More CEL fun...

[VirtualTed]

Hey everyone,

This is a great forum. I'm reading everything and learning a lot. Hopefully I'll be able to give a little back at some point. Here's the situation:

I just purchased a used 97' Boxster with 96K miles on it. Seems to run well - there are no obvious signs of problems like backfires, sputtering, or rough idle. Purchased from a corner car dealer who probably put regular unleaded in it and disconnected the battery to erase the error codes prior to sale. I got a great price so I'm not complaining.

Upon driving it the second day, I got error codes 1124 and 1126. I did the following:

• I cleaned the MAF sensor with CRC per advice found here. (didn't look dirty though).
  
• Cleaned the air filter (filthy! In the process of getting a new one asap.)
  
• Filled tank with 12 gallons of premium.
  
• Reset MAF/CEL by disconnecting battery for 30 seconds.
  

I then proceed to drive about 10 miles. Just as I'm pulling into the garage, I notice CEL light once again. I now have the following codes...

• P0130 - Oxygen Sensor Ahead of Catalytic Converter (Cylinders 1 - 3) - Intercore Short Circuit or Limited
  
• P0150 - Oxygen Sensor Ahead of Catalytic Converter (Cylinders 4 - 6) - Intercore Short Circuit or Limited
  
• P1124 - Oxygen Sensing Adaptation Area 1 (Cylinders 1 - 3) - Rich Threshold
  
• P1126 - Oxygen Sensing Adaptation Area 1 (Cylinders 4 - 6) - Rich Threshold
  

Not what I was hoping for. I have an OBD2 reader that can display live stats which I'll post here if it's helpful. Otherwise, do you guys have any advice on what to try first? Given that I have no history on this car, my initial guess is to start replacing oxygen sensors, but from what I've read here, that may not really be the problem.

Any and all help is appreciated.

-VT

[VirtualTed]

More information...

I let the car idle in the garage and it sits between 715 - 815 RPMs. I then removed the plug to the MAF sensor. The idle RPM dropped noticeably and then stabilized out quickly afterward, but the RPM speed fluctuated slightly broader than before (650 - 850+ RPMs). I had expected that there would be no difference at all when unplugging the MAF sensor, but it does react somewhat. Does that mean it's working after all? My OBD2 tool which has live reporting is stating a zero reading for the rate of airflow at all times - I suspect it just doesn't know how to read it correctly.

So, I think there are 4 possibilities at this point.

• Something is wrong with the O2 sensors.
  
• Something is wrong with the MAF sensor.
  
• I've got something wrong with the air/oil separator. (cracked/torn baffle problem?)
  
• There's a possible vacuum leak (related to #3 I guess - could be a hose).
  

I'm looking it over, but visually it all appears in good shape.

[Loren]

Solve one problem at a time.

A car with that many miles likely needs new O2 sensors if they have not been changed. It is rather odd that both sides (P0130 and P0150) would go bad at the same time - so I would have a look at the wiring before changing the sensors.

For the other codes start by cleaning the MAF and the throttle body.

[VirtualTed]

Thanks Loren. While there may be multiple issues with the car, I was assuming that any one of the issues I listed could potentially cause the error codes shown since they are all related to emissions. Cleaning the throttle body is on my todo list, but could a dirty one cause error codes like the ones I posted? I'm focused on the CEL problem at thr moment.

I'm going to check the voltages on thr MAF later today in an effort to rule it out as a possible problem.

-VT

[Loren]

No, that is why I say solve a problems at a time.

The idles problem is likely related to a dirty throttle body.

[VirtualTed]

Thanks Loren.

The last couple times I've driven the car, I've consistently got the 1124/1126 codes. The Idle Speed Regulator is giving off a crazy humming or buzzing noise as soon as I turn on the ignition (the car is not started). Sounds like there's something wrong. Is it possible to clean this thing or do I have to buy a new one? Do you think this is a possible cause of 1124/1126 codes?

The P0130 and P0150 codes have not returned since my initial post.

I'm getting ready to dissect the Throttle Body and clean it this weekend. I'm guessing it's going to be ugly...

Thank you!

-T

Edited October 3, 2008 by VirtualTed

[1schoir]

Thanks Loren.

The last couple times I've driven the car, I've consistently got the 1124/1126 codes. The Idle Speed Regulator is giving off a crazy humming or buzzing noise as soon as I turn on the ignition (the car is not started). Sounds like there's something wrong. Is it possible to clean this thing or do I have to buy a new one? Do you think this is a possible cause of 1124/1126 codes?

The P0130 and P0150 codes have not returned since my initial post.

I'm getting ready to dissect the Throttle Body and clean it this weekend. I'm guessing it's going to be ugly...

Thank you!

-T

Ted:

Here's a good set of DIY instructions from one of the gurus on PPBB: http://www.pedrosgarage.com/Site%203/DIY%2...tle%20Body.html

Regards, Maurice.

[VirtualTed]

I just took the Idle Control Valve off. Check out the top opening...

Is the default state supposed to be open? It sits at this position when unplugged, as well as plugged in when the ignition is turned on. At $350.00, I really want to know if this needs to be replaced or not before blindly ordering another.

Any and all help is appreciated.

-T

Edited October 3, 2008 by VirtualTed

[1schoir]

I just took the Idle Control Valve off. Check out the top opening...

Is the default state supposed to be open? It sits at this position when unplugged, as well as plugged in when the ignition is turned on. At $350.00, I really want to know if this needs to be replaced or not before blindly ordering another.

Any and all help is appreciated.

-T

Ted:

Take a look at this thread, it's got lots of info related to what you are facing:

http://www.renntech.org/forums/index.php?showtopic=17313

Regards, Maurice.

[wvicary]

The pic looks fine but dirty, they sit slightly open in the default position.

[VirtualTed]

Thank you Maurice, that is excellent information to have. I did a search and didn't see it before.

With that humming sound, I'm kinda wondering if the solenoid is able to actually move the little door back and forth as it should. As soon as I plug it in, it hums but nothing moves. I would expect it to go wide open.

I'll try running the car with it disconnected from the throttle body but still plugged in to the harness. If I see it move back and forth at all, that means it's functional. If it doesn't move when I give the car gas or after it's warmed up, something is probably wrong.

Not sure if this has anything to do with 1124/1126 P-codes, but I might as well remove it from the list of possible offenders.

-T

Edited October 3, 2008 by VirtualTed

[1schoir]

Thank you Maurice, that is excellent information to have. I did a search and didn't see it before.

With that humming sound, I'm kinda wondering if the solenoid is able to actually move the little door back and forth as it should. As soon as I plug it in, it hums but nothing moves. I would expect it to go wide open.

I'll try running the car with it disconnected from the throttle body but still plugged in to the harness. If I see it move back and forth at all, that means it's functional. If it doesn't move when I give the car gas or after it's warmed up, something is probably wrong.

Not sure if this has anything to do with 1124/1126 P-codes, but I might as well remove it from the list of possible offenders.

-T

Ted:

You are most welcome. Your approach is a sound one. As Loren said, tackle one problem at a time and eliminate each one as a possible contributory factor to the symptoms that your engine is exhibiting.

Keep us posted.

Regards, Maurice.

[VirtualTed]

Ted:

You are most welcome. Your approach is a sound one. As Loren said, tackle one problem at a time and eliminate each one as a possible contributory factor to the symptoms that your engine is exhibiting.

Keep us posted.

Regards, Maurice.

I think I've found the problem, but let me explain what I did first...

So, I tested Idle Control Valve by disconnecting it from the Throttle Body, but keeping it connected electrically. The car started, the little trap door swung open, and it seemed as though it was operating correctly. As my wife gave it some gas, the door opened and closed as I think it should. So, I won't be buying one at the moment.

I also removed the throttle body and cleaned it up, as well as the ICV and they are as good as new. Here's what the throttle body looked like...

Not as bad as I thought it would be for a car with 95,000 miles. I suspect someone got in there before I did but I still cleaned out all the other connected pieces. No problems there. Then I found this behind all the removed air intake equipment....

I think we have a winner! I can only assume these two vacuum lines are supposed to be connected. From my earlier observations, they were - but I couldn't see the whole picture until I removed the other parts. I guess I'll need a way to connect these back together. It appears about 4-6 inches was snapped off between them, but I couldn't find the missing piece.

We'll see what happens tomorrow. I definitely gotta clean that engine up too.

Edited October 4, 2008 by VirtualTed

[1schoir]

Ted:

Excellent work! Thanks for sharing the details of your progress. All of this info contributes to the body of knowledge and is sure to help future posters.

Regards, Maurice.

[RFM]

The black/white valve ( on the right ) and the tube ( on the left ) are connected to the rubber pieces which you have removed, and not with each other IMHO, take a good look before if it make sense. In this case your problem is still there.

[VirtualTed]

The black/white valve ( on the right ) and the tube ( on the left ) are connected to the rubber pieces which you have removed, and not with each other IMHO, take a good look before if it make sense. In this case your problem is still there.

Yep, you're absolutely right. I didn't see the connections in the rear of those two rubber pieces. I guess I was just eager to find a solution and get the CEL problems handled. It's always possible they were never hooked up by the last guy, which would have caused my problem. They're hooked up now though and we'll see what happens.

The good news is that my idle is now as smooth as silk and fluctuates very, very little (10-15rpms). After cleaning the Idle Control Valve, it also does not "buzz" like it used to. So, there are two problems solved without any expenditure of cash.

Thanks again guys.

Edited October 6, 2008 by VirtualTed

[1schoir]

The black/white valve ( on the right ) and the tube ( on the left ) are connected to the rubber pieces which you have removed, and not with each other IMHO, take a good look before if it make sense. In this case your problem is still there.

Yep, you're absolutely right. I didn't see the connections in the rear of those two rubber pieces. I guess I was just eager to find a solution and get the CEL problems handled. It's always possible they were never hooked up by the last guy, which would have caused my problem. They're hooked up now though and we'll see what happens.

The good news is that my idle is now as smooth as silk and fluctuates very, very little (10-15rpms). After cleaning the Idle Control Valve, it also does not "buzz" like it used to. So, there are two problems solved without any expenditure of cash.

Thanks again guys.

Ted:

Those are the always the most satisfying repairs. :clapping:

Regards, Maurice.