Tonight I received a phone call from a forum member telling me their short block will need replaced. Cylinder #4 is toast.

This is the 3rd instance I have personally heard this story! The common denominator in all 3 stories is they all had the IMRC connected for an extended period of time (think thousands of miles) while using the high boost pulley.

If you're running the high boost pulley please please PLEASE! disconnect your IMRC! A new short block is not a cheap purchase and certainly one you do not want to make.

 

hmm.. thanks, just disconnected mine... just push it to the side?

 

Yeah just unplug it. Maybe use some electrical tape to cover the exposed ends of the harness and actuator.

 

thanks for the reminder!
ive been running with it connected since i got it installed in July... hopefully no damage has occurred?

 

Just checked my car....couldn't find the IRMC (might have just taken it off?), but I did see the plug hanging there so all is good. Thanks for the reminder. Clinton

 

so is the IMRC charge causing silent detonation? i dont really get it. has there been a dyno before/after of IMRC opening/closing? just curious. didnt know the IMRC could fry a cylinder. wat exactly happened? rings/pistons?

 

I was getting a quick lean spot during the imrc engagement, i upped the duty cycle just prior to it engageing and took care of it. perhaps those with the HBP without emanage might consider doing the emanage route.

 

That's what I've decided to do since I'm in CA with 91 octane. I get occasional detonation with the standard boost pulley right before VTEC changeover.
Boomslang Harness & E-Manage
http://www.boomslang.us/emanage.htm

 

i bought a boomslang harness, not for emanage, but for afc, and the work is outstanding, and they sent it out in only a couple days. you won't be disappointed.

 

I have the standard boost pulley on mine... Is the general thought to disconnect the IMRC even with the standard pulley. I live on the east coast where 93 octane is commonly accessible. I had a slight bit of detonation, but nothing extremely noticeable.

 

Cool thanks! Gotta make sure i do that ASAP! Good thing i don't get on it that often.

 

That's what I don't get?! So, if it's disconnected how do you guys with the Type-S open up the secondary plenum? Wouldn't you be throwing a CEL?

 

it won't throw a CEL.

the thing is.. i would only assume VTEC changeover to have a stronger effect of detonation than the imrc would, i would just like to know the diagnosis of why cyl 4 failed.

 

Another thing to worry about MOPTH)(*@#74234


Thank god this car aint being driven for the winter anymore.

 

UMMMMMMMMMMMMMMMMMMM how about in english for the noobs? lol I have no idea whats going on!
CEL?
AFC?
IMRC?
High boost pulley?

Thanks

 

CEL=Check Engine Light
AFC=Air Fuel Controller
IMRC=Intake Manifold Runner Controller (opens up the plate that seperates the upper intake manifold down the middle)
High boost pulley only is for supercharged guys. Name kinda speaks for itself.

 

 

The opening of the IMRC adds a significant amount of air into the intake. With the supercharger many of us were experiencing "ping" right around 5,000rpm where the motor starts to run lean. When it runs lean and begins to knock the ECU starts to kill timing. So any potential gains due to the increased air with the IMRC connected is negated by the ECU interfering by playing with timing.

Disconnecting the IMRC limits the amount of air entering the intake but the AFR stays flat (for the most part) and there's no interference by the ECU playing with timing due to knock. Eliminating the knock also saves the motor.

 

Looks good... thanks for the info.

 

Glad to hear you had a good experience. Comptech uses them at times from what I understand too.

 

That's my assumption too. I have not tested this but my assumption is manifold vacume at VTEC changeover and it's affect on the FPR is the cause. I'm going after the cause which is a lot more expensive. But in either case, as Steve points out, addressing the symptom is the most important factor to protect your motor.

 

If you're running standard boost and are running 93 octane, I'm surprised you're getting detonation. Does it mainly happen when it's cold? It's backwards from what most people think. When it's cold out, the ECU doesn't pull timing like it does in hot weather. That's why the Mugen cooling mod is good for HP.

 

Im running standard pulley w/ 93 octane. On vtec changeover haven't had any issue, do i still need to unplug the IMRC?

 

I would say no. There are benefits to having the IMRC plugged in. If you don't get detonation or pinging, you should be fine.

 

Thanks makes a hell of a lot more sence to me now

 

There really are no benefits of leaving the IMRC connected once you are boosted.

The "resonance" effect created by the dual stage intake manifold is relying on vacuum. Once we introduce positive atmospheric pressure into the manifold the resonance effect is greatly reduced or eliminated all together.

It's based on the Helmholtz resonance theory. Although back in 1860 I don't think he knew it would be applied to a Honda J32A2.

 

The reason why we don't experience detonation at the VTEC engagement is because the ECU automatically compensates for the VTEC engagement by ramping up the fuel a LOT just prior to engagement. If you've ever played with a AFC type piggy-back on this car (UniChip or eManage) you'll see what I mean.

 

So basically... If you are boosted make sure you unplug It is what im getting out of this thread..

 

You guys are confusing the topic and IMO believe inadvertantly giving wrong information. Steve, you mention 5000 rpm, thats vtec changeover, the IMRC happens at 3800rpm. I know you know this, but I got a little confused by some of the posts. ALthough there is a quick lean spot at 3800rpm while under boost, it's not prevalent all the time. I experimented with various boost levels and at 4.5 lbs does not create enough of a significant lean to cause det, at the higher levels, yes, one quick bang of det but not severe, but added up over time could cause a failure. I'd think the guys with the stock pulley on the SC will not have a problem, don't forget, I also had the SC and ran it with the stock pulley. the guys with the high boost pulley's only alternative without emanage is to up the fuel pressure, but then your fat all across the rpm range.

Yes, the computer does compensate with vtec changover and probabley IMRC engagement as well. However, the adjustment to the IMRC seems to be enough for up to 4.5 -5psi. The puter was mapped for atmosphere engagement of the IMRCand theres always a little fudgefactor.

As for the IMRC not making a difference, I beg to differ. At 6psi I saw roughly 20hp difference between being open and closed. It causes a ramming effect and if it's not open, you lose that ram effect.

If you want to monitor knock, go here http://www.linkecu.com/products/Anci...ices/KnockLink
simple to install and is better than listening for it, the motor wot gets loud

 

You're correct when under boost. The dyno charts do not represent real drivng conditions though - only full throttle peak. Under light throttle, you may not be under boost thereby utilizing the first stage of the intake.

 

Thanks for the link. I was going to ask where you got yours.

 

I agree with ThinJim

Low Boost = leave it hooked up.
Hi Boost = disconnect it.

On my low boost set up it was worth almost 20hp

 

I just looked up your Dyno
https://acurazine.com/forums/showthread.php?t=181821

 

The adjustment on the FPR would be my hypothesis as to why the great difference in power was made there. The car runs at about the same AFR up until VTEC where it remains around 12.0:1. I wouldn't want to go much leaner than that.

 

IMRC function is to put up more air between 3500RPM-4000RPM was put there to help out SOHC to perform better, having it connected while boosting more than 6psi will create turbulence (tornado like...) inside the manifold and could messed up the a/f mixture (lean=less fuel/more air and rich=less air/more fuel) i guess that's why Comptech went on a safe side and didn't advertised HB pulley. 6+psi boost can come as early as 3000RPM. However, running more than 6psi can feel some significant changes around 3500RPM-3800RPM (disconnected) in normal driving, which explain the lack of "uumph!" on that area even @ WOT. e-manage and other air/fuel management/controller can correct "most" of that problem...

i myself experience some knocking/pinging at WOT, using 91octane. but nothing occurs when i mixed it up w/ 5 gal of 100octane. but i doubt...

how accurate is this knocklink monitor? where did you hook it up? wideband AFR gauge doesn't help?

i'm no guru and i still yet to learn more about J32A2 engine, so correct me if i'm wrong on my opinion.

 

It connects to the knock sensor wire, it just splices into it and shares the signal to the ecu. You'd be surprised how much this motor will det, and not even know it. There is a difference between ping and knock btw.

 

that's what scares me. the silent assassins. this monitoring device might help, but what can i do if det is present? also can you explain it briefly what det and ping?

 

to keep it simple, you get pre ignition prior to the spark plug firing, a pinging sound. This is usually caused by something hot in the combustion chamber, carbon buildup, bad plug etc, something that acts like a glow plug.

Detonation occurs when the air fuel mixture doesn't ignite evenly, a good burn starts at the spark plug and work it's way out smoothly, det happens when the the mixture just explodes rather than the slower burn. Both are damaging.

 

Seems that this information is still relevant today.

I think the IMRC is okay no matter what with proper tuning using a piggyback like the Greddy Emanage or better. I would also think that the IMRC opening up would lower boost levels a little due to the extra volume now provided.

 

The effect of opening the runners increases the volume which is supposed to slow down the airflow and thus increase density (increase "boost") which is why we see problems with the HBP and IMRC.