When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
We recently swapped our engine in our G35, for a used one we found that had 39K miles.
Everything seems ok, we have observed a slight hesitation in some circumstances, and the O2 sensors are reading a bit lean (they hang around 0.3V, no matter how much throttle is given). I know this probably isnt that big of a deal just yet, but it is something I would like to solve.
Any ideas on what it could be? All the readiness monitors are ready, and there is no pending or stored codes, and no MIL/CEL/SES. The only lights currently on are VDC off and SLIP, but I believe that is a unrelated problem (brake fluid needs to be changed due to too much moisture [pedal is slightly spongy], but level is fine)
O2 sensor (top right) just sits around 0.3V, doesnt alternate between lean and rich like all my other cars. Doesnt seem right...
Have you verified the o2 sensors are wired up? How old are the o2 sensors?
How do you like the dash command obdII thing you're using?
I am pretty sure they are wired up... wouldnt them not being wired up throw a code? I have no codes at the moment, and strangely the wheel alignment I got today fixed the SLIP/VDC error (still dont know how that is possible).
I love Dash Command, I use it all the time just for live monitoring, friends ask me all the time how it works. Im really geeky and just like to know what is going on, but it comes in real handy whenever you need debug issues as it does far more than just read codes, and on an easy to read interface like a smartphone. Connecting it can be a bit difficult depending on what OBDII reader you get, but the one I have works great and I havent had to do any manual wifi configuration on my iPhone with it, just connected to the hotspot, opened Dash Command and all works perfectly once Dash Command connects to the reader.
the obdII reader i got, yes I cheaped out there are better ones out there, but this does the job fine without getting the super cheap chinese ones lol.
Ive had it for about three months now. If you get one, just know all but one specific bluetooth adapter will not work with an iOS device. Majority of the bluetooth ones are Android only. The one bluetooth one for iphone is expensive, but might be worth it as you lose your internet connection if you use a wifi one.
But anyway, now that my SLIP/VDC error is gone all I have left is this lean issue and my front suspension is squeaking (might be because i had the car on jack stands for a month lol). Oxygen sensors are original, 192,900 miles old. lol I probably should have replaced them when the engine was swapped, but I didnt think about it as everything was fine before with the old engine except the motor itself lol.
Last edited by Scredeur4; Jan 2, 2015 at 11:57 PM.
Are you monitoring your O2 sensors or the A/F sensors? The rear O2 sensors just tell if you the the A/F sensors are working properly I believe. You would need to monitor the fuel trim levels to get a better idea probably. I was told by a Nissan/Infiniti tech it should run within +- 10%. When my car was running lean at 125% (+25) it was due to a HUGE vacuum leak in the brake booster seal. It was a PITA for me tracking that down.
Are you monitoring your O2 sensors or the A/F sensors? The rear O2 sensors just tell if you the the A/F sensors are working properly I believe. You would need to monitor the fuel trim levels to get a better idea probably. I was told by a Nissan/Infiniti tech it should run within +- 10%. When my car was running lean at 125% (+25) it was due to a HUGE vacuum leak in the brake booster seal. It was a PITA for me tracking that down.
I can monitor fuel trims with dash command, what is the best way to monitor them though?? There is long term and short term. Should I just go for a drive and see what long term is?? or do i need to let the car just sit and idle for a few minutes or etc; what is process by which I should monitor the fuel trims
I can monitor fuel trims with dash command, what is the best way to monitor them though?? There is long term and short term. Should I just go for a drive and see what long term is?? or do i need to let the car just sit and idle for a few minutes or etc; what is process by which I should monitor the fuel trims
You want the car to reach operating temperature and while at idle monitor the short-term fuel trim levels. I use a Consult 3, which shows it in percentages, so if it's between 90-110% then I know it's within specs. I think your numbers might run between between -25% to 25%.
If you are not getting any codes about running lean though, I think you should be fine. You should get a P0171 I think if that were the case. At idle my car RPMs would increase and then decrease every couple seconds. I hooked a vacuum gauge up and saw it dropping/increasing, I made a DIY smoke machine and found a huge leak at the brake booster.
I'd also do an ECU reset if you haven't the computer stores your fuel trim levels and you want to relearn those.
You want the car to reach operating temperature and while at idle monitor the short-term fuel trim levels. I use a Consult 3, which shows it in percentages, so if it's between 90-110% then I know it's within specs. I think your numbers might run between between -25% to 25%.
If you are not getting any codes about running lean though, I think you should be fine. You should get a P0171 I think if that were the case. At idle my car RPMs would increase and then decrease every couple seconds. I hooked a vacuum gauge up and saw it dropping/increasing, I made a DIY smoke machine and found a huge leak at the brake booster.
I'd also do an ECU reset if you haven't the computer stores your fuel trim levels and you want to relearn those.
Got a chance today to take a look at the fuel trims, and at idle they were ranging from 3.9-4.7% Short term. Not sure what "scale" this app is using or what I can compare it to?? I might need to try a different software idk.. but anyway here is some pics of highest and lowest I saw. I dont know much about fuel trims to be honest, willing to learn.
The fuel trim levels just show how much air or fuel needs to be added/decreased. Since you're only running between 3-4% you're within specs. If you were at 11% or -11% then I'd start looking to troubleshoot it.
You should have bank 1 and bank 2 readings though, so I would double check both of them.
The a/f sensor is kinda like a more advanced O2 sensor. The two rear O2 sensors monitor the a/f sensors are working correctly. That explains why your voltage in your original posting was misleading.
The fuel trim levels just show how much air or fuel needs to be added/decreased. Since you're only running between 3-4% you're within specs. If you were at 11% or -11% then I'd start looking to troubleshoot it.
You should have bank 1 and bank 2 readings though, so I would double check both of them.
The a/f sensor is kinda like a more advanced O2 sensor. The two rear O2 sensors monitor the a/f sensors are working correctly. That explains why your voltage in your original posting was misleading.
Ok i got you. Thanks for clearing that up.
well it might have bank one and two, but i have no way of reading both of them currently. know of any software that is perhaps more advanced that will work with my ELM327 wifi OBDII reader?? (im thinking maybe ill be able to see it then) I do have a laptop so I can use that if i need to.
Im also wondering if DashCommand is just giving an average of the two banks? I wouldn't know what it is doing.
