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Old 05-26-2011, 01:21 PM   #1 (permalink)
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Question NA- Runs like shit until...... also turbo fact or fiction

This morning (cold start) I started the miata and I noticed that the rpm's don't go as high (around 1100) when its warming up the car and the oil pressure gauge goes up to 60lbs. And when I start to drive it; it runs like shit. there's a hugh lack of power until high rpms and hesitation. But when the car is nice and warmed up, it runs fine. The oil pressure goes to normal and little or no hesitation when driving like a "normal" person.

My brother thinks it might be the cat. since it starts to run fine after the car warms up. And he also thinks I need a valve adjustment too (car putters from the exhaust and I can hear ticking )

Turbo fact or fiction???
- I heard that you don't need a fuel management system with a turbo kit IF you're running low psi (like 6psi). Is this TRUE?!?!?
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Old 05-26-2011, 01:35 PM   #2 (permalink)
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Default Re: NA- Runs like shit until...... also turbo fact or fiction

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Originally Posted by munchlax View Post
Turbo fact or fiction???
- I heard that you don't need a fuel management system with a turbo kit IF you're running low psi (like 6psi). Is this TRUE?!?!?
No.
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Old 05-26-2011, 02:06 PM   #3 (permalink)
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Default Re: NA- Runs like shit until...... also turbo fact or fiction

cold start + high rpms = a good way to wear the shit out of an engine.
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Old 05-26-2011, 02:19 PM   #4 (permalink)
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Default Re: NA- Runs like shit until...... also turbo fact or fiction

Temperature up, viscosity down

Viscosity down, oil pressure down
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what kind of an idiot would put a fwd engine in a rwd car?
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Old 05-26-2011, 06:13 PM   #5 (permalink)
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Default Re: NA- Runs like shit until...... also turbo fact or fiction

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Temperature up, viscosity down

Viscosity down, oil pressure down
Thats not necessarily true. Since most oils used in cars now are multi-viscosity oils, they are different at different temperatures. So a 0w30 will act as an SAE 0 oil on cold start and as an SAE 30 oil once up to 212F. Its a common misconception that the "w" stands for weight, it actually stands for Winter (or cold temps). Interestingly we tend to remove the "-" out of it, but if you look at most oil containers it will say 5w-30, to differentiate between which of the two are for what temperatures.

There is obviously different ways to measure temperature and the viscosity of the oil, so my explanation is lacking in detail, different manufacturers will use different temperatures, but the idea is the same. This helps eliminate dry running the engine on cold start ups.

With that said, the car runs higher PSI on start-up. Thats pretty normal and its another method of reducing the dry running time of an engine. I doubt its the cat, just seems to me that if its clogged then it will be clogged all the time, on cold-start up or warmed. Try a google search on "miata runs bad on cold start" (replace runs bad with any other similar term).
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Old 05-26-2011, 10:00 PM   #6 (permalink)
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Default Re: NA- Runs like shit until...... also turbo fact or fiction

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Thats not necessarily true. Since most oils used in cars now are multi-viscosity oils, they are different at different temperatures. So a 0w30 will act as an SAE 0 oil on cold start and as an SAE 30 oil once up to 212F. Its a common misconception that the "w" stands for weight, it actually stands for Winter (or cold temps). Interestingly we tend to remove the "-" out of it, but if you look at most oil containers it will say 5w-30, to differentiate between which of the two are for what temperatures.

There is obviously different ways to measure temperature and the viscosity of the oil, so my explanation is lacking in detail, different manufacturers will use different temperatures, but the idea is the same. This helps eliminate dry running the engine on cold start ups.

With that said, the car runs higher PSI on start-up. Thats pretty normal and its another method of reducing the dry running time of an engine. I doubt its the cat, just seems to me that if its clogged then it will be clogged all the time, on cold-start up or warmed. Try a google search on "miata runs bad on cold start" (replace runs bad with any other similar term).
Viscosity still decreases as temperature increases. An oil acting as 0 weight oil at "cold" temperature will still be more viscous than a 30 weight oil at operating temperature. I see what it is you're getting at, but my statement is still correct, even when applied to multi-weight oils.
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what kind of an idiot would put a fwd engine in a rwd car?
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Old 05-26-2011, 10:17 PM   #7 (permalink)
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Default Re: NA- Runs like shit until...... also turbo fact or fiction

Yeap, just felt it needed a better explanation.
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Old 05-26-2011, 10:23 PM   #8 (permalink)
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Default Re: NA- Runs like shit until...... also turbo fact or fiction

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Originally Posted by munchlax View Post
This morning (cold start) I started the miata and I noticed that the rpm's don't go as high (around 1100) when its warming up the car and the oil pressure gauge goes up to 60lbs. And when I start to drive it; it runs like shit. there's a hugh lack of power until high rpms and hesitation. But when the car is nice and warmed up, it runs fine. The oil pressure goes to normal and little or no hesitation when driving like a "normal" person.

My brother thinks it might be the cat. since it starts to run fine after the car warms up. And he also thinks I need a valve adjustment too (car putters from the exhaust and I can hear ticking )
check to see if you have an exhaust leak before the o2 sensor. a good way to check is just un plug it and if it runs fine after a cold start then you got a leak. same thing happened with my car
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Old 05-26-2011, 10:40 PM   #9 (permalink)
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Default Re: NA- Runs like shit until...... also turbo fact or fiction

how are the plugs and wires? has the o2 been replaced before? did you check the timing?
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Old 05-30-2011, 02:34 PM   #10 (permalink)
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Default Re: NA- Runs like shit until...... also turbo fact or fiction

Mine hesitated when cold accelerating below 3k rpm. It turned out to be low timing degree btdc. It was at 2*btdc. Set it back to factory recommended 10*btdc. I run premium all the time now so i advanced it to 14*btdc. Runs solid at any temp. Hope this helps.

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Old 05-30-2011, 02:49 PM   #11 (permalink)
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Default Re: NA- Runs like shit until...... also turbo fact or fiction

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Old 05-30-2011, 03:37 PM   #12 (permalink)
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Default Re: NA- Runs like shit until...... also turbo fact or fiction

I would agree with Twibs...check plugs and wires... one of my HT leads was badly corroded and car was hesitating and slow to pick up at low rpm with a cold start. Was ok once warm or going faster, just like you said.

Changed 'em out for new leads and plugs and she ran sweet again......
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Old 05-30-2011, 05:24 PM   #13 (permalink)
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Default Re: NA- Runs like shit until...... also turbo fact or fiction

Quote:
Originally Posted by Hella_Rare_Yellow View Post
Mine hesitated when cold accelerating below 3k rpm. It turned out to be low timing degree btdc. It was at 2*btdc. Set it back to factory recommended 10*btdc. I run premium all the time now so i advanced it to 14*btdc. Runs solid at any temp. Hope this helps.

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Huh, odd. I've been meaning to check my timing for a while and this might explain everything I've been experiencing. Thanks for the heads-up.
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what kind of an idiot would put a fwd engine in a rwd car?
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Old 05-31-2011, 10:28 PM   #14 (permalink)
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Default Re: NA- Runs like shit until...... also turbo fact or fiction

thanks everyone, ill get the timing checked out and plugs and wires changed once i get paid. ill post up the results
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Old 06-12-2011, 07:10 AM   #15 (permalink)
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Default Re: NA- Runs like shit until...... also turbo fact or fiction

Hey thanks everyone, after I changed the spark plugs and wires, the car runs A LOT better now. Now I just need to get rid of the loud engine noises
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Old 06-17-2011, 02:01 PM   #16 (permalink)
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Default Re: NA- Runs like shit until...... also turbo fact or fiction

Quote:
Originally Posted by munchlax View Post
Turbo fact or fiction???
- I heard that you don't need a fuel management system with a turbo kit IF you're running low psi (like 6psi). Is this TRUE?!?!?
lmao
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