Ok guys a have searched a lot about this lately but everything I do doesn't seem to fix it.
I keep throwing a code system too lean P0171


here's my deal.

97 accord lx f22b2 w/ 169,000 miles w/ custom t25 turbo setup
My car has been boosted for 20k miles and I do this every year come emissions time.

I take out my DSM 450 injectors and my p06 ecu out in favor of my stock 0bd2 injectors and ECU. also hook back up my EGR ****. (take off the block off plate and put the solenoids etc back in) and hooked my evap stuff back up, and disconnect my wastegate flapper.

I keep throwing that stupid code and fixing things but it still comes back

here's what I have done so far
replaced 02 sensor (w/ bosch universal)
Replaced injectors w/ another stock set i had at home
replaced fuel filter
new dizzy cap and rotor
ran lucas fuel injector cleaner thru a tank
ran 1/2 bottle seafoam thru IM and 1/2 thru the tank
cleaned out the Idle air control valve
swapped AEM FPR out and put my stock one back in
cleaned out the EGR valve and all the EGR ports.


the only aftermarker piece in my fuel system right now is my walbro 255 pump.


My helms said to check valve clearance...could that really cause it to throw that code? I can't remember last time a valve adjustment was done. Could that also cause hesitation during acceleration?


Could it be a small problem with the EVAP system?


help guys, I posted this in the accord forum and no one knows anything in there.


I'm about to just pay someone off cause my tag is over a month expired now, I have been trying to pass since january.




Modified by brads94accord at 3:43 PM 3/12/2007

 

I have diagnosed many cars w the lean condition lately. The cause for most of them is bad fuel (oxygenated, high ethanol/gas mixture (anything over 10%+) The oxygen content is so high in the fuel that the pcm fuel trim can't richen it enough w out having to pass the threshold. Before anything check fuel pressure, if it checks out drain the fuel or just run it empty and fill up at any large busy gas station, clear the tdc and reset the pcm.
A loose valve clearance and a stuck closed egr valve will also cause a lean condition.

 

I doubt its the EGR sticking do the fact I have cleaned it (and the system)out and made sure the valve would move.

I have already burned through about 3 tanks now trying to pass emissions so i also doubt its the gas, I have never had any problem from the gas station I fill up at in the past. I run 93 octane in the car since its FI


I will check the valve clearance then. I can't remember the last time A valve adjustment has been done on my car.

 

sounds like you have some carbon on the top off the pistons or your timing is off. i would get some SEA FOAM that will get the carbon out. did you allso cheak your cat to see if it was pluged that will do it to.

 

If you read my orginal post it says I already sea foamed the car. plus I sea foamed it about six months ago too. to add to that my car is turbocharged and when im boosting most of that carbon gets burnt off.


Also I do not have a cat so my Cat cannot be clogged. I run 2.5" exhuast from turbo back with just a muffler.

whats strange is I have never had any problem the past two years passing emissions come emissions time. all of a sudden this year I'm having this issue.

I'm gonna check out the valve clearance when i get back from vacation next week.

Could a small problem with my EVAP system cause this too lean condition?

 

bump...anyone have anymore suggestions.


thanks Flexmyrex your post was helpful and you sound like you know what you are talking about.

 

Bump...


I did a valve clearance adjustment last night, car feels like the hesitation is gone however that could be due to the fact I havent driven it in 6 days. We will see in about two days if I throw the code again...


anyone else have any suggestions?

 

Alright now I'm pissed...

I did a valve adjustment the other night and reset the code, i still dont feel the hesitation. but...


On my way to school this morning I threw the code again...

I give up.

 

Just to give you some assurance... the evap unless the purge solenoid is open will not cause a lean condition.

I would go to the source and check your O2 sensor to see if it is doing what it is suppose to. then make sure the signal is correct at the ECU.

Do you have any exhaust leaks?
Vacuum leaks?
Next would be EGR. Check if it holds a vacuum and apply a vacuum at idle and the car should stall or almost.
Check the fuel pressure too.

Check these and get back to us.

 

I need to test the 02 sensor I guess...maybe the bosch I bought is bad and I need another one.

I followed the helms and put vacum on the purge solenoid, it holds vacum so i believe its ok

Do you have any exhaust leaks?
I dont believe so.

Vacuum leaks?
Nope, I've checked and double checked, car idles perfect but I can double check it again tonight.

Next would be EGR. Check if it holds a vacuum and apply a vacuum at idle and the car should stall or almost.
I have already done that with the EGR and it is doing its job correctly
Check the fuel pressure too.
still need to do that...I swapped out my AEM FPR with my stock one which should raise the fuel pressure a little with my walbro pump.

I hope my walbro pump isnt going out.

 

you probably have a vaccum leak. try monitoring the oxygen sensor
while spraying a little water around the intake manifold or any where vaccum can leak. when you see the oxygen sensor voltage go up and stay high thats where it is leaking.