Thread: What are normal MAF CFM readings at WOT? 2000 CFM?!?

The car 05'GTP, 3.8" pulley, slightly larger than stock exhaust, 3" intake with K&N behind the headlight, Knock sensor issue resolved. Honeycomb found and reinstalled into the MAF.

Ok so I have had this issue for a while and I have the computer not letting me go into boost and getting 0068 and an O2 sensor low reading yesterday after doing a full throttle run. Well I have gotten this same issue before, I am thinking that the O2 reading low is just because it is dead rich so the chart drops to 0V out. I didn't get a good log last night because I forgot to reset the interval to 100ms instead of 5 seconds. I will try again tonight and then see if I can get the readings graphed into a spreadsheet and properly scaled so they are readable. Either that or I'll post them as different images.

Another odd thing is once the MIL was set the O2 maxed out lean reading .9V or so and pretty much stayed there unless I let off the gas then it dropped to 0V or dead rich. I cruised home and it was lean the whole time, but I was just at cruise and watched everything else. Timing stayed in the 30* range and but the normal spikey back and forth of the O2 stopped. When I was able I pulled over shut the car off in park, opened the door, closed the door and restarted the engine and everything went back to normal.

That brings me to my question. What is a normal WOT CFM reading at near 4K RPM? I have gotten as high as 2000 cfm. My car idles around 50 cfm and cruises at about 200 cfm and will go to about 650 or so at brisk acceleration at about 5-7" Hg. Normally I will see peaks of 1400 to 1600 CFM, of course the engine still lays over.

Now recently Scottydogg stated that my MAF may be bad and I trust his information, but I do not replace parts that I can see as working just to see if it's the problem unless I happen to have a spare, as that gets really expensive so I want to be absolutely positive that that is the problem.

Recently I logged the same data on a 14' Impala 3.6 and had similar readings but only had about 1400-1700 cfm max at full throttle through 1st and 2nd gears. It's a smaller engine but has a higher output of 305HP.

It takes a lot of air to make horsepower so I am waffling on whether or not my MAF readings are too high and that is why I am having the issues I am having.

If it is the MAF, what other cars can I pull from? Anything from 04+ or does it need to be an 05'?

Jeff

No there is only Kgs/Sec or CFM. Im using Torque Pro with the BAFX adapter. I knew the output was in Hz, but I didn't see an option for picking it.

Jeff

Your chart shows an output of .916V and 11.1AFR, which is rich isn't it?

Well that would explain the engine laying over, but now I have no idea why it's going lean, but do know why it's pulling timing and commanding the bypass open. Fuel pressure is a steady 65psi all day everyday at the rail. I used my fuel pressure gauge and after checking it I removed the gauge and installed an oil pressure sender and gauge and drove around for 3 days like that. May not have been the best solution but it got the information I needed. After that test I used the signal wire that was going to the gauge and attached a micro switch under the bypass grounded one end then connected my Fluke to measure continuity so it would beep when closed. it would start to beep then I would get to about 5psi and it would open and boost would drop to 0. You would think that if the ECM saw that much air it would go dead rich. Should I log pulse width and cylinder balance?



Jeff

My LTFT and STFT are all wacked too.

-3.9 to -18.8 and 14.8 to -19.5 respectively.

It did it with the 3.4 as well but I saw more times where it would go into boost. I am going to buy a credit for HP tuners my friend has a copy and is a tuning buddy from my SC days.

This is a rolling full throttle with itching over then to a cruise.