P1128/p1130 - 986 Forum - The Community for Porsche Boxster & Cayman Owners

ramo80 · 05-15-2013, 09:36 AM

Hi All,

Let me start by saying that i did a lot of research on this forum about these error codes but my problem is slightly more unique. A few month ago i got both these error codes P1128 and P1130. I reset it and drove it a few days before putting in winter storage. I had rough cold idle issue as well. When the car warmed up it ran perfectly. Cleaned MAF and cleaned the throttle body. I think the rough idle was due to bad gas because that went away. Here is where things get weird. Now that i'm driving it in the spring again I got error code P1130 only after driving for a month. I checked for vacuum leaks and replaced my oil filler tube cause i thought it was broken. It wasn't. I reset again and after driving for 2 days i got error code P1128 only.

Does this sound like a MAF failure issue? Why do i keep getting one error and not the other. attached are the read outs for my O2 sensors. Do they seem normal?

Topless · 05-15-2013, 01:26 PM

The car is running lean. Probably either an intake air leak or failed MAF. Each O2 bank sensor induces independent fuel trim so it is possible to get one code on Monday and a mirror code on the other bank in a few days. You are on the right track.

ramo80 · 05-15-2013, 02:47 PM

Thanks Topless.

One more update. I tried removing the oil filler cap while the car is running and it was on there good. There was a huge vacuum holding it in place. When i did remove it i can hear a sucking sound into tube.

Does that automatically mean that its a bad air/oil separator?? Should i replace it??

Jager · 05-15-2013, 06:24 PM

Quote:

Originally Posted by ramo80

Thanks Topless.

One more update. I tried removing the oil filler cap while the car is running and it was on there good. There was a huge vacuum holding it in place. When i did remove it i can hear a sucking sound into tube.

Does that automatically mean that its a bad air/oil separator?? Should i replace it??

You will have some vacuum at the oil fill tube... Did the RPMs drop allot? Did the motor almost die? I have seen these trouble codes when the AOS goes bad.

ramo80 · 05-15-2013, 06:38 PM

Thanks Jager

I just tested it. when I wrestle the cap off i wouldn't say the rpm goes down but the car sputters and runs rough until i put it back on.

Bad AOS?

Jager · 05-15-2013, 07:30 PM

Quote:

Originally Posted by ramo80

Thanks Jager

I just tested it. when I wrestle the cap off i wouldn't say the rpm goes down but the car sputters and runs rough until i put it back on.

Bad AOS?

If the AOS is good the RPMs will actually increase but the motor will shutter a bit. A bad AOS the RPMs will drop, the motor stumbles and sometimes stalls. While the motor is running and you take the oil fill cap off does it sound like a shop vac at the opening? Put your hand over the oil fill opening, is there allot of vacuum (like a shop vac) grabbing your hand?

ramo80 · 05-15-2013, 07:46 PM

Checked again. there is no change in RPM. Stays a hair over 800 or right at 800. car sputters when cap is removed. I put my hand over it and it left a mark. it did feel like a shop vac. Its was on there good.

Jager · 05-15-2013, 07:56 PM

Quote:

Originally Posted by ramo80

Checked again. there is no change in RPM. Stays a hair over 800 or right at 800. car sputters when cap is removed. I put my hand over it and it left a mark. it did feel like a shop vac. Its was on there good.

If there is that much vacuum the AOS is bad.

Jager · 05-15-2013, 07:58 PM

Quote:

Originally Posted by ramo80

Checked again. there is no change in RPM. Stays a hair over 800 or right at 800. car sputters when cap is removed. I put my hand over it and it left a mark. it did feel like a shop vac. Its was on there good.

Have you ever had a large cloud of smoke on start-up?

ramo80 · 05-15-2013, 08:14 PM

Nothing out of the ordinary with respect to smoke. I probably should have started with this but the car has 145,000 kms. I have owned it since it had 50,000 km and i have never replaced the AOS. I don't know if the previous owner did. Here is what i found about the symptoms of a fail AOS on pelican parts

"The failure of the air-oil separator is often (but not always) accompanied by huge amounts of white smoke exiting the vehicle's exhaust and a generally poor running engine."

Jager · 05-15-2013, 08:27 PM

That much vacuum (shop vac) tells me the AOS is bad, it's a common problem with the M96 motors. You have been fortunate to go that many km without replacing the AOS. If you decide to replace it are you going to do it yourself or take it to a shop to have done?

ramo80 · 05-15-2013, 08:36 PM

i very rarely take my car to a mechanic. I love DIY projects. I'll order up all the parts as described in pelican parts and tackle this when they get here.

Jager · 05-15-2013, 08:46 PM

I recommend this tool (or similar) to remove and install the lower hose clamp.

Craftsman Cable Operated Hose Clamp Pliers - Tools - Mechanics & Auto Tools - Automotive Specialty Tools

ramo80 · 05-16-2013, 05:55 AM

So you think its AOS for sure. I shouldn't worry about the MAF?

Jager · 05-16-2013, 06:50 PM

I believe you have an AOS problem. An AOS is less expensive than MAF sensor but a PITA to replace compared to MAF replacement.

You can try cleaning the MAF sensor and then see if the trouble codes come back. You will need an anti tamper torx and some MAF sensor cleaner.
Here is a good write-up on the MAF sensor:

https://sites.google.com/site/mikefocke2/checkenginelightcausedbymassairflowsensor

ramo80 · 05-22-2013, 12:13 PM

After following Jager's advice it did turn to be the AOS. Having a bad AOS will give you both or one of the subject error codes. I have replaced it over the weekend. Took a long time but got it done. the surprising thing is that i drove the car for a couple of days and the CEL light just went off on its own. My buddy with the code reader was out of town. All is good again.

Thanks for the help!