PCV & MAFT Question

[Ninharu]

Ok i've gone through all those long PCV threads and from what i gather the general consensus is that you should run a factory setup with catch cans and a check valve to ensure the PCV doesn't leak under boost. Now my question is what do the people with a MAFT blow through do? I can't seem to come up with a viable alternative. Currently I am experiencing all the common problems with VTA of my PCV and VC to a RRE catchcan. I have a distinct fuel smell at idle and a slight hiccup at idle after a good hard run. So i'm guessing it is because i am not removing all the crankcase fumes at idle. As well i have a slight hiccup in my fuel pressure at ilde. It occilates a 1-3 psi from my gauge after the car has warmed up, it is intermittant but only when the car is warm. So i am guessing it is all related to my current PCV set up. I have an idea but i dont know if it will work. If i reinstall the PCV to its stock configuration with an inline check valve and catch can at idle i will be pulling unmetered air correct? but say i take my VC breather connect an inline catch can and tap a NPT fitting to the elbow between my GM MAF and throttle body, this would mean i would be pulling in metered air right? Would this eliviate the PCV problem associated with running a GM MAF blow through? All my mods are listed in my profile.

 

[turbosax2]

Maybe you have already seen this thread?
http://www.dsmtuners.com/forums/showthread.php?t=268203&highlight=pcv

I think your concerns are similar to his. He never got an answer, but maybe something in that thread will give you some ideas.

I'm interested in this solution too.

 

[Ninharu]

From what i gather you would need to run 2 check valves although i cant figure out a way that would work properly. One that under normal vacuum would pull at the pcv to get rid of excess crankcase fumes but the air would have to be drawn post MAS through the VC breather. then under boost the PCV 'should' close and the excess blowby is pulled/vented via the air intake preturbo. His diagram will pull under idle from both the PCV and VC, which isnt ideal, because there is no fresh air source ( i dont know if you would consider this unmetered air or not ). But under boost the checkvalve will block boost from going back into the PCV or VC and the excess blowby should get sucked in by the preturbo air inlet. The only thought i would have to bypass this is could you run a small electrical vacuum pump that would run all the time and pull say 18 mmHg from the pcv and or vc (through a catchcan) and just vent it to the atmosphere? Would this work? Or would there be some other problem that this would cause?

 

[oldman]

Ok i've gone through all those long PCV threads and from what i gather the general consensus is that you should run a factory setup with catch cans and a check valve to ensure the PCV doesn't leak under boost. Now my question is what do the people with a MAFT blow through do? I can't seem to come up with a viable alternative. Currently I am experiencing all the common problems with VTA of my PCV and VC to a RRE catchcan. I have a distinct fuel smell at idle and a slight hiccup at idle after a good hard run. So i'm guessing it is because i am not removing all the crankcase fumes at idle. As well i have a slight hiccup in my fuel pressure at ilde. It occilates a 1-3 psi from my gauge after the car has warmed up, it is intermittant but only when the car is warm. So i am guessing it is all related to my current PCV set up. I have an idea but i dont know if it will work. If i reinstall the PCV to its stock configuration with an inline check valve and catch can at idle i will be pulling unmetered air correct? but say i take my VC breather connect an inline catch can and tap a NPT fitting to the elbow between my GM MAF and throttle body, this would mean i would be pulling in metered air right? Would this eliviate the PCV problem associated with running a GM MAF blow through? All my mods are listed in my profile.

1. I seriously doubt that your idle/fuel pressure hiccup has to do with your crankcase ventilation setup, did you Teflon both the vacuum fitting as well as the adjustment rod on your AFPR?

2. The problem with your NEW crankcase setup is that not only you will have no ventilation under WOT, you will be pressurizing your crankcase. I would go ahead and setup the 2 catch cans/check valve with the breather side connected to the intake pipe and deal with unmetered air using your low settings on the SAFC. Proper ventilation of the crankcase is the priority in your case (for the sake of your motor) because you have the means to deal with unmetered air at idle and part throttle.

 

[Ninharu]

I didnt bother setting it up that way yet, it was just an idea i had, but then thinking about it i realized it would not work for just the reasons you mentioned. I like to ask people first before i do something stupid and blow something up Right now i have the RRE catch can VTA setup. But as far as the teflon taping, i did use gasline tape for both the fuel presure sensor off the rail (i have an AEM rail with my sensor on it) & the npt cap on the AFPR. Though i did not tape the vacuum fitting or the adjustment rod (and for that matter how do you tape the adjusment rod? and i'm guessing that i havn't this means i have a new vacuum leak). Its strange because it only does it intermittantly, most of the time the idle fuel pressure is fine. My RPM will also seem to hiccup intermittantly as well, but both of these conditions are met when the car is warmed up. I can actually hear the pump's whine change and as well at idle the car seems to randomly hiccup as well, while the rpm ocillates + or - ~50 RPM, so i just thought the 2 might be related. But running it the way you mentioned wont i lose vacuum at idle? And im guessing the small electrical vacuum pump isnt a viable idea either? For what venting a BOV is worth, im contemplating just going back to the stock setup. either that or speed density. But i know you have posted at length about this considering your trials/results and im just supprised that with the number of people running a maft no one has come up with a solution for this. I guess i will give it a shot and see how it runs. I am also guessing that how this guy set it up is also a bad idea.

http://www.dsmtuners.com/forums/show...&highlight=pcv

Thanks for the help, i appreciate it

 

[oldman]

I didnt bother setting it up that way yet, it was just an idea i had, but then thinking about it i realized it would not work for just the reasons you mentioned. I like to ask people first before i do something stupid and blow something up Right now i have the RRE catch can VTA setup. But as far as the teflon taping, i did use gasline tape for both the fuel presure sensor off the rail (i have an AEM rail with my sensor on it) & the npt cap on the AFPR. Though i did not tape the vacuum fitting or the adjustment rod (and for that matter how do you tape the adjusment rod? and i'm guessing that i havn't this means i have a new vacuum leak). Its strange because it only does it intermittantly, most of the time the idle fuel pressure is fine. My RPM will also seem to hiccup intermittantly as well, but both of these conditions are met when the car is warmed up. I can actually hear the pump's whine change and as well at idle the car seems to randomly hiccup as well, while the rpm ocillates + or - ~50 RPM, so i just thought the 2 might be related. But running it the way you mentioned wont i lose vacuum at idle? And im guessing the small electrical vacuum pump isnt a viable idea either? For what venting a BOV is worth, im contemplating just going back to the stock setup. either that or speed density. But i know you have posted at length about this considering your trials/results and im just supprised that with the number of people running a maft no one has come up with a solution for this. I guess i will give it a shot and see how it runs. I am also guessing that how this guy set it up is also a bad idea.

http://www.dsmtuners.com/forums/show...&highlight=pcv

Thanks for the help, i appreciate it

If you didn't Teflon the vacuum fitting or the adjustment rod, I guarantee you have a boost/vacuum leak there causing richer idle and leaner WOT, spray soapy water on both and running a boost leak test and you shall see. Furthermore I would also make sure that the pump o-ring was installed properly, a ripped pump o-ring will cause pressure loss causing your pump to work harder to keep up with the same pressure. As for recirculating your BOV, I say why not, even with a MAFT setup, you're still losing recirculated air that can help keep your turbo spooled in between shifts by venting.

The link didn't work for me.

 

[Ninharu]

sorry i just cut and past the link, but it was the one that is previously mentioned up the thread.

http://www.dsmtuners.com/forums/showthread.php?t=268203&highlight=pcv


try that.

it is the second picture. i think the way he has it rigged will work, kinda. but there is no fresh air source at idle. and does someone even make a little vacuum pump that will pull 18mmhg and at a low enough flow to be benificial but not cause any damage to the engine? I was racking my brain as of a way to set it up but i cant come up with anything that works. And how do you teflon the adjustment rod? i have a aeromotive AFPR. it has a threaded rod that inserts into the reg and a lock nut and washer that will hold it in place.

 

[oldman]

sorry i just cut and past the link, but it was the one that is previously mentioned up the thread.

http://www.dsmtuners.com/forums/showthread.php?t=268203&highlight=pcv


try that.

it is the second picture. i think the way he has it rigged will work, kinda. but there is no fresh air source at idle.

You're correct, no fresh air source at idle. That setup will only do half of what the setup should do, pressure relief which isn't really an issue at idle and part throttle. It will end up building vacuum in the crankcase which can promote seal leaks, not to mention it will do a poor job of removing contaminates, kinda like trying to pour gasoline out of a closed container without opening the relief valve.

and does someone even make a little vacuum pump that will pull 18mmhg and at a low enough flow to be benificial but not cause any damage to the engine?

Yes there are electric or belt driven vacuum pumps out there (search Summit Racing) but I don't like it because it robs engine power as well as the possibility of pump failure causing havoc. If you decide to go this route, make sure you leave one side of the VC vented to the atmosphere for the same reasons cited above.

I was racking my brain as of a way to set it up but i cant come up with anything that works.

What can be think of has pretty been thought of. I would either deal with the unmetered air like I already said OR recirculate the BOV and set the MAFT up as draw through OR sell the MAFT and go back to 2G mas. 2G mas might not be a bad idea since MAFT are known for inconsistency, might even be the cause of your idle hiccups after warm up. http://www.dsmtuners.com/forums/showpost.php?p=151282240&postcount=3

And how do you teflon the adjustment rod? i have a aeromotive AFPR. it has a threaded rod that inserts into the reg and a lock nut and washer that will hold it in place.

Set your base pressure and mark the rod, remove the rod and wrap liberal amount of Teflon (due to the large threads) right under the mark, reset the base pressure. Make sure you retest until it seals, it took me 3 times to get it right because the amount of Teflon needed was a lot more than I expected.

 

[Ninharu]

Its funny how i never even thought of that being an issue, nor have i ever even looked at it as a source. Thanks for all the help, i appreciate it.

 

[oldman]

No problem