D-Twelve

I am getting code 0115 (Bank 1 too Lean) I am overdue on inspection now, and found that after moving to NY no-one will pass it with the light on while I figure this out.

So far I have...
1. Replaced the aftermarket intake with the stock one. (there was a hole in the aftermarket one the size of my thumb)
2. Cleaned the MAF and TB.
3. Replaced the spark plugs. (the back 3 were black)
4. Replaced the fuel filter.
5. Sprayed starter fluid around to check for vaccume leaks.
6. Tested the MAF sensor. (tested good)
7. Replaced all 3 intake gaskets.


Thank you for being patient, and for all your help over the years with my MAX!!!

Dave

dwapenyi

iTrader: (3)

Are your O2 sensors really old? If so, they get tired. And they wont turn on your CEL. And I mean the O2 sensors in the exhaust manifold, the ones that get the hottest.
Try just replacing the front one. Right behind the radiator.

I did that on my buddies 99 I30 even tho he had no engine codes. His car was acting a little strange even after a total tune up...spark plugs, air filter etc

Once I replaced that front O2 It was like a new car.

Oh, and I suggest the front one because, from reading the FSM, and correct me if I'm wrong, it looks like the ECU uses the front O2 primarily to determine correct air/fuel readings.

DW

asand1

iTrader: (1)

Bank 1 is the rear of the engine. I would go to a shop and smoke it.

D-Twelve

As far as I know they are the origional O2 Sensors

I just replaced all 3 intake gaskets, and do not hear any intake leaks. what else would the smoke do for me?

I keep geeting mixed signals as to which way to go. I keep getting O2 Sensor, Injectors, and Intake Leak. I really dont want to flip this $100+ coin... I would really like to be able to rule out some of these on the cheap!

dwapenyi

iTrader: (3)

I am aware of that, but like I said, I think the ECU uses the front O2 to have the most sensitive "Sniffing" capabilities

DW

dwapenyi

iTrader: (3)

It's definitely not the injectors. Fact is, since you have never replaced the O2 sensors, both of them are done. OK, not done, but not performing optimally.

You will need to replace both of them. You can try replacing one.

Replace just the front O2 now and thank me later

DW

D-Twelve

Are the o2 sensors on www.racepages.com that don't have plugs any good? And if so what ones are the 2 I need? Or is there a better cheaper place to get them?

dwapenyi

iTrader: (3)

That depends on your car. Best thing to do is look at your O2 sensor and see how many wires it has.


DW

asand1

iTrader: (1)

Replacing the "front" sensor wont do **** for you. You have a bank 1 code. How the heII is changing the bank 2 sensor gonna help?? You have 3 sensors.
Front to back they go bank 2 sensor 1, bank 1 sensor 1, and bank one sensor 2(AKA after cat). If you are going to change a sensor (not the problem BTW) at least change the one pertinent to the code. You need to diagnose, rather than throw parts. A smoke test will tell you if its leaking vacuum, and exactly where at.

D-Twelve

Anybody else have an opinion on this? Is this really a coin toss?

dwapenyi

iTrader: (3)

Damn, dude. D-12 needs to make up DEE mind

DW

jholley

iTrader: (13)

The FSM refers to the FRONT O2 sensor as in 'Front of the CAT', not the front bank. In the FSM both upstream O2 sensors are referred to as FRONT O2 sensors.

With code 0115 referring to a lean mixture in bank 1 (firewall) then I would suggest changing the upstream O2 sensor in that bank. You've tried just about everything else but the smoke test that asand suggested.

dwapenyi

iTrader: (3)

OK. Maybe I did not make myself clear. I completely understand that his CEL is telling him to change the firewall O2. I got it. But if you've worked with computers a long time, you'll find that they aren't perfect, especially when readings are iffy, very close to threshold but not quite.

This thing with O2s getting tired is a relatively new thing, and most car computers can't deal with it.

Now, from the FSM, it looks like the ECU uses the front O2 (radiator) primarily to accurately determine the correct air/feul ratio. In other words, if the front 3 cylinders are firing their best, it's all good. The Back O2 (firewall), again, I believe, basically just makes sure that the rear 3 cylinders are running about as well, meaning approximately. The rear O2 isn't sniffing as hard as the front one, so to speak.

Ever notice how the 3 rear ignition coils have a completely different resistance/makeup than the front 3 ign coils? Shouldn't all 6 ign coils be exactly the same?

Like I mentioned earlier, my friend has a 99 I30. Even after regular tuneup, the car still acted funny. NO CEL. On a hunch I replaced the front (radiator) O2. After the change the car was like a bat out of hell.

The idea of smoking to find air leaks is logical and makes sense, but tired O2 sensors aren't logical



DW

DBrames

You can check your O2 sensors by just measuring the resistance. Read the FSM, it tells you all the acceptable ranges. That would help rule it out