LasVegasMac
New Member
- Joined
- August 25, 2004
- Messages
- 5
- Reaction score
- 0
- City, State
- Las Vegas, NV
- Year, Model & Trim Level
- '94 XLT
My 94 4.0L is giving me fits - time to ask the experts for help!
Starting about a month ago the beast developed a rough idle when started - never when cold, always after being driven for awhile.
After reading on this forum, I decided to give the MAS a cleaning - never had and have over 90,000 miles on it. That reduced the pinging considerably, but had no effect on the rough idle.
This past Sat the check engine light came on. Went to Autozone to have the codes read, but they said they did not have the adapter to read OBD-I, so I bought an Actron CP9015 code scanner.
This is what the symptoms are: when cold, idle is fine. After engine gets warm the CEL comes on. When at speed - goes off. Stop at light - the rpm's drop, has never died but close, and the CEL comes on. Get up to speed, CEL goes off......
Did not notice this until this morning - after the CEL comes on, engine idling very rough, I get some light black smoke and water out of the tail pipe. Had the kid wipe it up and I bumped the idle up to 1500 for a minute or so, CEL goes out, no smoke (according to the kid) and no water from tail pipe. As soon as the CEL comes on - smoke / water out the tail pipe.
There has been a very quick hesitation about half dozen times in the last two days- always when accelerating. Very quick - by the time you feel it, and it is noticable - the engine is back to normal.
The first codes I got were 57 and 58. Not in my book. called a buddy, he calls Autozone - they say 57 is Heater Control Circuit bank 2 low and 58 is Heater Control Circuit bank 2 high -- Heater Control Valve. That did not make sense to me. Replaced anyway - only $17 and 5 minutes to replace it.
Hooked the battery back up and drove it for 20 minutes. No light - at first. Then the same cycle started. Put the code scanner on it and the only code it gave was 57 - twice in a row.
I had been wondering about the IAC (read alot here) so I decided to check it out. Book says that there should be 7 - 13 ohms resistance between the leads. Mine was at 7. Took the meter with me to Autozone and measured a new one - 10.5. Bought / installed new IAC valve. Hooked the battery back up and drove it. Same same for the CEL.
Ran the code scanner again. The only code it gives is 57 - twice in a row.
And the only place I can find code 57 is in the manual that came with the scanner - it says Neutral Pressure Switch (NPS) - open circuit failure or , Circuit failed in Neutral position, or Octane adjust service pin installed.
NPS ??
Sorry this is so long - wanted to give all the ugly little details. I'm starting to have thoughts about the timing chain or worse.
Thanks for your help in advance,
LVM
Starting about a month ago the beast developed a rough idle when started - never when cold, always after being driven for awhile.
After reading on this forum, I decided to give the MAS a cleaning - never had and have over 90,000 miles on it. That reduced the pinging considerably, but had no effect on the rough idle.
This past Sat the check engine light came on. Went to Autozone to have the codes read, but they said they did not have the adapter to read OBD-I, so I bought an Actron CP9015 code scanner.
This is what the symptoms are: when cold, idle is fine. After engine gets warm the CEL comes on. When at speed - goes off. Stop at light - the rpm's drop, has never died but close, and the CEL comes on. Get up to speed, CEL goes off......
Did not notice this until this morning - after the CEL comes on, engine idling very rough, I get some light black smoke and water out of the tail pipe. Had the kid wipe it up and I bumped the idle up to 1500 for a minute or so, CEL goes out, no smoke (according to the kid) and no water from tail pipe. As soon as the CEL comes on - smoke / water out the tail pipe.
There has been a very quick hesitation about half dozen times in the last two days- always when accelerating. Very quick - by the time you feel it, and it is noticable - the engine is back to normal.
The first codes I got were 57 and 58. Not in my book. called a buddy, he calls Autozone - they say 57 is Heater Control Circuit bank 2 low and 58 is Heater Control Circuit bank 2 high -- Heater Control Valve. That did not make sense to me. Replaced anyway - only $17 and 5 minutes to replace it.
Hooked the battery back up and drove it for 20 minutes. No light - at first. Then the same cycle started. Put the code scanner on it and the only code it gave was 57 - twice in a row.
I had been wondering about the IAC (read alot here) so I decided to check it out. Book says that there should be 7 - 13 ohms resistance between the leads. Mine was at 7. Took the meter with me to Autozone and measured a new one - 10.5. Bought / installed new IAC valve. Hooked the battery back up and drove it. Same same for the CEL.
Ran the code scanner again. The only code it gives is 57 - twice in a row.
And the only place I can find code 57 is in the manual that came with the scanner - it says Neutral Pressure Switch (NPS) - open circuit failure or , Circuit failed in Neutral position, or Octane adjust service pin installed.
NPS ??
Sorry this is so long - wanted to give all the ugly little details. I'm starting to have thoughts about the timing chain or worse.
Thanks for your help in advance,
LVM
