redbird555

iTrader: (14)

Hi guys, had the mail order tune done for my headers, exhaust lid and other bolt ons everything was going good! Recently though Ive had a couple issues and im starting wonder if the maf is bad and if u may be able to help. Recently my car threw codes p102 p1153 and p1133 I understand the latter 2 may be because of the lts and I had a k&n filter so that may be the cause of the first. Cleaned the maf and cleared everything drove about 200 miles and after shutting off the car once it started to miss heavily on acceleration and wanted to die at idle it threw code p0171 bank 1 lean. I have a scanner and was watching the maf and o2 sensors the bank 1 sensor was not switching well hovering at about .015-.03 volts the other was switching fine. The maf was showing a reading of .78 lbs of airflow fluctuating slightly and also with throttle. I will be checking my extensions as one did have a solder job on one wire, however I'd think if the wire was bad the sensor would not be working at all. The car also seems to run fine in open loop and as soon as it switches to closed loop starts to run bad so i dont think its a vac leak. Is there anything I can do to test the maf? I verified the wiring up to the maf is good with 12v and 5v at the plug with the maf unplugged. Could the k&n oil have ruined the maf? I'll be switching the o2 sensors to see if the problem follows but I really dont think its a sensor issue especially because they are bosch's with only 5k on them.
Thanks for the help Dan-

redbird555

iTrader: (14)

i should also add theat even while in open loop the car is running ok but the bank 1 o2 sensor still displays the same inactivity and low voltage reading.

WeathermanShawn

iTrader: (1)

It sounds more like your O2 sensors are not switching properly.

If the MAF is bad, I would think you would throw codes P0101 - P0103.

So, I would start with the O2 sensors first. I have a K&N and have had no problem. The oil issue might have been over-hyped. But, a MAF can go bad. My wife's Monte Carlo has had two MAF failures in the last two years. Each time it threw codes P0101-P01103. The car would barely drive and then stall.

Hope that helps.

redbird555

iTrader: (14)

Ok thats what I'm kinda thinking too but most people have told me that its not an o2 code and that something else is making the one go lean. But nevertheless I'm going to switch them this weekend and see what happens. If it was a vacuum leak the car would idle rough in open or closed loop correct?

WeathermanShawn

iTrader: (1)

Thats what I would think.

With a vacuum leak, I would think your RPMs would jump all over the place at idle.

I am more in the tuning arena right now, so the mechanical issues are not my strength. But, I always think it is best to start with the easier issues before tackling the more expensive ones.

Good luck. I think you are on the right track..

redbird555

iTrader: (14)

Ok well i just tried a few things and Im 90% sure the maf is fine its reading correctly and amazingly the car is running just fine no codes etc. The beellow behind the MAF was not clamped tho and may have been causing some kind of leak, however I still think the problem lies with he o2 sensor. When I had the scan tool hooked up I could see the sensor operating normally then for some unknown reason the voltage on the sensor would drop to 0 and remain low for a few secs then come back and fluctuate normally I dont have time to work on it today but atleast the cars running correctly now and I can drive it as little as I need to until I get time. This is a bosch sensor and after hearing the problems people have ill be going denso on the next ones.

1_fast_gto

iTrader: (1)

if you want to test your mass air flow really easy, just unplug it, let it throw the codes and then go drive it, the vehicle goes into a default mode and will operate without it, but from what you have said before in the thread i would think you o2 sensor is bad

turbolx

If your MAF curve in the PCM's tune (airflow vs frequency) does not match the hardware on your car, there is little chance that much else will be right. Even a change as simple as most aftermarket lids can shift the MAF curve by 10% or more. What's worse is that the shift is not one fixed percentage across the range, but varies with airflow. This will easily lead to symptoms like bank lean codes as the PCM struggles to figure out the proper amount of fuel to add for what is really an unknown air mass delivery. The proper solution here is to take some solid measurements and recalibrate the MAF transfer function table in the PCM to better match your hardware. Once that's dialed in, you'll find that several other little nagging behaviors will also be fixed.

redbird555

iTrader: (14)

Thanks guys thats what I'm figuring from what Ive read the o2 sensor should never really drop to 0 unless its shorting itself out. I mean Ill be driving normal and the sensor will be working like it should with the other side and all of a sudden the volts will drop to 0 for no apparent reason stay there for a sec come up to like .05 then jump back up and operate normally for the next minute or so. I'll have to wait till Im home from college next weekend to change it tho because I lack to the tools here I tried it yest and its seized up in the thread so I dont wanna force it and break it 200 miles from home idc if i eat gas on the way back I just need to get there lol. Once home ill just trash both sensors and get vette ones.

redbird555

iTrader: (14)

Oh and like shawn said above I think if this were a vac leak it wouldnt have gotten better overnight, it would always be there vacuum leaks dont just disappear.

redbird555

iTrader: (14)

hey guys the car is still driving like normal but the scanner just showed Closed loop fault bank 1. Does anyone know what this means its not a code and no ses light the o2 sensor on that side still dips down low while the other doesnt however it goes back up to normal readings after a sec, just wondering if it may cause that.