"Check Engine Light" on again

[MN-Gopher1]

Can't seem to solve this problem on my 2000 I30.Have been getting "code P171"(Fuel Injection System too lean-Bank 1)

CEL came on with a P171 and then I added Techron to gas. CEL went off after a few miles. I added another bottle of Techron to the next tank just to be sure and no problems.Filled it up again and now the CEL is back again. Code 171

The injectors must be dirty as the light went off after I added the first bottle but I can't keep adding a bottle of Techron to every tank! Is it time to have the dealer do an injector cleaning?

Just dropped $325 for all new coils, has new plugs, and new 02 sensor at bank 1. Has 126,000 miles.

Your advise would be greatly appreciated.

[maxhopper]

I would try switching the injectors from bank 1 to bank two (and vice versa) to see if the code then changes to P0174. If it does, you have one or more bad injectors. If the P0171 returns, it could that you got a bad 02 sensor.

[audtatious]

Unfortunately, without a Consult-II, it is hard to diagnose the problem. Could be an injector problem, front O2 sensor, exhaust leak, fuel pressure, lack of fuel, or Mass air flow sensor.

[chinaonnitrous]

o2 sensor.....best bet. its one of the main things controlling a/f mixture.

Otherwise MAF would control A/F..but its only for one bank.

I doubt its the injectors. With that many miles, you should change the o2 sensors anyway.

oxygensensors.com

[audtatious]

o2 sensor.....best bet. its one of the main things controlling a/f mixture.

Otherwise MAF would control A/F..but its only for one bank.

I doubt its the injectors. With that many miles, you should change the o2 sensors anyway.

oxygensensors.com

I agree the 02 is the way to go (after validating there is no exhaust leak at the head, which is unlikely). Sux the FSM uses Consult for this problem, which is "relatively" common.

[MN-Gopher1]

This vehicle has 4 02 Sensors. I replaced Front 02 Sensor, Bank 1 this summer. The remaining Sensor is the Rear 02 Sensor, Bank 1. Would the back sensor trigger this fuel mixture code?

I also have replaced all of the coils just lately(probably not related to this issue)I spoke to a dealership today and they suggest to bring it in(of course)Their thoughts are that it may need reprogramming. Would replacing one sensor and changing out the coils require a computer reprogramming?Thanks ------

[maxhopper]

Manufacturers are always coming out with PCM and TCM updates to solve certain drivability problems. It may be true that there is a TSB that recommends a reflash.

The reason I pointed to the O2 sensor and injectors as the posible problem is that your code indicates a lean condition in bank 1. First, an O2 sensor does (to a certain extent) help in governing your fuel mixture in certain rpm ranges. Second, that is the sensor that you have had replaced recently. Lastly, there is (as far as I know) only one fuel pressure regulator for the entire fuel rail, which leads me to believe that is the injector or the fuel control - otherwise bank 2 would show lean if it were a fuel delivery problem.

[MN-Gopher1]

Thanks for the reply.Your reasoning makes a lot of sense. PO171 does indicate Bank 1. I guess I could have gotten a bad 02 sensor for the front Bank 1 that I changed out last summer.Wouldn't one of the other codes for the Bank 1 02 sensor have come up if it wasn't doing the job? (PO130 to PO141 for Bank 1)

Originally I thought that the Bank 1 injectors were dirty because of the light going off with Techron in the gas. I have found where they sell BG44K locally so I will try some of that next. To change the injectors from one side to the other for testing them may be beyond my abilities, I think. I'm sure you guys could lead me through though!Also, the temp is going to be around zero this coming weekend so that makes for tough garage work in Minnesota!

Another Infiniti service manager says that the generic scan tool is probably giving up the wrong code and that I need to have them pull off the code. Just bring it in. They'll take care of me(and slap me with a large service bill you can bet!) While I don't mind paying for service, I feel a bit like I'm the sheep and they are the wolf most times. I'd be glad to hear any other thoughts you have on this.Thanks------

[maxhopper]

I would tend to agree with you on the O2 sensor throwing an O2 specific code.

Here are some instructions on how to change the injectors.