NC with Cosworth making only 150 hp????

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fredmuggs
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Joined: Sun Mar 13, 2011 6:40 pm
Location: Sheldon SC

Re: NC with Cosworth making only 150 hp????

Post by fredmuggs »

OM-ARC wrote:Seriously... reach out to Jay. He knows his stuff and is working with some Cosworth owners and their troubles... You can find him here and in miata.net as blackone....

Ha!!! I found him.

Thanks,
Fred
jboemler
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Location: Mukilteo WA

Re: NC with Cosworth making only 150 hp????

Post by jboemler »

fredmuggs wrote:
OM-ARC wrote:Seriously... reach out to Jay. He knows his stuff and is working with some Cosworth owners and their troubles... You can find him here and in miata.net as blackone....
Hi ON-ARC"

I must be in the wrong fourm or something over at miata.net. Couldn't find a "Jay" or "blackone."

Just before I email the Moderator over there, do you have any additional contact info for Jay?

Thanks,
Fred
Here's Jay's member info:
http://forum.miata.net/vb/member.php?u=25738
fredmuggs
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Joined: Sun Mar 13, 2011 6:40 pm
Location: Sheldon SC

Re: NC with Cosworth making only 150 hp????

Post by fredmuggs »

jboemler wrote:By "pressure gauge", do you mean the same fixture that's used for leak-down testing? I somehow doubt that's a valid test, since it's intended to measure something that's almost fully sealed, using very small flow numbers. With the rest of the exhaust very open by comparison, the flow required for any meaningful value would have to be much larger than the leak-down fixture can provide. I also wonder how much the potentially open valves in the head would distort the readings.

Basically, I'm just not sure your 2-pound number means anything at all, but willing to be convinced.

Hi, jboemler:
After talking with the shop, I am having them pull down the exhaust pipe and visually inspect the front converter -- best they can. I don't know if one can actually see all the way through the front converter -- the one that's built into the exhaust manifold. Presumably, there is a way to inspect and even replace that unit, short of replacing the manifold. Will have to research that.

I'll let you know what we find.

Thanks again,
fred
jboemler
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Re: NC with Cosworth making only 150 hp????

Post by jboemler »

It'll be interesting to see what they come back with. My recollection is that you can see the first converter from the bottom, without removing the header. Not sure that you could see THROUGH it enough to truly inspect it, but I doubt you'll be able to see it at all from the top. You may find that you don't get any benefit from removing it, but hopefully others will jump in on that score.

BTW, in talking about the shop's measurements, I didn't mean to imply that there was an undiagnosed blockage in your system -- I have no indication one way or the other.
fredmuggs
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Re: NC with Cosworth making only 150 hp????

Post by fredmuggs »

Ted928 wrote:I went back and looked at your original post where it says you have an automatic tranny. Maybe that is not able to transmit all the new torque. Since the engine has boost and rich fuel, the engine must be making high power.

i am just guessing as I am not experienced in SC or automatic trannys.

Keep us informed.
Sorry, jay928, my response of a few days back apparently went somewhere else.

On the AT, I tried some research a while back. Here's part of that post.

Found from four (unvalidated) sources that the AT in my '07 Miata should be SJ6A-EL (Miata '06 - '08) which is also used in the RX8 ('06-'09).

First source [of info on the NC AT] Level 10, which offers value body rebuild for $600 to sharpen shifts. Level10 says the trans is not controlled by the ECU, but by a separate trans controller which they can reflash or supersede for DOLLARS.
Second source: http://www.transtec.com/selector_guide/Mazda.htm
Third: http://www.autotransparts.com/MazdaTransmissions.html
Fourth: http://amtrans.nl/mazda.pdf

If the SJ6A-EL is, in fact, the correct trans [in the NC], and is also used in the RX8, it should take a lot of power right out of the box. With a very little tricking, it should take a lot of really hard use.


The only place the power could go is "absorbed" into the converter or the trans control unit is telling the ECU to back off. There's no apparent slippage in the trans and no variation in the tach, so I doubt the first. The second, calibration parameters, don't show anything untoward in the DashDyno logs the tuner and I looked at.

That does not mean you are wrong about the AT.

Thanks,
Fred
fredmuggs
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Location: Sheldon SC

Re: NC with Cosworth making only 150 hp????

Post by fredmuggs »

jboemler wrote:It'll be interesting to see what they come back with. My recollection is that you can see the first converter from the bottom, without removing the header. Not sure that you could see THROUGH it enough to truly inspect it, but I doubt you'll be able to see it at all from the top. You may find that you don't get any benefit from removing it, but hopefully others will jump in on that score.

BTW, in talking about the shop's measurements, I didn't mean to imply that there was an undiagnosed blockage in your system -- I have no indication one way or the other.
At this point, I'm actually hoping to find a bad cat and an easy fix. There's still some "exotic" gremlins left to chase around: "bad" cams or cam timing from some rebuild before I got the car, bad head, trans control communicating with the ECUu, ya-da, ya-da .... I really don't want to mess with those.

Right now, or rather next week, I should find out something about the converters. I'm actively looking at those and the bypass valve. Cosworth responded to my inquiries (in timely fashion I must add) by suggesting the bypass valve linkage might be jammed, the bypass could be leaking internally, or (here's the best one) the rotors might be "damaged."

They suggested disconnecting the vacuum control line from the bypass actuator, blocking the line, and running the car again to see if there is any difference. Theory is that the bypass valve is opened to bleed boost by engine vacuum. So, when you disconnect the actuator, you should make boost all the time. The amount of boost would then be a function only of engine/compressor speed.

I guess they think the bypass valve may be standing open or opening and closing under some conditions related to the actuator. So, when you take the actuator out of the loop, boost levels should stabilize.

One of the serious problems with this blower system is the lack of sources from which to measure boost pressure. The only boost measurement port tells you nothing about what's going on at the head and I don't believe it tells you anything about what's going on behind the bypass valve. That leaves me in the dark diagnosing the problem. I almost drilled and tapped a port in one of the runners. But, naw, there wouldn't be any problems with this simple bolt on. Grrrrrrrrr!

Thanks again for your input,
Fred
fredmuggs
Posts: 41
Joined: Sun Mar 13, 2011 6:40 pm
Location: Sheldon SC

Re: NC with Cosworth making only 150 hp????

Post by fredmuggs »

jboemler wrote:
fredmuggs wrote:
OM-ARC wrote:Seriously... reach out to Jay. He knows his stuff and is working with some Cosworth owners and their troubles... You can find him here and in miata.net as blackone....
Hi ON-ARC"

I must be in the wrong fourm or something over at miata.net. Couldn't find a "Jay" or "blackone."

Just before I email the Moderator over there, do you have any additional contact info for Jay?

Thanks,
Fred
Here's Jay's member info:
http://forum.miata.net/vb/member.php?u=25738
Hey!!!
I jst sent Jay an email via the Miata.net forum. Will let you know.
Thanks,
Fred
Brian
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Re: NC with Cosworth making only 150 hp????

Post by Brian »

Brian wrote:Indeed, bypass or some other mechanic source or leak is resulting in the air not reaching the cylinders.....it's the only reasonable explanation. Bypass is the most likely source.

Either that or the converter is stuffed/melted resulting in no flow...I think you mentioned a joy ride in the car BEFORE doing the tune? It would not take much of a joy ride without the tune being loaded to melt down the cat (except this should result in really HIGH boost readings and since you are not getting that, I am back to my first sentence above as the logical source).

Sounds like option number two that I suggested above was the answer afterall....
Brian Goodwin
Good-Win Racing
www.good-win-racing.com
fredmuggs
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Joined: Sun Mar 13, 2011 6:40 pm
Location: Sheldon SC

Re: NC with Cosworth making only 150 hp????

Post by fredmuggs »

Ted928 wrote:I went back and looked at your original post where it says you have an automatic tranny. Maybe that is not able to transmit all the new torque. Since the engine has boost and rich fuel, the engine must be making high power.

i am just guessing as I am not experienced in SC or automatic trannys.

Keep us informed.
TED928:
Sorry this reply didn't get back to you sooner. I guess I didn't post it properly.

For the AT to dump the torque, seems to me it would have to either slip, which I should be able to hear and/or feel, or the trans controller (separate from the ECU) would have to talk to the ECU and detune something like fuel, advance or throttle. I don't hear or feel any slipping either on the road or the dyno and the logs don't show anything anomalous like fluctuations in advance or throttle position.

I'm not looking at the converters. The shop just reported today that they found the element of the front converter cracked with some debris falling out. I'll either get it replaced with a new exhaust manifold, or dump it all together and see if I find the missing HP.

Thanks for the response,
Fred
fredmuggs
Posts: 41
Joined: Sun Mar 13, 2011 6:40 pm
Location: Sheldon SC

Re: NC with Cosworth making only 150 hp????

Post by fredmuggs »

Brian wrote:
Brian wrote:Indeed, bypass or some other mechanic source or leak is resulting in the air not reaching the cylinders.....it's the only reasonable explanation. Bypass is the most likely source.

Either that or the converter is stuffed/melted resulting in no flow...I think you mentioned a joy ride in the car BEFORE doing the tune? It would not take much of a joy ride without the tune being loaded to melt down the cat (except this should result in really HIGH boost readings and since you are not getting that, I am back to my first sentence above as the logical source).
Sounds like option number two that I suggested above was the answer afterall....
Hi, Brian:

I haven't seen the front cat, yet. But the shop said it was "broken." I'm now beginning to wonder if the cat may have been bad all along. Maybe that's why I got such a low mileage used car -- 'cause it wouldn't pull the hat off the head of the guy who had it before me. I'll never make another big change without a dyno pull or some other solid starting reference.

When I took the car out before the tune, I wasn't in the throttle but about 50% for more than a couple of seconds -- just long enough to hear the almost instantaneous spark knock. Maybe that was enough, maybe not.

I called a cooperative local Mazda dealer and was told that the smog control stuff is under a huge warranty. If the cat element is actually "cracked" it's still covered. As long as the manifold shows no external damage like from those Porches I catch in the corners at Roebling Road or other road such debris.

Sure hope that's the problem. We're all running out of ideas. I'll retrieve the car from Charleston tomorrow and get it to the Mazda dealer. Will post when I get some news.

Thanks,
Fred
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