Weird P0101 code with idle rpms drop

philip B

philip B

Silver Member
2012 Mazdaspeed

Ever since I ported intake manifold( new gasket was used) and did throttle body coolant bypass (reused stock gasket) and added a CFM oil cap breather I keep getting p0101 code intermittently with weird idle fluctuation when ac compressor is on only.
Idle stays at 700 rpm’s no ac on.
Cold start Ac on idle rpms will go up to 780 -compressor on, compressor off it drop down to 700 like normal.
After engine is warm Ac on idle rpms will go up to 780 then drop to 640 a couple of times not all the time but a lot for a split second then shoot up to 780 again and come back down to 700 as if it’s hunting it’s ideal idle during this when it gets below 690 range the engine feels like it starts to bog down and I have Damond rear motor mount so the vibration in the engine is easily felt as it changes rpm’s and I can tell what it’s ideal idle feels like which is 700 or higher.
No ac on it doesn’t do this at all.

The p0101 code comes on every couple of drives or after a couple wot pulls during logging very sporadic. I have wiggled the wires while logging to see if there any fluctuations and nothing out of the ordinary cleaned maf as well no change mad sensor voltage read .98 at idle and goes up to 3-4 volts at wot as normal. So could it be bad mag sensor but would I not see weird logging numbers of it was.
I’ve looks at ltft which stays at -7 percent and stft don’t go above 20 percent I’ve done a smoke test nothing between the intake and throttle body.

Currently getting tuned for e30. Why om trying to figure this out.

Recent Mods done listed above are the only thing done before the code and issue started to appear. Before that it was fine with mods listed below.

Grimmspeed EBCS 3 port mode.

.Injectors Cleaned by RX injectors before tuning process began.

.Valves soaked and cleaned with b12 and vaccumed before tubing began.

3" Exhaust Cat back titanium tips -ULTIMATERACING

. EGR Delete w/ block of plate -DAMONDMOTORSPORTS

. Oil Catch Can vta- DAMONDMOTORSPORT

. High-pressure Fuel Pump Internals/e85 gasket kit combo -CORKSPORT

. Spark plug replaced/ LTR6BHX .26 gap -AUTOZONE

. Turbo Oil Restrictor bolt -DAMONDMOTORSPORTS

.PCV plate upgrade -DAMONDMOTORSPORTS

. Rear motor mount -DAMONDMOTORSPORTS

. Dual VTA Bypass Valve -CORKSPORT

. 3.5” Downpipe cat-less -CORKSPORT

. 3.5-inch Mazdaspeed 3 Power Series Intake System -CORKSPORT

. TMIC Top Mount Intercooler -CORKSPORT

.VCTS deleted completely plugged intake manifold hole.

.Software using Versatuner/Damond tuned

.oil pennzoil 5w-30

.Corksport injector seals installed

.Compression 180,180,175,180 after new injector seals
 

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what is p0101?

who is tuning you?

try using a piece of cardboard etc to block flow from the radiator fans hitting the air filter. the corksport intake has an air straightener but you never know.
 
Easter Bunny said:
what is p0101?

who is tuning you?

try using a piece of cardboard etc to block flow from the radiator fans hitting the air filter. the corksport intake has an air straightener but you never know.
Click to expand...

P0101 indicates a problem with the Mass or Volume Air Flow ("A") Circuit Range/Performance

Damond tuning. Did my 93 tune with out issues. I’ve asked about he said it could be a connection wiring issue if not a vaccume leak.

My radiator fans do come on every time the compressor comes on with engine up to temp which is every 10 -20 seconds with ac on low.
 
Yes they come on 1-2 seconds after the compressor comes on.
As soon as the compressor comes on the rpms hit 780 then the fans kick in and the rpm’s start to drop and sometimes make it go 640 before it tries to bounce back up to 700 almost like it’s fighting whatever is causing the drop of rpm lower than it likes. Once the and fans shut off rpms go back to 700-740 until its cycles back on.


Radiator fans sound like air being blown out through a hole in the engine compartment when it kicks on. Don’t recall hearing that before. You can hear it vividly in the cabin and distinguish it from the cabin fan.

it gets worse as the engine idles seems to not drop below 680 until after 15 min of sitting it will start to go as low as 640ish with ac on.
 
It's the fans messing with the maf getting a stable reading. It happens with bigger intakes. Usually adding a honeycomb air straightener fixes it but the corksport has a built in air straightener
 
Well damn. The corksport one I have has just two bars in the middle that’s it. I wonder if that’s enough.
 
Did some test driving with oem oil cap on instead of the cfm breather and did 5 wot pulls back and forth. no codes but the rpms dropping below ideal idle still persist. And I can conclude as the compressor gets hotter sitting in idle and fans running harder the idle drop to 640-650 every now and then after awhile does not seem to go any lower so I guess I can live with it.
 
Couple of things you can try:
1. Rotate the air filter you have currently, see if that helps
2. Buy a bigger (ideally longer) air filter as that may reduce the turbulence inside the filter a bit; do NOT use a K&N filter for this.
3. Get a honeycomb air straightener; these can be bought from Treadstone and should be crushed on the sides to fit (just barely enough to slide it in, you don't need to weld or glue it or anything and it doesn't matter if the outside is a little fucked up, it's the middle area that's most important here).
 
Well I be….. I rotated the maf housing about 10 degrees to the right clockwise to where bars are slightly in a diagonal position not straight up and down and no longer does it bog down when the compressor and fans come on. Seems I had it like this previously until I took of the intake manifold again and reinstalled the maf housing upright.
Talk about sensitive.


I still orded honey comb aluminum kit just in case, it does slightly go down past 700 but not like it was before it’s 2 times better than it was beofre. Not sure if the code was effected by this or just the oil cap breather will put it back on to see if I get the code again.
 
The honeycomb is all you need. Be careful when installing, you don't want to make it sit in there loose, as that can cause issues. Just crush the parts that don't want to fit and it should press in just fine (even if it becomes loose, it won't get past the MAF).

IMG_20230520_135427279.jpg IMG_20230520_135418633_HDR.jpg
 
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