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VTEC intermittent

Engine/Gearbox questions and discussion
ek9sid
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VTEC intermittent

Post by ek9sid » Mon Aug 24, 2020 7:39 pm

Have you checked your oil level? Only time mine would do as yours is doing is when it was low on oil and the oil sloshing would cause it to disengage vtec

Scott560
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VTEC intermittent

Post by Scott560 » Tue Aug 25, 2020 8:20 am

The oil weight wont affect the vtec - you either have the required pressure or you don't , a slight change or variation in the viscosity doesn't bother it much (i think i've had 5w-40 , 10w-40 and 10w-60 in it).

It's worth removing the vtec solenoid again, and checking that its clean, the passages and gasket are clean, and that it actuates when you apply 12v to it (I always keep a spare 7ah 12v SLA alarm battery in my garage to check such little things with a small pair of crocodile clips). If you can see it actuate then its one thing ruled out.

If everything is starting to check out - then look towards the other test, a bulb on the 12v feed. This will tell you if have an oil pressure problem or not. The ECU will not call for VTEC if it sense a lower than optimum oil pressure. I've only ever triggered that when i'm not overfull of oil, coming out of a chicane at 45-60mph on the track - i can't imagine ever hitting oil starvation on the road. Double check you do not have an oil leak and have the correct level. If you did not change the oil filter yourself personally, check that you haven't double sealed it or similar. For the sake of a few quid, replacing it can't hurt, although most filters should have a bypass to keep the pressure up should the filter media become clogged. A leak should be obvious though from smell alone.

The only other possibility through lack of use is the oil pump pressure relief valve. I have seen the piston get stuck in the open position, which caused low oil pressure. I don't know how or why it got jammed open, but it was enough to stop VTEC working all the time, and eventually lead to the engine being ruined.

Do you have the service manual? After performing all the tests mentioned, if its still intermittent, i would buy an oil pressure gauge, or take it to a garage to have it checked.

The only other possibility is you mention the poor driving improves as the car warms up. Perhaps the temperature sensor is on the way out - id expect a CEL , but perhaps it also needs testing to confirm its working as expected. Im not sure exactly which sensor is used to determined if vtec is allowable or not - but it will be in the manual, with a set of resistance values for cold/warm.

If the car drives like poo out of vtec, then as mentioned you have other problems that need addressing...
'00 UKDM 2.2VTI H22a8
'21 'e' Advance

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