Miata Valve Cover vents and PCV explained
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- čas přidán 31. 08. 2022
- Sorry its just a screen recording over a static image. If you care about the information, I htink its very valuable. Ill do my best to make future videos like this more intertaining.
after 45 years of working on my cars, I finally understood what the PCV is for. This was a GREAT video!
Thanks so much for this! I just bought a Miata NB and I’m in the process of getting to know. You deserve a lot more subscribers!
Great video thanks..
hey this is a really cool! I didn't fully understand PCV systems until this video :) so tyvm for your effort
Fantastic explanation. Keep them coming!
Great video. Love the simple and easy to understand format.
Very informative and very helpful. Keep the wisdom flowing our way brother. Thank you 🙏 🤌🤙 I subscribed for this video it’s great
Ah, finally understand purpose of pcv valve and the other tube.
Very useful buddy thank you
Thank you for the very useful information.
Good content I learning more and more please do more
awesome explanation, subscribed!
Great explanation !..
Thank you for your explanation! Really helpfull and clear 😀
Amazing video, thank you!
Gread vid, big thanks!!
Would you recommend running an oil catch can on a Stock NA 1.8? Also great video, I better understand why breather filters are a nuisance on a stock application.
This was helpful
Great explanation! it sounds like it is a bad idea then to install a catch can on the hotside vent if running a factory ECU, since the ECU will no longer be aware of the air that is being drawn by the valve cover to the intake.
Would you interested in an explanation of the EGR tube on the header, and whether that could be capped off if going aftermarket headers
Thank you : )
Chris, I learnt a lot from this thank you. Can you explain please, where you said ‘the sealed catch can set up works for the naturally aspirated setup’ Why is that? Why is it beneficial? Also can you explain please, you mentioned about replacing the oil that accumulates in the catch can, but what about without the sealed catch can, what happens with the oil that comes out through the PCV valve? it must go back into the engine via the intake plenum and get burnt - is this right? Just asking as part of a learning process. I have a stock NB (2004) 1.8 SVT Sport.
When you have both the throttle body and intake capped off and put a breather vent with oil catch hooked up to the valve cover vent and crankcase vent no are is being sucked into the throttle body and also no oil vaper or oil is going into your throttle body. The is vented naturally and any oil in caught in the oil catch can.
I have a NA8 and just got a link ecu and I got it tuned 3 times but it's having trouble cold starting and idling as it sits at 1500 rpms till you cycle the car (turn it off and on again) then it goes from 1500 to 1000 but if you touch the throttle it repeats the process. I have been told it's a vacuum leak but am not to sure... any insight is welcome
Can I delete the hot side valve cover vent if I am running a turbo and no maf? I’m on a stand-alone
I know this is an old video but I have a question related to venting. What is the purpose of venting the suction line to atmosphere. Why would you do it and what does it gain you?
what if you added pcv valve on the hot side too
alright i got a question. i plan on doing a valve cover cut to expose my cam gears, but when i do that the bracket/hose won’t be able to be attached leaving the hose to dangle. instead of doing that would a catch can on the hot side of the engine be a solution ? or would it be better to find a longer hose and route it differently ?
I’d route with a different hose. Exposed cam gears do look pretty cool but definitely run the factory under tray if you do it because you don’t want a pebble to fly up and get into the timing area.
I wanna ask a stupid question... Recently, I was chasing a low idle on a NA8. I had had the intake manifold off to get it powder coated, so I was partly convinced the problem was related to intake air. I took off my hot side vent hose wile the engine was idling, and I felt pulses of air leaving the engine. If that's the intake side for the crankcase vent, why was air exiting the engine through that port at idle?
I have 2 theories.
One is that it could have been difficult to tell that the moving air you felt was actually coming out of the vent or into the vent. Assuming that you accurately determined the air was coming out of the vent, my other theory is that your PCV valve was jammed shut.
The PCV valve is a one way check valve that should only let air come from behind the valve cover and into the intake manifold when it’s under vacuum. In order to replace that air, there MUST be inward flow from the hot side.
If both of the above are incorrect, then my last theory would be that one or more of your 4 pistons are making incredibly poor compression and the blow by is giving the crankcase enough positive air pressure to need to vent out of both openings on the valve cover.
Without being able to diagnose your car in person it’s hard to say what caused your experience.
What would be the optimal solution for an itb setup without an intake plenum? I've seen conflicting opinions but one I've a seen a lot is deleting the intake side valve and joining both to a vented catch can. Is that ok for the engine?
I do not have first had experience running an ITB setup but I'd say off of my understanding of the theory alone, if you don't have a vacuum source, I would just route both Valve cover outlets to a vented catch can. If you are running a vacuum block I would route a more traditional PCV circuity on the intake side of the VC with a sealed catch can between the PCV and the vacuum block. Then I would run the exhaust side breather to a vented catch can, You still don't want a small cone filter on the hot side because there is always the potential that the engine may lose some oil out of it and you don't need to be dumping oil onto your exhaust header.
It's important to note in the instance of ITBs, that the metering and air/fuel mix issues I focus on in this video would not apply as an ITB setup absolutely cannot be ran on an OEM ECU.
Well the o2 will correct over time. But everything in the video is still correct.
I can’t say you are wrong but these are 35 year old ECU’s. I don’t think they were that smart back then
not sure if NA have a one way check valve on the intake PCV side. But NB have a check valve on the intake PCV side. We can run a breather on the exhaust PCV side on stock ECU. It wont change the AFR condition at all. Already verified by many people with an AFR gauge long ago including myself.
The PCV valve is the same part for all 1989-2004 Miatas. The check valve allows airflow into the intake from the VC and not the other way around. In order to facilitate moisture evacuation, this pulls air in on the hot side. Which is behind the MAF in all OEM applications.
Without a high resolution log mapping throttle, intake pressure, and AFR data overlaying, it would be very hard to confirm this by just watching an AFR gauge. It wouldn’t make much difference under and sort of load but again it can cause drivability stumbles and hesitates going on and off of a fully closed throttle for milder stop and go traffic, parking lot, or rolling onto throttle while in gear on the highway type of driving situations.
Yeah I don’t know why people do that. It’s silly
Thanks for this explanation, its clearer than ever ! 🫡