Fit Engine Modifications, Motor Swaps, ECU TuningReference Library for Engine Modifications, Swaps and Tuning
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The hell? Why are these people saying their cars have more power uphill by cleaning the solenoid
Quote:
the first time i did mine on my old motor, there was so much build up. after i changed it, vtec hit so damn hard! i had forgoten that it was supposed to feel like that.
How the hell can Vtec hit harder? lol
Correct me if I am wrong, but it has a pretty simple function;
The solenoid pops out and changes the timing by engaging a second set of rockers at a pre-set RPM by the computer. Unless it is stuck (in which case Vtec would not engage and I am sure the ricer boys would be sh!tting themselves) then this makes no sense... there is no "performance" advantage to clean it unless it is flat out malfunctioning.
Maybe, just maybe it reduces the time it takes for the solenoid to pop out... but like by fractions of a second.
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Last edited by Sugarphreak; 07-24-2008 at 12:49 AM.
Location: SAN JOSE, CA U.S., Earth, Milkyway Galaxy
Posts: 1,808
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The guy that posted it was trying to convince me that I needed it ... and this being my first vtec engine wasn't sure... that's why it was so important to get input from my fitfreak bros. & sisters!
Thanks,
Rob
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'07 A/T Milano Red Fit Sport (rebadged jazz)
5% Tint, K&N, Zeta Hood Deflector & Dead pedal, Honda floormats, cargo cover, red trim pkg, "remove before flight checktape equipped"
I've had the gasket leak between the passages to the point that vtec wouldn't engage when the computer told it to, all pressure just bled between them. That motor had 140k miles and 10 years of hard use on it at the time.
I've had the solenoid stick ON, yeah that wasn't fun, 1500rpm idle on an auto FTL. That motor was only 4 years old with about 80k miles.
--relevant info---
Never seen shavings make it past the filter up to that gasket screen. Maybe by some turn of bad luck you get an oil filter that doesn't have the filter media sealed, you might have to clean the gunk out of the screen.
Rule of thumb-- if vtec isn't working, you'll know it because it will fall fat on its face before redline (esp. "vtec-e" 12v when it's not working like the L15A1). If it's working, don't mess with it because its really too easy to snap off the bolts that hold the solenoid valve to the head and really too hard to get the bolt ends OUT.
--ok that's all for on-topic---
As for how "hard it hits," or more accurately how quickly the lifters lock, that is pretty much constant. Whether it works at all is determined more by oil pump wear, main/ rod bearing wear, how quickly the filter can pass oil after the pressure drop, and what kind of oil you use (high-viscosity additives in high-mileage oils tend to slow up the works in my experience). A motor with good bearing clearances and a good pump usually won't care what kind of filter and oil you use; a motor with worn bearings and an old pump will probably need a filter with a bypass valve as well as non-"75000+" mile oil to work quickly. I know, my old tired y8 wouldn't lock the valvetrain without that combo. Even with a K&N oil filter, on max life oil the engine would need to be at 2000 rpm or more for at least 5 seconds before accelerating so the ECU would see the 65psi at 5500 rpm that it requires, so in 1st gear it only rose to about 60psi because it didn't have the time. Switch to regular oil, same viscosity, 70 psi in 1st.
Helps to have an oil pressure gauge sometimes.
Two weird vtec behaviors that only occurred once on that motor--
Once, a single lifter locked to the high rpm lobe and didn't unlock until I shut the car off. That was a FUNKY idle.
Accelerating onto the highway, vtec engaged, disengaged, then engaged again before I upshifted. ECU saw the pressure drop.
Since I have a feeling this would have started into debate anyway
As for sound change, if the engine is tuned perfectly with the vtec crossover where it should be (low-cam torque matches high-cam torque), since torque is in indication of volumetric efficiency at a particular rpm, the transition would be almost if not inaudible.
With low-high lobe vtec engines like b16a/b18c#/k20a-2 /k24a /d15b vtec /d16z6-y8 series, it can be audible from the difference in the low cam lobe duration to the high lobe duration. Greater difference in duration, greater sound change. On a disabled-valve type vtec like the d16y5/k20a3/k24a2/L15A1 the duration is the same on low- and high-rpm vtec modes so the change isn't so pronounced soundwise.
Aftermarket intake typically has the effect of leaning out the A/F mixture on any honda engine save the MAF-equipped ones (no the L15A1 does not have a MAF sensor! the k20z1 in the new Si does though). This tends to lower the best vtec transition rpm, so when it occurs "late" on the stock ecu it makes more sound (valvetrain suddenly got efficient again) as well as bumping torque in a hurry. That's why my old y8 would start spinning in the rain at 5500rpm 1st gear on cheap tires after the cai was installed. Really too bad, if the car had a chipped ecu with a good tune, and vtec engagement was lowered to the proper point it would have that higher torque number earlier, with smoother delivery.
Free-flowing exhaust quiets vtec transition noise from the intake and makes it more audible through exhaust, and conversely excessive backpressure makes intake noise the loudest thing in town, but who wants the lack of power and the blown headgaskets.
vtec solenoid cleaning... do we need to do it?
Linear Mode
