Stupid obd1 question

OldJunk · Nov 18, 2008

On obd2 cel stays on until problem is corrected/cleared. On obd1 cel came on briefly and went out,no problem with vehicle runs great in all aspects and cel comes on/off at start cycle. so does the cel only come on when a cond is pres. and goes out if cond. subsides ? is there a code stored ? just wondering, truck is a 93 F350 w460 E4od

Wicked_Sludge · Nov 18, 2008

the CEL comes on when a sensors input is percieved to be outside of an acceptable range. if the sensor corrects itself, the code is stored and the light goes out.

OBDII vehicles are the same way.

Explorin94 · Nov 18, 2008

OBD1 only stores a code if it stays on longer than 30 seconds. OBD2 stores a code as soon as the light comes on.

OldJunk · Nov 18, 2008

THANKS!!! I not going to worry about it now, it happened over a year ago, for maybe 20 sec at hwy speed and has never reoccured since. someone was talking about obd1 and it jogged my memory. I guess im over protective of it beacause its the " flagship" of my fleet w/ only 22,000 miles.

Wicked_Sludge · Nov 18, 2008

if the battery hasnt been unhooked since then, you could still pull the code just for fun.

Psychopete · Nov 18, 2008

Wicked_Sludge said:
if the battery hasnt been unhooked since then, you could still pull the code just for fun.

I thought CM codes reset themselves after 40 start cycles for OBD-I?

Pete

Wicked_Sludge · Nov 18, 2008

i dont think so. sensor baselines and multipliers are stored for the past 80 drive cycles...but i dont think trouble codes go away until cleared.

OldJunk · Nov 18, 2008

Must not be anything wrong, mpg lately have actually gotten better. Im now getting 12 mpg!!!!!!!,instead of 11 WOW!!

Wicked_Sludge · Nov 18, 2008

ya "fuel efficient" and "big block" dont generally occupy the same sentance. but you can pull just about anything you want from gas station to gas station

.

Psychopete · Nov 18, 2008

Wicked_Sludge said:
i dont think so. sensor baselines and multipliers are stored for the past 80 drive cycles...but i dont think trouble codes go away until cleared.

Ah, I was slightly mistaken:

(Technical Library)

These codes are kept in memory for 40 warm up cycles. To clear the codes for purposes of testing or confirming repair, perform the code reading procedure. When the fault codes begin to be displayed, de-activate the test by either disconnecting the jumper wire or releasing the test button on the hand scanner. Stopping the test during code transmission will erase the continuous memory. Do not disconnect the negative battery cable to clear the codes; the keep alive memory will be cleared and a new code (19) will be stored for loss of PCM power.

Perhaps this bit of information is incorrect?

Pete

Wicked_Sludge · Nov 18, 2008

ahh, well there ya go.

OldJunk · Nov 18, 2008

Truck gets 12 unloaded w/ canopy on it. 10.9 w/ 2,200 lb camper, towing an 18ft boat hwy mpg. better than my old 460 w/ holley 4bbl 77 f250, it got 8mpg.

MAKG · Nov 18, 2008

Psychopete said:
Perhaps this bit of information is incorrect?

The quote was fully consistent with the Ford emissions manual for 1991. But of course Ford manuals aren't 100% reliable either....

But I certainly have seen that #@@$%^$#^&%$&%&*%( KAM code myself.

Stupid obd1 question

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