Issues idling/running lean with no CEL

Hello all, I have been having an issue with my speed for a while now and I think I may have found the cause finally but would like to hear what more experienced members might think. Everything went south last winter when I installed my intake system, I had broken the elbow connector I needed to connect the valve breather hose to the intake. Needed to drive the car back to college and after talking to multiple people decided I'd get there fine since it could still "breathe" and I put a cork in the intake to stop it from sucking in there. I did end up getting a running lean code right as I got there after about an hour drive but the car seemed to drive fine. Drove back home the next weekend, and fabricated a solid connection with a similar elbow off another Mazda (I did have to modify it to fit the intake but 99% sure there is no leak here). Everything seemed good, but ever since then I have begun to develop worse issues idling and hard starting began to happen most recently. I have used the soapy water method to check for leaks and found none but re installed anything I had put on just incase, I also noticed my MAF will read weird by dipping down into the 2's and up to the 5's at idle. Most of the time it reads around 4 though, same with the fuel trims, they only go wonky when it begins idling poorly. My conclusion is that in the short time I had the valve cover breather exposed to the outside air instead of the air from the intake (plus the intake not creating vacuum which I did not consider at the time) enough gunk could have accumulated to clog the PCV valve and cause issues? I'm also unsure of if a bad/slightly clogged PCV would mess with the MAF readings like that? Like maybe its expecting the air to come in the intake from the PCV system and its not, idk. I plan on meeting up with another speed owner asap to swap his MAF to my car and see if it ends up just being that, but I doubt I'll be that lucky.

Considering this started after the intake specifically I'd assume its not related to my other mods, and I'm sure I need to add it to my profile but my total mod list is: HPFP, SRI, TIP, CPE TMIC. On cobb stage 1+sf tune as my full plans are to get a test pipe and then proper tune, however I'm really trying to solve this before spending more money on mods.

 

Cobb tune, I'm guessing OTS? Is Intake larger than stock ~2.67" ? If so then you could revert to stock tune, then troubleshoot with a known tune. Once that happens, give us your logs. To much is better than to little. Short description of what now is the codes and drivability issues. MAF swings could be the issue, starting issues could also be from MAF swings. Reading MAF voltage is a better troubleshooting indicator when flow numbers jump too.

 

I considered it could be the cobb tune so went to stage 0 and same issues. Again haven't had any engine codes post addressing the disconnected breather hose. Not sure when I will be able to meet up to swap MAF's with the other speed to check that way, but tomorrow if I will try to take a log using the voltage reading at startup/idle and hopefully that will give more insight. Is there anything else specific I should log along side it or just start there?

I don't know the exact intake size I think it is just slightly bigger than stock maybe, it is the cobb sf which is why I prefer to run the OTS tune at least. Am I missing something I should have done with that? I saw some super old stuff about people doing mafcals but no idea how I would do that or if its even necessary for the setup.

 

Okay, this morning I decided to just let the car idle for 20 mins and then the 15 with the ac on blast as I have reset the tune a few times recently. Got in and readings seemed much more stable and I was ecstatic. Shut it off, few hours later go to take it for a driving test, hard start again but idling pretty good. After driving around the neighborhood I noticed something really interesting, my fuel trims were pretty stable while driving yet when I would press the brake peddle STFT would fluctuate and this is when the car runs weird, after releasing the brake and waiting for a moment the STFT returns to normal. First log is driving through the neighborhood and the second is sitting at a stop and occasionally pressing the brake peddle, you can see STFT go slightly more negative when pressing down and as I was releasing they would go positive and the car would run poorly before returning to normalization. Any ideas?

 

Yep this is going to drive me insane, after doing some of my own research it is probably normal for the fuel trims to change some while touching and releasing brakes. So below I have attached my hard start log, perhaps this is injector or idk wtf related!

 

Is your battery older? I had a ton of weird shit for about a year before mine went bad enough to not start

 

Voltage looked good when I've checked it every once in a while on the accessport, but I do think its getting older so I've been checking more frequently.

As an update I took the car into a shop and explained everything to them. The tech said he could not get it to misfire at all while it was there and that there was not even a lot of misfire codes stored in the PCM for it to be enough to worry about (though I wonder if reflashing tune resets this as I did that multiple times recently). He essentially said it might be a slight issue with the tune or that I needed step colder plugs, but that he was sure it was something small. Had to pay a hundred bucks for that but the guy was at least helpful in answering all my questions and they did look at it for a while. When I got home I changed the plugs out for a new set I had around even though they weren't that old (10-20k), however they did look pretty beat, and they had been run for a while when I had that intake leak. So far after driving the car I think the cause was legit just some fouled/burnt plugs because its been a lot smoother. Personally I have not considered it completely fixed because some time without issues needs to pass, however I will update if the time comes.

*EDIT*
I totally just realized I didn't even mention the misfires in the first post, they were an intermittent issue during the intake leak which went away, however I had an engine code come up again for it a few days ago which led me to the mechanic. This thread is honestly just a mess, can you tell its my first time doing a major diagnosis on a performance car?

 

You do not need colder plugs at your mom's level

Post a pic of old plugs for reference please

 

The buggers themselves, on the short but spirited drive I got in I also noticed much more desirable maximum knock retard readings, so it definitely did something.

 

They look a little ashy but I would think they would have still worked. Hopefully one was bad and that was the problem