P0171 CODE NEED HELP PLEASE

[UnderDawg]

Need some help diagnosing this code.

Cleaned MAF, no change.
Plugs, wires, cap and rotor, no change.
Checked all vac hoses and all are good.
Changed cracked intake hose, no change.


What else... it doesnt effect performance as far as I can tell but, I dont like the fact that somethings wrong and I cant fix it.

Thanks guys

 

[skhochay]

95% is MAF sensor is bad or not reading well. 5% is a leak in the intake manifold. Inspect it and see if you did not pinched any hose wire .

 

[UnderDawg]

How can I test MAF to see if thats the problem?

 

[ChiTown]

A scan tool with a live data read out (if you're obd 2).

 

[UnderDawg]

I dont have access to one of those ... anything or anyone else?

 

[landtank]

it's a complicated code to diagnose. It basically means that the ECU is over compensating for a lack of fuel that it expects it should be delivering.

basically if the ECU thinks X amount of fuel should be the correct amount. It is actually taking 2X to satisfy the oxygen sensor.

Any and all components could be the cause.

fuel filter
fuel sock
fuel pump
fuel regulator
fuel pump relay
O2 sensor
cracked Y pipe
engine harness
dirty injectors
dirty or bad MAF sensor
vacuum leak, anywhere

and I'm sure more

start with easy fixes and replace known items that are overdue anyway like possibly the fuel filter.

 

[UnderDawg]

I've got a fuel filter sitting on the work bench.... been dreading it. Any links for a how to with tips?

 

[ppc]

Loosen gas cap to remove any pressure buildup. Loosen the banjo connections on the filter first before mounting bolts. You can cut slots in the new filter so that you can start the bolts then slip the filter with the lines loosely attached and tighten. Trying to thread the bolts whilr holding the filter is a pita. Use new copper washers on the banjo fittings. You should be able to search the forum for pictures of the slots cut.

 

[UnderDawg]

Loosen gas cap to remove any pressure buildup. Loosen the banjo connections on the filter first before mounting bolts. You can cut slots in the new filter so that you can start the bolts then slip the filter with the lines loosely attached and tighten. Trying to thread the bolts whilr holding the filter is a pita. Use new copper washers on the banjo fittings. You should be able to search the forum for pictures of the slots cut.

Thanks bro.

 

[UnderDawg]

Ok well changed out the fuel filter.. still throwing the code. Now what?

 

[ChiTown]

You need a scan gauge or something with a data readout to check the maf

 

[UnderDawg]

You need a scan gauge or something with a data readout to check the maf

Thats my next Cruiser purchase. As of right now I'm thinking its the MAF. Looks original and could probably use changing. I cleaned it a few weeks ago, maybe I didnt get it good enough.

 

[UnderDawg]

Well just got back from a 600 mile trip in the Cruiser and ...... no more light. Changed out the filter and light came back on. Checked code and cleared it... filled up with fresh 94 octane and drove to Michigan, no light. Just got home about 3 hrs ago and... no light. IDK but I'm happy about the light... not so much on going back to work tomorrow