1995 Accord power loss over 4500 RPMs

I have a 1995 honda accord LX f22b2 (2.2 L, no VTEC), manual transmission. Recently it started making a scraping or sucking sound when I go over about 4500 RPMs. This sound correlates with a very severe loss of power.

What is causing this?

Reply to
jfindlay
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you have a vacuum hose that's not connected?

Reply to
Elmo P. Shagnasty

I looked over the vacuum system and found nothing disconnected. One of the= metal tubes that hooks into the main intake tube maybe isn't sealed very w= ell after 17 years. I guess I could check other things, but what vacuum co= mponent could cripple engine power so severely? I thought all vacuum lines= serviced systems inessential to basic engine function. Could it have some= thing to do with stoichiometry?

Reply to
jfindlay

"Elmo P. Shagnasty" wrote in news: snipped-for-privacy@news.eternal-september.org:

crankcase PCV valve hose? restricted air filter? maybe sucked up something into the intake ducting? Or your valve springs are tired and the valves are floating at high RPMs.

Reply to
Jim Yanik

common myth, completely untrue. spring steel does not change stiffness over time. period. if there are any issues with wear in other componentry, there may possibly be float, but absolutely not as a function of springs becoming "tired".

Reply to
jim beam

I'm a physics graduate student, and I know a few, but not many things about= solid state physics:

- ordinary metals are crystalline with a partially filled conduction band. = Metallic atomic electronic configurations are far from the complete comple= ment of spherical harmonics possessed by noble gases, so their atoms are ha= rdly insular. This often results in great pliance, while maintaining some = sort of crystalline strength.

- alloys derive their properties from impurities in the crystal structure, = which alter the energy shape of the valance electron bands. In steels, the= basic impurity is carbon, but it is often augmented with other metals and = main group elements, like silicon.

- No material will last forever; everything has a mean lifetime. The spect= rum of EM and cosmic radiation incident on the biosphere provides both ther= mal and ballistic means for spontaneous chemical decay. Integrated over th= e lifetime of an object, these effects can be quite significant. Mechanica= l stress is effectively thermal in the microscopic regime. The convolution= of these effects over time can cause either fatigue or a rupture along cry= stal grain boundaries depending on how heterogeneous the crystal domains ar= e, how significant the valance band energy structure is along grain boundar= ies, and how specific the mechanical stress is.

Every metallic structure from the Eiffel tower to the 16 valve springs in a= straight 4 will find some destructive way to increase in entropy. For spr= ing steel, I personally don't know whether this means a fatigued state (per= manent deformation), or a macroscopic fracture, or some other form of physi= cal change, but it will be something deformative.

Reply to
jfindlay

I'm a physics graduate student, and I know a few, but not many things about solid state physics:

- ordinary metals are crystalline with a partially filled conduction band. Metallic atomic electronic configurations are far from the complete complement of spherical harmonics possessed by noble gases, so their atoms are hardly insular. This often results in great pliance, while maintaining some sort of crystalline strength.

- alloys derive their properties from impurities in the crystal structure, which alter the energy shape of the valance electron bands. In steels, the basic impurity is carbon, but it is often augmented with other metals and main group elements, like silicon.

- No material will last forever; everything has a mean lifetime. The spectrum of EM and cosmic radiation incident on the biosphere provides both thermal and ballistic means for spontaneous chemical decay. Integrated over the lifetime of an object, these effects can be quite significant. Mechanical stress is effectively thermal in the microscopic regime. The convolution of these effects over time can cause either fatigue or a rupture along crystal grain boundaries depending on how heterogeneous the crystal domains are, how significant the valance band energy structure is along grain boundaries, and how specific the mechanical stress is.

Every metallic structure from the Eiffel tower to the 16 valve springs in a straight 4 will find some destructive way to increase in entropy. For spring steel, I personally don't know whether this means a fatigued state (permanent deformation), or a macroscopic fracture, or some other form of physical change, but it will be something deformative.

I agree completely

Reply to
MLD

oh. and all this time i though it was cottrell/bilby dislocation atmospheres.

appeals to authority and pronounced credentials don't mean shit on usenet kiddo. that's why i don't announce mine.

now, for your [needed] continuing education, deformation doesn't affect modulus. wear affects spring pre-load, but it doesn't affect spring rate. plastic deformation doesn't affect spring rate, it simply shortens the spring. fatigue affects spring rate [mechanically - given that the springs dimensions effectively change], for a short period as the crack grows. but as you might learn later, the life of a spring once a crack has nucleated and has started to grow, is short. the o.p. would never know until it broke. [and a broken spring is not a "floating" spring.]

as for your "entropic analysis", you also need to consider the statistical reality that this vehicle has 16 valve springs. now, given that the failure rate is less than 1 in 10^7 in 10^5 miles, i'm sure even a physics undergrad can lower themselves to do the basic stats on the likelihood of fatigue initiation and growth rates producing "synchronized" results.

really, you should know better. look up valve float - what it actually is and how it happens. then go look up honda's history on how they were early adopters of the "new" cam profiles and how it's enabled them to dispense with the "old" float mitigation techniques like dual springs on their high revving engines.

Reply to
jim beam

I learned something today. I'm just not sure what it was.

Reply to
dgk

Recently it started making a scraping or sucking sound when I go over about 4500 RPMs. This sound correlates with a very severe loss of power.

Mass Airflow Sensor failure ?

or does that cut power above 2500 rpm, I'm not sure.

Al Moodie.

Reply to
Al Moodie

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