Chasing vacuum leaks and goes no where

[theWalkinator]

My car is 2001 2.7, the original MAF is Bosch F 00C 2G2 064, the replacement MAF is also Bosch, the part number is 0280 218 055/986 606.125.02, I ordered it from RockAuto, and before I ordered it, I double checked FCP Euro and Pelican Parts, they all show this MAF for my car, is this replacement MAF not the correct one?

Also, my codes are
P1128, P1130 Adaptation idle range Below Limit Value
P1126, P1133 Adaptation lower load range Exceed Limit Value.

I searched and saw someone posted that for P1128, P1130 Adaptation idle range Below Limit Value, the car is running rich and ECM is trying to take fuel away and reaches the limit, and STFT is around 25% and RKAT is pegging at 4.5%, I am confused, is the car running lean or rich? If it is running rich then that explains why there is no vacuum leaks detected.

The causes for P1128, P1130 Below Limit Value could be:
– Incorrect signal from MAF sensor
– Fuel pressure too high
– Fuel injector leaking
– EVAP canister purge valve open

So
- Incorrect signal from MAF - wrong MAF sensor?
- Fuel pressure too high - Pressure tests at the fuel rails are fine, idle 3.3 bar, engine off 3.5 bar
- Fuel injector leaking - how to test leaking injectors? the car only have 33km so leaking injectors seems unlikely
- EVAP canister purge valve open - EVAP vacuum leaks cannot be detected by intake smoke test, correct? the purge valve is under driver side intake manifold so that is my next thing to check, how can I check it without fighting to remove it ?


I also add that the car was running fine but the codes popped up after I cleaned throttle body, not immediately after but for a while it developed rough idle and eventually those 4 codes popped up.

[JFP in PA]

Originally Posted by theWalkinator

My car is 2001 2.7, the original MAF is Bosch F 00C 2G2 064, the replacement MAF is also Bosch, the part number is 0280 218 055/986 606.125.02, I ordered it from RockAuto, and before I ordered it, I double checked FCP Euro and Pelican Parts, they all show this MAF for my car, is this replacement MAF not the correct one?

Also, my codes are
P1128, P1130 Adaptation idle range Below Limit Value
P1126, P1133 Adaptation lower load range Exceed Limit Value.

I searched and saw someone posted that for P1128, P1130 Adaptation idle range Below Limit Value, the car is running rich and ECM is trying to take fuel away and reaches the limit, and STFT is around 25% and RKAT is pegging at 4.5%, I am confused, is the car running lean or rich? If it is running rich then that explains why there is no vacuum leaks detected.

The causes for P1128, P1130 Below Limit Value could be:
– Incorrect signal from MAF sensor
– Fuel pressure too high
– Fuel injector leaking
– EVAP canister purge valve open

So
- Incorrect signal from MAF - wrong MAF sensor?
- Fuel pressure too high - Pressure tests at the fuel rails are fine, idle 3.3 bar, engine off 3.5 bar
- Fuel injector leaking - how to test leaking injectors? the car only have 33km so leaking injectors seems unlikely
- EVAP canister purge valve open - EVAP vacuum leaks cannot be detected by intake smoke test, correct? the purge valve is under driver side intake manifold so that is my next thing to check, how can I check it without fighting to remove it ?


I also add that the car was running fine but the codes popped up after I cleaned throttle body, not immediately after but for a while it developed rough idle and eventually those 4 codes popped up.

The fact that the codes you are seeing is an impossibility (overly lean and rich at the same time) says something is wrong. Most likely problem is that you inadvertently "upgraded" to the later MAF (part number ending in 125 01 or higher) when you replaced the original MAF, which REQUIRES the DME be recoded in order for it to work properly, which requires access to a PIWIS system.

[theWalkinator]

Originally Posted by JFP in PA

The fact that the codes you are seeing is an impossibility (overly lean and rich at the same time) says something is wrong. Most likely problem is that you inadvertently "upgraded" to the later MAF (part number ending in 125 01 or higher) when you replaced the original MAF, which REQUIRES the DME be recoded in order for it to work properly, which requires access to a PIWIS system.

Right, that puzzled me as well, but with my original MAF I also got those 4 codes, so I will put the original MAF back and replace the vacuum reservoir which is bad then reset ECU and test drive the car to see if codes comes back again.

[AK986]

Originally Posted by theWalkinator

Right, that puzzled me as well, but with my original MAF I also got those 4 codes, so I will put the original MAF back and replace the vacuum reservoir which is bad then reset ECU and test drive the car to see if codes comes back again.

Hey, i'm running in to the similar issue with my 98 Boxster. I checked the car for vacuum leaks by using the smoke detector ,and couldn't not find any.

Any updates on your progress?

[theWalkinator]

Originally Posted by AK986

Hey, i'm running in to the similar issue with my 98 Boxster. I checked the car for vacuum leaks by using the smoke detector ,and couldn't not find any.

Any updates on your progress?

I replaced vacuum reservoir and that helped to get rid of P1128 and P1130 (idle below limit) codes, but P1126 and P1133 (lower range exceed limit) codes still present.

I also replaced fuel filter which is really dirty (fuel came out of the filter is cloudy and contains fine black sediments), after replaced fuel filter, I re-checked the fuel pressure, idle at 3.3bar which is right on the spec, but engine off fuel pressure is kept at 3.5bar which is 0.3 bar lower than the spec, but I don't think it really matters. Also replaced the spark plugs with NGK Iridium plugs as well as spark plug tubes since they are leaking oil and might also leaking vacuum, but all that didn't resolve P1126 and P1133 codes.

Other things checked:
1. Checked vacuum at the Y hose connector, it holds vacuum
2. Fuel regulator, pulled out the small vacuum hose from the fuel regulator, it is dry no fuel came out, the small vacuum hose has suction so both fuel regulator and vacuum are good.
3. Checked EVAP purge valve with my scanner and a hand vacuum pump, I can command the valve open and close, when it is closed, it holds the vacuum but when I command it open, the vacuum drops to 0 so that ruled out the EVAP purge valve.

I also tried with the MAF plug disconnected, P1126 and P1133 codes did not show after 10 miles test drive, so at this point I think most likely it is the wrong MAF sensor that I bought from RockAuto which is 98660612502, though all online sellers (FCP Euro, Pelican Parts, RockAuto, etc.) give this MAF sensor as the correct one for my car, but the original MAF sensor in the car is Bosch F00C2G2064, I couldn't find anywhere that this MAF sensor fits my car or any boxster, except one eBay seller who has a list of Bosch 99660612400 but the item picture shows Bosch F00C2G2063. My car is 2001 2.7L but the production date is in Sept 2000 so 99660612400 might be the correct MAF sensor for my car, this website https://www.eurospares.co.uk/Porsche/Boxster_986/Boxster_986_(2001)/PartDiagrams/106-000/AIR_CLEANER?ref=7 listed both 99660612400 and 98660612500 fit 2001 boxster 2.7L.

If 99660612400 won't resolve the P1126 and P1133 then the last thing is the fuel pump?