when i was goin to school my check engine light came on. when i went to advance to get it checked the code was P1131. air fuel metering. the guy said that a cold air intake could cause this to happen. he said it was getting too much air. has anybody else had this problem or could there be somthing else?

 

Something else for sure.

 

Does your CAI use an oiled filter (K&N) or something similar? If so the oil from the filter could actually destroy your MAF sensor...

 

I have this one code remaining as well, and I can't figure it out.
I have a regular paper air filter. I'll keep an eye on this thread.

 

I had this when I had one of the o2 sensors on the way out.

 

p1131 indicates the air/fuel ratio is correcting rich for an overly lean condition. Shows that your o2 for bank 1 is below .45v telling the pcm your running lean so it richens the mixture. Possible causes to inspect for
Fuel system

Excessive fuel pressure.
Leaking fuel injector(s).
Leaking fuel pressure regulator.
Low fuel pressure.
Contaminated injector(s)
Induction system

Air leaks after the MAF.
Vacuum leaks.
Restricted air inlet.
PCV system.
Fuel purge system.
Improperly seated dip stick.
EGR

Leaking gasket.
Stuck open EGR valve.
Leaking diaphragm.
Base engine

Oil overfill.
Cam timing.
Cylinder compression.
Exhaust leaks before or near the HO2Ss.
Check air intake for leaks, obstructions and damage.
Check air filter, air filter housing for blockage.
Verify integrity of the PCV system.
Check for vacuum leaks.

It wouldnt have anything to do with the cold air intake unless it was causing a restriction.

 

i put a new clutch in it this past weekend and we had to remove the y pipe, but i made sure to watch out for the o2 sensors. still might of hit one. i talked to my teacher at school and he said it delt with the o2 sensors. i checked all the connections and they are fine.

 

I had the same type of code pop on my 06 when I put my K&N intake in. Kept popping the too lean code on bank one and two. I took the truck in and the dealer put the stock back on and it cleared. I have since put it back on and havn't had a code pop yet. They said it was the intake but i don't see how. anyways just take the kit off put the stock back on and see if it clears and stays gone. if so you know what your problem was.

 

I don't see how the CAI could cause his problem. The pcm should make the adjustment to run correctly. hmmmmm....

 

well, the reason I say CAI is because the oil from the K&N filters have been known to destroy the MAF. The MAF monitors the amount of air going through the intake, if unmonitored air is getting passed the MAF (because it's not reading right) this will basically act as a vaccum leak. If the MAF isn't registering then the PCM can not make adjustments.

 

You dont have to just replace the O2 Sensors though, you can get a read of the O2's with a basic OBDII reader. The one I have is a Rotunda, but there are a few out there, my uncle has a MAC. Anyway, you can plug this into the OBDII and do a KEY ON KEY OFF test, and it will give you readings of the O2's.

 

If it's oiled correctly it should not cause a problem. I'd clean the MAF and the filter and re oil and see what happens.

 

yeah, your right, it shouldn't, but you know what they say...also, another thing to check before you go replacing things, is run your motor, and spray carb cleaner around the upper intake mani. If the idle increases, definate upper intake vaccum leak. They say that the 4.0 is natorious for lower intake mani. gasket leaks, so a way to check for this is to pop out the pcv valve, and spray carb cleaner in the hole. This also should not increase the idle, if it does, then once again...vaccum leak, however that one is not so fun...

 

i dont see how the cai would cause it. i have had it on there for about 7 months now. so why would it all of a sudden start acting up? i will clean the maf sensor tomm and see how it does.

 

I have a cold air intake on they 94 and i put 1 of those knock off chips which goes into the MAF connection which requires that i can't plug the MAF back up. Resulting in the check engine light to stay on but the engine runs ten times better with twice the throttle response. Im not really worried about it...

 

well. it ended up being my 02 sensor. hooked up the scan tool at school and put it where it showed graphs of both sensors. the teacher created a lean and rich problem and the 02 never responded like the other one when it was hooked back up. it was pretty much a flat line instead of an up and down like it should of been.

 

Which o2 sensor was it that was bad?

Most people with this code report the sensor upstream of the cat (I think but now I'm not sure). How much did you have to give for an o2 sensor?

Glad to hear you got it figured out. And thanks for posting up your experiences here. It really helps out, especially with a vague code such as P1131

 

it was bank 1 upstream. payed $50 at advance for a new sensor.

the funny thing about it, when i read the codes at school, it had 3 codes all for the same sensor. it was reading too lean, too rich, and slow response