Robin 993DX

I have been having P1128 + P1130 (always at the same time) error code go off on a regular basis. Only goes off when the car is sitting at a light, or stuck in slwo moving traffic. Never at higher RPM highway driving.

I don't have any leaks, haven't had a chance to ck the oil separator bellow yet. Cleaned the MAF about a year ago.

Time to clean MAF again? Or is this a symptom of the bellow going bad? Or maybe even cracked exhaust...

TIA

DFC

Robin - here is some info. Cleaning the MAF only takes a few minutes so it may be a good place to start. Also, a search on "1128" will provide a bunch of info.

GL

1999Porsche911

In addition to cleaning the MAF, check for a good fit on your oil cap as well as all intake connections after the MAF.

Tbred911

make sure you oil cap is on the right way and its tight.... I had these exact 2 codes after I played around with my oil cap... turned out it was loose and was letting air in....

pretty sure that if you get 2 codes at the same time its either your oil cap loose or some type of a leak in the funnel that the oil cap sits on... check it out.

Robin 993DX

Thank you guys for the input. I know I am not really running too lean as the exhaust tips are carbon up pretty good.

Oil cap is on nice and tight, the oil filler tube looks good too. Engine bottom bone dry, I do need to get it on the lift to see if I can see the bellow.

Th frequency varies, if I don't get stuck in traffic or sit in idle too much the light doesn't really go off for a long time. But if stuck in traffic too much light goes off once every couple of days. I have the scan Tool II hooked up all the time, so I just reset it on the fly, the engine doesn't feel any different, there is no hic up, or rough idle prior to throwing the CEL.

Barn996

I had the same CEL codes twice now on my 99 996 over a period of several months. The first time I came off the highway and was sitting at a long light. I deleted the codes and they reappeared about 3 weeks later. I once again erased the codes and they have not come back.

joes c4 cab

I had the same codes - first replaced the 02 sensors and then it came back - MAF needed replacing. Give it a good cleaning and hope for the best.

exlondoner

Recieved a P1130 about a month ago, cleaned the MAF, Throttle body and filter and all is excellent.

Also added some Techron to the fuel tank to clean up the injectors.

Granger968

Does anyone know how to troubleshoots the MAF and the O2 sensors? I've already gone through cleaning of air filter and MAF, and codes keeps coming back. I don't want to just throw money at sensors, I'd like to verify first...

Thanks!

99firehawk

Robin: Do you have the ability to read sensor data, fuel trim or o2 sensor signals?

Granger : What years your car, what kind of car. What faults are you getting, how are you reading them. You really should start your own thread

salayc

check the AOS

stevells

Is the air filter housing securely tightened?

1999Porsche911

In addition to checking for intake leaks, including oil filler tube and cap, check your electric changeover valve connections. Valve closes and opens at startup and stays closed from 3100 - 5200 rpm. During those engine speeds, if the hose returning to the resonance flap is disconnected or otherwise leaking, it will generate these 2 codes.

razor558

what is a electronic change over connections?

Tbred911

I had this same problem when my shop,accidentally over oiled my k&n filter...

I replaced with stock filter to trouble shoot and then realized there was filter oil on the MAF... I cleaned and cleaned and even after the cleaning it felt like I got 40ho back the codes came back

I bought a new Bosch MAF sensor from autopartsway.com to troubleshoot and what I found was interesting indeed.

Because the MAF was contaminated with oil the car was running leaner and losing tons of ho.... I headed to the dyno with new MAF and stock paper filter and I made 12 more hp with the new MAF.... Sometimes even though you clean the old MAF and it feels good it's running leaner so a dyno session with AF reading was in order to ensure I was running within spec... I put in the old cleaned MAF and confirmed the ho loss... I then switched back to the new MAF and wanted to test the k&n filter....NO HP difference..... My car is a 99 3.4 running a GIAC flash so maybe it doesn't like the extra air because it did t show up on the dyno!!!

I'm now running with stock paper filter and new MAF and problems solved.

How old is your MAF? Do you have a stock or k&n filter?