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Discussion Starter · #1 ·
Question for those that switch from SD to MAF in order to get the car to perform readiness -- Initially thought everything was going well, uninstalled AP, disconnected battery, re-installed AP with MAF map, started car & all was well. Left it idling for a minute before jumping in to begin the drive cycles and then it threw a CEL (PO237). Cleared it, but came right back in on re-start.

I was warned about this, running a MAF tune with TIAL Q (VTA) so I knew it could be a problem....gotta admit, I was surprised how quick it came in.

What course of action works for this, heavier spring?
 

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Are the valves physically open at idle?
 

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try unplugging the line running to the BOV and cap it off.
 

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Discussion Starter · #4 ·
try unplugging the line running to the BOV and cap it off.
I will -- thanks!

Are the valves physically open at idle?
It did appear they were lifting off their seats, so I've ordered a pair of 11psi (yellow) springs. I should have had these handy when I flipped to MAF, like I said, I was warned about this by a reputable tuner....I'm dumb :headshake:
 

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I will -- thanks!

It did appear they were lifting off their seats, so I've ordered a pair of 11psi (yellow) springs. I should have had these handy when I flipped to MAF, like I said, I was warned about this by a reputable tuner....I'm dumb :headshake:
Once you unhook the line and cap it off you won't have any vacuum on the top port opening the valve. At this point the valve will only open when the force (boost pressure x valve area) (lbs) on the face of the valve exceeds the spring force. Therefore, as long as you keep the car out of boost you should be good to go, but please let us know if this works.
 

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Discussion Starter · #7 ·
Once you unhook the line and cap it off you won't have any vacuum on the top port opening the valve. At this point the valve will only open when the force (boost pressure x valve area) (lbs) on the face of the valve exceeds the spring force. Therefore, as long as you keep the car out of boost you should be good to go, but please let us know if this works.
I should have the springs tomorrow so I'll just install them and try that out. If that fails, I'll move onto capping.

I'll update the thread after the install though -- I'm sure this type of thing affects more than a few of us.

Thanks for the help :thumbsup:
 

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I run the yellow springs with MAF, but blow through and after the BOV so I don't have those issues with converting back from SD. You may still need to disconnect the lines, but maybe not.
 

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It's not your question, but I believe that when going back and forth between MAF and SD with your AP, disconnecting the battery is not also needed. In any event, as you know, the emission sensors must re-enable themselves after an indefinite number of re-starts and mileage. (As far as I know, no one knows how to speed THAT process up)

Alexd
 

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Discussion Starter · #10 ·
Thanks Alex — you’re probably right, I just thought I’d add that step to 100% eliminate that from the equation.


Sent from my iPhone using Tapatalk
 

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The only real fix here is to run the QR BOV's. It is as simple as that.

You should not run Q's with an MAF. Venting to atmosphere will always screw with the MAF

Running a heavier spring is also not a fix. QR's are

MotoPro
 

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Discussion Starter · #12 ·
No argument here -- will only be on MAF for as long as it takes to get readiness & then switch back to SD
 

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Discussion Starter · #13 ·
Update (was away for long wknd) -- Installed the yellow springs and added 240Z's suggestion of capping the lines leading to the BOVs. So far so good -- after about 15 miles, got evap to go ready. o2, cat & secondary air still to go but probably need a few more cold starts & drive cycles to get 2 of 3...then I'm good!
 

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Discussion Starter · #14 ·
Secondary air ready after just one more cold start -- did one of those extensive drive cycles & put about 40 miles on but still have o2 & Cat in. Tonight I'll put in another cycle..
 

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Discussion Starter · #15 ·
About 275 miles on now and it's still stuck at the same spot. One thing I didn't do after the uninstall was to run the car on the stock map @ idle for a minute before reinstalling the AP as mentioned in another thread -- doing that tonight!
 

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Discussion Starter · #16 ·
Final Update -- I passed this morning!!

Turns out my map was still missing the checked box for enable diagnostics in advanced options. Once I loaded this updated map, cat went ready within 10 miles, unbelievable :clap: Evap cleared even before that. One more cold start this morning and secondary air was ready. o2 was the only not ready I had, but I only had 25 miles since the reflash so I imagine it was only a matter of time but we're allowed 1 so f*ck it, I'm done...already switched it back to SD so I can have some fun with it again!! :paddleshift:
 

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Final Update -- I passed this morning!!

Turns out my map was still missing the checked box for enable diagnostics in advanced options. Once I loaded this updated map, cat went ready within 10 miles, unbelievable :clap: Evap cleared even before that. One more cold start this morning and secondary air was ready. o2 was the only not ready I had, but I only had 25 miles since the reflash so I imagine it was only a matter of time but we're allowed 1 so f*ck it, I'm done...already switched it back to SD so I can have some fun with it again!! :paddleshift:
That's awesome and don't forget to hook up the BOV's :dance:

I will say this after having gone through this year after year with my EVO, I am SO GLAD that I recalibrated the MAFs (No SD) and use a blow through setup because I can support 850hp with the MAF setup running VTA Tial's and don't have to do anything to pass inspection. The only thing you need to make sure is the MAFs are the original Hitachi and not recalibrated FORD MAFs.
 
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