Lost vtec

[aznstyler]

I was driving around today, and just realised i have no vtec.. it was working yday !
its a B18C, and normally crosssover at about 4500-4700. But instead from about 5000RPM onwards i get a very werid rattling noise coming from the engine bay, sounds like stones hitting metal..
What could it be?
no check engine light came on aswell.. Oil level is fine

[dc5r91]

4700rpm Vtec? U got a Vtec controller? If u do might wanna check that out or the Vtec solenoid

[joel89]

Check the solenoid mate

[matty.c]

stones hitting metal sounds like your describing pinging... in conjuction with the solenoid, i'd make sure you have a bit of good fuel in there... (top up, or fill up with some 98 RON)

[TheSaint]

if its a B18c2 (VTIR) than crossovers should be in the mid 4k range and the high 6k range
if its a B18c7 (ITR) than the crossover is in the 6k range

simple checks should be that the engine has oil pressure to engage vtec - check the oil levels and find out when the oil was last changed (Honda FEO 10w30 and Honda Filter are the best way to go)
the oil must also be at running temperature for vtec to engage - so the car must be warmed or running / driving for around 10mins before vtec will engage

'stones' sound could be pinging - you might want to top up with Caltex Vortex 98 or BP Ultimate 98 depending on what servos are around (clean fuels - deppos are better)
i would also run a dose of injector/valve cleaner with the tank - goto your local Auto1 store and ask the guy at the desk - nulon is a good brand

also check your plugs for signs of fouling so that you may further diagnose the problem

[matty.c]

the OP suggested his oil level was checked, but some good advice from thesaint - does your car reach operating temp quickly and stay there?

recently i've been changing alot of thermostats that have been stuck open (very common fault with age) which in turn doesn't let the engine heat up to it's proper temp... this also causes increased fuel consumption... funny thing is that alot of people only think it's a problem during winter, cos the heater isn't really that hot... but it has effects elsewhere...

as we know if the car hasn't heated up enough, the change over will not occur..

most of the cars i've replaced thermostats on latley have just been completley knackered and are simply stuck in the open position.. and honestly for a $12 thermostat brand new (oem spec) why would you bother testing..

But if you wanted to test... pull your thermostat out... and you will notice when cold.. it will be in a shut position... put it in a small saucepan on the stove, and bring it to the boil... if you have a kitchen thermometer that would be brilliant! as you can see what temp it starts to creep open... but not essential to see if it actually works... open when hot... then close when cold...

[TheSaint]

ah thermostat! - i forgot about that one - great advice +1!

[aznstyler]

I was driving for atleast a good 30 mins, the tempreture didnt go up very high, but it was cold last night and 90% of the driving was one the freeway. also the car is very sluggish in high rev's esp. after 5k

[matty.c]

if the thermostat is doing it's job, and the cooling system is in good order, the needle should reach halfway, and not move..

regardless of driving conditions... it's sole job is to keep the engine at the desired temp at all times, when the water is too cold (freeway winter conditions) it will close up untill the engine itself heats up enough for it to open, then it will close when too cold etc.. it's job is to make sure engine temp is consistant, opening and closing etc several times whilst driving...

if your gauge gets cold when your on the freeway... i suggest you get a new thermostat, as i said there not that expensive for a proper reputable OEM quality brand like Trindon or Gates (or you can be hella sick JDM and get Genuine)... even if you have to pay retail for them... 'sometimes' it's benificial to use a slightly cooler thermostat.. but this is only a few degrees.. i doubt if any increase in power will be noticed.. so don't get sucked into that mentallity...

[aznstyler]

It does not happen, every time. but atleast 4 out of 10 times

[aznstyler]

Hmm.. changed new plugs and injector cleaner. still pings everynow and then and vtec doesnt crossover everytime

[aaronng]

I was driving for atleast a good 30 mins, the tempreture didnt go up very high, but it was cold last night and 90% of the driving was one the freeway. also the car is very sluggish in high rev's esp. after 5k

The temperature needle should be pointing close to the middle of the gauge after 30 minutes of driving. If it is showing a low reading after that much driving, especially on the freeway, then the thermostat may have failed open.