Yes, its my first post... and yes I'm sorry for the gratuitious 'help me, help me, HELP ME' nature of this topic.... For this I apologise, but I'm desperate.

I'm completely new to hondas, vtec, and anything associated with the aforementioned

Through an odd series of events (involving a lexus ls400 with a lot of issues and a very good part-exchange offer) I find myself in posession of a bb4 jdm si-vtec h22a1 'lightweight spec'.... also with a few issues

The problem in hand doesnt seem to affect the way the engine runs, or the car drives, just sounds rubbish and annoys me. I'vw grown to love this car, in a very short space of time... gotta love the whole VTEC thang!... but I want it to run right, and not sound like santas sleigh

My engine jingles... it doesnt rattle, it jingles, like a bell on santas hat.... Its coming from inside the inlet plenum thingy. You can kinda almost hear it in this vid. Only happens at mid-high revs (but not affected by vtec being on or off), and became ever so slightly less noticeable when I topped the oil up (though that seems to be psychogenic cos no oil goes in there, does it?)


Any ideas?

And while you're here...

Whats this? Its hanging loose on a broken bit of metal.



Thanks in advance for any help you may be able to give. (I'm in the uk, if that makes any difference?)

 

First of all welcome to the Lude society!

Is it a manual or auto Prelude?

If its a manual it could be the throw out bearing making the nois. It would be apparant under the distributor though and it would go away when clutch pedal is pushed in.......not in any area u suspect though....

The black thing on the broken off tab is a solenoid which increases fuel pressure once VTEC is engaged.
Mine also sits on a broken tab (come to think of it, I havent seen one still attached...LOL)

GL with the troubleshooting!

 

lol. thanks for the reply.

Was beginning to wonder if I'd posted right cos of lack of replies.

I guess that means its not a common issue which sucks. I'm happy with spanners, but prefer to be fixing, not researching lol.

Well... I've got a weekend of tinkering with it ahead of me so I think I'll whip off the inlet and see what I can see.

I guess it cant be anything too fatal cos it doesnt seem to have any effect on anything except my ears and patience.

It is a manual. but the noise is definitely from the inlet. It may be the sound travelling from the cams, but with my ear to the rocker I couldnt hear anything so fingers crossed its not. I presume its nothing completely detached as it would have ended up inside the engine a long time ago if it was. It only happens as the revs climb, in or out of gear.

I will report back.

Cheers merv

 

One more thing I thought of, check if the IAB plates are preloaded ie that spring on it works

There is a throttle type rotor that sits above the intake temp sensor. it is vacuum actuated and should open up butterflies in the intake around appr. 5000 RPM.....havent seen a spring come off, but I could imagine it flapping with air rushing through IF the spring failed or wasnt installed at all ...........

For all its worth, might even be a washer around a loose bolt somewhere resonating at certain RPM!!!!

GL with the troubleshooting and let us know how it turns out!

 

I'm guessing you mean this?



I questioned its purpose on another forum (non honda lol) and it was presumed it was some sort of variable intake type thing. No idea what IAB means but I'm guessing its something along those lines.

The vacuu actuator and it seem to work fine, I was out of the car so couldnt see the exact revs, but at mid revs it does its thang and pushes that butterfly open all the way. Everything seems to be ok with that and it springs back nicely. So for now I'll rule that out.

I'm aware that I sound like a complete technical idiot... I'm not, I promise lol. I'm just used to older, less complicated, engines. Old bmw 6-pots are my normal poison... 12 valves, one cam... simple... hehe.

Hence wanting to arm myself with some info before I start undo-ing things on this beasty.

 

Trust me, you dont sound like an idiot!
youre exactly right, its a variable intake system that utilizes the narrow runners @ lower RPMS (butterflies closed = better air speed = low-end + midrange) and opens up a extra set of runners at higher RPM's!!!! (= max volume = max power).

I also have a RHD SI VTEC and Ive worked on and rebuilt these engines on various occasions, so I can help u out if any info is needed!
LMK!
Merv

 

is that really what that black solenoid does?!? because i took that off of my JDM h22....should i have not done so? i removed it along with my EGR and a bunch of other things.. i never heard of that helping VTEC, or having any performance increase to it..

or am i reading what you said wrong?

 

The black solenoid opens up and bleeds any vacuum that might have been in the system.

Its not on USDM engines

I think the reasoning behind it is that the JDM engines have higher CR and thus its a added failsafe when engine enters VTEC at part throttle (ie. still vacuum/part load)

At WOT I dont see any added function the solenoid provides since there shouldnt be vacuum in the manifold to begin with..........

The point is that the solenoid raises fuel pressure independent of the vacuum state (load on engine during VTEC.

I cannot attest removal of it adding or hindering performance...

 

i could have sworn my USDM H23 had this, i will go check that! it has run fine with it removed. i never heard anyone say what you said about it, so it just caught my attention! i am pretty sure it was mounted on the firewall right next to my MAP sensor... im almost positive =/

 

I think there is also a similar system on the firewall, IIRC that s for the EVAP system

Were getting a bit off topic though, srry to OP!

 

yeah somewhat off topic, but he did actually ask what it was! and i think that is the EVAP too, because it looks exactly the same with the same hookup. hmmm. seems we are not entirely sure what this is..=/

 

Actually the one on the firewall functions as part of the EVAP system, the one on the manifold functions as part of the fuel enrichment system for VTEC

Theyre both the same, meaning they are either closed and hold the vacuum of open and release vacuum (= atmospheric pressure)