Fault codes

[CHAZ2]

My garage tells me I have codes P1130 and P1138 showing - what are the likely causes?

1999 Carrera 4 tiptronic.

[JFP in PA]

My garage tells me I have codes P1130 and P1138 showing - what are the likely causes?

1999 Carrera 4 tiptronic.

 

Are you sure the code are P1130 and P1138, or could they be P1130 and P1128?

[CHAZ2]

Could be I guess - they have said P 1138 by email - could be a typo I suppose!

[JFP in PA]

Could be I guess - they have said P 1138 by email - could be a typo I suppose!

 

Reason I ask is the 1128 and 1130 are commonly occurring code pair caused by an air leak (overly lean mixture condition).

[Silver_TT]

Be sure your shop that emailed you is using a Porsche-specific reader.

[CHAZ2]

OK thanks I'll query it - I,m sure the diagnostic's equipment will be Porsche specific - it's a well regarded independant.

Assuming codes are as you say where is likely source of air leak?

[johneevans2]

My 2001 C2 is throwing the same codes (P1128 and P1130)....it has done that since I bought it.  Porsche dealer says it's the MAF. I haven't replaced it yet but I have cleaned it twice and cleaned all other areas around intake and throttle. Still throws the code. Has anyone found a more than likely fix for this problem?? 

[Porschetech3]

Codes p1130 and p1128 are codes indicating the mixture adjustment has reached its adjustment limit. It could be the max limit lean or the max limit rich. The  best way to tell is to look at the RKAT values before erasing any codes or resetting values , if the RKAT is at -.38 the system is at the lean limit indicating a rich condition( usually a faulty MAF sensor) , if the RKAT is +.38 the system is at rich limit indicating a lean condition(usually from an air/vacuum leak). Using this method will help keep from false diagnosis.

[johneevans2]

I have been getting the p1128 and p1130 for a while and the Porsche dealer recommended I start with MAF but no guarantee. So after some deliberating I ordered a new MAF along with a new air filter and installed....5 - 10 miles into test drive I got p1128 and p1130 codes I had already been getting but also got p1125 and p1132. I erased the codes and continued driving and since then (3 days) I continued to get only p1128 and p1130 codes. The Check engine light comes on only when I'm at idle at a stop light, never while driving.  

 

Could an aftermarket exhaust cause back pressure that would trigger the code? I have looked for leaks around intake also and I have found none...however I haven't used smoke, just visual inspection.

[Ahsai]

I have been getting the p1128 and p1130 for a while and the Porsche dealer recommended I start with MAF but no guarantee. So after some deliberating I ordered a new MAF along with a new air filter and installed....5 - 10 miles into test drive I got p1128 and p1130 codes I had already been getting but also got p1125 and p1132. I erased the codes and continued driving and since then (3 days) I continued to get only p1128 and p1130 codes. The Check engine light comes on only when I'm at idle at a stop light, never while driving.  

 

Could an aftermarket exhaust cause back pressure that would trigger the code? I have looked for leaks around intake also and I have found none...however I haven't used smoke, just visual inspection.

 

A few questions:

- What year and model is your car?

- Is your new MAF genuine Porsche or Bosch?

- Do you have Durametric or other OBDII scanner that can read real-time MAF and O2 sensor voltage?

- Have you tried reset the codes, unplug the MAF and see if you get those codes?

- What are the exact intake the exhaust mods?

[johneevans2]

My Bad, sorry for the lack of info.

 

-2001 Carrera C2.

-Bosch part # matches the old one and also matches the part # that indicates it's E-Gas.

-Unfortunately I do not have Durametric or a code read for real-time...I'm currently researching options, I would like Durametric.

-I have not traveled further than 10 miles with MAF unplugged....one post said to do that and see if performance improved. When I did so I got a few other lights that popped up on the dash and was worried I may mess something up.

-Only aftermarket product is an Agency Power exhaust that was installed by the previous owner. The air filter I perchased was Mann.

 

The previous owner said he didn't get those codes...but I have gotten them since I have owned the vehicle (4 months)

Edited June 20, 2016 by johneevans2

[Ahsai]

A few points then:

 

- When you disconnect the MAF, it's normal to get a CEL (which you can clear with any scanner later). Durametric would be a good choice. If not, at least a wireless ODBII dongle. It's very cheap if you use Android devices.

- 1128 and 1130 could be either too lean or too rich hence we need a scanner to check the fuel trims to point us in the right direction

- Exhaust leak can be one of the reasons but again, we need to see if it's too lean or too rich though

- Check your oil filter tube for air leak. Can you remove the oil filler cap with a bit of vacuum suction?

 

 

My Bad, sorry for the lack of info.

 

-2001 Carrera C2.

-Bosch part # matches the old one and also matches the part # that indicates it's E-Gas.

-Unfortunately I do not have Durametric or a code read for real-time...I'm currently researching options, I would like Durametric.

-I have not traveled further than 10 miles with MAF unplugged....one post said to do that and see if performance improved. When I did so I got a few other lights that popped up on the dash and was worried I may mess something up.

-Only aftermarket product is an Agency Power exhaust that was installed by the previous owner. The air filter I perchased was Mann.

 

The previous owner said he didn't get those codes...but I have gotten them since I have owned the vehicle (4 months)

[johneevans2]

I just removed the oil cap and it seems to be set and sealing properly but there is no suction (engine not running).

I will get online tonight and see if incan find a reader that will get me those values until I pull the trigger on the durametric. I will post the results when I get it along with any other info I come across. Thank you for your help thus far.

[Ahsai]

The engine needs to be running for the oil cap test. For a generic OBDII scanner, you can get either wifi or bluetooh dongle.

Wifi is more expensive but will work for both iOS and Android. Bluetooth only works for Android. If iOS, get the "OBS Fusion" app. If Android, get the "Torque Pro" app. All those read sensor values and fuel trims in real-time.

[johneevans2]

Ok Torque Pro it is.

 

Also, if I unplug the MAF, how long am I able to drive (miles) before creating issues. It usually takes a drive cycle to replicate the issue....or sometimes a little longer.

[Ahsai]

You can drive it for a few drive cycles. The power may be reduced though but it's ok. If the P1128/1130 don't show up again with the MAF unplugged, then it's pointing to the MAF.

 

With the scanner, you can check the MAF reading directly. It should read about 15kg/hr with a fully warmed up engine idling with no electrical load on it such as a/c, headlights, etc.

 

These numbers are for the 3.6L engines. Yours is a 3.4L so yours may be a little bit lower but this will give you a good idea.

 

Idle: 15-20 kg/hr

At 3,000 rpm: 50-70 kg/hr

 

Ok Torque Pro it is.

 

Also, if I unplug the MAF, how long am I able to drive (miles) before creating issues. It usually takes a drive cycle to replicate the issue....or sometimes a little longer.

[johneevans2]

Ahsai...thanks man. I will update as soon as it comes in.

[Ahsai]

BTW, don't erase the fault codes yet because it you do, you reset the DME and all the fuel trims back to 0's...loosing all the clues.

 

Just scan for codes first, then read the short-term and long-term fuel trims on both banks, which will then tell us whether the engine is running lean or rich (positive fuel trim means engine is running lean and negative means rich).

 

Then fully warm up the engine and let it idle to do the MAF reading (with the MAF stay plugged in).

[johneevans2]

Ahsai, reader still hasn't arrived...however some info you requested earlier I have. 

 

With the motor running I do have suction.  

 

Also I tried driving to work this morning with MAF disconnected. Within 5 miles I got CEL but codes were different. I got P0102 and P0112. I didn't get the usual P1128 and p1130. I believe P0102 is still the MAF but the P0112 indicates Air Temperature Sensor.  Could those have come up just bc I disconnected the MAF? But having disconnected the MAF, I didn't see the P1128 and 1130 which leads me to believe the new MAF may be faulty.

 

Something else to note, the other night I went out in the country and drove the car pretty hard and in 2nd gear when I step on the gas hard (meaning 75% - 80% to the floor) it would throw no CEL but it would throw my ABS and PSM lights on the dash. So at a stop sign I turned car off and restarted to have the light turned off, and then I went normal through 2nd (no lights) and then in 3rd I again pushed gas to about 80% I got the lights again. So I drove the car normal to ensure I didn't mess anything up.  Then yesterday while on the highway, I decided to test it in a higher gear, so I downshifted from 6th to 5th and again hit the gas hard and the lights came on. Every time I get those lights when pushing has hard I feel a lag in throttle response, like it stops pulling. If I continue to push the gas it will eventually come out of the lag I was describing and start accelerating like it should.  So does that sound like the throttle (since it's e-gas) isn't being told to open by the computer? Or could that be a fuel pressure issue? Or could it still go back to the MAF?  I know when the OBD reader comes in, I will be able to post some values that will help as you have recommended. I wish I had somewhere local to get one bc it's driving me nuts and I feel like i'm damaging the car. 

[Ahsai]

The P0102 and P0112 are both due to the unplugged MAF. The MAF has an air temp sensor integrated inside. Actually I checked the diagnostic manual the P1128/1130 codes may be suppressed in the presence of other fault codes so this unlpugged MAF test wont be conclusive. We still need to check the actual MAF/O2 reading.

 

Is your MAF Bosch 0280218009?

[johneevans2]

Yes sir that is the MAF part number. Well since this reader is coming from another planet I guess I'm going to try and find one local today and post some values.

[Ahsai]

A few same-day shipping from amazon prime such as this one:

https://www.amazon.com/Veepeak-Bluetooth-Scanner-Automotive-Diagnostic/dp/B011NSX27A/ref=sr_1_3?ie=UTF8&qid=1466880977&sr=8-3&keywords=Bluetooth+obdii

[johneevans2]

Ok FINALLY!! And thank you for the advice I did just that in going through amazon.  I'm not sure what all needed to be logged but I got the STFT and LTFT values for both banks...the STFT values stayed around the -4 to +4 but sometimes climbed up as high as 10 or 11.  The LTFT values are around +25.  Research I have done says this indicates it's running lean and possible issues could be;

 

-vacuum leaks at manifold or surrounding areas

-Weak fuel pump, fuel line issues or regulator issues

- MAF

-Injectors

-spark plugs (these have been recently replaced)

-Compression leaks

- exhaust manifold

-Bad O2 Sensor

 

Are there any other readings I could gain from the Torque readings that would lead me in the right direction on any of these.

 

 

 

 

[Ahsai]

Yes, it appears that the engine is running lean. I suggest focusing on air leak (e.g., the intake rubber boot and the oil filler tube), MAF, and fuel regulator.

 

Verify the MAF reading at idle and at 3k rpm as listed in post #16.

 

Log the four O2 sensor readings when engine (fully warmed up) is idling and the car is stationary for say a few minutes. The precat sensors should swing between 0.3v to 0.7v about every second and the post-cat sensors should more or less stay at 0.7v.

 

Verify fuel pressure is not too high (should be 3.3~3.8 bar). Have you replaced your fuel filter in the transmission tunnel area?

[johneevans2]

OK, it looks like my MAF is giving low values...like the highest value was 44....and the low value was 7.  

 

I haven't replaced my fuel filter or anything having to do with the fuel system.

 

I will get those other values on the way to the house tonight and post.