Mazda MX-6 Forum banner

1 - 17 of 17 Posts

·
Registered
Joined
·
1,426 Posts
Discussion Starter · #1 ·
After changing my timing belt and waterpump last weekend (ask me if you need tips on this procedure), I was messing about in the engine compartment and noticed that my secondary throttle adjust screw was screwed in all the way...

It got me thinking about a problem I've had for as long as I've owned the car; peaky, non-linear throttle response, and I'm not talking about peakyness from the turbo. I mean it's always seemed that I was getting full throttle when my foot was only 2/3-3/4 the way to the floor, and if I put my foot down further it didn't go any faster. I've talked to AK from the Yahoo Club about this and he seemed to think it was a common problem but didn't know a solution. He called it the "famous half-throttle mystery".

....So I'm looking at this screw screwed in all the way and I think to myself "self, that screw is making the secondary butterfly open too soon. Maybe that's causing the messed up throttle response. Hmmmm..." So I backed the screw off about 3-4mm (there is a nut under the screw, adding another nut under would be about the same) and WHAT A REVELATION. I can't imagine that changing the timing belt or waterpump would change the performance any so this is what must have done it. My throttle is now completely linear and full throttle comes when my foot is on THE FLOOR and the car feels so much faster because it is WAY EASIER to extract power from it; no more guessing where full throttle is. If any of you are experiencing the "half throttle mystery" maybe you could try this. It's worth a shot.

Perhaps the cars were rigged with a hair-trigger throttle from the factory to make people think there was more power than there was (is that neccessary?) and sell more cars? Just a guess.
 

·
Registered
Joined
·
1,426 Posts
Discussion Starter · #3 ·
Not really a mod...more of an adjustment. Look on your throttle body, and then at the turny thing that your throttle cable attaches to. The screw is on there, and you use it to adjust when the secondary butterfly opens. Just turn (open) the throttle by hand and watch it's action and you'll figure out what I mean.
 
G

·
Ok I turned the screw out alot untill it doesn't touch the other piece of metal anymore and then locked down the little nut... I noticed a little difference but it's nothing major,, I wonder if I did it right,, Can you describe again exactly how much you turned it out... thanks.. Should it still touch the little thingie when it's all the way WOT? or should it never touch it again??

thanks
 

·
Registered
Joined
·
270 Posts
I tried turning the screw out, but it didn't do anything for me either. I noticed that the screw didn't touch the metal thing on full throttle either. Maybe we are messing with the wrong screw?? antiSUV, is it the screw facing straight up (on closed throttle)?
 

·
Registered
Joined
·
1,426 Posts
Discussion Starter · #6 ·
I'll take a pic and post it tonight to show what I mean.
 

·
Registered
Joined
·
1,426 Posts
Discussion Starter · #7 ·
Sorry it took so long...

See here's what happened:
I changed my timing belt and water pump, and in the
process you have to remove the spark plugs. Well 2 of
my spark plugs were cross threaded so when I removed
them the threads got all warped. They were also
covered in white ashy stuff which I think means I'm
leaking coolant into the combustion chamber. Well I
bought new spark plugs and wires (because the wires
actually ripped out of their crimped connection to the
plugs - doh) and I installed them after I put
everything back together. THEN I started looking at
that screw deal and "screwing" around with that, and
this was before I ever test drove it. When I first
drove my car I noticed a very significant power gain
but now I know that this was probably because I
replaced the plugs and wires (I had forgotten about
that when I made that first post). I didn't
figure it all out until I happened to look under the
hood a week or so later and see that since I didn't
use thread lock when adjusting that screw, it had
vibrated back into it's original posistion - and I
still was experiencing some of my gain in power.
I still stand by my logic in thinking that making my
2nd-ary butterfly open later would eliminate my
"half-throttle mystery", but it turns out it may not
be the case.
They made it adjustable for a reason. It DOES change
when the 2nd-ary butterfly opens, and that should have
some effect on the car. My understanding of it
though isn't what I'd like it to be. Sorry about
that.
One thing that sucks about having such a high mileage
car is that there are all kinds of small problems that
pop up and over-lap, making it difficult to isolate a
single one and fix it.

Here's the pic:

http://users.clas.net/~mcdonald/james/engine.jpg

[Edited by antiSUV on 01-17-2001 at 11:07 PM]
 
G

·
Hold the phone there cowboy,,, WHOA,,, LEAKING WHAT into the combustion chamber!!,, COOLANT!!,, that sounds like a HEAD gasket,,, but I don't think thats why the sparks are white!!,, I think you are just burning a little oil in that cylinder or something, ,maybe your turbo is blowing oil past the seal or something.. IS your boost up?,, because the the stock IHI leaks oil at 15psi on the last 3 turbos i've had...two mx-6's...
CHECK on that COOLANT THING...i don't think you busted a headgasket though...just burnin a little oil's all!!..
 

·
Registered
Joined
·
134 Posts
Hey antisuv....

can you tell me exactly where this screw is so that I can try this. Did it really make that much of a difference? Thanks for this bit of info.
 

·
Registered
Joined
·
1,426 Posts
Discussion Starter · #10 ·
Hmm. thanks for making me re-think this.

I didn't know what the white stuff meant. All the spark plugs had an equal amount of "white ashy stuff" on them, so I figured it's something with how the car is running in general. And I guess since they are all white it can't be the head gasket since it would likely only leak into 2 adjacent cylinders right?
Now that you mentioned the turbo I'm thinking that's what it is. My turbo I KNOW is leaking oil. I don't even think my car uses very much oil at all; I think the TURBO is leaking it either on the ground or out the turbine or both.
So thanks for the tip. I knew my turbo was leaky, but I just wasn't putting it all together in my head.

I'm still going to replace the head gasket anyways since I figure it's just a good preventative maintenance thing to do at my mileage...

It was people at Autozone who told me white stuff on the plugs was due to coolant in the chamber. I don't know why I listened to them, as I am well aware that they are usualy morons. Oh well, we're all trying to learn right?

So, do you know a good place or person to rebuild my turbo?

RE: MAZDAMAN:
I posted a link to a pic that shows a red arrow pointing to the screw in that long post up there which contained excerpts from the e-mail I sent you. The screw is next to the throttle body. Open your hood and stand by the driver's side wheel. Try to find the part on your engine which looks like the pic. Hope that helps ya....tell me how it goes.

[Edited by antiSUV on 01-18-2001 at 01:13 AM]
 

·
Registered
Joined
·
375 Posts
turbo rebuild

A good place to get your turbo rebuilt is Texas Turbo, I see you dont live down in Texas, but they are a good reputable turbo rebuilders. Check it out at http://www.turbochargers.com I got mine rebuilt by them. It cost me $375, but thats because I snaped the main shaft in half. If it wasnt it wouldve been $275. Just look around like in the back of magazines, like Turbo or Sport Compact Car, alot of turbo rebuilders advertise there. Hope I helped.
 
G

·
Hey importhead...

I am looking to do a little head work on the mazdarati!!..,,I have exhaust,downpipe,intercooler pipe upgrade, no cat, GFORCE RACE GAS CHIP, with 101 octane fuel, 15 psi,, EGR mod...

I am looking to get around 350HP or something... Is this possible with the stock motor.. can i achieve this with head port and intake port...Do i need to strenthen the rods?, I think HP now is around 275HP crank... It feels good however it could feel alot better...I also want to upgrade the Turbo and leave the boost at 15psi.. can you recommend which turbo mod to go with... I want to get away from the leaky stock IHI...

any ideas
 

·
Registered
Joined
·
375 Posts
engine rebuild +

Brads, the stock engine would more than likley blow up. You would definatly need to upgrade the internals to some forged rods @ pistons and even getting it blue printed. As for the turbo upgrade I'd go for a T3/T4 hybrid from Thomas Knight. I plan on getting this in 2 months. Its only $650 with exchangecheck it out at: http://www.geocities.com/knightturbos/upgrade.html
I've also seen somewhere in this site (mx6.com), that you can use a KKK turbo off a SAAB, a 16G of an Eclipse, or even one of a Ferrari F40. It all depends on your budget. Hope I helped.

[Edited by Importheadmp89 on 01-18-2001 at 02:50 AM]
 
G

·
Thanks for the info:

I gotta catch an edge somewhere,, because my friend just bought a Z-28 and i gotta smoke that thing, it's only like 320 HP.. but it's heavier.. the mazda is light and hooks up good... so if i can get 350 or so maybe 400HP it could get real interesting in the mazdarati!!..

I am about to buy a used mazda from a guy that sustained some body damage on the thing... I'm going to pull that motor and build it and then when it's all perfect i'll swap it out and build the motor that I pull out even more trick than the one I put in... I also better upgrade to a light flywheel and good clutch to clamp the extra HP's..

anymore info would be great.. thanks..
 

·
Registered
Joined
·
375 Posts
engine build

Brads, thats pretty cool! I also plan on getting a used engine to rebuild and make it a monster. If you want to make some serious power I would recomend having your engine built by a profesional or at least getting some advise to resch your goal. As for the Z-28, I would think you should be able to blow the doors off his car if you had 320 hp. Another thing make sure you have enough fuel, upgrade the fuel pump and injectors. Have you raced a Z-28? I have and some times won. This one time I was coming home on a Saturday night and some jack-ass in a new Z-28 flashed his lights at me, so I pull to the side. He pulls up to me and floors it, so I do the same. Man you should've seen his face as I hung right next to him. We were dead even but he backed of once we hit 130 mph. I kept going untill I reached 140 mph. Is your friends Z stock? Have you run the 1/4 mile? I havn't yet but Im hoping for mid to low 13's. Later.
 
G

·
Importhead;

Any particular fuel Pump in mind on that fuel upgrade, also what higher capacity fuel injectors are you running...

P.S. on the 2000 Z-28, I got all excited when he bought it and was thinking about buying one, and then I drove it and It sucks, it's very UN-smooth.. and for a V8 it should move alot better than that, maybe it's just too darn heavy..Oh well, he's gonna put a paxton on it and then it should be good, but i gotta do better,, Plus that Z-28 just refuses to hook up off the line,, my friends slk compressor kicks it's ass off the line and it takes him a LONG ass time to catch up to that quick little benz.....and god help it once he has a supercharger on the z-28 stock rearend,, forget hookup all together....
 

·
Registered
Joined
·
375 Posts
fuel pump

Im in the process of getting this, a Walbro 255 ltr/hr fuel pump. You can find it here at a good price:
http://members.home.com/syclone/APE/
scroll down the page
I have Venom stage 1 injectors, they are all matched and flow 10% more than stock. These are doing well for now, but once I start making more power, I'll go with RX-7 injectors or some RC injectors. If you want the Venom injectors you can find them at http://www.autopartsgiant.com for about $217 for all 4.
 
1 - 17 of 17 Posts
Top