engines, but don't know how to align the cams (timing belt), let alone what he's referring to?

http://www.miata.net/garage/timingbelt.html

Check that link out. I followed that to a T and had no issues on my first one years ago.

Goodluck.

Vash-
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Old 09-16-2008, 07:37 PM   #5
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Well, actually i ripped the whole engine apart, put in forged rods, threw a 6-speed transmission on it, new flywheel, clutch, depowered the rack, ripped out the a/c, and swapped all the electronics. I made marks on the belt, cam gears, and crank gear, but I had this feeling that I messed up 1 of the 3 times I had to do it (yea, learning as I go along...). I've never read the garage with regards to the timing belt, and my service manual never mentioned anything about those marking.

I'll try to get out there and take the plastic covers off the belt and have look, i'd prefer to not have to rip off the valve cover yet again.

Thanks guys.
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Old 09-16-2008, 07:42 PM   #6
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Read this page too homie.

http://www.miata.net/garage/ignition.html

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Old 09-16-2008, 08:03 PM   #7
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Perhaps you have a bad vacuum leak. Check and make sure you have all the vac lines hooked up. Compression test will usually tell you if the cam timing's off.
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Old 09-16-2008, 09:00 PM   #8
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i vote for insta-ban if he fucked up the timing belt
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Old 09-18-2008, 01:16 AM   #9
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Listen to the cams in that baby!Whoo-hooo!

Just kidding.Was it running good before the swap? Did you assemble the engine correctly with the proper clearances on the bearings and torque specs for the fasteners? Is your head torqued down? If your not sure on the cam timing I'm kind of suspicious of the engine build. It's not just a matter of throwing a new set of rods in it. It is possible for it to be too tight.

Providing that's ok,I'd go with what Vash,Spooky and Patsmx5 said. Vacuum or timing. Check to make sure all the vac lines and sensors are hooked up. Make sure your intake tube is on and tight. Spray starting fluid around your itake manifold if you think you may have a leak there.The engine idle should fluctuate dramaticly if the starting fluid gets sucked in.

Check to make sure you didn't cross a spark plug wire. Line up the crank pulley with Top Dead Center. Take the top timing belt cover off and see if the timing marks on the cam gears are lined up correctly with the marks on the timing cover mounting plate. Are the cam gears on right?

Everything should be in your service manual. It just might be in a different section.Check the simple stuff first.Hopefully that's what it is.

Is there gas in it? Just kidding again.Good luck,hope you find the problem.
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Old 09-18-2008, 10:47 AM   #10
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haha. Ok, well this is my first time ever doing more than changing an alternator or battery on a car. I build computers in my spare time, and the basics of troubleshooting and working on it are similar. I torqued the rods to spec, and tripple checked them (oh god i hope i did this right). Also ive been getting advice and troubleshooting help from a friend who owned a machine shop for 30 years.

So i checked the vaccum lines and they were hood from what i could see. So my fear from when i assembled the engine came true, and i fucked up the timing belt, and exactly like i thought. The crank was off by 1 tooth.....

So i ripped it apart and put it back together in a little under an hour, and not surprisingly, it now runs better than the old one did, and refuses to stall. Idle holds a little high though, goes between 800 and 1k rpm, most of the time holding at 900. This is also only with running the car for a few minutes, not even close to warming up yet. I assume this will drop to 800 when fully warmed up. But it revs much faster ane smoother than before. I can see some vibration in the engine when idling, not the huge jumping from earlier. And it looks perfectly still when reved.

And i actually am almost out of gas! Also for anyone wondering why someone would tackle such a project without any prior experience, im a 21 year old who loves getting way too deep in projects and being forced to learn as i go. Sure takes care of that extra free time that was going to waste!
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Old 09-18-2008, 11:55 AM   #11
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Glad to hear that man, good work!

I'm the same way. Hands on, gotta teach myself as I go. Diag is my weakness.

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Old 09-18-2008, 12:26 PM   #12
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Quote:
Originally Posted by Vashthestampede View Post
Glad to hear that man, good work!

I'm the same way. Hands on, gotta teach myself as I go. Diag is my weakness.

Vash-
That's what most mechanics say too! Diagnosis is the hard part.

Glad to hear you got it figured out.
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Old 09-18-2008, 09:57 PM   #13
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GJ - it's not hard to mis a tooth - getting that belt on is a bitch..
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Old 09-18-2008, 10:04 PM   #14
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Quote:
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GJ - it's not hard to mis a tooth - getting that belt on is a bitch..
Use a little KY!!!LOL!
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