Check Engine Light Question.

5ohCOUPE · 12-19-2002, 09:48 PM

I pretty much know OBDII processors and information inside and out. But, I have a 91 5.0 (not OBD II

) and im not really up to speed on this system. I was driving down the road and my check engine light came on. No big deal, car was still running good. I have my list of codes with me and my jumper wire to check the code. I pull over and turn the car OFF. I turn the key on and begin to check the code and THERE WAS NO CODE. I started the car and the light was OFF. My question is do these computers store the code in memory or do they purge the code as soon as the problem seems ok?? The check engine light hasnt come on sence. Just wondering.

84LX89GT · 12-20-2002, 01:57 AM

Unfortunately as you know OBDII cars have continuous codes...but OBDI does not. OBDI only recognizes on demand codes, you can drive it and be lucky to get a code with the engine still running, once you shut off the key the code goes away. If i were you, i'd wait till it comes on again and try and get the code immediately. Chances are some sensor went out of range for a moment or stuck out of range and it set the code and the computer reset after you turned the key off.

bigred90gt · 12-20-2002, 02:06 AM

I was under the inpression that the codes went into Continuous Memory and stayed for about 75, or 100, turns of the key, or until you reset the computer. I have a 90 GT and I get KOEO, CM, and KOER codes. The CM are when something isn't right and the computer stores it for the allotted time. Someone feel free to correct me if I'm wrong, but I'm almost positive I'm not.

Caymon

PKRWUD · 12-20-2002, 10:21 AM

Quote:

Originally posted by 84LX89GT
Unfortunately as you know OBDII cars have continuous codes...but OBDI does not. OBDI only recognizes on demand codes, you can drive it and be lucky to get a code with the engine still running, once you shut off the key the code goes away. If i were you, i'd wait till it comes on again and try and get the code immediately. Chances are some sensor went out of range for a moment or stuck out of range and it set the code and the computer reset after you turned the key off.

I'm sorry, but that is 100% incorrect.

The continous codes are stored for between 75 and 100 ignition cycles.

Take care,
~Chris

saltzstang · 12-20-2002, 10:47 AM

I'm going to agree with prkwud & bigred90gt.......a great resource is Understanding Ford Electronic Engine Control (I hope I got the title right, someone correct me if Im wrong....Im at work and dont have the book on me). The book will go deep as you ever want to go on theory of control, operation stategies, and troubleshooting of all eec components. The book is pretty thick and not a bad price@ 29.95 at your local big book store.

84LX89GT · 12-24-2002, 02:58 AM

My mistake...i'm full of bs

I guess the processor in my car is crap and i'm just used to it. You are right though, i looked it up and i am in fact an idiot

Sorry to blow smoke up your bum.

I have trouble keeping continuous codes in the processor in my car. the check engine light will come on and then maybe a day later when i check for codes none appear, i ASSUMED that your car would be like mine.

PKRWUD · 12-24-2002, 03:40 AM

Dude, you're not an idiot, you just made an honest mistake. Cut yourself some slack. Hell, if you were an idiot, you wouldn't be here in the first place!

Merry Christmas

84LX89GT · 12-24-2002, 10:16 PM

Thanks chris, merry christmas to you as well

I just feel bad when i give people bad info. on something i could have easily checked, oh well sh/t happens

PKRWUD · 12-25-2002, 12:20 AM

Thank you!

12-19-2002, 09:48 PM	#1
5ohCOUPE Registered Member Join Date: Sep 2001 Location: ORANGE PARK FL. USA Posts: 208	Check Engine Light Question. I pretty much know OBDII processors and information inside and out. But, I have a 91 5.0 (not OBD II ) and im not really up to speed on this system. I was driving down the road and my check engine light came on. No big deal, car was still running good. I have my list of codes with me and my jumper wire to check the code. I pull over and turn the car OFF. I turn the key on and begin to check the code and THERE WAS NO CODE. I started the car and the light was OFF. My question is do these computers store the code in memory or do they purge the code as soon as the problem seems ok?? The check engine light hasnt come on sence. Just wondering. __________________ 91 LX COUPE, 3.73 gears, 2 1/2 inch H-Pipe, 1 5/8 MAC long tube headers, 73 MM C&L MAF, 70 MM MAC TB, LUNATI cam,1.7 TFS Rockers, TFS Track Heat heads, TFS Track Heat intake, T5 with PRO 5.0 shifter, Griffin aluminum radiator, Fluid Damper, SSM traction bars, 190 GPH in tank fuel pump. And more to come.

12-20-2002, 01:57 AM	#2
84LX89GT Mustangs Join Date: Jul 2000 Posts: 1,938	Unfortunately as you know OBDII cars have continuous codes...but OBDI does not. OBDI only recognizes on demand codes, you can drive it and be lucky to get a code with the engine still running, once you shut off the key the code goes away. If i were you, i'd wait till it comes on again and try and get the code immediately. Chances are some sensor went out of range for a moment or stuck out of range and it set the code and the computer reset after you turned the key off. __________________ 2005 Suzuki Hayabusa GSX1300-R 1980 Ford Thunderbird - 255 V8 ported heads, 5.0L ported stock headers, O.R. H-pipe and Flowmaster 2-chambers, dual roller timing chain hi-po Mack Truck hood emblem 1985 Mustang GT 5.0L T5, F-303, GT40p, headers, off-road h, flowmasters, MSD stuff, etc. Sold 02/06/04 1989 Mustang GT ET: 13.304@102.29 mph (5-24-03) Sold - 1998 Mustang Cobra coupe, 1/4 mile - street tires: 13.843@103.41 (bone stock)

12-20-2002, 02:06 AM	#3
bigred90gt 2 Stangs in the Stable Join Date: Apr 2002 Location: Baytown, TX Posts: 1,209	I was under the inpression that the codes went into Continuous Memory and stayed for about 75, or 100, turns of the key, or until you reset the computer. I have a 90 GT and I get KOEO, CM, and KOER codes. The CM are when something isn't right and the computer stores it for the allotted time. Someone feel free to correct me if I'm wrong, but I'm almost positive I'm not. 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

12-20-2002, 10:47 AM	#5
saltzstang Registered Member Join Date: Sep 2002 Location: southeast texas Posts: 90	I'm going to agree with prkwud & bigred90gt.......a great resource is Understanding Ford Electronic Engine Control (I hope I got the title right, someone correct me if Im wrong....Im at work and dont have the book on me). The book will go deep as you ever want to go on theory of control, operation stategies, and troubleshooting of all eec components. The book is pretty thick and not a bad price@ 29.95 at your local big book store. __________________ AFR 1492 heads,Track Heat Intake, d.s.s super pro bullet 331, lakewood bell, king cobra, 3550 ,UPR shifter, aluminum shaft, 4.10, 31-spline, spool,hoosier27x10, moroso ds-2, 175-juice, egt...11.40 on motor spray pass coming.

12-24-2002, 02:58 AM	#6
84LX89GT Mustangs Join Date: Jul 2000 Posts: 1,938	My mistake...i'm full of bs I guess the processor in my car is crap and i'm just used to it. You are right though, i looked it up and i am in fact an idiot Sorry to blow smoke up your bum. I have trouble keeping continuous codes in the processor in my car. the check engine light will come on and then maybe a day later when i check for codes none appear, i ASSUMED that your car would be like mine. __________________ 2005 Suzuki Hayabusa GSX1300-R 1980 Ford Thunderbird - 255 V8 ported heads, 5.0L ported stock headers, O.R. H-pipe and Flowmaster 2-chambers, dual roller timing chain hi-po Mack Truck hood emblem 1985 Mustang GT 5.0L T5, F-303, GT40p, headers, off-road h, flowmasters, MSD stuff, etc. Sold 02/06/04 1989 Mustang GT ET: 13.304@102.29 mph (5-24-03) Sold - 1998 Mustang Cobra coupe, 1/4 mile - street tires: 13.843@103.41 (bone stock)

12-24-2002, 03:40 AM	#7
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Dude, you're not an idiot, you just made an honest mistake. Cut yourself some slack. Hell, if you were an idiot, you wouldn't be here in the first place! Merry Christmas __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

12-24-2002, 10:16 PM	#8
84LX89GT Mustangs Join Date: Jul 2000 Posts: 1,938	Thanks chris, merry christmas to you as well I just feel bad when i give people bad info. on something i could have easily checked, oh well sh/t happens __________________ 2005 Suzuki Hayabusa GSX1300-R 1980 Ford Thunderbird - 255 V8 ported heads, 5.0L ported stock headers, O.R. H-pipe and Flowmaster 2-chambers, dual roller timing chain hi-po Mack Truck hood emblem 1985 Mustang GT 5.0L T5, F-303, GT40p, headers, off-road h, flowmasters, MSD stuff, etc. Sold 02/06/04 1989 Mustang GT ET: 13.304@102.29 mph (5-24-03) Sold - 1998 Mustang Cobra coupe, 1/4 mile - street tires: 13.843@103.41 (bone stock)

12-25-2002, 12:20 AM	#9
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Thank you! __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

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