Disconected MAF and this happened.....
Registered User
Joined: Dec 2002
Posts: 252
From: BREW CREW, WI
Originally posted by Robert95z
Not to intrude your thread but im having some problems...
When I disconnect my MAF while the engine is running, the motor will die... Motor also does not run if you try to start it with the MAF disconnected
Not to intrude your thread but im having some problems...
When I disconnect my MAF while the engine is running, the motor will die... Motor also does not run if you try to start it with the MAF disconnected
What it sounds like to me is that disconnecting your MAF is a good thing for our cars , so it would be ok if I did do that and run it for long periods of time?
Registered User
Joined: Nov 2001
Posts: 3,515
From: Kansas
Originally posted by Robert95z
so whats wrong with my car?
so whats wrong with my car?
Thread Starter
Registered User
Joined: Jul 2003
Posts: 1,103
From: Hawaii
Your car dies when you disconnect the MAF?
If your car will not start with the MAF on I bet one of your sensors is not conected properly or is not functioning.
Marvin
edit: and the oxygen sensors too.
Registered User
Joined: Dec 2002
Posts: 252
From: BREW CREW, WI
on my car when i disconnect the MAF and the IAT the car still runs and when i turn it off and restart it , it starts fine...
Now when i have everything connected and the car runnning and they disconect the IAT the car will still run but no change in engine sound... May I have a bad IAT?
Now when i have everything connected and the car runnning and they disconect the IAT the car will still run but no change in engine sound... May I have a bad IAT?
Thread Starter
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Joined: Jul 2003
Posts: 1,103
From: Hawaii
May I have a bad IAT?
How do you accidentaly disconect the MAP?? easy. My conector is brittle and I broke the little tab that keeps it from comming off the sensor. I was scanning her and moving the connector left and right to see if there was a loose wire when for no reason I lightly pulled down... the whole thing came off and the car didnt even noticed it
The IATs are cheap and easy to replace. I did mine no long ago. I also replaced the MAP sensor because at WOT if would read changes in the atmospheric barometric pressure (BAR). The new one fixed that. I also replaced the Coolant temp sensor just a couple of days ago only because I had purchased a new one long time ago and did some temperature testing with it. It was just laying around collecting dust and since I was changin my coolant then it was the perfect time to bolt it on. see if you can find my posting "things that make you feel stupid" it has a nice tip on how to replace that old booger.
Did it make a diff to replace the coolant temp sensor? well on the scanner there was a diff in temp reported. Old sensor 173*f with the A/C on. New Sensor 166*F with A/C on. obviously our PCM is only as good as the sensors its connected to. I have the 160*f thermo so I like my new Coolant Temp sensor better than the old one.
Marvin
Last edited by MentalCaseOne; Jan 13, 2004 at 01:05 PM.
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Joined: Oct 1999
Posts: 1,171
From: Henry, VA USA
That is cool! I want to try that on mine now. My BLMs are alright right now, usually around 126/122 cruising. But that MAF thing has me wondering. I also have the stock MAF w/ screen.
Keep us updated please.
Keep us updated please.
Thread Starter
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Joined: Jul 2003
Posts: 1,103
From: Hawaii
Update: 1/13/04 Update:
Soooo... I finished the Coolant change, bleeding over several hot and cold cycles... Let the lady warm up, turned her off.. Plugged the scanner on,,, Plugged the MAF sensor back on.. Crancked her up and inmediatelly I noticed the scanner reporting only 5grms/sec at 650RPMs.
Thats even a lower reading than I was loggin before,, the BLMs dropped to 114 and 116 and the integrators at 128 average both.
the slight misfiring became very aparent and when I revved her up between 1200 and 2000 RPMs she felt like either one cylinder was dead or she had a very bad balance problem....
So I decided to run a log test for the MAF sensor with no engine load... just run an RPM versus grms/sec log and this is what I found out. Read on for a brief explanation.
The purpose of this test was to find out how linear is my MAF sensor readings in comparison to engine RPMs. Ofcourse I did not expect the MAF to follow the RPMs with an exact increase in grms/sec. I expected some non-linearities but... it was way more than just a bit.
After I logged the engine, I transfered the resulting data to a spread sheet to perform a simple calculation.... divide RPMs by number of grms/sec, thats it. The resulting number shows the relationship between those two readings at a the given RPMs. for the test purpose I am gunna call them "Ratio units" ... the idea was to find out if the "ratio units" remained linear throught the RPM band (give or take a small percentage).
The Ratio units were anything but linear...
at:
RPMs Ratio Units
650== 130
675== 135 *
875== 125
1250== 113.64---End of block learn cell 1
1350== 112.50
1525== 108.93
1750== 109.38
1925== 106.94
1975== 109.72
2025== 96.43---End of Block Learn cell 2
2425== 97.00
2750== 101.85
2925== 86.03
3375== 88.82
3525== 85.98
4050== 71.05
4675== 69.78 *
4950== 72.79-Test ended on Block Learn cell 3
EGR Duty Cycle was 0% during the entire test.
MAP reading max was 1.29 volts and min was 0.82 volts
So in this tests conclussion the EGR can not be blamed for
any ratio units irregularities since it was never activated.
The discrepancy between the min and max ratio units is just too great to be ignored.. the amount of air measured by the MAF sensor at 4675 RPMs is nearly twice as much as the reported at 650 RPMs.. (ratio half as much at higher RPMs)
remember the MAP sensor (engine vacum) readings changed very little so I doubt I can blame this big discrepancy to my engines volumetric efficiency.
There was no load to the engine except for the Alternator... everything else was not in use.
My next step is to calculate the amount of air per rpm reported by the MAF at those RPMs. Hopefully that will display a more clear picture of what I am trying to describe. There was no engine load therefore the discrepancy shouldve been much smaller that almost 100% betwee min and max Ratio Units.
I will get back to you guys soon. any ideas will be greatly apreciated.
Marvin
Soooo... I finished the Coolant change, bleeding over several hot and cold cycles... Let the lady warm up, turned her off.. Plugged the scanner on,,, Plugged the MAF sensor back on.. Crancked her up and inmediatelly I noticed the scanner reporting only 5grms/sec at 650RPMs.
Thats even a lower reading than I was loggin before,, the BLMs dropped to 114 and 116 and the integrators at 128 average both.
the slight misfiring became very aparent and when I revved her up between 1200 and 2000 RPMs she felt like either one cylinder was dead or she had a very bad balance problem....
So I decided to run a log test for the MAF sensor with no engine load... just run an RPM versus grms/sec log and this is what I found out. Read on for a brief explanation.
The purpose of this test was to find out how linear is my MAF sensor readings in comparison to engine RPMs. Ofcourse I did not expect the MAF to follow the RPMs with an exact increase in grms/sec. I expected some non-linearities but... it was way more than just a bit.
After I logged the engine, I transfered the resulting data to a spread sheet to perform a simple calculation.... divide RPMs by number of grms/sec, thats it. The resulting number shows the relationship between those two readings at a the given RPMs. for the test purpose I am gunna call them "Ratio units" ... the idea was to find out if the "ratio units" remained linear throught the RPM band (give or take a small percentage).
The Ratio units were anything but linear...
at:
RPMs Ratio Units
650== 130
675== 135 *
875== 125
1250== 113.64---End of block learn cell 1
1350== 112.50
1525== 108.93
1750== 109.38
1925== 106.94
1975== 109.72
2025== 96.43---End of Block Learn cell 2
2425== 97.00
2750== 101.85
2925== 86.03
3375== 88.82
3525== 85.98
4050== 71.05
4675== 69.78 *
4950== 72.79-Test ended on Block Learn cell 3
EGR Duty Cycle was 0% during the entire test.
MAP reading max was 1.29 volts and min was 0.82 volts
So in this tests conclussion the EGR can not be blamed for
any ratio units irregularities since it was never activated.
The discrepancy between the min and max ratio units is just too great to be ignored.. the amount of air measured by the MAF sensor at 4675 RPMs is nearly twice as much as the reported at 650 RPMs.. (ratio half as much at higher RPMs)
remember the MAP sensor (engine vacum) readings changed very little so I doubt I can blame this big discrepancy to my engines volumetric efficiency.
There was no load to the engine except for the Alternator... everything else was not in use.
My next step is to calculate the amount of air per rpm reported by the MAF at those RPMs. Hopefully that will display a more clear picture of what I am trying to describe. There was no engine load therefore the discrepancy shouldve been much smaller that almost 100% betwee min and max Ratio Units.
I will get back to you guys soon. any ideas will be greatly apreciated.
Marvin
Last edited by MentalCaseOne; Jan 14, 2004 at 02:36 AM.
Thread Starter
Registered User
Joined: Jul 2003
Posts: 1,103
From: Hawaii
Update:
Today I will clean the EGR just to make sure there arent any vacum leaks developing there and re-log the engine RPMs... I then will transfer the numbers to cubic feet of air per rpm
I will use some formulas provided by Injuneer to be as accurate as possible. Although the test is just to show linearity issues it pays to be accurate....
wish me luck cleaning that freaky EGR.
Marvin
Today I will clean the EGR just to make sure there arent any vacum leaks developing there and re-log the engine RPMs... I then will transfer the numbers to cubic feet of air per rpm
I will use some formulas provided by Injuneer to be as accurate as possible. Although the test is just to show linearity issues it pays to be accurate....
wish me luck cleaning that freaky EGR.
Marvin
Registered User
Joined: Mar 2003
Posts: 4,287
From: Palm City, Florida
Hey guys -- when I disconnected my MAF with the engine off as soon as it started it died like the other guy. When I unplugged it with the engine running it didn't stall.....so what's the deal?
Thread Starter
Registered User
Joined: Jul 2003
Posts: 1,103
From: Hawaii
A woman is like a teabag. You never know her strength until she's in hot water."- Nancy Reagan
Sometimes I just crack my self up
now dont go around givin me the "Stink eye" ok?
oh I almost forgot... I am waiting for this 40mph wind and rain to calm down before I go out and yank the EGR off my car...
Marvin
Thread Starter
Registered User
Joined: Jul 2003
Posts: 1,103
From: Hawaii
Hey guys and gals, I did the extra calculations on a spread sheet.
I calculated the grms of air per minute and then calculated how much of that air is per one revolution of the cranckshaft. Then using the Idle speed of 650 RPMs I calculated in percentages how much of deviation there is for the previous readings I posted here... as it turned out. Per MAF readings, my engine is requiring a 192% more air, per cylinder, per crankshaft turn, to keep a similar engine vacum, when its at 4675RPMs. This is totally unaceptable. As stated earlier the only engine load is the Alternator and even at maximum load on the alternator. I was expecting an increase of about 10 percent.. maybe 15 percent as the engine rotated faster to compensate for Alternator drag, water pump drag, Camshaft drag.
Now remember the drag of this items already exist at idle... The engine is already rotaring all of them with their equivalent loads... so I dont see why my engine would be requiring so much more air just to keep what is basickly the same loads only at higher speeds...
I graphed my MAF readings in relationship to engine speed and it does not increase smoothly and gradually acording to engine speed. At this point I am suspecting my fuel trim problems are a result of my MAF sensor...
I got the following information directly from AutoZone....
----------------------------------------------------------------------
Hot-Wire-Type MAF Sensors
The test procedure for heated resistor and hot-wire MAF sensors varies depending on the vehicle make and year. Always follow the test procedure in the appropriate service manual. A frequency test may be performed on some MAF sensors, such as the AC Delco MAF on some General Motors' products.
To check the MAF sensor's voltage signal and frequency, connect a voltmeter across the MAF voltage signal wire and ground wire.
Start the engine and observe the voltmeter reading.
On some MAF sensors, this reading should be 2.5 volts.
Lightly tap the MAF sensor housing with a screwdriver handle and watch the voltmeter pointer.
If the pointer fluctuates or the engine misfires, replace the MAF sensor.
Some MAF sensors have experienced loose internal connections, which cause erratic voltage signals and engine misfiring and surging.
Set the DMM so that it can read the frequency of DC voltage.
With it still connected to the signal wire and ground, the meter should read about 30 Hz with the engine idling.
Now, increase the engine speed, and record the meter reading at various speeds.
Graph the frequency readings. The MAF sensor frequency should increase smoothly and gradually in relation to engine speed.
If the MAF sensor frequency reading is erratic, replace the sensor.
---------------------------------------------------------------------------------
here is the web page if you guys want to read the whole info
http://www3.autozone.com/servlet/UiB...3d8004fa92.jsp
This post is got too large for a new reader... I may have to end my posting here and start a new one with final information or do you guys want me to keep updating this one??
Marvin
I calculated the grms of air per minute and then calculated how much of that air is per one revolution of the cranckshaft. Then using the Idle speed of 650 RPMs I calculated in percentages how much of deviation there is for the previous readings I posted here... as it turned out. Per MAF readings, my engine is requiring a 192% more air, per cylinder, per crankshaft turn, to keep a similar engine vacum, when its at 4675RPMs. This is totally unaceptable. As stated earlier the only engine load is the Alternator and even at maximum load on the alternator. I was expecting an increase of about 10 percent.. maybe 15 percent as the engine rotated faster to compensate for Alternator drag, water pump drag, Camshaft drag.
Now remember the drag of this items already exist at idle... The engine is already rotaring all of them with their equivalent loads... so I dont see why my engine would be requiring so much more air just to keep what is basickly the same loads only at higher speeds...
I graphed my MAF readings in relationship to engine speed and it does not increase smoothly and gradually acording to engine speed. At this point I am suspecting my fuel trim problems are a result of my MAF sensor...
I got the following information directly from AutoZone....
----------------------------------------------------------------------
Hot-Wire-Type MAF Sensors
The test procedure for heated resistor and hot-wire MAF sensors varies depending on the vehicle make and year. Always follow the test procedure in the appropriate service manual. A frequency test may be performed on some MAF sensors, such as the AC Delco MAF on some General Motors' products.
To check the MAF sensor's voltage signal and frequency, connect a voltmeter across the MAF voltage signal wire and ground wire.
Start the engine and observe the voltmeter reading.
On some MAF sensors, this reading should be 2.5 volts.
Lightly tap the MAF sensor housing with a screwdriver handle and watch the voltmeter pointer.
If the pointer fluctuates or the engine misfires, replace the MAF sensor.
Some MAF sensors have experienced loose internal connections, which cause erratic voltage signals and engine misfiring and surging.
Set the DMM so that it can read the frequency of DC voltage.
With it still connected to the signal wire and ground, the meter should read about 30 Hz with the engine idling.
Now, increase the engine speed, and record the meter reading at various speeds.
Graph the frequency readings. The MAF sensor frequency should increase smoothly and gradually in relation to engine speed.
If the MAF sensor frequency reading is erratic, replace the sensor.
---------------------------------------------------------------------------------
here is the web page if you guys want to read the whole info
http://www3.autozone.com/servlet/UiB...3d8004fa92.jsp
This post is got too large for a new reader... I may have to end my posting here and start a new one with final information or do you guys want me to keep updating this one??
Marvin
