Pesky Lean Code

[Kazteel]

Well, I recently had a clutch replaced in my 04 corolla, just to have it start misfiring. I tried to do alot of digging to find out what was causing my car to throwing a random misfire code, as well as all 4 cylinders misfire code and a Bank 1 too lean code. I decided to look around on the internet, lots of people/videos said it would be a bad intake manifold gasket. Well I replaced that as well as the throttle body gasket while I was in there, still same codes, still the same rough idle....Anybody have any ideas on what this could be? I know its a vacuum leak somewhere, but Ive looked at all the hoses and they are all connected, the only thing I can think of is that somehow one of the hoses got torn/cut in the process of reinstalling the clutch. Any good fast way to figure out if any of the hoses are compromised?

[oldcodger]

Hi,

What are the actual error code numbers ?

[Konrad C]

Look at this post - 

The fault was a simply a dirty MAF sensor in that case. You said you inspected the hoses for connection security, but have you checked the main inlet hose between the air filter/MAF sensor to inlet manifold for splits/tears? That will be item 17881 in the picture. 

 

Here is another picture showing the ventilation hoses, one which goes to the inlet hose.
I would still look at the MAF sensor being dirty, but there could be something that I forgot to mention! 
 

[DeTomato]

Not sure if this suggestion of mine will help, but I found putting injector cleaner in a quarter tank of petrol and running until hot helped.

But also found the pre-inlet plastic hose to the Airbox (not the engine side rubber hose) was loose due to foam seal deterioration. Replaced the foam so the intake was tight and it ran much smoother because air flow was delivered more consistently over the MAF without the leak.

[Kazteel]

On 7/26/2019 at 3:56 PM, oldcodger said:

Hi,

What are the actual error code numbers ?

I'd have to pull the codes in the morning, Except that info in about 6-10 hours from this post

[Kazteel]

18 hours ago, Kazteel said:

I'd have to pull the codes in the morning, Except that info in about 6-10 hours from this post

Ok so its throwing 7 codes

P0300 - Random/Multiple Cylinder Misfire

P0301 - Cylinder 1 Misfire Detected

P0302 - Cylinder 2 Misfire Detected

P0303 - Cylinder 3 Misfire Detected

P0304 - Cylinder 4 Misfire Detected

P0130 - O2 Sensor Circuit Bank 1 Sensor 1 (Although I've already replaced both O2 sensors....)

P0171 - System Too Lean Bank 1

[Kazteel]

Does anybody have some insight on this? I inspected all the possible air line hoses for any leaks and I cant find any. All hoses are intact and not compromised.

[furtula]

When DTCs for misfiring cylinders are randomly set, but DTC P0300 is not set, it indicates that misfires have been detected in different cylinders at different times. DTC P0300 is only set when several misfiring cylinders are detected at the same time.

If any DTCs other than P0300, P0301, P0302, P0303 and P0304 are output, troubleshoot those DTCs first.

You can try this manual

https://www.autocats.ws/manual/toyota/auris_corolla_zze-zr-nde-ade/rm04f0e/repair2/html/frame_rm000000xh3031x.html

 

For P0171

https://www.autocats.ws/manual/toyota/auris_corolla_zze-zr-nde-ade/rm04f0e/repair2/html/frame_rm000000wc302nx.html

[Kazteel]

The one thing I havnt checked into yet was the MAS, gonna look into clearing that off today.

[Konrad C]

Try disconnecting the MAF sensor with the engine running to see if the idle changes. Check the crank and cam position sensors too, for security of fitting and connection. I wonder if the manifold has a crack?
 

[Kazteel]

I pulled out the MAF sensor and it was quite dirty, and I cleaned it off with some plain water and cotton swabs until a new swab was bring up no dirt. That solved my Too lean code, now its just 5 codes, random misfire and misfire cylinders 1 through 4. So we are making progress maybe? One thing I did notice when I replaced the O2 sensor after the catalytic coverter, is that someone crossthreaded the hole and I had to do my best to rethread it but it kind of still went in ever so slightly crooked, could that be a problem although its made a good seal?

[Kazteel]

On 8/3/2019 at 6:01 AM, Konrad C said:

Try disconnecting the MAF sensor with the engine running to see if the idle changes. Check the crank and cam position sensors too, for security of fitting and connection. I wonder if the manifold has a crack?
 

I disconnected the MAF sensor while engine was running and it immediately shut off, a smooth decline in RPMs until it finally just stopped, as if I turned the key in the ignition off.

[Konrad C]

5 hours ago, Kazteel said:

I disconnected the MAF sensor while engine was running and it immediately shut off, a smooth decline in RPMs until it finally just stopped, as if I turned the key in the ignition off.

That means the MAF sensor is working properly. 
Next test is to spray water around the to inlet manifold and vacuum pipes, to see if the engine idle changes. Not too much, just enough to make a seal. Check the vacuum to the brake servo. 

It's going to be a long search, until someone has the right answer, or you find it by chance.

[Kazteel]

4 hours ago, Konrad C said:

That means the MAF sensor is working properly. 
Next test is to spray water around the to inlet manifold and vacuum pipes, to see if the engine idle changes. Not too much, just enough to make a seal. Check the vacuum to the brake servo. 

It's going to be a long search, until someone has the right answer, or you find it by chance.

I will check that in the morning, I actually bought a spray bottle for that, But I only sprayed around the intake manifold, I did not notice any change in rpms. I'll spray around a bit more and see what happens. Thx for helping me with this Konrad, this is boggling for me lol