Cel 1124 & 1126

[rexcramer]

1124 1-3 and 1126 4-6 Oxygen Rich Limit

These 2 codes started last October. They were intermittent in the beginning, continuous now. The car runs as good as it ever has and the fuel mileage has stayed consistent. Generic OBD show the CAT and the OS2 not ready. I am forced to deal with it for CA smog testing/registration. The car is stock 97/Tip with 26K on it. I have had the AOS and associated oil lines X/O in January. Tubes and plugs were done at the same time.

I have searched both here and Planet 9 for answers. If I understand correctly (big if) these are the possible causes;

1. Air leak somewhere. I have used my eyes, stethoscope and propane to try and find something to no avail.
2. Oil cap leaking. It appears to be sound.
3. Gas Cap leaking. It appears to be sound.
4. Fuel pressure related, pump/pressure, filter and or injectors. I can’t test the pressure myself.
5. MAF. I have cleaned it twice.

I have hooked my OBD up to my 09 S to compare the MAF readings. I am not sure if that is applicable. The 09’s MAF response is much faster than the 97’s. And it registers higher values of lbs/s. The CAT values are also consistent from side to side on the 97. With the car running, I pulled the plug from the MAF. The idle stumbled but kept running and stabilized. I think I read somewhere that the car should stall? Mine didn’t.

What else should I be looking for/considering before I drop her off at the indie? Thank-you in advance for any suggestions.

[thstone]

You've already done the most obvious things. The only remaining item I'd suggest is to check the AOS and associated tubes (including the oil fill tube). They can also leak and act as air source. When you remove the oil fill cap, does the engine stumble and then recover as expected?

I also still worry about the MAF. You could try clearing the codes and disconnecting the MAF. Then drive the car. I would expect the engine to run poorly at first but then improve. If the problem is the MAF, the codes won't come back. If you have an air leak (or something other than the MAF), the codes should re-appear.

[Gelbster]

Originally Posted by rexcramer

1124 1-3 and 1126 4-6 Oxygen Rich Limit

These 2 codes started last October. They were intermittent in the beginning, continuous now. The car runs as good as it ever has and the fuel mileage has stayed consistent. Generic OBD show the CAT and the OS2 not ready. I am forced to deal with it for CA smog testing/registration.

On RennTech we discussed this subject .I was in exactly the same situation as you.
Suggest you Search for "Drive Cycle" & "Readiness".
I found a Durametric very useful for observing Actual Values.
Is your SAI pump & SAI system operating correctly? That is a very common fault area.Also covered on RennTech recently.
Systematically examine every clamp and hose .For example, it is easy to get the big Intake hoses out of position.
If you use propane , you need a long curved wand and plenty of very flexible hose.It works. You just have not found the leak with it yet.Try Carb Cleaner ?

[rexcramer]

Originally Posted by thstone

does the engine stumble and then recover as expected?

I also still worry about the MAF. You could try clearing the codes and disconnecting the MAF. Then drive the car. I would expect the engine to run poorly at first but then improve. If the problem is the MAF, the codes won't come back. If you have an air leak (or something other than the MAF), the codes should re-appear.

1. Yes
2. So far, so good. I have driven farther than it would take to trigger the 1124/1126. I did get 0102 and 0112 almost immediately after disconnecting the MAF and starting. Which I think makes sense cause it is missing entirely. So I agree that it looks like the MAF needs R&R.

Thanks for your time/input.

[rexcramer]

I do have the Drive Cycle and Readiness instructions ready, as soon as I have the problem fixed.
My OBDII does graphing and has been helpful. Durametric someday.
The SAI Pump comes on (cold start) and runs for a bit and then shuts off like it has always done. I believe it is good.
I have yet to start poking every connection and I am hoping it doesn't come to that. I am concerned I may cause old brittle plastic to snap making the problems worse. I will try your suggestion of using a longer hose with the propane. I also have a camera/snake that I have poked into most everywhere.

I think I have enough data to justify replacing the MAF. Thanks again, both of you for sharing your ideas. Safe travels.

[Gelbster]

Great progress .Well done.

[rexcramer]

Update; I changed out the MAF and my OBD shows better reaction time on the graphing. But, the codes come back within +/-25 miles. The mystery continues.

[Gelbster]

Good, that has eliminated the MAF as a potential issue - assuming you fitted the correct part number.
The obvious next step is to measure Vacuum at the oil filler cap with a digital manometer.While you wait for that to arrive do the tedious vacuum leak hunt with your preferred tool - smoke,carb cleaner ,propane etc.

[Toppy986]

I chased these same codes 1124 and 1126 for over 6 months, looking for an air leak, cleaned MAF sensor, changed AOS, clearing codes after each attempt, only to have them return. my problem was I never let the system completely reset, the evap system is I believe the last one, it wasn't until i was about to give up, that the evap system reset and i got a new code. turned out I had a bad evap purge valve, sticking open causing my vacume leak, this would not have shown up with a smoke test, or propane. changed the valve, and have been code free for over 2 years. Have you let the system completely reset all systems?

[Toppy986]

another proplem that seemed to be associated with the purge valve sticking open was hard starting when hot, not every time though

[Gelbster]

Originally Posted by Toppy986

I chased these same codes 1124 and 1126 for over 6 months, looking for an air leak, cleaned MAF sensor, changed AOS, clearing codes after each attempt, only to have them return. my problem was I never let the system completely reset, the evap system is I believe the last one, it wasn't until i was about to give up, that the evap system reset and i got a new code. turned out I had a bad evap purge valve, sticking open causing my vacume leak, this would not have shown up with a smoke test, or propane. changed the valve, and have been code free for over 2 years. Have you let the system completely reset all systems?

THe Purge valve stuck open should cause a CEL and code. P0446 ,certainly a P044x and Durametric would have identified this fault.
https://www.renntech.org/forums/topic/36978-code-p0446/?_fromLogin=1
If propane or other techniques do not work,it is because they are not being applied in the leaking location(in this case under the fender liner!)

[Toppy986]

Originally Posted by Gelbster

THe Purge valve stuck open should cause a CEL and code. P0446 ,certainly a P044x and Durametric would have identified this fault.
https://www.renntech.org/forums/topic/36978-code-p0446/?_fromLogin=1
If propane or other techniques do not work,it is because they are not being applied in the leaking location(in this case under the fender liner!)

you are correct, I did have code P0441, however I did not wait for the system to run a full diagnostic reset between clearing codes after i tried somthing with the intake, the evap code didn't show up until the evap system reset, which I believe is the last system to set, just want to make sure the same mistake is not being made that i did, with clearing the codes

[san rensho]

Use a durametric and check the maf flow. It should be around 15. If it's significantly less the you have a vacuum leak. Now the fun starts. You have to find the leak.

[Gelbster]

Here is an explanation:
https://www.youtube.com/watch?v=lBA26EmH79Q
or search Popular Mechanics "How to Find a Vacuum Leak" for the methods of finding the leak.

[rexcramer]

Originally Posted by Toppy986

my problem was I never let the system completely reset, the evap system is I believe the last one, it wasn't until i was about to give up, that the evap system reset and i got a new code.

Maybe I haven't driven it enough? My commute is 50 miles RT. The CEL comes back on after +/-25. I think I have driven to work 3 times and reset twice. How many times are you suggesting that I reset it before moving on to the next step. My OBD shows that the CAT and OS2 are not set. Everything else is set/good.

The purge valve should be easy enough to get to and check. I have not seen those specific codes though.

My OBD has graphing and I will compare the value to 15. It maybe time to spring for the Durametric.

Thanks for the Pop Mechanics suggestion. I used to read that religiously.

I have some more home work to do. Thanks again everyone for your suggestions.

[rexcramer]

I dropped it off at the indy. After 3 hours of smoke testing and pulling the intake apart, the mechanic found a hose that had come undone. The mechanic that found it was out when I went to pick the car up so I am still not entirely clear which hose. All of the sensors were set except the CAT when I picked it up. A 20 mile run over the dam set the CAT. I stopped for the smog test on the way back and all is right with the world.

Thanks again for everybody's input.

[Gelbster]

As these cars age, such problems become more common. For this reason I have replaced as much of the vacuum system with silicone hose and brass fittings.
The parts cost is trivial .The best way to do the job is as part of a "While you are in there" job .