lambda regulations and cylinder misfires?

[AdamE53]

Me again, new issue which is growing.
I've been getting these codes pretty regularly now and i've done some reading but haven't figured out exactly where I should start investigating.
After clearing the codes yesterday, today i'm getting:
CA(202) lambda regulation limit bank 1
CB(203) lambda regulation limit bank 2
misfire cylinders 1, 2 and 3.
Sometimes there will be another lambda code that goes along with those ones and 2 days ago I had misfires across all 6 cylinders.
This issue seems to be growing because the engine light comes on consistently after 5-10 mins of driving and its always a random number of cylinder misfires.
First, if i'm correct, lambda refers to oxygen sensors?
For a bit of history, i've replaced all spark plugs 10,000km ago and replaced the oxygen sensor after the cat appr. 5000km ago.
Any ideas where I can start diagnosing? I have INPA on my laptop so I have the ability to do some basic diagnostic

[80stech]

With misfires across all cylinders I think the most likely problem is a vacuum leak. The intake boot being ripped is the most likely culprit. There is lots more info posted here if you do some searching.

[AdamE53]

I have done some searching but it seemed like this could be an issue with a wide range of causes. My first direction seemed to be something to do with oil coating and buggering the o2 sensors as someone ona different site mentioned.
As for the vacuum leak, I had planned to do a smoke test this week. I did one awhile back and found it was leaking through the valve cover fasteners. After rebuilding the disa valve, I wanted to do it again anyways.
Thanks for your input.

[Bdc101]

Have you looked at the air mass flow rate while driving or idling yet? That can help you isolate a vacuum leak or a bad MAF. (Both of which seem to be common issues around here)

[AdamE53]

The MAF was on my list of things to check. Do you know the value range I should be seeing?

[X5chemist]

What are short term and long term fuel trims?

[Bdc101]

Originally Posted by AdamE53

The MAF was on my list of things to check. Do you know the value range I should be seeing?

I believe around 3.0 to 4.0 g/s is the proper reading at idle. The idle reading is a good way to check whether there is a vacuum leak or a bad MAF. Under load it's difficult to say exactly whether the reading is correct.



Fuel trims is another good way of detecting vacuum leak or MAF problems, as well as other things like fuel pressure issues.

[workingonit]

Originally Posted by Bdc101

I believe around 3.0 to 4.0 g/s is the proper reading at idle. The idle reading is a good way to check whether there is a vacuum leak or a bad MAF. Under load it's difficult to say exactly whether the reading is correct.



Fuel trims is another good way of detecting vacuum leak or MAF problems, as well as other things like fuel pressure issues.

I had a problem with lean codes P0171 & P0174 setting off the Service Engine Soon light, very soon after clearing codes. My O2 sensors were acting as expected:
O2 data shows good operative status

My O2 sensors were nearly new when I took that data, so I did the normal smoke and carb cleaner testing (many times), and cleaned the original Siemens MAF, and still had the lean codes, but to no avail.


Here are readings from my original MAF sensor, which seemed OK, as the readings were what I expected:
MAF graph at 1k, 1.5k, 2k rpms
from an earlier thread:

Originally Posted by workingonit

I had trouble keeping the speed exactly on the marks of 1k, 1.5k, and 2k rpms, but it is close enough. 1k yields roughly 6 g/s, 1.5k yields about 8 g/s, and 2k rpm yields slightly over 10 grams per second.

Since a rule of thumb on a MAF's air flow rate at 500 rpm is 1 gram per second per liter of engine displacement (or 3g/s for my 3.0l), my graph is just about right at 6g/s at 1k rpms, a bit low at 1.5k rpms, and really low at 2k rpms (it should be 3x4=12 g/s).

But I still was getting the codes tripping the SES light, so I tried a cheap MAF sensor, just to compare. It did the trick! The fuel trim numbers dropped, the MAF number gained a bit, and no SES light anymore. Either my old Siemens MAF was underreporting airflow, or the new cheap MAF is overreporting airflow (and there might be an undiscovered vacuum leak still present), but no codes appear now, and my goal of passing inspection was achieved.

As suggested, check your fuel trims, even if your O2 sensors appear to be working OK. I looked to solve my problem for six months before I tried the cheap MAF sensor. Whatever it takes....

[AdamE53]

Thank you very much for the valuable information.
I was able to get some data, but this is just at operating temperature, and idling in the driveway. I'm going to get some driving data later tonight.
Currently, the MAF at idle is between 3.1 and 3.7 g/s.
The trims at idle:
long term bank 1 = 0%
long term bank 2 = 1%
short term bank 1 = 15%
short term bank 2 = -3.5%
I'm going to go for a drive later that will involve a fair sized hill and some city driving so I will graph it and see what I get.

[AdamE53]

Alright, so I uploaded my log from my drive. I dont know how to upload the file for whoever wants to view it nor do I really know what I need to look at to identify a problem.
From what I can see, bank 1 long term stayed around 5 for both banks.
Short term values obviously fluctuated with engine load and rpm. I noticed that around the 2000 rpm mark, both banks were pushing between 20 and 25.
The MAF readings got as high as 50 when i was going up the hill hitting 3krpm.
So, all in all I don't really know how to interpret my log. If im correct, since my values all seem to be highly positive, I would assume that points to vacuum leak? This is all very new to me and i'm trying to understand as best as I can. Hopefully with your help I can pull something out of this data.
Also happy to share the log with anyone who wants to see it.