Help me pass emissions(CEL)

[General Axe]

I have a 98 ranger ex 4.0 Auto My check engine light is on all the time. So I cant pass an emissions test. I pulled the codes they are 171 and 174 Bank 1 and bank 2 lean. I mistakenly assumed this meant My O2 sensors were reading lean and replaced all three. So after blowing $150 and nearly dislocating my shoulder to replace them I still have a problem.
What are the probable causes of these codes? I erase the codes and they come back in about three drive cycles so the problem is ongoing.

 

[MAKG]

You've already wasted $150. What would it take to get you to spend $60 or so on an hour of professional diagnosis?

'Cause that's what you need.

Lean codes are not appropriate to learn basic diagnostic procedures with. You're going to go in circles.

 

[General Axe]

Anyone else got any ideas? I had to borrow the first $150 and I only got four days left on my temp registration. A basic definition of what the codes mean would suffice. Does it mean there is extra fuel entering the engine from somewhere other than the injectors causing them to be driven to abnormally low pulse widths or that the injectors cant keep up running wide open?
I've never owned a vehicle I couldn't fix myself with a little helpful information.

 

[AllanD]

I will resist to my dying breath engaging in "dartboard diagnostics"
on EEC-V controlled vehicles.

In this case there is NO substitute for professional diagnostics.


AD

 

[BlackBII]

lol don't take my advice seriously, take allans or makg's, but take out the lightbulb behind your cel, get it passed,(if the shop doesn't check that it works) then put it back in and fix the prob......

Something that I have done...

 

[MAKG]

That's fraud, and besides it won't work.

The MIL is lit because the engine can't control the mixture. If it's correct that it's lean, NOx will be high. If it's wrong, HC is going to be ridiculously high. Getting the vehicle designated a gross polluter won't make passing emissions easier, and may make it substantially harder.

And it wastes time.

You don't think MILs are for decoration, do you?

 

[Bird]

GA - You've probably got either a vacuum leak allowing extra air into the engine or the air tube running from the intake tube to the oil fill tube isn't connected. CAREFULLY check all vacuum lines and all tube / line connection points to make sure everything is in good shape. If you don't find anything wrong, then take it to get properly diagnosed as the other alternatives will require a good diagnostic.

Bird

 

[Hardwareman]

I had a lean condition code one time on my Ranger and when I looked at my aftermarket K&N filter it had com loose from the housing.

After I reclamped it airtight the code never came back.




Allen

 

[General Axe]

Thanks to the experts for letting me know theyre as clueless as me. And thanks to the others for reminding me not forget the simple stuff. So since Ill be visiting a mechanic soon do you recomend I go to the dealer or some private shop. All the chains like tuneup masters tunex went out of business here years ago.
By the way turning off the light didnt work this year (new regs)Scanning the computer is part of the emissions test here now. Even if the code is cleared they can still detect the Emissions readiness of the computer based on drive cycles since the reset.

 

[MAKG]

The dealer is for warranty work. If this qualifies, go there. Otherwise go to a qualified mechanic. OBD-II diagnostics are not at all a dealer-only procedure.

I'd suggest a basic litmus test -- ask your mechanic to explain what a "pending code" is (this is why it takes a few drive cycles for your codes to come back). If he can't or it doesn't make sense or you think he's FOS, go somewhere else.

If you have no Kwiki-Lube chains, consider yourself lucky. There is a reason they went out of business....diagnostics require more than 30 minutes of training and an 8th grade education.

 

[General Axe]

So I finally went to see a mechanic. he didnt bother to do any diagnostics or anything.
After I told him the codes I had he said "its a fairly common problem with these trucks".
He told me that the fuel injectors are hung open with crud and the engine is actually running rich at idle. The lean code is a result of the the injector duty cycle being so much lower than its intended parameters trying to compensate for the excess fuel leaking past them.
I switched out the injectors myself and the light turned off after three drive cycles. The engine runs much smoother at idle now.
Thanks for the help and hopefully this will help others with the same problem.

 

[reno]

WOW, most of the time the problem is a vacuum leak. But a diagnostic more than just reading the codes should be in order, did he at least test the injectors before he stated this? That is a lucky call if he did not. Sure would have hate to see you spend all the extra money on injectors, then find out it was just a vacuum line cracked\split.

 

[97ranger4x4]

yeh when I had that code on my truck it was the intake manifold gaskets that were leaking air.

 

[Kona]

Any mechanic that does not back up his experience with a print out or diagnosis that has facts to interpret is not worth much.