PCM LOSES MEMORY OVERNIGHT BUT IS FINE DURING THE DAY.

  • Tiny
  • scotthillspa
  • 1998 Ford Explorer
  • 213,000 miles

My 98 explorer has a problem of not being ready for the emissions test.
Every morning when I start it, it's acting as if it's re-learning the engine all over again, rough idle etc.
I checked the fuses in the power distribution box and their all good.
It's fine all day long, but if it sits more than 8 hours then it's back to square one again, the morning routine of letting the pcm learn the engine all over again.
I checked for any loose connections, and found nothing.

any ideas on troubleshooting the core problem? Is it the pcm?

I'm running out of time on the emissions test grace period. I'm a student and I cant afford for this truck to be down. Or any major repair costs.



Do you
have the same problem?
Yes
No
Wednesday, July 24th, 2013 AT 3:08 PM

7 Replies

  • Tiny
  • hmac300
  • Expert
  • 44,397 posts

Scan for codes and check fuel pressure with a gauge, clean throttle plate with choke cleaner on both sides. For emission test, replace air filter and change oil an d oil filter, drive 20 miles on eway then get it tested.

Was this
answer
helpful?
Yes
No
Thursday, July 25th, 2013 AT 6:16 AM
  • Tiny
  • scotthillspa
  • Member

Been driving around for several days, the shop I took it to told me to drive around.(I did for about 250 miles, and on several different day's). It is in a not ready state, the first one that clicks in is egr but the others are not in a timely manner.

Ive been doing the driving every day and still the same result.

Like I said at night it forgets everything. Starting the engine in the morning I have to wait for the computer to recognize the engine again.

The battery is good ( cranks in the morning no trouble )

Was this
answer
helpful?
Yes
No
Thursday, July 25th, 2013 AT 3:44 PM
  • Tiny
  • hmac300
  • Expert
  • 44,397 posts

Have the battery tested for condition and load test, not it's good cause it cranks in morning. Ok what engine is in this and check the tings in pic that I have pointed out

Was this
answer
helpful?
Yes
No
Thursday, July 25th, 2013 AT 5:37 PM
  • Tiny
  • scotthillspa
  • Member

Ok, I have had the battery tested, and I also have checked all of the fuses inline.

Finally received a trouble code stating an o2 sensor was slow, could that be the cause of this problem? Also it still forgets the engine over a 5 hour period on not being run.

Was this
answer
helpful?
Yes
No
Monday, August 12th, 2013 AT 11:44 AM
  • Tiny
  • hmac300
  • Expert
  • 44,397 posts

The O2 sensor wouldn't cause it to lose memory it may be an ecm problem if the battery and connections check ok or conections to the ecm

Was this
answer
helpful?
Yes
No
Monday, August 12th, 2013 AT 12:10 PM
  • Tiny
  • scotthillspa
  • Member

New info.
I ran a memory test with the engine off and got the error Theft Detected - Engine
Disabled

Could this be the cause of the whole problem?

Was this
answer
helpful?
Yes
No
Thursday, August 15th, 2013 AT 9:10 AM
  • Tiny
  • hmac300
  • Expert
  • 44,397 posts

Have you ever tried resetting your anti theft? I would say this is probably the problem can't think of anything else. Check your manual on how to reset it.

Was this
answer
helpful?
Yes
No
Thursday, August 15th, 2013 AT 9:46 AM

Please login or register to post a reply.

Similar Questions