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Old 04-04-2011, 11:29 PM   #1
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Default So, what do I need to rebuild in my engine?

First off, I'll start by saying I'm very unfamiliar when it comes to engine internals. I've never had an engine apart myself or removed one.

Background on the car:
I bought the car when it had ~125,000 miles
131,000 miles now on original, stock motor
Turbo'd since ~100,000 miles
Garrett GT2554 pushing 190whp and 200wtq
Stock cooling system and radiator

After reading this thread, it's really sparked my interest:
http://forum.miata.net/vb/showthread.php?t=415090

I have very similar symptoms, and my spark plugs look alike.

A few weeks ago, all was well. It burned a little oil, puffed some whiteish smoke out the tail pipe after sitting for a while, spat a little black stuff out the tailpipe, and smelled funny when I got on it. It was tuned pretty rich (lower 10's on my A/F wideband in boost at WOT). Other than all that stuff, it ran good and pulled hard.

About a week or two ago, it started to act up with what felt like a misfire. It wasn't terrible, but noticeable for sure. I change the wires, no help. Then I did other random things, but none worked. Then took out the plugs, they were pretty dark because it runs so rich. Put new ones in at the preset gap from NGK. And it ran better. At first I thought things were fixed, but something still seems a little off. It still does all the the things listed above, but now once I get in boost, my wideband goes way lean. So I took off the wires and inspected the plugs, and they were very hot. The tips look like the ones from the link at the top... maybe even a little worse. The engine was very hot and it seemed like a little smoke was coming from the plug holes.

Just now the previous owner told me he thought the valve guide seals were going/bad already.

I have a lot, if not all of the symptoms in the following link:
http://www.ehow.com/how_7340441_test...ide-seals.html

At thing point I know something is wrong. What needs replacing? And if the engine needs to be taken out and rebuilt, what else should I replace while it's out? I want it to be able to handle the boost, and maybe even turn the boost up and make some more power if I can upgrade some things.

I'm on a college kid budget, with pretty much no money right now. So this might take a while to get fixed. I'm currently in my dorm away from the car and won't be able to look into more until this weekend. I do want to do things right the first time around though, I don't want to take shortcuts.

Thank you.
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Old 04-04-2011, 11:33 PM   #2
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Where Are you at in Wisconsin? If you are close by I could take a look at it for you.
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Old 04-04-2011, 11:37 PM   #3
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I would love for someone to come check it out. I don't have the money to bring it in anywhere or anything. There are few Miata enthusiasts in the area, and I have a hard time meeting up with fellow owners and I'd love some input.

Anyway, I'm in the Appleton area, it's about 30 minutes south of Green Bay and about an hour north of Milwaukee. You're probably not close by, but I would love for someone to help me out here. I should've known what I was jumping into.
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Old 04-05-2011, 12:51 AM   #4
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Quote:
Originally Posted by _spyder View Post
I would love for someone to come check it out. I don't have the money to bring it in anywhere or anything. There are few Miata enthusiasts in the area, and I have a hard time meeting up with fellow owners and I'd love some input.

Anyway, I'm in the Appleton area, it's about 30 minutes south of Green Bay and about an hour north of Milwaukee. You're probably not close by, but I would love for someone to help me out here. I should've known what I was jumping into.
I know Appleton! Grew up more or less in Greenville. I was the only turbo miata guy around there for a while. Of course, now I don't live there any more.

FWIW, I've had good interactions with Extreme Performance (they're in Neenah now, I think) and never got charged for showing up and asking questions.

I have a friend that lives in Menasha that might be able to help. He's more of a muscle car guy but he's rebuilt plenty of engines and is somewhat familiar with miatas. Lemme know and I'll see if he can help out.
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Old 04-05-2011, 01:04 AM   #5
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I know Appleton! Grew up more or less in Greenville. I was the only turbo miata guy around there for a while. Of course, now I don't live there any more.

FWIW, I've had good interactions with Extreme Performance (they're in Neenah now, I think) and never got charged for showing up and asking questions.

I have a friend that lives in Menasha that might be able to help. He's more of a muscle car guy but he's rebuilt plenty of engines and is somewhat familiar with miatas. Lemme know and I'll see if he can help out.
Damn, I wish I could have someone else like you around lol. But I've heard of that place, I heard they also tune Megasquirt as well? What else do they do and what other questions should I ask?

And if you're down to ask your friend that'd be great. I'd need help pulling the engine, but I might just go with a used one (if I can find a good one) instead of building the current one. I just want to save some money right now. If your friend wants to check things out and help me find out what the exact problem is, that'd be cool. Not sure how old he is, but I'm 19.
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Old 04-06-2011, 02:29 AM   #6
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PM sent on the local help.

Before you do that, though, you need to get a good handle on your tuning setup.

What piggback/ecu do you use? Are you familiar with tuning? You need to give a more detailed description of your setup.

Also gotta do some more troubleshooting. My gut feeling is your engine is fine and that something else is the problem. Do a compression test. That'll eliminate most engine fears.

It's okay for your spark plugs to be a bit whitish, just means they're getting a little hot.Also, always gap your plugs. Preset doesn't mean **** and you're going to want to drop the gap down a little bit if you're running the stock ignition anyways.

It's a little hard to throw up suggestions with what you've provided so far. Many things could be at fault -- fuel system, coilpack, various sensors, etc.
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Old 04-06-2011, 02:50 AM   #7
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Originally Posted by messiahx View Post
PM sent on the local help.

Before you do that, though, you need to get a good handle on your tuning setup.

What piggback/ecu do you use? Are you familiar with tuning? You need to give a more detailed description of your setup.

Also gotta do some more troubleshooting. My gut feeling is your engine is fine and that something else is the problem. Do a compression test. That'll eliminate most engine fears.

It's okay for your spark plugs to be a bit whitish, just means they're getting a little hot.Also, always gap your plugs. Preset doesn't mean **** and you're going to want to drop the gap down a little bit if you're running the stock ignition anyways.

It's a little hard to throw up suggestions with what you've provided so far. Many things could be at fault -- fuel system, coilpack, various sensors, etc.
Thanks, I got the PM. I'll respond shortly.

Right now it's running on a AEM FI/C piggyback, and no, I am not familiar with tuning. That's a weak point for me. The previous owner said he had it dyno tuned at a local speed shop. I have the dyno sheet at home, but can't remember what it showed. I know I was making around 190whp and 200wtq. I can check that this weekend and reply with the results. It has always run rich, until just now after changing the plugs. I wish I had the money to just go Megasquirt and see if that fixes the problem.

I did a compression test but didn't do it with wide open throttle. It came back 123, 90, 85, 87. Not so hot. I wanna do another test with the throttle open and hopefully see better results. It doesn't really run as if it has those bad of numbers, just seems way too lean. What gap should I be running? I can change that easy enough. I wish I had someone local to check those suggestions out. Maybe this would be a good time to hit up your buddy.
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Old 04-06-2011, 03:31 AM   #8
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Compression testing: http://www.ehow.com/how_5913286_do-c...sion-test.html

You're gonna need the throttle wide open.

What do you mean seems too lean? Does it have stoich AFRs in cruise/idle? Does it run bad just in boost or under all conditions?

Dyno sheet won't help you. Read up on the FIC. You gotta learn how to tune. Getting a megasquirt would not help you in the least right now, stick with the KISS principle. Like I said, your engine is more than likely fine.

Find out how the FIC is wired in. Maybe it was done with a pnp harness and you can just pull it out and run just on the stock ecu. Look for any shady wiring, loose connections, etc. Do you have an AFPR or bigger injectors? Fuel pressure gauge? Maybe your fuel pump is taking a ****. You've gotta learn how the whole system works. It can be a steep curve, but you'll learn a lot from troubleshooting this.
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Old 04-06-2011, 02:45 PM   #9
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Originally Posted by messiahx View Post
Compression testing: http://www.ehow.com/how_5913286_do-c...sion-test.html

You're gonna need the throttle wide open.

What do you mean seems too lean? Does it have stoich AFRs in cruise/idle? Does it run bad just in boost or under all conditions?

Dyno sheet won't help you. Read up on the FIC. You gotta learn how to tune. Getting a megasquirt would not help you in the least right now, stick with the KISS principle. Like I said, your engine is more than likely fine.

Find out how the FIC is wired in. Maybe it was done with a pnp harness and you can just pull it out and run just on the stock ecu. Look for any shady wiring, loose connections, etc. Do you have an AFPR or bigger injectors? Fuel pressure gauge? Maybe your fuel pump is taking a ****. You've gotta learn how the whole system works. It can be a steep curve, but you'll learn a lot from troubleshooting this.
I've checked out that link. I'll be doing another compression test this weekend with the throttle wide out and injectors disconnected.

By too lean I mean, it used to run low 10 AFR's in boost, now it's going down to maybe 12 and then shooting up making the gauge read "---" as soon as I hit some good boost. In was running bad all around, but better after I swapped the plugs and it warmed up. At cruise the AFR's seem pretty normal at around 14.

I hope my engine is fine. I'll take a look at the AEM FI/C this weekend, I don't like the rest of this car's wiring, so I wouldn't be surprised if this thing is wired pretty "ghetto" either.

The car has a BEGI AFPR and green top 305cc injectors from a Supra. It's got a fuel gauge in there. Here is a thread the original builder of the car made:
https://www.miataturbo.net/diy-turbo-discussion-14/fuel-feed-line-4223/

And here is another about him worrying about the valves:
https://www.miataturbo.net/general-miata-chat-9/burning-oil-smell-decel-10930/

The car smokes a little and spits black stuff out the tailpipe. Another reason I've been worried about the motor. I just wish I knew more stuff, knew tuning and all that. I'm trying to learn and I've learned a **** ton, but I wish someone could come take a closer look. I might hit up your buddy once I've got some time. I don't wanna sell the car but I keep thinking about it
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