signal

My car has thrown this code a few times and I have cleared it. Finally I am gathering the diagnostic info and its in this message, can someone tell me how to fix?

CODE P1128

Calc Load 4.7
Coolant Temp 201

Short term fuel trim, B1 -2.65%
Long term fuel trim B1 0.655%
Short term B2 -3.65
Long term B2 0.655%

RPM 819
Ignition Advance 7 degrees
Intake Air temp 153 deg F
Air Flow 0.91b/m
Throttle 3.1%

Oxy B1, S1 845mv
Oxy B1, S1 (Fuel trim) -5.65%
Oxy B1, S2 820mv
Oxy B1, S2 (Fuel Trim) 99.2%
Oxy B2, S1 825mv
Oxy B2, S1 (Fuel trim) -6.65%
Oxy B2, S2 815mv
Oxy B2, S2 (Fuel trim) 99.2%


Does anyone know based on the above what I should do?

signal

Bump. Does anyone have an answer on this? I included all the oxygen fuel trim info etc, which is what most people dont have when they post these codes. Just trying to figure out a game plan to fix this. I hear alot say spray electronics cleaner on the maf and then spray carb cleaner into the throttle body.........i could try that, just need to buy the special torx wrenches for the maf.

1999Porsche911

Well, you idle MAF reading is fine, maybe slightly high. Intake temp is very high leading me to believe that the MAF is the culprit. Calculated load is very high also. Do you have the stock air filter setup? Have you sprayed the MAF with electronic's cleaner to remove residue? Has there been an increase in your oil usage?

The P1128 is reporting that bank 1 is running lean, either because of to much air or too little fuel. The amount of fuel is partially determined by a calculation of intake air temp, load and volume of air. I would suggest first cleaning MAF and test again before moving to more difficult diagnosis.

signal

Car was idle when I took those mesurements. I have the stock air box and stock porsche brand air filter changed maybe 2 months ago. I have never sprayed the MAF/cleaned it. I have owned the car for about 20k miles, car has 50k on it. No increase in oil usage, I really never add oil. I changed the oil maybe 2 months ago (every 15k miles) with mobile 1 ow40, factory filter, etc. My car does not leak a drop.

I bought the security torx tonight, and was going to pull the MAF and spray it and let it dry, then reinstall to see if that helps.

I have been throwing this code every 5k miles or so. The last time it happened, I shot a bottle of Techron into the tank to help clean any injectors, but that doesn't seem to have fixed anything.

I will clean the MAF, reset the computer (disconnect battery for a few minutes) and then take new ODBII readings......thanks, appreciate the help.

Brian

SpDfReAk980

Dude, just put a new Air Mass Meter in it and be done with it, don't try to clean it. Your RKAT's and FRA's are a typical Air Mass Meter.

signal

They aren't exactly cheap.....$300 or so for a MAF, and it could be something else right? like an injector or an O2 sensor? I think cleaning the MAF is simple enough to "try" it.

SpDfReAk980

02 sensor faults would throw 02 sensor faults, injector = misfire faults (have yet to see a problem with an injector FYI), put an air mass meter in it, clear the fault, and enjoy your car for another 50,000 miles until you need another one, lol. Or you can check for a vacuum leak if you must. Doubtful you will find anything, but if you must. No vacuum leaks, put an Air Mass Meter in.

SpDfReAk980

Whoops, my bad, I have food on the mind, making dinner, lol. Don't check for a vacuum leak because you don't have one, your RKAT's and FRA's would both be positive. Air Mass Meter

heelix

Working through a MAF issue myself right now. So

Adaption, range 2 (FRA), bank 1: 1.29%
Adaption, range 2 (FRA), bank 2: 1.30%

Adaption, range 1(RKAT), bank 1: -1.78
Adaption, range 1(RKAT), bank 2: -1.64

rules out a vacuum leak?

1999Porsche911

No, it does not rule out vacuum leak. A vacuum leak would cause O2 sensors to add more fuel which would increase your FRA. But, so would dirty injectors, dirty or bad MAF and several other things.

SpDfReAk980

Yes is does rule out a vacuum leak!!! Both RKAT's and FRA's would be positive
RKAT's in your little quote are negative, therefore taking away fuel, running rich, lack of air for the amount of fuel injected. Adaption range 1 is not positive therefore there is no vacuum leak. AIR MASS METER.
FYI, your FRA's are higher load range, higher rpm, where vacuum is really non-existant

SpDfReAk980

Yes is does rule out a vacuum leak!!! Both RKAT's and FRA's would be positive
RKAT's in your little quote are negative, therefore taking away fuel, running rich, lack of air for the amount of fuel injected. Adaption range 1 is not positive therefore there is no vacuum leak. AIR MASS METER.
FYI, your FRA's are higher load range, higher rpm, where vacuum is really non-existant

SpDfReAk980

sorry about the double post, thought i lost my internet connection for a moment there, i wish i had a Mac, lol

1999Porsche911

Long term fuel trim takes up the correction factor of the short term fuel trim, and therefore the STFT will not necessarily ( and most often will not) show adding fuel when there is a vacuum leak. The LTFT will show the added fuel. Therefore, you cannot rule out a vaccum leak just because STFT is negative.


Your statement of "FYI, your FRA's are higher load range, higher rpm, where vacuum is really non-existant" is not correct, and I have no idea what hat you pulled that out of.

SpDfReAk980

Short term fuel trim will always show a vacuum leak first, Long term fuel trim will follow accordingly the longer the engine is driven with the vacuum leak, hence why they call it SHORT TERM and LONG TERM