P0172 , + stalling at the lights...any other idea?

[djtc]

Hi guys , I finally got my 4runner on the road today after 2 months it passed the emissions test.I've beeen trying to trouble shoot this P0172 code(running rich bank 1) ever since I bought it.I've changed the pcv valve, both 02 sensors with denso units ,new oil,seafoam in the gas tank ,seafoam through the intake,new spark plugs,air filter,cleaned the the mass airflow and the trottle body somewhat..

After I changed the 02's yesterday the code disapeared.Today I went for my Emissions test and while I was comming off the highway I put it into neutral ,the revs dipped down and it died.It did that t'ill I reached the Emissions shop.....The emissions tech told me I had passed and when I jumped back into the truck I noticed the check engine light had came back on.It never died on the way home...

It idles fine and drives nice so I'm not sure what else it can be since it doesn't happen constantly.

I'm thinking to change the Idle air control valve and the coolant temp sensor next.

Let me know if you guys have any ideas please!!!

 

[Harleydoc]

I am going to say clogged injector on 1 st bank or MAF or coolant temp sensor bad.

 

[BigFishAllDay]

I'm thinking to change the Idle air control valve and the coolant temp sensor next.

Let me know if you guys have any ideas please!!!

I have a few observations to make here...

First, in this picture, notice the Long Term Fuel Trim on Bank 1!! WHOA...

The ECU is cutting fuel 39.8% on Bank 1 (which is the side that the MIL is referring to as well). The short term fuel trim (SHRTFT1) refers to immediate changes in fuel occurring several times per second. The long term fuel trims (LONGFT1) are driven by the short term fuel trims. LTFT refers to changes in STFT but averaged over a longer period of time.

If your ECU is cutting fuel by that much, there's only one culprit in my mind and that is a leaking fuel injector.

The reading on your Engine Coolant Temp looks fine, so I doubt your coolant temp sensor is causing the problem. If the ECTS ws the problem, it would be giving a low reading, causing the ECU to run the engine in "warm up" mode, adding additional fuel @ all times, rather than only immediately after a cold start. This would cause the engine to run rich, but not so rich that the fuel trims would reach -39.8%... Again, WHOA!!!

Second, in this picture. Notice the Hydrocarbon #'s (HC ppm) both @ idle and @ 2500 RPM. Hydrocarbon's are essentially soot, aka black smoke, aka... running rich. The idle number is pretty high, and getting close the limit for passing your smog test. To me, this again indicates that the ECU is having to work very hard to control the amount of fuel entering one (or more) of the cylinders on Bank 1. It takes a much finer degree of control to keep the truck idling than it does to keep it running @ 2500 RPM. This is probably the reason it is stalling... Too much fuel and the ECU can't trim enough to keep it running @ low RPM's.

Every sign here points to a leaky fuel injector that is introducing too much fuel into one of the cylinders on Bank 1, which should be the Driver's side.

The fact that you have replaced both 02 sensors eliminates the possiblity of a faulty AFR reading causing the ECU to trim fuel.

If it was your ISC motor, you'd be experiencing issues @ idle... either too much air (high revs) or not enough air (stalling)... in any case, unless you spend hours with the truck idling, there's no way a problem w/the ISC motor would result in fuel trim #'s that high.

Finally, a clogged fuel injector (as suggested by harleydoc), would result in POSITIVE fuel trim #'s as the ECU would try to increase fuel delivery to compensate for the reduction in fuel on the clogged injector, and the resulting LEAN running condition.

Good luck!

 

[shootmymime]

 

[Harleydoc]

The reason I said the coolant sen is because if the extra fuel it dumps if reading cool..

The MAF would cause you ECU to say hey when need more fuel ad make it run rich at times.


But I really thing it is the injector after looking at the info again this morning. If my be something simple as well maybe an air leak by the injector but most of the time when removing old injectors they break anyways.

I would pull the plugs and see with one is really really back and replace the injector that goes to that cylinder (s).

You may try and run it for a while and see if you get any crazy temp readings on the ETC but the injector is a quick and not to much of a hit to the wallet.

 

[djtc]

Thanks!

Thanks guys , I was thinking about the injectors being the problem but the car usually runs well. It just happened that one time yesterday. Although , when i removed the plugs last week they did smell like gas. I also notice a gas smell upon start up yesterday...

I guess next step it to to remove all the injectors and get them cleaned up.

 

[LittleCaesar]

If you have the ability to be without your 4runner for three days, try these guys to clean all six thoroughly:
WitchHunter Performance - Injector Cleaning & Flow Testing Services

But being in Canada, I don't know how much the shipping will be for you.

 

[djtc]

We have a disel injector service shop nearby that charges 25$ for each injector so ill go see them. Ill have to use my turbocharged miata for next couple of days hopefully it doesnt snow soon!

 

[Harleydoc]

Well let us know what you find out hope the injectors take care of the problem

 

[djtc]

Ill definately update this situation. The threads I usually find with p0172 problems never report how or what fixed the issue.

Im going to replace the temp sensor just for good measures.

 

[shootmymime]

check you oil to see if it smells like fuel. that will determine if you have a clogged injector or a leaky one.

 

[djtc]

Wouldn't it smell regardlessly since its running rich..?

 

[BigFishAllDay]

You guys are funny, continuing to mention/suspect a clogged injector. :ybrick:

A clogged injector would result in POSITIVE fuel trims... aka the ECU adding fuel, aka a LEAN condition...... not a NEGATIVE 39.8% fuel trim, aka the ECU removing fuel, aka a RICH condition like the OP is experiencing.

Pull the injectors on Bank 1, have them cleaned and flow tested. ONE or more will be leaking and/or spraying more fuel than they should.

BTW, harleydoc:

If my be something simple as well maybe an air leak by the injector but most of the time when removing old injectors they break anyways.

Air leaks result in a LEAN condition... the ECU would trim the fuel up (positive). This is NOT an air leak.

 

[djtc]

I'll probably just get them all cleaned and tested.If one bank is nice and clean and the other side not so much wouldn't the ecu have troubles then?I like to do it right the first time that way I could know that all injectors are flowing the same.

 

[BigFishAllDay]

I'll probably just get them all cleaned and tested.If one bank is nice and clean and the other side not so much wouldn't the ecu have troubles then?I like to do it right the first time that way I could know that all injectors are flowing the same.

Now that's some good thinking. When I said "pull the injectors on Bank 1", I said that because that is the side having the problem.

As you posted, having the entire set of 6 cleaned up and flow matched would be best. That way the job is done once and for all.

 

[djtc]

Just got the injector out its getting cold here!Anyways, The intake plenum smelled like gas ALOT! The injectors looked dry and didnt smell like fuel that much which I found a little weird.Hopefully I dont spend this 180$ on cleaning for nothing..

 

[djtc]

So I got the injectors all cleaned and flow tested.Supposedly they were not that bad before the cleaning.Assembled everything back with new gaskets and o rings.

First impression , the car idles a little higher and after a day the check engine light came on again but this time with a P0171 Lean code....Check for vaccum leaks and cleaned maf again, code returned.
Some scanner shots.

I also noticed that the car has a hard time starting once in a while (every 3 to 4 starts ,mostly cold starts) Here are two videos, 1 how it usually start and 2 when it has difficulties.Notice how when it starts properly the idle is lower.I also noticed that the car take more fuel and I just stepped down from e load tire to c loads so that doesnt make sense..

 

[djtc]

nobody has any clues ?

 

[Harleydoc]

Intake leak maybe

 

[Harleydoc]

Spray some carb cleaner around it and see if the RPMs go up when you spray it