m05fastbackGT

Hate to disagree, however Metco motorsports also makes the same type of breather.. Their filtering design is slightly different compared to CFM's, but functions in the same manner and also includes a one way check valve..

Their prices are just $10.00 cheaper compared to CFM at $69.99.. Therefore I would just stick with the CFM breather, as they're the original designer/manufacturer..

http://metcomotorsports.com/proddetail.asp?prod=MBR0005

07 Boss

Don't hate. I am the ignorant one who didn't know Metco also made one. Consider it a privilege to educate the ones that are less fortunate or ill informed.

m05fastbackGT

UPR also makes them, but they don't list them for the 05-14 GT nor 07-14 GT500, but only for the F-150 and 15-17 S550 models..

Anyhow it's not your fault that you didn't know about Metco also making them.. Only reason I knew, is that I came across Metco when doing a vendor search nearly 2 years ago to find a one way check valve breather for my car.. So following my research between Metco and CFM, In the end I decided that CFM offered the better design, product support and lifetime warranty which were all important factors to say the very least

Left Lane Muscle

Well, update guys! With normal oil cap in place, the problem is gone in open loop. Once it switches into closed loop, the problem reappears. Maybe that's why the problem has been getting worse, the o2's are slowly going. I read that they can either go bad abruptly or over time. I'll get under the car this weekend (I work 7-9 tomorrow) and disconnect them so it stays in open loop. If the problem is gone after a few miles of driving around, problem solved. So as of now, it appears I had two problems, one of which are solved. Thanks for all the help so far guys.

m05fastbackGT

I can tell you what part of your problem is.. The oil cap breather you had installed didn't have a one way check valve.. This was allowing un-metered air into the crankcase and causing your air/fuel mixture to run lean which led to your car to misfire when in open loop, but as soon as you re-installed the factory oil cap, the problem stopped until going into closed loop..

Therefore if your going to run an oil cap breather with your car's factory PCV system still active and connected, you must make certain the oil cap breather has a one way check valve.. Otherwise just stick with the factory oil cap..

In the meantime, let us know how you make out with your 02 sensors.. If you happen to find out that your 02 sensors aren't going bad ? Then I highly suggest once again that you have your tuning specialist diagnose your car and have your calibration tune and fuel trim parameters checked !

07 Boss

Maybe try resetting your KAM data by unhooking the battery for a while or reflashing your tune. Your car has been making wild adjustments for the air flow and it keeps that knowledge. If the unmetered air has been the problem in closed loop it will correct itself over time but you could help it along by making it relearn that **** with the proper air flow. Just a thought. And it doesn't cost anything.

Maybe try an idle relearn also.

Left Lane Muscle

I didn't have time to sit down this weekend but I did some testing. The car ran a little rich in open loop since the leak from the breather was fixed (tuner made some small adjustments which now have less air than it was meant for). With the o2's unplugged, it runs normal until when it would normally switch to closed loop. My obd2 reader isn't working, so I don't know if it is still trying to be in closed loop or what. It began running richer than my wideband would read, and my vacuum read 10. Sounded like I had a cam. I shut it off and plugged them back in, that problem went away.

I said **** it and ordered new o2's. I got the Bosch ones from Amazon, they had great reviews. When I put them in today, the same problem happened as when I had no o2's connected. Super rich and low vac. Since it's the same problem as with no o2's I'm not going to assume something is bad with my new sensors. I guess I'm going to go have my tuner datalog for me. I need him to adjust the open loop mixture anyway.

I'm not worried about the cost of the o2 sensors I ordered, if the datalog shows him the problem and it isn't them, I can just return the new ones. They were in the car with the engine running for a total of under five minutes. I assume there's no small break in period for new sensors.

I did reset the KAM and did an idle relearn, no results. Also, I got my proper breather in and installed. It definitely feels more high quality than the, what I assume was Autozone junk that I had. I'm getting sick of dealing with the problems that come from this car. I knew when I bought it that I would have more things to keep an eye out for than my previous eco car, but Jesus man. It's getting ridiculous. I'll post back when I get an answer from my tuner. His hours and mine don't work well, so it may be a while.

m05fastbackGT

Having your tuner datalog your car is your best option.. This way you'll know exactly what's causing your cold start issues, rather than assuming what might be causing them only to find out that your not getting any further ahead than where you started from to begin with anyhow..

Left Lane Muscle

So I got with my tuner and we did some testing. He said the o2's were working properly and looked like they were adjusting for a vacuum leak. This was still after clearing the KAM. He changed the fuel delivery down under 2k (where the problem shows itself) and is driving perfectly fine now. The only problem is that at idle and cruising, it seems to normally be around 13.8 afr. Obviously this is a band aid, so I'll get the leak found and fixed whenever I can, then we can get it back to normal ratios.

Thanks for all the help guys, you have no idea how happy I am this is partially resolved and that I now know the problem.

m05fastbackGT

Just to make certain we're on the same page.. When you refer to changing the fuel delivery, do you mean making adjustments to the fuel trims or is changing the fuel delivery related to something entirely different

Left Lane Muscle

I know this is an old thread but I might as well give y'all (and anyone in the future reading this) an update.

Two retunes later, the problem is still there. It doesn't matter if the car is warmed up or not anymore. I'm not missing right now, but like the last two times I got the car retuned, the mixture is slowly reading more and more lean as time goes by. I've done absolutely everything I can. Performance shops don't know what's going on, my tuner doesn't know what's going on, and neither does anyone in the mustang facebook groups I'm in lol. Each time I have my tuner retune it, it's drivable for about half a year and then it starts missing again. I know tuning around a problem is something that shouldn't be done, but at this point I don't have much of an option.

Not the update I hoped to post back when I made this thread, but oh well lol.

m05fastbackGT

I remember quite well about the tuning and lean conditions you were having on this thread. Unfortunately, I'm completely stumped and don't know what else to recommend other than consider going with a different tuning shop, as it would seem IMHO that your issues are directly related to your calibration tunes, especially knowing that after two different re-tunes, you're still having the same lean condition issues as before. Have you considered looking into Lund racing, VMP, and Lito? All 3 are considered as some of the best tuning specialists in the industry and have the most experience in tuning for the 05-10 3v Mustangs.

Either way, you can't go wrong with either one. Therefore I really think it would be in your best interest to contact them about your issues and find out what they can do for you? I'd also strongly recommend in having them walk you through how to go about recording a data log file from your car's ECM in which they'll use the parameters taken from the data log file when tuning your car also known as remote dyno tuning. At any rate, I would most definitely look into this as your next best option