Please help ASAP! 2 pending codes, P1271 & P1281, won't rev over 2,500 rpm
 

Hi Guys

I need some help/input ASAP! I have a 2004 350Z that is a dedicated track car. I recently replaced my sub frame bushings and fuel pump and took it to the track yesterday for the first drive. (it is a full race car with no tag so I can only drive it on the track). I went to the track yesterday took my car out of the trailer and it was a crazy storm here we get in the summer in South Florida. I waited an hour and drive my next session just to see how the car is, I figured I would just take it easy and drive slow since its so wet out anyway. When I say wet, I mean wet. Just to note, I never drove the car in rain, it is the first time. I went on track for 15 minutes and all seemed well. Then when I went to accelerate I had no power, I thought my tranny went, but quickly realized it drive just did not let the engine rev past 2,500 rpm. I limped back off track and reved the engine a few times in neutral and it did not let me rev past 2,500 still. I shut the car off, and looked around, and could not realize what it was. I thought maybe my new fuel pump??? About 40 minutes later I restarted the car, and drove in the parking lot, now after the restart it let me rev past 2,500 and seemed to drive normal. I went as fast as I can in an empty parking lot and it seemed fine. So I was next up on track, I pull on to the track and accelerate hard and immediately same thing happened. I limped very slowly around the entire track and came off. I have no check engine light or anything. But I checked for codes, I had no stored codes, but I had 2 pending codes, P1271 which said Air Fuel Ratio Sensor 1, and then Code P1281 which had no description but I think its similar. I put the car in my trailer and came home. I pulled the car into my garage and it let me rev freely. Its been parked since. So now a few things I been thinking of, and to take into consideration here. Like i said, its a full race car, its not a water tight car anymore and its never been driven in rain, my thoughts were something got wet that never did and shorted?, but then after thinking more, I also don't even have the front fender liners anymore, and I have a AEM cold air intake which sits low in the driver side front bumper and with no fender liner the air filter is right in front of the tire. I later thought since this was a serious downpour and the track was drenched that that amount of water flying inside the wheel wells soaked my air filer and then the engine started to suck in moisture and it wet the MAF? late last night I went into the garage pulled he MAF, and it seemed dry, however it had plenty of time to dry, there was 2 small dirt marks that i had to use my finger nail to get off on the metal surface of the MAF. So I know the air filter got absolutely soaked, but do we believe I would have got those codes from my MAF getting wet? Wouldn't I have got a specific MAF code instead of the 2 I got? I am stumped because being it is a track car not registered to drive, it is very hard for me to test the car out without going to the track every time. I sometimes test it in my neighborhood at night when its late, but there is only so much I can do. So it is very hard to drive the car to see if it happens again or to fix something to see if it happens again without being at the track. And in 2 weeks my next event was at Barber Motorsports in Alabama and I don't want to drive 700 miles each way and get there and have something wrong. Or is this a coincidence and is something wrong with my O2 sensors/air fuel ratio sensors? All help is appreciated, I do all the work on my car, so if anyone has any input on what or how to test something I will do it.

Thanks, sorry for the long post.

The MAF was just soaked from the intake so the car went into limp mode. I used to have that problem with my AEM intake. It wouldn't hurt to clean the MAF also

Thanks, did you get those 2 codes also from this? I took my air filter off yesterday and it was still soaked so I threw it away and ordered a new one, I am also not risking the fact that my MAF went bad from this, so I am ordering a new one. I took my intake off and see signs of dried water, see this picture. I am just hoping this was it and with a new MAF and filter and NOT going in rain anymore it will be fixed.

Aside from clearing the codes and doing some hard on-ramp pulls there is really no other way to verify that was your only problem and that no other damage was done. There are track days at both HMS and PBIR this weekend that you can go test at.

But seriously, in the future dont run it in the rain in its currently state. Remove the CAI, return to stock or similar, and install those fender liners if you want to be prepared for wet running.

Sadly I cannot do any on ramp pulls, I have no tag or anything, i feel its to risky. I have a new MAF and air filter coming tomorrow, will even clean the throttle body. I really hope that is it. I will drive the car as best as I can around my neighborhood at night, but its so risky taking a 700 mil trip for my next event. I cannot make it to any events this weekend either. I will tell you one thing, I will NEVER drive the car in rain again. So far all that last event did was cause me time, money and aggravation.

Or you could just run the stock airbox and not have to worry about rain

I am not against the OEM airbox, i would need to buy once since the previous owner of my car I got it from sold it to me with a real ghetto intake already. My car is not setup for rain or I would change it, it has lexan windows, most weather striping is gone, there are some random holes in the chassis and also no side windows at all, to much water can get in areas they should not be. So not driving in rain is the best bet.

Your best bet is getting the stock airbox and an apexi filter from coz. You clearly are running into issues, not even driving in the rain, so..

You mean issues driving in the rain? you said issues not even driving in the rain, which I don't understand.

You're having issues driving in wet conditions. With your setup, driving in the rain would be a disaster. The stock airbox is superior to any conical filter mainly due to the maf housing not having a comb on the inlet or outlet. The panel filter acts as the comb. I bet your maf readings are inconsistent. I'm also betting your filter is oiled, which causes more issues mainly due to the oil laden dust that turns polar--insulating the maf wires. It's not the oil, its the oil laden dust.

Ironically running wet can save you money in brakes and tires, but youre right. Between mechanical gremlins and increased offs/crunches its definitely riskier. On the flip side you learn so much getting seat time in the wet.

Agree wet driving is helpful yet also more dangerous, I just don't enjoy it at all in the rain.

I only use dry filters in all my cars and trucks, I never use an oiled filter. However I will be happy if this issue is only from a wet MAF. So far no one was able to confirm those 2 codes are from a wet MAF. Why did't I get a specific MAF code? My new MAF and air filter will be here today, so we will see.

Those nissan codes are for the "A/F sensors" bank 1 & 2 respectively, which on an 04 de 350 are the upstream heated o2 sensors. Heater could be failing, sensor or harness shorted or poor connection.

Do you still have the undertray?

Not sure if water ingestion would cause those or water penetration into something electrical, and still may be related to the maf readings.

No undertray at all. I am hoping the water hitting the maf is the issue here. I really hope its not a short or something. I will know more tomorrow/weekend when I drive it after the new MAF and dry filter and cleaned throttle body.

Hoping it works out, if me id do as little as possible until you recreate the issue. Doubt there is still water in the system if youve run it warm already.

I doubt much water got in, but I was thinking, anyone think my plugs may be effected at all?

Check fuses. A/F heater fuse may have blown. Seen it before. Those codes are NOT related to the MAF sensor.

The blown fuse doesn't fit to me because I mentioned the car went into limp mode, then after I restarted it a few minutes later it was good for a little then went back into limp mode right when I got on track, Wouldn't it be in limp mode all the time from a blown fuse? and not be ok after a restart?