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FUEL TRIM LEVELS-what are the acceptable fuel trim levels for 997 4S? Durametric reads FUEL TRIM MEAN VALUE OF 0.9846 AND 1.0025 and FUEL TRIM ADAPTATION CLOSE TO IDLE (RKA) OF -2.109 % AND 0.984 %. All new fuel injectors and coils.
THx
Awesome explanation. I was worried that my engine that i just totally rebuilt was running too lean and potentially damaging my engine. From what i can gather from Tony's video (Which is excellent), itns seems that being between 1 and -2 are okay number results for the RKAT.
Trying step by step to rule out issues. engine is totally rebuilt with the majority of parts replaced. Just replaced all the fuel injectors, coils, MAF, air filter ands O2 before cat sensors. Have only put about 2000 miles on the new engine so far. Runs smoothly. Cleared all error codes and then can drive the car without any engine light warnings until i restart the car next time i drive and then i get the codes. P0300,P0301, P0302 and P0021. Car runs smooth, can not hear any misfires. It seems like i have maybe a faulty Cam Adjuster on Bank 2. strange as i would have thought then i would get misfires in bank 1 not 2.
Mean Values should be exactly 1.00000. A number lower than that means the DME is sending a rich condition and pulling fuel and a number higher tger than that means it's sending a lean condition and adding fuel. You don't say which bank is giving you which readings, but the 301 and 302 codes mean you're getting misfires on Bank 1 on 2 cylinders. If that's the side with the trims above 1.00000 and the lean message, smoke test for a vacuum leak.
Mean Values should be exactly 1.00000. A number lower than that means the DME is sending a rich condition and pulling fuel and a number higher tger than that means it's sending a lean condition and adding fuel. You don't say which bank is giving you which readings, but the 301 and 302 codes mean you're getting misfires on Bank 1 on 2 cylinders. If that's the side with the trims above 1.00000 and the lean message, smoke test for a vacuum leak.
Durametric reads FUEL TRIM MEAN VALUE OF 0.9846 AND 1.0025 and FUEL TRIM ADAPTATION CLOSE TO IDLE (RKA) OF -2.109 % AND 0.984. i believe these are in acceptable range? After clearing codes, i am still getting P0021 but do not have any misfire codes. The misfires I have experienced might have been at cold starts. Maybe it takes time for the computer to learn as i replaced all the coils, Fuel injectors, MAF and O2 sensors(before Cat) about 500 miles ago. I am now at about 2,500 miles in breaking in the engine rebuild. Started with 38 error codes, done to a handful now....getting there
I am still leaning to the cam Solenoid on Bank 2 being defective....The alternative being my Cam timing is off which if true, I guess i would have to drop the engine and re time it? Not exactly easy to Check CAM timing with engine in the car, although I have been told it can be done. If my timing was off would there not be other signs, like rough running engine?
Good idea re the smoke test, will need to do it. I did replace all lines and tubes.
Thanks
Mark
Last edited by markus7062; Jul 7, 2023 at 09:52 AM.
Durametric reads FUEL TRIM MEAN VALUE OF 0.9846 AND 1.0025 and FUEL TRIM ADAPTATION CLOSE TO IDLE (RKA) OF -2.109 % AND 0.984. i believe these are in acceptable range? After clearing codes, i am still getting P0021 but do not have any misfire codes. The misfires I have experienced might have been at cold starts. Maybe it takes time for the computer to learn as i replaced all the coils, Fuel injectors, MAF and O2 sensors(before Cat) about 500 miles ago. I am now at about 2,500 miles in breaking in the engine rebuild. Started with 38 error codes, done to a handful now....getting there
I am still leaning to the cam Solenoid on Bank 2 being defective....The alternative being my Cam timing is off which if true, I guess i would have to drop the engine and re time it? Not exactly easy to Check CAM timing with engine in the car, although I have been told it can be done. If my timing was off would there not be other signs, like rough running engine?
Good idea re the smoke test, will need to do it. I did replace all lines and tubes.
Thanks
Mark
Which bank is which fuel trim numerical value? If running your scan tool in live value mode while you're driving, do they stay at the numbers you've shown here or move up and down. If accelerating hard, they may change momentarily, but should return to 1.0000 even as the acceleration continues as the DME adjusts the fueling. Are the mean values the same at idle as they are when driving? Vacuum leaks are more pronounced at idle then when underway.
What are the bank 1 and bank 2 camshaft deviation readings?
Here's are screenshots from my durametric on fuel trim mean valuess. As you can see, my car is tuned a little rich by RUF because of the supercharger, so my mean values show that fuel is being pulled (numbers below 1.0000) when it's driving and accelerating. Based on my numbers, I'd actually be interested to see what fuel trims on a 997 Turbo look like since my car is actually running a TT DME because of the forced induction.
Durametric reads FUEL TRIM MEAN VALUE OF 0.9846 AND 1.0025 and FUEL TRIM ADAPTATION CLOSE TO IDLE (RKA) OF -2.109 % AND 0.984. i believe these are in acceptable range? After clearing codes, i am still getting P0021 but do not have any misfire codes. The misfires I have experienced might have been at cold starts. Maybe it takes time for the computer to learn as i replaced all the coils, Fuel injectors, MAF and O2 sensors(before Cat) about 500 miles ago. I am now at about 2,500 miles in breaking in the engine rebuild. Started with 38 error codes, done to a handful now....getting there
I am still leaning to the cam Solenoid on Bank 2 being defective....The alternative being my Cam timing is off which if true, I guess i would have to drop the engine and re time it? Not exactly easy to Check CAM timing with engine in the car, although I have been told it can be done. If my timing was off would there not be other signs, like rough running engine?
Good idea re the smoke test, will need to do it. I did replace all lines and tubes.
Thanks
Mark
Originally Posted by Petza914
Which bank is which fuel trim numerical value? If running your scan tool in live value mode while you're driving, do they stay at the numbers you've shown here or move up and down. If accelerating hard, they may change momentarily, but should return to 1.0000 even as the acceleration continues as the DME adjusts the fueling. Are the mean values the same at idle as they are when driving? Vacuum leaks are more pronounced at idle then when underway.
What are the bank 1 and bank 2 camshaft deviation readings?
Here's are screenshots from my durametric on fuel trim mean valuess. As you can see, my car is tuned a little rich by RUF because of the supercharger, so my mean values show that fuel is being pulled (numbers below 1.0000) when it's driving and accelerating. Based on my numbers, I'd actually be interested to see what fuel trims on a 997 Turbo look like since my car is actually running a TT DME because of the forced induction.
At idle
Driving 1
Driving 2
Fuel Trim Mean Value(Short Term Fuel Trim) is 0.95 Bk1 & 0.996 Bk2 at idle and barely moves will accelerating. RKAT (Long Term Fuel Trim) is 0.234% Bk1 & 1.92% Bk2. My understanding based on the Video above by Tony Callas usually the Short Term Fuel Trim is not worry about as it is suppose to be in the range of 0.75 to 1.25 (with 1.0 being ideal). The Long Term Fuel Trim is more important as it can range from -6.0% to +6.0% (with 0 being ideal). Anything within the range of -3.0% to +3.0% should not be worrisome.
I do need still to do a smoke test but doubt i have any leaks as everything is new...but we will see as mistakes will happen.
I swapped my Cam Adjuster Solenoid in Bank2 (Code P0021) and seems to have cleared the issue. I have not driven the car other than starting and idling and revving bit as the car is on jacks at the moment. I get no misfire codes or P0021 error codes....so it seems the Adjuster was at fault at lease partially. Car continues to run smoothly but I have big concerns about my Cam Timing that i could have possibly screwed up. Camshaft Deviation in Bk1 is 0.0 and -3.9688 in Bk 2. I am not clear if that means it is off by almost 4 degrees or how bad of a deviation it is as the car seems to run well. I need to test the Cam timing for Bk 1 & 2. Not even sure that i can do the test as it is so tight around the cam caps , especially Bk2.
Fuel Trim Mean Value(Short Term Fuel Trim) is 0.95 Bk1 & 0.996 Bk2 at idle and barely moves will accelerating. RKAT (Long Term Fuel Trim) is 0.234% Bk1 & 1.92% Bk2. My understanding based on the Video above by Tony Callas usually the Short Term Fuel Trim is not worry about as it is suppose to be in the range of 0.75 to 1.25 (with 1.0 being ideal). The Long Term Fuel Trim is more important as it can range from -6.0% to +6.0% (with 0 being ideal). Anything within the range of -3.0% to +3.0% should not be worrisome.
I do need still to do a smoke test but doubt i have any leaks as everything is new...but we will see as mistakes will happen.
I swapped my Cam Adjuster Solenoid in Bank2 (Code P0021) and seems to have cleared the issue. I have not driven the car other than starting and idling and revving bit as the car is on jacks at the moment. I get no misfire codes or P0021 error codes....so it seems the Adjuster was at fault at lease partially. Car continues to run smoothly but I have big concerns about my Cam Timing that i could have possibly screwed up. Camshaft Deviation in Bk1 is 0.0 and -3.9688 in Bk 2. I am not clear if that means it is off by almost 4 degrees or how bad of a deviation it is as the car seems to run well. I need to test the Cam timing for Bk 1 & 2. Not even sure that i can do the test as it is so tight around the cam caps , especially Bk2.
Good news that moving the variocam solenoid has made the error go away. If it comes back but on the other bank, you'll know what to change.
I don't quite understand why at idle your car can't hit the 1.0000 fuel trim values, but maybe that's not a big deal. With your numbers being below 1.000, it means the DME is pulling a little fuel from a slightly rich condition.
I think as long as the total deviation between the cams is within 5 degrees you're OK. Mine is 3.72
Good news that moving the variocam solenoid has made the error go away. If it comes back but on the other bank, you'll know what to change.
I don't quite understand why at idle your car can't hit the 1.0000 fuel trim values, but maybe that's not a big deal. With your numbers being below 1.000, it means the DME is pulling a little fuel from a slightly rich condition.
I think as long as the total deviation between the cams is within 5 degrees you're OK. Mine is 3.72
Interesting to see your Cam deviations....Maybe I am okay after all with roughly a -3.6 to -4.0 deviation on bank 2 when i am at zero on Bank 1.....maybe my Cam timing is okay. I was going to try and check the CAM timing but probably will now hold off unless i see error codes again. As i have replaced all the know culprits for variances in fuel trim (injectors, coils, plugs, MAF, O2 before Cat sensors) I will smoke test the engine as I actually believe i am running slightly too rich and maybe have a leak.
I did a hard reset (Drained all power from Car) when I replaced the Cam Solenoid and ended up with error codes for the PAS system. Weird but I had originally had error codes for the PAS but they where all cleared when I had a 4 wheel alignment at my Porsche dealer. I am wondering if I am getting the codes as the car is on jacks and needs to be on the road to reset.
I guess time to put the car back on the road and see what happens
Thank you for sharing your Durametric readings...helpful.
Interesting to see your Cam deviations....Maybe I am okay after all with roughly a -3.6 to -4.0 deviation on bank 2 when i am at zero on Bank 1.....maybe my Cam timing is okay. I was going to try and check the CAM timing but probably will now hold off unless i see error codes again. As i have replaced all the know culprits for variances in fuel trim (injectors, coils, plugs, MAF, O2 before Cat sensors) I will smoke test the engine as I actually believe i am running slightly too rich and maybe have a leak.
I did a hard reset (Drained all power from Car) when I replaced the Cam Solenoid and ended up with error codes for the PAS system. Weird but I had originally had error codes for the PAS but they where all cleared when I had a 4 wheel alignment at my Porsche dealer. I am wondering if I am getting the codes as the car is on jacks and needs to be on the road to reset.
I guess time to put the car back on the road and see what happens
Thank you for sharing your Durametric readings...helpful.
Hope the car is running well now! This info has been helpful as I'm trying to resolve a slightly rough idle and on throttle stutter so I'm going to check my fuel trims and see whats up.
I just had the car on stands with the battery off and had the same PAS error which went away after the first min of driving.
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Fuel Trim Acceptable Levels
