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I posted a while back in Bill's electrical thread, and I'll post that exchange below. Here's the general synopsis.
It's my son's '98. (Used to be Mark C5's car, if anyone remembers Mark :angel: )
It has roughly 130k miles.
Being a '98, it has the 3-wire MAF and a separate IAT sensor.
A couple years or so ago, I was driving the car when Liz owned it. Accelerating moderately (not floored), and around 55mph, it died. Shut off. Quit running. Coast into the nearest driveway kind of died.
Can’t recall the code that it threw back then, but I ended up disconnecting the IAT, and it ran well enough to get home. Kevin73 put in a new IAT, it seemed to run ok for a while and then died again. Seemed ok with the IAT disconnected. Of course, this points to not being ok in MAF, but being ok in speed density.
Fast forward, the car ended up in my son's hands. The problems have persisted. Driving along and it's f'n dead with a P0101. Pulling the IAT (going to speed density) makes it generally happy, but even in those conditions, the car will occasionally cough. Don’t know how else to put it. It’s not a misfire, not a backfire, it’s a cough as if the ignition was shut off and immediately restarted. Like one “pbth” from Speed Buggy and then it keeps going. Once in a while it’s sustained for maybe a second before it catches its breath and keeps going.
It had an aftermarket intake with oiled filters. Seemed easy enough. The oiled filters fouled the MAF as they usually do, right? Cleaned and then replaced the MAF with NO CHANGE. It was also throwing a P0113 IAT code at some point so I replaced the wiring harness at the IAT, and the wiring all the way back to the ECM to rule out an intermittent wiring issue. NO CHANGE.
Fast forward and I’m taking data with my cheap bluetooth scanner and Torque PRO.
Steady speed @ 50-55 mph and suddenly the MAF data suddenly spikes, as does the indicated throttle position. Then they fall as the car dies, of course. Interestingly enough, you can clear the code(s) while driving, and it starts back up until it gets mad again, which could be mere seconds later. Until it dies again, the data looks completely normal.
Throttle and MAF spikes seem weird, since the MAF and the throttle signals should be independent, in different modules that are generally unrelated and only communicate through CAN
The data rate on my bluetooth scanner is too slow to see what’s leading/trailing. Is the throttle opening? Is there a coincidence? Can't quite tell, sooooo.....
Since I have a 2001, it’s simple to do a part swap. Swapped the throttle body and TAC between the cars cars. NO CHANGE (though I do notice a different throttle response from the polished throttle body that was in his car when it went into mine).
So the car now has:
New MAF
New IAT
Known-good throttle body
Known-good TAC module
I checked every ground in the ECM and didn't find any of them with high resistance.
I pulled apart the ground junction block near the driver's headlamp (because it was easy) and when I popped it open, it looks brand new. Way better than the "after" photos of people who have cleaned them up after being corroded.
So at this point, I'm stumped on where to head next. Thankfully it's cold and crappy in Michigan right now, but if summer comes on a weekend this year, it'd be nice to be able to go for a drive.
Here's the previous exchange in Bill's electrical thread to refresh some memories:
Originally Posted by ddecart
Hey Bill (or anyone else)
Do you have anything showing the splice pack locations? Specifically looking for the common link between the MAF and the TAC module. Having some funky issues with the car ('98 coupe) shutting off while driving and throwing a MAF code, even though the MAF is new. OBD data shows a spike in the MAF signal when this happens and it's also showing a spike in the throttle position data. The only link between these two that I know of is the ground side. Cleaning the lot of them will be on the list, but finding these specific points is first up.
Thanks!
Dave
Originally Posted by C5 Diag
What MAF DTC are you seeing ???....the MAF, TAC Module, and PCM share a common ground which is above the starter (G106). What is exactly "spiking"... MAF and TPS voltage ?????
Originally Posted by ddecart
P0101
The reported airflow will suddenly jump to 4-5x the actual value. Not sure what full scale is, but it must be close. At the same time, the indicated throttle position spiked to near 100% as well. Then the car dies.
MAF is brand new since the issue started, throttle body and TAC were swapped with my '01. Not much wiring in common between the MAF and TAC.
Originally Posted by C5 Diag
With the P0101 I'd look at the MAF voltage unplugged...12 volts on the PINK, 5 volts on the YELLOW (signal) and the black/white is ground...I'd also look at the MAP sensor and with KOEO you should see around 14.9 at sea level. You can check both TPS signal voltages ( dark blue and pink wires) with KOEO at idle and WOT...report the 4 voltages you are seeing !!
Originally Posted by ddecart
Been travelling, so not much time to fiddle around with this thing.
Driving at 55mph, MAF (via scanner on the ALDL) is 25-30 g/cm3. Throttle position ~17%, Engine load ~17%, Timing advance ~41deg. Manifold Pressure=3.2psi. Everything looks fine.
Then...
MAF jumps to about 98g/cm3, Throttle Position then jumps to 65, then 86%. MAP also jumps to 6.6psi. Engine load jumps to 58%.
As this happens, the engine sputters and dies.
The high values all last for about 6 seconds (which was probably the amount of time it took to reset the code, at which time the engine refired).
Data rates suck, so it's impossible to tell for certain which signal is leading/trailing the others, if at all.
So there are 2 coincidental spikes (MAF & ThrottlePos) which are completely disconnected to each other except through the grounds. Thus the search for the splice packs and ground location. G106 is the battery negative terminal, so there has to be a splice somewhere nearby.
Originally Posted by Bill Curlee
Unplug the MAF and see if the problem persist.. What year C5 do you have??
Originally Posted by ddecart
It's a '98
Haven't unplugged the MAF, but unplugging the IAT will make it run better, but it will occasionally "cough". Just enough of a stumble to jerk the car before it recovers. On occasion, it'll be severe enough and long enough to lose considerable speed. Need to dig up the data in that condition....
Originally Posted by Bill Curlee
Get or obtain a scanner that can read LIVE SENSOR DATA. See what each sensor reads with the KEY ON ENGINE OFF (KOEO) and see what they read with the engine running. Example- That IAT Sensor should read ambient air temp at KOEO and should read close to outside ambient when air is flowing through the intake ducting. The temp reading will rise some due to engine /under hood temps but it should be close to outside temp. Same with the coolant temp sensor. Should be outside /under hood temp at KOEO cold engine and rise as engine heats up.to normal operating temp.
Bill
Originally Posted by ddecart
I can read live, it's just a slow update rate. No issues with either the IAT or ECT. IAT goes to -40 when unplugged, as it should.
Originally Posted by Bill Curlee
C heck the O2 sensor heater voltage and current.. Make sure its in spec.
BC
Originally Posted by ddecart
I certainly can do so. I'm not seeing an obvious link. What are you thinking?
*edit* ran both cars at idle from a cold start. Roughly 50 degrees outside.
On the '98, the sensor cycles between ~150mV to ~800mV.
My '01 does nearly the same, except the low-side is just under 100mV.
Originally Posted by ddecart
Should the car be able to idle with the MAF disconnected? It won't. Separate IAT and MAF on the '98, so it's only the MAF being disconnected.
Did you remove the MAF ground G106 (above the starter) and clean it and reinstall ??...you don’t check grounds using resistance !!...either PCM or body grounds...you have to load the ground circuit to check properly...I ALWAYS use a headlight bulb connected to battery positive and the black lead goes to the ground you are checking...if the headlight bulb is not bright your ground circuit is bad !!...this is the best way.
Did you remove the MAF ground G106 (above the starter) and clean it and reinstall ??...you don’t check grounds using resistance !!...either PCM or body grounds...you have to load the ground circuit to check properly...I ALWAYS use a headlight bulb connected to battery positive and the black lead goes to the ground you are checking...if the headlight bulb is not bright your ground circuit is bad !!...this is the best way.
That's a bolt into the block? It's listed as a battery negative in a lot of references. Haven't checked a block connection... yet.
Yes !!...it’s a block ground...there are a few wires connected there...I removed, wire brushed, and reinstalled mine last spring as part of my annual “spring cleaning”...all other block grounds cleaned too !!
Yes !!...it’s a block ground...there are a few wires connected there...I removed, wire brushed, and reinstalled mine last spring as part of my annual “spring cleaning”...all other block grounds cleaned too !!
I'll clean it this weekend. Might be able to check the current during a lamp test before and after, too.
Seeing that its a 98, I will pose the possibility of an IGNITION SWITCH problem.
When the car dies or is having issues, find the fuses for the MAF, PCM, BCM &TAC and see if they have proper and full battery voltage under load on each fuse. With the key ON, read the two test points on the top of each FUSE to a good ground. You should see full battery voltage on ALL of the Ignition Switch power fuses for both test points.
I would also pop out the fuses and make sure the blades are not corroded/burnt or loose in the fuse block slot.
If the ignition switch contacts are faulty/damaged, they can deliver under voltage at times and the modules will have a fit and or shutdown until the voltage returns to an acceptable voltage.
Do you ever see U series DTCs or Under Voltage DTCs for the other modules? Especially the Door Control Modules!
Seeing that its a 98, I will pose the possibility of an IGNITION SWITCH problem.
When the car dies or is having issues, find the fuses for the MAF, PCM, BCM &TAC and see if they have proper and full battery voltage under load on each fuse. With the key ON, read the two test points on the top of each FUSE to a good ground. You should see full battery voltage on ALL of the Ignition Switch power fuses for both test points.
I would also pop out the fuses and make sure the blades are not corroded/burnt or loose in the fuse block slot.
If the ignition switch contacts are faulty/damaged, they can deliver under voltage at times and the modules will have a fit and or shutdown until the voltage returns to an acceptable voltage.
Do you ever see U series DTCs or Under Voltage DTCs for the other modules? Especially the Door Control Modules!
BC
Good question on the other modules, Bill. I'll check.
But.... I did replace the ignition switch some time ago with an AC Delco replacement. Forgot to mention that.
When the problem does happen and it does, clearing the codes is sufficient for it to start running again.... until it happens again, which might be <10 seconds later, or possibly longer.
Potential clues: (?)
It has never had a problem at idle.
The problem almost always occurs at speeds over ~45 mph
To get to a main road from home, I have almost 3 miles to drive. 1/2 mile down a dirt road at 15mph or less, then almost 2.5 miles of 25mph. It's died on a part-throttle run-up to 55mph at that point.
Engine temp doesn't seem to be a correlating factor, and it'll idle fine indefinitely after I get home.
After it dies, it will not start until the code is cleared.
May also be a failing crank sensor shutting the car down...unfortunately you’ll need a scope to check the signal wire while driving to see if the signal is dropping out !!...did you check the sensor ground if you are still throwing the P0101 ??
May also be a failing crank sensor shutting the car down...unfortunately you’ll need a scope to check the signal wire while driving to see if the signal is dropping out !!...did you check the sensor ground if you are still throwing the P0101 ??
That should pretty reliably return a crank sensor code, not a MAF code though, dontcha think?
That should pretty reliably return a crank sensor code, not a MAF code though, dontcha think?
Helping a member about 1 1/2 years ago that was having starting issues...no DTC’s current or history but we had actually figured out he had a shorted cam sensor that actually caused the crank sensor not to operate correctly so go figure !!...and you must remember if you have an O2 sensor DTC for instance doesn’t mean the O2 sensor needs replacement...a lean running engine can sometimes set an O2 DTC ...these engine computers are funny birds !!...have you checked that MAF ground ??...not visually but actually load test it ???
You certainly have a tough problem. What code is set when the car won't start. Just having a P0101 code stored won't cause the car to not start. Are you using the DIC to get the codes? There would have to be a bad or out of normal range sensor output or an improper input to the PCM to cause the car not to start. P0101 will be set if the MAF is not providing the airflow value expected for a given operating condition.
I had a car that would run for about 15 minutes and then it would die. It turned out to be a sensor that was shorting out the +5 volt bus for other sensors like the TPS, MAF and accelerator pedal position sensor after it warmed up. I would get a scanner that can monitor all of the individual signals related to the engine speed control. I would expect that if you compare the sensor data with the key on and no failures with the data when the car stalls you may see something. That's how I found my problem. The fly by wire throttle control system uses redundant signals and the engine management software may not let the engine run or start if the signals are not what's expected.
Any unmetered air flow can cause the code to set as well as a bunch of other issues including a bad PCM. Codes don't tell you what to replace they tell you where to start looking for the problem. Here are a few aids from the diagnostic procedure that is listed for code P0101.
Diagnostic Aids
Important: Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM\TAC modules. If you cannot find any problems with the ignition feed circuit to the component, inspect the IGN
mini relay for proper operation. Probe both sides of the ENG IGN 1 fuse with a test lamp connected to ground in order to determine if the IGN mini relay is supplying the power. Refer to Ignition Relay Diagnosis for further diagnosis of the IGN mini relay.
• The following may cause an intermittent:
- Mis-routed harness
- Rubbed through wire insulation
- Broken wire inside the insulation
Any un-metered air may cause this DTC to set. Check for the following:
• An engine vacuum leak
• The PCV system for vacuum leaks
• An incorrect PCV valve
• The engine oil dip stick not fully seated
Specific Troubleshooting procedures for a 1998 P0101 MAF Code;
Circuit Description
The Mass Air Flow (MAF) sensor measures the amount of air ingested by the engine. The direct measurement of the air entering the engine is more accurate than calculating the airflow from the MAP, the IAT and the engine speed (speed/density). The MAF sensor has a battery feed, ground, and a signal circuit.
The MAF sensor used on this engine is a hot wire type. This engine uses the MAF sensor to measure air flow rate. The MAF output frequency is a function of the power required to keep the air flow sensing elements (hot wires) at a fixed temperature above the ambient temperature. Air flowing through the sensor cools the sensing elements. The amount of cooling is proportional to the amount of air flow. The MAF sensor requires a greater amount of current in order to maintain the hot wires at a constant temperature as the air flow increases. The MAF sensor converts the changes in current draw to a frequency signal read by the PCM. The PCM calculates the air flow (grams per second) based on this signal.
The PCM monitors the MAF sensor frequency. The PCM can determine if the sensor is stuck low, stuck high, not providing the airflow value expected for a given operating condition, or that the signal appears to be stuck based on a lack of signal variation expected during the normal operation. This diagnostic checks the range/performance of the MAF sensor. The MAF system performance or rationality diagnostic uses the MAP, the IAT, and the engine speed to calculate an expected airflow rate. The PCM then compares the rate to the actual measured airflow from the MAF sensor. The PCM only compares the actual MAF value and the calculated value during conditions where the values are likely to match. This DTC sets if the actual MAF reading is not within a predetermined range of the calculated reading.
Conditions for Running the DTC
• DTCs P0102, P0103, P0107, P0108, P1120, P1220, P1221 not set.
• The engine speed is greater than 50 RPM but less than 2800 RPM.
• The TP sensor angle is less than 50% when engine vacuum (BARO-MAP) is greater than 65 kPa.
• The change in TP sensor angle is less than 3%.
• The ignition voltage is greater than 10.0 volts but less than 16.0 volts.
• All above conditions stable for 2 seconds
Conditions for Setting the DTC
• The MAF frequency is 50% greater than the speed density calculation.
• All conditions met for 10.0 seconds.
Action Taken When the DTC Sets
• The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
• The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure records.
• The PCM utilizes speed density (RPM, MAP, IAT) for fuel management.
Conditions for Clearing the MIL/DTC
• The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
• A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
• Use a scan tool in order to clear the MIL and the DTC.
Diagnostic Aids
Important: Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM\TAC modules.
If you cannot find any problems with the ignition feed circuit to the component, inspect the IGN mini relay for proper operation. Probe both sides of the ENG IGN 1 fuse with a test lamp connected to ground in order to determine if the IGN mini relay is suppling the power. Refer to Ignition Relay Diagnosis for further diagnosis of the IGN mini relay.
• The following may cause an intermittent:
- Mis-routed harness
- Rubbed through wire insulation
- Broken wire inside the insulation
• For an intermittent, refer to Symptoms .
• An engine vacuum leak
• The PCV system for vacuum leaks
• An incorrect PCV valve
• The engine oil dip stick not fully seated
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. The MAF system performance or rationality diagnostic uses the MAP sensor signal along with other inputs in order to calculate an expected airflow rate. The PCM then compares the expected flow rate to the actual measured airflow from the MAF sensor. The first few steps of this table verify that the MAP sensor is working properly. Correct any MAP sensor DTCs first. Refer to DTC P0107 Manifold Absolute Pressure (MAP) Sensor Circuit Low Voltage if the MAP sensor voltage is less than 0.8 volts. Refer to DTC P0108 Manifold Absolute Pressure (MAP) Sensor Circuit High Voltage if the MAP sensor voltage is greater than 4.0 volts.
3. The sensor is difficult to remove. Twist the sensor towards the front of the vehicle and lift upward in order to remove the MAP sensor.
6. Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed. For any test that requires probing the PCM or component harness connectors, use the Connector Test Adapter Kit J 35616 . Using this kit prevents any damage to the harness connector terminals.
7. Any un-metered air causes this DTC to set. Check the PCV system for vacuum leaks. Also inspect the dip stick for being pulled out. Check the oil fill cap for being loose.
8. This step verifies the signal circuit from the MAF sensor electrical connector to the PCM.
9. This step verifies whether a ground and B+ circuit is available.
10. This step checks the signal circuit for an open.
11. This step checks the signal circuit for a short to B+
(OBD) System Check?
--
Go to Step 2
Powertrain On Board Diagnostic (OBD) System Check
2
If any MAP sensor DTCs are set, refer to the applicable DTC before proceeding.
1. Idle the engine. 2. Monitor the MAP sensor voltage parameter using a scan tool.
Is the MAP sensor voltage outside of the specified range?
0.84 volts
Go to DTC P0107 Manifold Absolute Pressure (MAP) Sensor Circuit Low Voltage or DTC P0108 Manifold Absolute Pressure (MAP) Sensor Circuit High Voltage Go to Step 3
3
1. Turn OFF the ignition. 2. Remove the MAP sensor from the intake manifold leaving the electrical harness connected. 3. Connect a hand operated vacuum pump to the MAP sensor. 4. Turn ON the ignition leaving the engine OFF. 5. Observe or record the MAP sensor display while slowly applying vacuum up to 20 inches Hg as indicated on the pump gauge. Each 1 inch of vacuum applied should result in a 3 to 4 kPa drop in the MAP sensor value on the scan tool and the value should change smoothly with each increase in vacuum.
Did the MAP sensor value change smoothly through the entire range of the test without any erratic readings?
--
Go to Step 4
Go to Step 19
4
Apply 20 inches Hg vacuum to the MAP sensor.
Is the MAP sensor reading on the scan tool the same or less than the specified value?
34 kPa
Go to Step 5
Go to Step 19
5
Disconnect the vacuum source from the MAP sensor.
Does the MAP sensor reading return to the original value that was observed is step 3?
--
Go to Step 6
Go to Step 19
1. Turn ON the ignition leaving the engine OFF. 2. Review the Freeze Frame and/or Failure Records data for this DTC and observe the parameters. 3. Turn OFF the ignition for 15 seconds.
. Install the MAP sensor. 5. Start the engine. 6. Operate the vehicle within the conditions required for this diagnostic to run, and as close to the conditions recorded in the Freeze Frame/Failure Records as possible. Special operating conditions that you need to meet before the PCM will run this diagnostic, where applicable, are listed in Conditions for Running the DTC. 7. Select the Diagnostic Trouble Code (DTC) option, the Specific DTC option, then enter the DTC number using the scan tool.
Does the scan tool indicate that this diagnostic failed this ignition?
--
Go to Step 7
Go to Diagnostic Aids
7
1. Check for the following conditions:
2. If you find a condition, repair as necessary.
Did you find and correct the condition?
• Objects blocking the MAF sensor inlet screen
• Intake manifold vacuum leaks
• Vacuum leaks at the throttle body
• Crankcase ventilation valve faulty, missing, or incorrectly installed
--
Go to Step 21 Go to Step 8
8
1. Turn OFF the ignition. 2. Disconnect the MAF sensor connector. 3. Turn ON the ignition leaving the engine OFF. 4. Measure the voltage between the MAF sensor signal circuit and the battery ground using the DMM J 39200 .
Is the voltage near the specified value?
5.0V
Go to Step 9
Go to Step 10
9
Connect a test lamp J 35616-200 between the MAF sensor ignition feed and the ground circuit at the MAF sensor harness connector.
Is the test lamp illuminated?
--
Go to Step 13
Go to Step 12
10
Is the voltage less than the specified value?
4.5V
Go to Step 14
Go to Step 11
1. Turn OFF the ignition. 2. Disconnect the PCM connector located on the opposite side of the manufacturer's logo. Refer to Powertrain Control Module/Throttle
. Turn ON the ignition leaving the engine OFF. 4. Measure the voltage between the MAF sensor signal circuit and ground.
Does the voltage measure near the specified value?
0.0V
Go to Step 20
Go to Step 17
12
Connect a test lamp J 35616-200 between the MAF sensor ignition feed circuit and the battery ground.
Is the test lamp illuminated?
--
Go to Step 15
Go to Step 16
13
1. Check for a poor connection at the MAF sensor. 2. If you find a poor connection, replace the faulty terminal(s). Refer to Body and Accessories/Wiring Systems.
Did you find a poor connection?
--
Go to Step 21
Go to Step 18
14
1. Check the MAF sensor signal circuit between the PCM and the MAF sensor for the following:
2. Repair the circuit if the MAF sensor signal circuit is open or shorted.
Did you find the MAF sensor signal circuit open or shorted?
• An open circuit
• A short to ground
• A short to the MAF sensor ground circuit.
--
Go to Step 21
Go to Step 20
15
Locate and repair the open in the ground circuit to the MAF sensor. Refer to Body and Accessories/Wiring Systems.
Is the action complete?
--
Go to Step 21 --
16
Locate and repair the open in the ignition feed circuit to the MAF sensor. Refer to Body and Accessories/Wiring Systems.
Is the action complete?
--
Go to Step 21 --
17
Locate and repair the short to voltage in the MAF sensor signal circuit. Refer to Body and Accessories/Wiring Systems.
Is the action complete?
--
Go to Step 21 --
18
Replace the MAF sensor. Refer to Mass Airflow Sensor Replacement
Is the action complete? Go to Step 21 --
19
Replace the MAP sensor. Refer to Manifold Absolute Pressure Sensor Replacement .
Is the action complete?
--
Go to Step 21 --
20
Important:: Program the replacement PCM. Refer to Powertrain Control Module/Throttle Actuator Control Module Replacement .
Replace the PCM.
Is the action complete?
--
Go to Step 21 --
21
1. Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool. 2. Idle the engine at the normal operating temperature. 3. Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool. 4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.
Does the scan tool indicate that this test ran and passed?
--
Go to Step 22 Go to Step 2
22
Select the Capture Info option and the Review Info option using the scan tool.
Does the scan tool display any DTCs that you have not diagnosed?
-- Go to the applicable DTC table System OK
Post up your findings and fix.
Cheers,
Goose
Here are the other codes. All of them are history. None current.
Right Door:
B2283
B2285
U1064
Left Door:
B2282
B2284
B2264
U1064
BCM: B2723
HVAC: B0363
Originally Posted by C5 Diag
Helping a member about 1 1/2 years ago that was having starting issues...no DTC’s current or history but we had actually figured out he had a shorted cam sensor that actually caused the crank sensor not to operate correctly so go figure !!...and you must remember if you have an O2 sensor DTC for instance doesn’t mean the O2 sensor needs replacement...a lean running engine can sometimes set an O2 DTC ...these engine computers are funny birds !!...have you checked that MAF ground ??...not visually but actually load test it ???
Been trying to put a new oil pump in my Suburban without dropping the oil pan. Good exercise in frustration. And been building a barn door for my wife. The C5 is a little ways down on the priority list. (funny how that works when it's snowing outside )
Specific Troubleshooting procedures for a 1998 P0101 MAF Code;
1. Turn OFF the ignition. 2. Remove the MAP sensor from the intake manifold leaving the electrical harness connected. 3. Connect a hand operated vacuum pump to the MAP sensor. 4. Turn ON the ignition leaving the engine OFF. 5. Observe or record the MAP sensor display while slowly applying vacuum up to 20 inches Hg as indicated on the pump gauge. Each 1 inch of vacuum applied should result in a 3 to 4 kPa drop in the MAP sensor value on the scan tool and the value should change smoothly with each increase in vacuum.
Did the MAP sensor value change smoothly through the entire range of the test without any erratic readings?
Whoever wrote that has never looked under the hood of a C5 and located the MAP sensor.
I hate to chime in here without really really reading all that stuff above and taking it all in but I think you guys are looking in the wrong place here. I'll try to be brief. Go ahead and tell me if I'm jumping to conclusions without all the data being collected here.
The op has a complete shutdown problem and I don't think this is mechanical or electrical at all. It sounds to me like somebody was wrenching around in the tune and they have the ve table off far enough that the math checks that are being done which are supposed to make certain that the airflow and fueling stay Within a certain range of parameters during transient moments, are no longer within those parameters. At that point the PCM will shut the car down. I think you got to get HP tuners involved here and this car needs a very basic tune.
now it's been a little while since I've played with a tune because I just haven't had time to mess with this stuff recently but, I'm pretty sure there are a couple of tables which if they are not within a certain percentage of error, it'll just shut the PCM down. It knows there's impending doom or at least it thinks there might be and it says yo yo yo we're stopping.
Here are the other codes. All of them are history. None current.
Right Door:
B2283
B2285
U1064
Left Door:
B2282
B2284
B2264
U1064
BCM: B2723
HVAC: B0363
P0101 can be caused by poor electrical supply due to bad connections between the battery and the unit. The left and right door B codes indicate you have voltage issues in both doors. It is extremely rate to have more than one failure. There is usually a single common cause for what looks like multiple failures. That more than likely means you have an overall electrical issue affecting the whole car. Either there is an issue on the +12V supply side or on the ground side. Start with checking the battery terminals to see if they are clean and tight. Work from there to make sure the ground connections to the frame are clean and tight and then check the voltage side to make sure you have proper +12V distributed to where it is supposed to be.
I just did a lamp-test, running the current through my Fluke multimeter. I have an old front-end wiring harness from a Silverado, so I plugged in a headlight bulb and ran the current thorough the Fluke.
Directly across the battery, nice bright light ~4.6 amps
I hit a large number of ground points, the block, MAF ground, throttle position ground, etc... everything was in the 4.4-4.6 Amp range.
Did the same thing with the ignition on and pulling from the MAF 12V wire. ~4.6 Amps and a nice bright light
I take it you are using the harness with the low beam light bulb with one lead attached to the battery positive terminal while moving the other lead around to various ground points to check current flow through those grounds.
PCM and MAF Sensor grounds are spliced together at Splice 120 and the splice is grounded at G106 which is on the engine above the starter. The PCM establishes reference voltages for various sensors. If it's ground connection is dirty/corroded the reference voltages can be off by some voltage level. The electronic signals used for various sensors operate on voltage levels in the +5V range and resistance raising corrosion that might not affect a light bulb may be enough to cause a shift in reference voltage levels.
Also check to make sure you have +12 V at the Under hood Electrical Center and if you can at the PCM.
01-31-2020, 06:27 PM
Engine Dies While Driving - MAF Code, Not the MAF
