Question on MAF Sensor

[VXtreme]

Does anyone know what the parameters of our MAF sensor? Does it use frequency or voltage feedback to the ECU? What are the frequecency or voltage ranges, minimum and maximum values?

The reason for the question is that I want to install a Split Second Frequency or Voltage clamp between the MAF and the ECU. I am having trouble tripping the CEL and getting the a problem code for the MAF. Apparently when I am under boost for a long period of time, the MAF is sensing more air coming into the engine then it can correct for. It trips the CEL light and then after about 20 - 30 minutes of normal driving, it resets itself. The problem is that when the CEL light is on, the engine will run erratically until it resets. From what I have read on the Split Second clamps, it should solve this problem. I just need to know what the spe'cs are for the MAF so they can progam the clamp for my specifications. You can go to this site and check out Split Second products: www.splitsec.com . Thanks for any help I can get. VXtreme

[Hotsauce]

Its a GM hotwire sensor.

No one else is having this problem, how much boost are you running?

John C.

[VXtreme]

About 6 PSI. I have spoken to John at Alpine Developments and he indicated that he has had similiar problems with the S/C that are running 5 PSI or higher. He also felt the frequency clamp would resolve the problem. The problem is that I live in Park City and have to drive up a steep 10 mile grade each day from Salt Lake City. On the dirve up, the S/C is under full boost for quite awhile and the MAF reads a higher them normal flow rate through it. The OBDII scan tool indicated that the fault code is on the high frequency parameter which is due to higher then normal flow rate going through the MAF. I spoke to Split Second and they feel confident that the frequency clamp will resolve the problem. They just needed to know what the frequency range is and whether it was registering a fault code on the low or high frequency signal to the ECU. I'll keep you posted on how the fix goes.

[Cyrk]

VXtreme about 6psi... how are you running that? Did you get a new pulley?
Good luck on the fix.

[VXtreme]

Yea, forgot to mention I had my 5PSI pulley machined down a little smaller then it was. My Autometer Boost guage shows a pretty constant 6 PSI of boost under full throttle now. It does run like hell when it is getting full boost, even at this altitude, but I have to fix the code problem. I'll let you know how it all works out.

[deton8r]

I'm having MAF issues at WOT with the Alpine s/c on my Axiom and have also talked to John at Alpine about it. I think the issue is compounded on the Axiom due to the 'drive by wire'. Another Axiom owner is getting the same OBDII codes I am. He tried the Split Second voltage clamp with no success. I considered the MAF Translator Plus but it could be an expensive mistake. I'm probably going to resort to a UNI-Chip solution which John said would definitely fix my problem and free up several ponies. I'm also watching the 0-60 times post regarding the Motec ECU to see if that's another option.

My s/c setup was great until I ditched the stock airbox/restrictive intake and went with a straight tube with a K&N cone filter. Initially I had the MAF screen removed but I still get the codes with the screen back on but things are slightly better. I have since learned to keep my foot out of it because when I hit the limit, the Axiom goes into Reduced Power Mode (limp) mode.

What codes are you getting? I get the following:

P1514 - TAC System MAF performance calc airflow vs. RPM vs. TPS

P1125 - Accelerator Pedal Position System

P1295 - ??? still researching this one.

[VXtreme]

P0101 MAF System Performance is the code I get. I did some research with my buddy a Isuzu master mechanic at the local Isuzu dealer. We looked up all the parameters on the MAF sensor. My MAF is supposed to register between 3 - 6 g/s flow rate at idle, which it does. From idle to shifting from 1st to 2nd it should register from 3 - 6 g/s at idle to as much as 100 or greater before making the shift from 1st to 2nd. Under full throttle, it should normally draw about 40g/s flow rate through the MAF. I took his Tech II tool home with me and monitored the flow rates on my drive up the canyon. Under full boost (6 PSI) and near redline my MAF is registering as much as 129 g/s of flow rate. The average flow rate going up the canyon at about 4 psi of boost is between 70 and 79 g/s. The ECU will trigger a code if it detects a flow rate greater then 40 g/s for a total of 50 percent of the last 200 samples monitored. A sample is taken every cylinder event. So in other words, going up the canyon with a flow rate of 70 - 79 g/s on average for a sustained amount of time will trigger the code. I spoke at great length with a guy named Mike at Split Second. After describing what the problems are, he feels very positive that he can program a frequency clamp to resolve the problems I am having. I am faxing him all the tech data on my MAF so any questions he may have will be in the tech sheets. He will set the clamp for a maximum frequency of 9000 Hz which is the upper limit of the MAF under full throttle. Hopefully it will work and the problem will finally be put to rest. I'll keep you posted. One other thing I just noticed is that you indicated your friend tried a Split Second voltage clamp. I don't know on the Axiiom, but on the Vehicross the signal sent back to the ECU is a frequency not a voltage. If your MAF is the same, you would need to have a frequency clamp not a voltage clamp.

[deton8r]

The Axiom has the same MAF as the VX which is actually the same one in the '95-96 Impala SS. The other Axiom owner used the Split Second VC-2 Hard Voltage Clamp - unsuccessfully. Are you going to try the Split Second PSC1-003 Programmable Signal Calibrator? With MAP? Let me know how it goes.

Good Luck

[VXtreme]

No.....I'm going to use the FC1 Split Second Frequency clamp. As I said if your MAF is the same as mine, the MAF does not send a voltage signal to the ECU, but rather a frequency signal to the ECU. Therefore the VC-2 probably did not work as the MAF used frequency rather then voltage to send it's signal to the ECU. By the way, I purchased a Granatelli MAF with cold air tuning for my VX. As you said it is SUPPOSED to be the same as a '95 -'96 Impala SS, which is what the MAF I received said, but the VX would not run at all using that MAF. We reset the ECU several times, tried several things and still could not get it to run correctly. The VX would wind up through 1st gear then after shifting to 2nd, the VX would sputter badly and nearly die. I spoke to Granatelli and their tech service rep said that the Granatelli MAF for the '95 - '96 Impala would not work on the VX. So don't waste your money ($350) on the Granatelli MAF. I'll let you know how the FC1 works on the MAF. I did remove the screen on my stock MAF and cleaned the sensing wires with an electronic cleaning solvent. So far no CEL, but I know it's just a matter of time. I really think the FC1 should resolve the problem.