Check engine light

TwiLighTBluEGT · 12-10-2002, 08:26 AM

On my way to school this morning I noticed that my check engine light flashed on and off a few times as I accelerated. This has never happened before. It stays off now, but does anybody have any ideas why it would just flash on an off a few times like that? Maybe a sensor going bad?

ChunkFunky · 12-10-2002, 08:52 AM

The check engine light is teh vaguest light in your car.. it means... SOMETHING happened.... it could mean MILLION different things... the only way to know what it means is to get a code reader... though if it goes out... and doesnt come on again.. I wouldnt even sweat it... people talk about readin the codes with a paper clip and a voltmeter... and I'm sure it works.. but I dont know how... so I got a code reader for 30 bucks... though like I said.. I wouldnt sweat this one ... my light likes to go on from time to time when its cold...I dont even know what the codes are.. it's too cold for me to bother looking...
-as

TwiLighTBluEGT · 12-10-2002, 10:07 AM

It went off when it was very cold out this morning.

SCOTTLT79 · 12-10-2002, 11:08 AM

I'm curious to hear answers to this question as well.

Whenever I really get on it, the check engine light will come on. It won't stay on long and seems to go off if I just give the gas a little tap. It is very strange. It did go on this morning and stayed on for a while. This only started happening once I put the off road H on there. But I just don't know why it goes on and off.

12-10-2002, 02:51 PM

You guys need to read your codes. It's very simple. Go buy a Chilton's (or Hanes, or the dealer manual which is expensive) and read how to do it. Even if your check engine light only goes on once in a while you'll need to pull the codes to see what "blips" the system found. I definitely wouldn't just ignore it like ChunkFunky said. Why not try to make your Mustang run as well as possible?

bigred90gt · 12-10-2002, 03:07 PM

My check engine light used to go on and off all the time. It got to a point where it stayed on. I let it go. When I replaced the BAP sensor, error code 22, I picked up .3 and 3mph in the 1/4. I would run the codes.
Caymon

TwiLighTBluEGT · 12-10-2002, 04:58 PM

After my check engine light flashed on and off a few times this morning, I went to autozone a few hours later and got my codes run just to see what it could be.... And no codes came up?!?!!?!?

HellRaiser92 · 12-11-2002, 03:14 AM

My car has been doing this lately also. The light will come on and off as it wants. It only seems to do this when the engine temp hasn't made it to the normal mark. I would suggest scanning your car for codes like everyone else has said. I have a friend with a scanner but I haven't made it to him yet.

Someone told me that scanners will only pick up codes when the engine light is on so you may want to try that. I had my car scanned a while ago when the light wasn't on and it still found codes so who knows. If I find my friend and we come up with codes for my car I'll come back here and post what we found.

ChunkFunky · 12-11-2002, 11:28 AM

you car should store codes for a period of time... not sure how it is on mustangs.. sometimes it's X amount of car starts or X amoutn of days or somethimes its X amount of codes.. it's allways a good idea to check your codes , cause they can lead to possible problems.. I was just saying that you shouldnt freak out if your check light comes on.. it could be something stupid... though it could be something more involved... though alot of things that trigger the light can fix themselves or just be informational rather then failures
-as

PKRWUD · 12-11-2002, 12:05 PM

The MIL (Malfunction Indicator Lamp, aka: Check Engine Light) will flash every time the ECM detects that something is not quite right. If a sensor sends back a signal that is not within the preprogrammed parameters, or if device that it told to do something didn't do what it was told, the ECM makes a note of this, and saves it as a code in continuous memory. It stays there for a period of 100 (average, some ECM's save it longer, some save it for fewer) cycles of the ignition switch. A cycle is each time the key is turned on and then off. If the event doesn't repeat itself during that time, the ECM erases it from continuous memory. If it does reoccur, the 100 cycle count starts all over again. The ECM triggers the MIL to flash when it makes this note to itself, alerting the driver that a problem was detected, and a code was stored, and that they might want to get it checked.

If the problem is one that doesn't change, and continuously triggers a problem, the MIL stays lit, basically because the ECM is continuously making a note of it, which continuously flashes the MIL. The hope here is that the driver realizes there is a constant problem, and will have it looked at immediately. Once it no longer detects the problem, the light goes off, and the 100 cycle count begins. That does not mean that everything is okay, however.

In short, every time the MIL flashes, the ECM stores the code for no fewer than 75 ignition cycles (usually 100). These codes will be stored as Continuous codes, and are read during a KOEO (Key On, Engine Off) search for codes.

When the codes are to be pulled, first a KOEO test is run. The engine needs to be at operating temp for this. The ECM then activates each of it's devices, and makes sure they all are responding. This is why you will hear clicks and buzzes while this test is being performed.

If any problems are found, those codes will come up first, followed by any continuous codes that are in memory. These codes must be corrected before the next stage in reading codes is performed.

The next stage is the KOER (Key On, Engine Running) test. It is critical that the engine be warmed up completely before starting this test. Some vehicles are required to depress the clutch pedal during the entire test, and there is usually a point during the test where you need to crank the steering wheel, and depress the brake pedal. lastly, there will be a point at which you need to quickly move the gas pedal to WOT.

When this test is finished, the codes that will be there will tell about problems the ECM found while running it's range of tests under running conditions.

Sooooo, anytime you see the MIL flash, you really should run the KOEO test, and see what codes are found.

Take care,
~Chris

HellRaiser92 · 12-11-2002, 04:11 PM

Good advice PKRWUD!

That's the same way me and my friend check for codes.

12-10-2002, 08:26 AM	#1
TwiLighTBluEGT Registered Member Join Date: Jun 2002 Location: Massachusetts Posts: 157	Check engine light On my way to school this morning I noticed that my check engine light flashed on and off a few times as I accelerated. This has never happened before. It stays off now, but does anybody have any ideas why it would just flash on an off a few times like that? Maybe a sensor going bad? __________________ 1991 Mustang GT Conv: 58,000 original miles, 2nd owner. Engine: FMS 65mm tb/spacer, C&L 73mm maf, MAC cai. Drivetrain: Built AOD w/ Edge 2800rpm lockup converter, hardened 3-4 inner shaft, Trans-Go shift kit, B&M supercooler, FMS 3.73 gears & aluminum d/s, rebuilt traction lock. Exhaust: BBK unequal length shorty headers, BBK o/r h-pipe, Flowmaster 2 chamber mufflers. Chassis/suspension/brakes: Kenny Brown supersubs. The rest is stock.

12-10-2002, 08:52 AM	#2
ChunkFunky Registered Member Join Date: Apr 2002 Location: Tustin, CA Posts: 465	The check engine light is teh vaguest light in your car.. it means... SOMETHING happened.... it could mean MILLION different things... the only way to know what it means is to get a code reader... though if it goes out... and doesnt come on again.. I wouldnt even sweat it... people talk about readin the codes with a paper clip and a voltmeter... and I'm sure it works.. but I dont know how... so I got a code reader for 30 bucks... though like I said.. I wouldnt sweat this one ... my light likes to go on from time to time when its cold...I dont even know what the codes are.. it's too cold for me to bother looking... -as __________________ '89 GT Convertible: TFS TW Heads, TFS Street Intake, TFS Stage 1 Cam, FMS 1.6 RRs, 24# Injectors, Pro-M 75mm MAF, No Name CAI, 3.73s, O/R H-Pipe, FlowMasters, AOD w/ Trans-Go Shift Kit

12-10-2002, 10:07 AM	#3
TwiLighTBluEGT Registered Member Join Date: Jun 2002 Location: Massachusetts Posts: 157	It went off when it was very cold out this morning. __________________ 1991 Mustang GT Conv: 58,000 original miles, 2nd owner. Engine: FMS 65mm tb/spacer, C&L 73mm maf, MAC cai. Drivetrain: Built AOD w/ Edge 2800rpm lockup converter, hardened 3-4 inner shaft, Trans-Go shift kit, B&M supercooler, FMS 3.73 gears & aluminum d/s, rebuilt traction lock. Exhaust: BBK unequal length shorty headers, BBK o/r h-pipe, Flowmaster 2 chamber mufflers. Chassis/suspension/brakes: Kenny Brown supersubs. The rest is stock.

12-10-2002, 11:08 AM	#4
SCOTTLT79 Registered Member Join Date: Aug 2000 Location: Raynham, Ma, USA Posts: 189	I'm curious to hear answers to this question as well. Whenever I really get on it, the check engine light will come on. It won't stay on long and seems to go off if I just give the gas a little tap. It is very strange. It did go on this morning and stayed on for a while. This only started happening once I put the off road H on there. But I just don't know why it goes on and off. __________________ 95 Red Mustang GT Pro 5.0, MAC fenderwall cold air induction kit, BBK Off-Road H-pipe with Magnaflow cat-back system Mostly stock(looking to modify) Rice Haters Club Member #63

12-10-2002, 02:51 PM	#5
Simi Stang Guest Posts: n/a	check engine light You guys need to read your codes. It's very simple. Go buy a Chilton's (or Hanes, or the dealer manual which is expensive) and read how to do it. Even if your check engine light only goes on once in a while you'll need to pull the codes to see what "blips" the system found. I definitely wouldn't just ignore it like ChunkFunky said. Why not try to make your Mustang run as well as possible?

12-10-2002, 03:07 PM	#6
bigred90gt 2 Stangs in the Stable Join Date: Apr 2002 Location: Baytown, TX Posts: 1,209	My check engine light used to go on and off all the time. It got to a point where it stayed on. I let it go. When I replaced the BAP sensor, error code 22, I picked up .3 and 3mph in the 1/4. I would run the codes. Caymon __________________ '90 GT Under construction Best E.T. = Fast @ High Speeds - OK So I Lie. So What!!! 04 F-150 STX 4.2L 5 spd Rice Haters Club Member #128

12-10-2002, 04:58 PM	#7
TwiLighTBluEGT Registered Member Join Date: Jun 2002 Location: Massachusetts Posts: 157	After my check engine light flashed on and off a few times this morning, I went to autozone a few hours later and got my codes run just to see what it could be.... And no codes came up?!?!!?!? __________________ 1991 Mustang GT Conv: 58,000 original miles, 2nd owner. Engine: FMS 65mm tb/spacer, C&L 73mm maf, MAC cai. Drivetrain: Built AOD w/ Edge 2800rpm lockup converter, hardened 3-4 inner shaft, Trans-Go shift kit, B&M supercooler, FMS 3.73 gears & aluminum d/s, rebuilt traction lock. Exhaust: BBK unequal length shorty headers, BBK o/r h-pipe, Flowmaster 2 chamber mufflers. Chassis/suspension/brakes: Kenny Brown supersubs. The rest is stock.

12-11-2002, 03:14 AM	#8
HellRaiser92 Registered Member Join Date: Apr 2000 Posts: 104	My car has been doing this lately also. The light will come on and off as it wants. It only seems to do this when the engine temp hasn't made it to the normal mark. I would suggest scanning your car for codes like everyone else has said. I have a friend with a scanner but I haven't made it to him yet. Someone told me that scanners will only pick up codes when the engine light is on so you may want to try that. I had my car scanned a while ago when the light wasn't on and it still found codes so who knows. If I find my friend and we come up with codes for my car I'll come back here and post what we found. __________________ 92LX 2.3ltr 5 speed Air Silencer removed, K&N Filter, Straight Pipe

12-11-2002, 11:28 AM	#9
ChunkFunky Registered Member Join Date: Apr 2002 Location: Tustin, CA Posts: 465	you car should store codes for a period of time... not sure how it is on mustangs.. sometimes it's X amount of car starts or X amoutn of days or somethimes its X amount of codes.. it's allways a good idea to check your codes , cause they can lead to possible problems.. I was just saying that you shouldnt freak out if your check light comes on.. it could be something stupid... though it could be something more involved... though alot of things that trigger the light can fix themselves or just be informational rather then failures -as __________________ '89 GT Convertible: TFS TW Heads, TFS Street Intake, TFS Stage 1 Cam, FMS 1.6 RRs, 24# Injectors, Pro-M 75mm MAF, No Name CAI, 3.73s, O/R H-Pipe, FlowMasters, AOD w/ Trans-Go Shift Kit

12-11-2002, 12:05 PM	#10
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	The MIL (Malfunction Indicator Lamp, aka: Check Engine Light) will flash every time the ECM detects that something is not quite right. If a sensor sends back a signal that is not within the preprogrammed parameters, or if device that it told to do something didn't do what it was told, the ECM makes a note of this, and saves it as a code in continuous memory. It stays there for a period of 100 (average, some ECM's save it longer, some save it for fewer) cycles of the ignition switch. A cycle is each time the key is turned on and then off. If the event doesn't repeat itself during that time, the ECM erases it from continuous memory. If it does reoccur, the 100 cycle count starts all over again. The ECM triggers the MIL to flash when it makes this note to itself, alerting the driver that a problem was detected, and a code was stored, and that they might want to get it checked. If the problem is one that doesn't change, and continuously triggers a problem, the MIL stays lit, basically because the ECM is continuously making a note of it, which continuously flashes the MIL. The hope here is that the driver realizes there is a constant problem, and will have it looked at immediately. Once it no longer detects the problem, the light goes off, and the 100 cycle count begins. That does not mean that everything is okay, however. In short, every time the MIL flashes, the ECM stores the code for no fewer than 75 ignition cycles (usually 100). These codes will be stored as Continuous codes, and are read during a KOEO (Key On, Engine Off) search for codes. When the codes are to be pulled, first a KOEO test is run. The engine needs to be at operating temp for this. The ECM then activates each of it's devices, and makes sure they all are responding. This is why you will hear clicks and buzzes while this test is being performed. If any problems are found, those codes will come up first, followed by any continuous codes that are in memory. These codes must be corrected before the next stage in reading codes is performed. The next stage is the KOER (Key On, Engine Running) test. It is critical that the engine be warmed up completely before starting this test. Some vehicles are required to depress the clutch pedal during the entire test, and there is usually a point during the test where you need to crank the steering wheel, and depress the brake pedal. lastly, there will be a point at which you need to quickly move the gas pedal to WOT. When this test is finished, the codes that will be there will tell about problems the ECM found while running it's range of tests under running conditions. Sooooo, anytime you see the MIL flash, you really should run the KOEO test, and see what codes are found. Take care, ~Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

12-11-2002, 04:11 PM	#11
HellRaiser92 Registered Member Join Date: Apr 2000 Posts: 104	Good advice PKRWUD! That's the same way me and my friend check for codes. __________________ 92LX 2.3ltr 5 speed Air Silencer removed, K&N Filter, Straight Pipe

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