View Poll Results: Will polishing the inside of an intake manifold improve performance?
Yes, it will improve performance
0
0%
No, it won’t do anything at all
3
100.00%
No, it will reduce performance
0
0%
Voters: 3. You may not vote on this poll
D17VTECPOWER threads consolidated - how a member should not behave
Dr Krieger of Modification
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Re: How do throttle body spacers work?
No you miss understand ITBs.
They don't eliminate volume they maximize it.
The volume in a manifold is the maximum amount of air that is available to be consumed by each cylinder.
Running an ITB set up basically places a TB on each intake port and allows each to breath in as much air volume as they can.
Last edited by mac25; Mar 18, 2018 at 08:51 PM.
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Rep Power: 119 Dr Krieger of Modification
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Rep Power: 229 Re: How do throttle body spacers work?
...you're swapping volume, atmospheric pressure and vacuum around with each other.
But yes throttle response is increased.
He literally says, at 2:30, with ITB "...you have instantaneous throttle response because the second you step on the throttle that atmospheric pressure [which is higher, not lower, as he explained earlier] is right there and it goes right in your cylinder...."
It has nothing to do with you're statement of "less volume under vacuum". Yes it's less volume under vacuum but less isn't better, in the case of the non ITB that has volume under vacuum, more is better, that's why upgraded intake manifolds have larger diameter runners (which may be shorter) and larger plenum volumes.
..............
The easiest way to picture an engine is as an air pump. The faster you can get the maximum amount of air into and out of an engine, the more power it will make. That's why large diameter throttle bodies, and large intake manifolds flow more air and make more power. With ITB basically the entire worlds supply of air is the intake manifold when you run ITBs the right way, which is with no intake manifold, which he also mentioned as seen bellow.
But yes throttle response is increased.
He literally says, at 2:30, with ITB "...you have instantaneous throttle response because the second you step on the throttle that atmospheric pressure [which is higher, not lower, as he explained earlier] is right there and it goes right in your cylinder...."
It has nothing to do with you're statement of "less volume under vacuum". Yes it's less volume under vacuum but less isn't better, in the case of the non ITB that has volume under vacuum, more is better, that's why upgraded intake manifolds have larger diameter runners (which may be shorter) and larger plenum volumes.
..............
The easiest way to picture an engine is as an air pump. The faster you can get the maximum amount of air into and out of an engine, the more power it will make. That's why large diameter throttle bodies, and large intake manifolds flow more air and make more power. With ITB basically the entire worlds supply of air is the intake manifold when you run ITBs the right way, which is with no intake manifold, which he also mentioned as seen bellow.
Dr Krieger of Modification
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Rep Power: 119 Bad gas mileage
I have a few problems with my Civic that I think are contributing to getting only 25-28 MPG. My questions are how much, if any, can each of these problems effect mileage? I’m going to fix all of it, but I’d like to know what is likely hurting my mileage the most. Here’s the list:
1. EVAP purge solenoid completely broken and non-functional
2. Fairly large crack in my exhaust header right above the upstream o2 sensor.(New header is on the way)
3. Front right plastic wheel well liner missing
4. Questionable wheel alignment
5. Whatever is causing my fuel trim to be -15 to -25
Could these issues reduce my mileage this much? I should be getting 32-35 MPG.
1. EVAP purge solenoid completely broken and non-functional
2. Fairly large crack in my exhaust header right above the upstream o2 sensor.(New header is on the way)
3. Front right plastic wheel well liner missing
4. Questionable wheel alignment
5. Whatever is causing my fuel trim to be -15 to -25
Could these issues reduce my mileage this much? I should be getting 32-35 MPG.
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Rep Power: 519 Re: Bad gas mileage
You must have been driving pretty dang conservatively:
https://www.fueleconomy.gov/
Fix the known issues first (everything on your shopping list) then recheck fuel economy.. Consider other contributing factors as well
https://www.fueleconomy.gov/
Fix the known issues first (everything on your shopping list) then recheck fuel economy.. Consider other contributing factors as well
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Rep Power: 119 Re: Bad gas mileage
You must have been driving pretty dang conservatively:
https://www.fueleconomy.gov/
Fix the known issues first (everything on your shopping list) then recheck fuel economy.. Consider other contributing factors as well
https://www.fueleconomy.gov/
Fix the known issues first (everything on your shopping list) then recheck fuel economy.. Consider other contributing factors as well
If you think a good mechanic is expensive, try hiring a bad one
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Rep Power: 519 Re: Bad gas mileage
My driving style hasn’t really changed either. Other than the list of problems above, I don’t know why my mileage decreased.
I might start with the exhaust leaks just to see how fixing that affects the fuel trims
When you say header, do you mean you're getting an OEM exhaust manifold?
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Rep Power: 119 Re: Bad gas mileage
I’ve put that header on a few people’s cars, and it’s great. It should be here Friday. I think the crack is pulling in air and making the o2 sensor falsely read lean, causing extra fuel to be added. However, I would think a cracked header would cause positive fuel trim, not negative. I expect the fuel trim to go even more negative with the new header.
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Rep Power: 519 Re: Bad gas mileage
No. My DC Sports header cracked, so I bought this one: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
I’ve put that header on a few people’s cars, and it’s great.
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Rep Power: 119 If you think a good mechanic is expensive, try hiring a bad one
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Rep Power: 119 Is manually shifting an automatic transmission safe?
When I do full throttle acceleration, I always put the transmission in a lower gear, and I upshift just before the rev limiter. If I leave it in D4, it upshifts much sooner and doesn’t accelerate as quickly. However, a friend that I took for a ride noticed, and he said I shouldn’t manually shift it. He said that I am causing a lot of extra wear on the transmission by keeping it in low gears too long. Is there any logic in what he said? To me, it seems like the transmission wouldn’t be harmed for staying in lower gears accelerating. However, I am far from a transmission expert, so if someone knows the answer to this question, please let me know.
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"Marge, anyone could miss Canada! All tucked away down there."
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Rep Power: 223 Re: Is manually shifting an automatic transmission safe?
Don't.
It's an automatic for a reason, let it do it's job.
Manualized valve bodies are a different story, but you don't have one.
Revving up to redline isn't good for fuel economy either by the way
It's an automatic for a reason, let it do it's job.
Manualized valve bodies are a different story, but you don't have one.
Revving up to redline isn't good for fuel economy either by the way
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Rep Power: 119 Re: Is manually shifting an automatic transmission safe?
Is forcing it to stay in lower gears for quicker acceleration damaging? The trans upshifts way before peak power is reached if I floor it in D4. Also, flooring it is obviously never good for fuel economy.
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Rep Power: 519 Re: Is manually shifting an automatic transmission safe?
If I leave it in D4, it upshifts much sooner and doesn’t accelerate as quickly.
Throttle ain't all the way open?
Pull the stack of floor mats out from under the pedals and retry it.
Have someone mash the gas pedal to the floor while you check that the throttle is actually fully opened. Maybe the cable has too much slack and needs adjusted.
Make sure TPS starts at 0.49v closed, and ends up around 4.5v at wide open
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Rep Power: 119 Re: Is manually shifting an automatic transmission safe?
This ain't right.
Throttle ain't all the way open?
Pull the stack of floor mats out from under the pedals and retry it.
Have someone mash the gas pedal to the floor while you check that the throttle is actually fully opened. Maybe the cable has too much slack and needs adjusted.
Make sure TPS starts at 0.49v closed, and ends up around 4.5v at wide open
Throttle ain't all the way open?
Pull the stack of floor mats out from under the pedals and retry it.
Have someone mash the gas pedal to the floor while you check that the throttle is actually fully opened. Maybe the cable has too much slack and needs adjusted.
Make sure TPS starts at 0.49v closed, and ends up around 4.5v at wide open
Re: Is manually shifting an automatic transmission safe?
When the gas pedal is floored it should go to redline and shift. Even my wifes Pilot does this.
Is this the same transmission that is at higher rpm at highway speeds then normal?
Is this the same transmission that is at higher rpm at highway speeds then normal?
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Rep Power: 119 Re: Is manually shifting an automatic transmission safe?
This car never revved up to redline before shifting in D4. And yes, the trans won't shift to 4th gear on the highway. However, if I disconnect the battery, the trans will shift to 4th gear for a few minutes, then it'll downshift to 3rd and not go back to 4th unless I reset it again. However, there are no codes, and the desired gear is always the same as the gear it's in. What does this mean? PCM problem?
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From: Midwest. Aiming about mid-chest
Rep Power: 519 Re: Is manually shifting an automatic transmission safe?
