MAF Sensor Problems after replacement

[Travis Ferreira]

Hey everyone,

So I have my 00 Camaro 3800 I just got a couple months ago at auction. The car is beautiful. Its been kept pretty well maintained, except for under the hood.

I’ve recently gone through the car to replace things that could eventually cause a breakdown. Since I’ve had the car, its had a severe performance issue where it runs awesome when its cold and as soon as it reaches operating temperature, I lose a lot of power. Before anyone says my head gasket is blown, I already confirmed that its not.. Because of this issue, I’ve replaced, the fuel pump, fuel filter, air filter, plugs, wires, and coils. Still had a severe lack of power after it warmed up. It even vibrates intermittently at idle. So next, I suspected the MAF sensor. To test, I just unplugged it and drove it. Obviously the engine light came on after a while, but i didnt lose any power at all. At this point I suspected the MAF sensor was bad or dirty, rather than cleaning it, I just sprung for a new one. After all this and replacing the sensor, I still get poor performance when its plugged in. My efforts here have hit a wall. Does anyone here have any ideas short of replacing the ECU?

Thanks!

Travis

Topic

[college man]

You could have a bad maf even new or a wiring signal problem.
What are your fuel trims doing and the MAF in live data?

[Travis Ferreira]

I’m going to run the test tonight and see what the readings are. I’m borrowing a friends scanner as mine does not do live data. He also told me that chances are, if I’ve replaced everything and it still runs poorly, that I could have a damaged or destroyed cat. I’ll get back with an update probably tomorrow.

[Dejan]

If you unplug the maf do you still loose power? Did you buy a aftermarket or an original sensor? Scan the car for fault codes. We can then go from here.

[Travis Ferreira]

When I unplug the MAF I get all my power back, I replaced the MAF twice now. first one was a basic duralast, and the second was delco. both made the car run poorly when plugged in. There were no codes stored in the ECU but the lack of power is definitely there. It also surges badly under WOT.

[Travis Ferreira]

Ok these are some readings I got from my scanner, One is at idle, and another is with a load on the motor at around 3700 RPM

This is with a SECOND brand new Delco MAF sensor.

See if you guys can make sense of this.

Thanks again!

___

Numbers of DTCs 0
Fuel system 1 statusCL
Fuel System 2 statusCL
Calculated Load Value(%)34.5
Engine Coolant Temperature(¡£F)213
Short Term Fuel Trim -Bank 1(%)0.0
Long Term Fuel Trim – Bank 1(%)3.9
Short Term Fuel Trim -Bank 2(%)7.8
Long Term Fuel Trim – Bank 2(%)4.7
Intake Manifold Absolute Pressure(psi)13.2
Engine RPM(rpm) 3759
Vehicle Speed Sensor(mph)26
Ignition Timing Advanece for #1 Cylinder(¡£)23.0
Intake Air Temperature(¡£F)116
Air Flow Rate from Mass Air Flow Sensor(lb/s)0.15
Absolute Throttle Position(%)45.5
Location of Oxygen SensorsB1S12–B2S1—
Oxygen Sensor Output Voltage Bank 1-Sensor 1(V)0.855
Short Term Fuel Trim Bank 1-Sensor 1(%)0.0
Oxygen Sensor Output Voltage Bank 1-Sensor 2(V)0.715
Short Term Fuel Trim Bank 1-Sensor 2(%)N/A
Oxygen Sensor Output Voltage Bank 2-Sensor 1(V)0.045
Short Term Fuel Trim Bank 2-Sensor 1(%)-6.3
OBD requirements to which vehicle is designedOBDII

__

Numbers of DTCs 0
Fuel system 1 statusCL
Fuel System 2 statusCL
Calculated Load Value(%)2.7
Engine Coolant Temperature(¡£F)212
Short Term Fuel Trim -Bank 1(%)0.0
Long Term Fuel Trim – Bank 1(%)-1.6
Short Term Fuel Trim -Bank 2(%)-1.6
Long Term Fuel Trim – Bank 2(%)3.1
Intake Manifold Absolute Pressure(psi)5.2
Engine RPM(rpm) 735
Vehicle Speed Sensor(mph)0
Ignition Timing Advanece for #1 Cylinder(¡£)21.5
Intake Air Temperature(¡£F)122
Air Flow Rate from Mass Air Flow Sensor(lb/s)0.01
Absolute Throttle Position(%)3.1
Location of Oxygen SensorsB1S12–B2S1—
Oxygen Sensor Output Voltage Bank 1-Sensor 1(V)0.755
Short Term Fuel Trim Bank 1-Sensor 1(%)0.0
Oxygen Sensor Output Voltage Bank 1-Sensor 2(V)0.720
Short Term Fuel Trim Bank 1-Sensor 2(%)N/A
Oxygen Sensor Output Voltage Bank 2-Sensor 1(V)0.655
Short Term Fuel Trim Bank 2-Sensor 1(%)-0.8
OBD requirements to which vehicle is designedOBDII

[Dejan]

i still think it’s a maf problem. Try comparing the results with your scanner of the old original and the new aftermarket. Because if it is like BMW they only work with OEM sensors.

[Tray]

Your airflow Rate looks low to me on both scan data pids. On both my GM vehicls They’re at .58 (lbs/m) at idle and increases with rpm. You may have a wire problem or excessive back pressure.

[Travis Ferreira]

My scanner for some reason transposes the reading from the MAF from LBS to Grams, when I also show the trim levels on the screen. I did a drive this morning and the MAF reported that I was getting 45.52 Grams at wide open throttle. But its not swapping over to open loop fuel, or if it does, it jumps between OL and CL while still at wide open throttle.

I’m not too convinced that there is too much back pressure, because like before, when I disconnect the MAF and drive it like that, I get all my power back and it runs pretty much normal, with an intermittent stumble from a stopped position (to be expected). I did trace the for the MAF wires back all the way to the ECM and they looked fine. I checked the voltage continuity and the ground is good as well as the 5V input.

What about the o2 sensors? could they sending false data to the ECU? I mean it doesnt richen the fuel up when its supposed to at WOT.

[Tray]

If you want to test the O2 sensors, pull the brake booster hose off when the car is in closed loop. The voltage should drop below .450MV on both O2 sensors B1 S1 and B2 S1. You can also test them by spraying propane,carb cleaner, or brake cleaner down the hose to see if they go above .800MV’

Try this after you’ve checked the O2’s. With the car warmed up, find a safe place and maybe have a buddy with you for safety reasons, floor it and both sensor voltages should read above 800mv before you hit second gear on the scan tool.

[Travis Ferreira]

So I tried this, and the sensors didnt budge. They are constantly fluctuating between 0.01 and 0.80 within split miliseconds of the each fluctuating. This occurs at idle and while driving. In looking at the line graph the scanner displays, the line is not a smooth flowing line between 0.01 and 0.80 . Its all over the place and very erratic, and when it goes to 0.80 at idle, the engine surges badly.. This is with both B1-S1 and B2-S1. However B2-S2 (behind the conerter) reads a normal flow and voltage increases with higher RPMs

[Tray]

Is the surging occurring in park at WOT or in drive at WOT?

When you pulled the brake booster hose the 02’s should have went lean (well under .450mv) and the STFT should have went way positive until it could bring the 02 back into stoic.

[Travis Ferreira]

The surging occurs only at idle, Its more of a strong vibration than a surge. RPM stay steady at 780 at idle. When in drive, and attempting to move from a stopped position. the car has no power to really get out of its own way. The only way to get going is to almost floor it. When I have the accelerator at about 85 percent, then it feels like something opens up and the car will get a surge of power, but only for a few seconds. just before it shifts into the next gear, the engine loses power at about 4500 RPM at WOT, and begins to stall, unless I back off the accelerator.

When I pulled the brake booster hose and sprayed carb cleaner in, the readings did not change. it just showed a very erratic reading between 0.01 volts and 0.80 volts. About every millisecond it would go to 0.8. at idle. I tested a friends Firebird with the same scanner, same engine, and his sensors were reading a steady flow. Would still fluctuate, but not nearly as erratic. It was a very smooth reading and would increase with more engine speed.

[Tray]

Those symptoms you described sound just like…….

1. Faulty/Dirty MAF- Since you’ve already changed the maf sensor do a wire check with a multimeter. Set the dvom to volts DC, unplug the maf, turn KOEO or KOER and test the pink wire with the red test lead and the black/white wire with the black test lead. You should absolutely read 12 volts not 5.

2. Back Pressure/ Exhaust restriction- Unlikeyly since the car operates normal with maf unplugged.

3. Low Fuel Pressure/ Fault fuel pressure regulator

4. Partially stuck open EGR valve. This doesn’t always throw a CEL and can be checked by removing the valve and visually inspecting the pintle.

Also, if your 02’s are being unresponsive to your attempts to make them lean/rich they should be changed. They should be fairly cheap on rockauto.com

[Travis Ferreira]

Replaced all O2’s, They read normally now. Replaced EGR and EGR Gasket, Fuel Regulator, Fuel Pump, Plugs, Wires, Coils, MAF sensor, MAP sensor, No leaks anywhere as far as vacuum is concerned. I’m at my wits end. Beginning to think its a mechanical issue with the motor. It started to knock and pink under heavy acceleration, Still has absolutely no power and is now running badly when both hot AND cold..

Possibly time for a new engine, Didn’t want to have to go that route as I dont have the facilities needed to undertake such a task.

[Wes]

Have you cleaned the throttle body? To me it sounds like a vacuum leak somewhere.

[Author]

Replies