QuestionHello, first off, I'm very appreciative of this help you're so generous to provide, and that I am in dire need of help, as is anyone having car problems.
To begin, I have a 1991 Mercury Sable GS with a 3.8L AXOD-E, 120,000kms.
I got it's transmission fixed and when I picked it up they told me that my spark plug wire had been rubbing against my dip stick tube and worn so bad it was arcing, and that I needed new spark plug cables. I said I'd just silicone and tape it, but they were insistent on new cables, like they had broken them and knew I needed new ones.
Anyways, I got the car back, and while driving, the check engine light came on, I scanned the codes right away and got 172, I use the jumper and flashing MIL light method. The light comes on at any random point while driving, turns off by itself too. In a 10 minute trip, it will turn on and off about 3 times, being on about 60% of the trip. 172 means the right HEGO is not switching or LEAN detecting, so maybe the transmission shop broke one of my cables and this was doing it. If a cylinder is grounded and doesn't fire, would this mixture of gas/oxygen passing the O2 sensor make it read lean?
Michael Louie on a forum says that one time a lady had her tranny rebuilt and they dropped the engine and pulled on the O2 sensor(firewall side) and broke it, that didn't occur in my case because the main wire harness is not secure and there was plenty of play.
The cables are in pretty bad shape, all the boots pretty much were damaged and would allow for arcing, I black taped them and siliconed them up and the problem was pretty much exactly the same, so perhaps the core had been broken.
I will buy new cables and install them tomorrow, but I don't really think this will fix my problem.
So could they have damaged something else in my system like the fuel metering and injection system?
The only code I'm getting is 172, again and again. I installed everything with dieletric grease also, lots of people don't use it, isn't it pretty much required to keep moisture out and voltage contained?
Sorry for the lengthy question, I know you're busy.
I really appreciate the help you're willing to provide.
One day when I an expert, I'll want to share the wealth also ;o)
Thank you very much.
Sincerely,
David.
AnswerThe spark plug wires should be replaced and the ECM
memory should be reset. A scanner should then be used
during operation of the car. O2 data ahould be examined
during the trip, lean=rich chageover should be noted.
O2 sensor may need to be replaced. The ECM is leaning
the air-fuel ratio due to rough idle.
