Post by ES_97Sport on Jul 10, 2015 17:45:43 GMT -5
So, four years of rebuilding ... I finally got the exhaust replaced (OEM down pipes, CAT and elbow before the muffler and 2.25" w/Flowmaster after) and picked up (but didn't install) a pair of new OEM O2 sensors to replace the ones in there now. Everything in the vehicle that's related to engine management has been replaced with new OEM in the last year.
Running like a top, except ....
I had a weird, intermittent 'delay' when pressing on the gas from a stop or letting off the gas. I've seen this before with improperly adjusted - or plain worn out - TPS. 'Cept, I just replaced it and had it adjusted twice by two different people - that wasn't it. So, what do you look at when EVERYTHING is NEW??? In addition to this, it seemed to idle a little rough sometimes. OH, and the exhaust was kinda smelly intermittently - which I figured would go away after the new CAT was install, but didn't. Everything was very intermittent.
Over the years the CAT has been replaced several times as have the O2 sensors. When we replaced the CAT the last time, it was with a different CAT that relocated the bung for the rear O2 sensor. The OEM O2 sensor wiring wasn't long enough to reach and the rear sensor was dead. I didn't want to put in another aftermarket one because those weren't working for me.
I had plans to replace the entire exhaust but that time was a ways in the future. So, I figured no problem, I'll extend the harness. That's easier said than done. The wire is stainless - not copper - so its very difficult to solder. That explains why I've always read and been told this is a stupid idea. While difficult, its not impossible. I extended the harness eventually and put everything together. Been driving on that for a while now.
Yesterday, during a brief reprieve from the crappy rainy weather, I crawled under the big Sport and replaced the rear O2 sensor with a new OEM - unhacked - sensor. Second to last thing I need to do before I'm officially done with 4 years of reconditioning. (didnt' have time to replace the front O2 sensor)
Anyway, started it up, let it idle for 10 minutes and then took off to work. Didn't pay much attention. Parked at work for the day, took off last evening to drive home. Hmmmmm. Running a little 'funny'. Not bad exactly, just a little different. Still didn't pay a lot of attention. Got up this morning for work, started it up and sat for 5 minutes while searching for an address and then took off. Ah, yes. By the time I got 30 miles to the dealership it was definitely running 'different'.
No smell. No hesitation. No rough idle. Absolutely nothing. Runs EXACTLY like my '03 3.5L. Glass smooth and dead quiet. Took it from 60 to 85 degrees, highway and town - same behavior. Perfect.
Which all makes sense and is why I wouldn't have ever done this if I had a choice and absolutely never would have done this if I needed a permanent solution. O2 sensors are ultra sensitive pieces of equipment and changes in resistance in the harness is going to totally skew the reading from the sensor itself. So, at least the behavior is explainable.
This, yet again, IMHO, clearly demonstrates that the rear O2 sensor IS used in fuel trim calculations, too. Contrary to what all the Mitsu techs claim.
Something I thought I'd pass on before the weekend. Ok short term solution if you're desperate, but that's all. I'm pretty sure it wouldn't have passed emissions even though it never did trigger CEL or pop a code.
Edward
Running like a top, except ....
I had a weird, intermittent 'delay' when pressing on the gas from a stop or letting off the gas. I've seen this before with improperly adjusted - or plain worn out - TPS. 'Cept, I just replaced it and had it adjusted twice by two different people - that wasn't it. So, what do you look at when EVERYTHING is NEW??? In addition to this, it seemed to idle a little rough sometimes. OH, and the exhaust was kinda smelly intermittently - which I figured would go away after the new CAT was install, but didn't. Everything was very intermittent.
Over the years the CAT has been replaced several times as have the O2 sensors. When we replaced the CAT the last time, it was with a different CAT that relocated the bung for the rear O2 sensor. The OEM O2 sensor wiring wasn't long enough to reach and the rear sensor was dead. I didn't want to put in another aftermarket one because those weren't working for me.
I had plans to replace the entire exhaust but that time was a ways in the future. So, I figured no problem, I'll extend the harness. That's easier said than done. The wire is stainless - not copper - so its very difficult to solder. That explains why I've always read and been told this is a stupid idea. While difficult, its not impossible. I extended the harness eventually and put everything together. Been driving on that for a while now.
Yesterday, during a brief reprieve from the crappy rainy weather, I crawled under the big Sport and replaced the rear O2 sensor with a new OEM - unhacked - sensor. Second to last thing I need to do before I'm officially done with 4 years of reconditioning. (didnt' have time to replace the front O2 sensor)
Anyway, started it up, let it idle for 10 minutes and then took off to work. Didn't pay much attention. Parked at work for the day, took off last evening to drive home. Hmmmmm. Running a little 'funny'. Not bad exactly, just a little different. Still didn't pay a lot of attention. Got up this morning for work, started it up and sat for 5 minutes while searching for an address and then took off. Ah, yes. By the time I got 30 miles to the dealership it was definitely running 'different'.
No smell. No hesitation. No rough idle. Absolutely nothing. Runs EXACTLY like my '03 3.5L. Glass smooth and dead quiet. Took it from 60 to 85 degrees, highway and town - same behavior. Perfect.
Which all makes sense and is why I wouldn't have ever done this if I had a choice and absolutely never would have done this if I needed a permanent solution. O2 sensors are ultra sensitive pieces of equipment and changes in resistance in the harness is going to totally skew the reading from the sensor itself. So, at least the behavior is explainable.
This, yet again, IMHO, clearly demonstrates that the rear O2 sensor IS used in fuel trim calculations, too. Contrary to what all the Mitsu techs claim.
Something I thought I'd pass on before the weekend. Ok short term solution if you're desperate, but that's all. I'm pretty sure it wouldn't have passed emissions even though it never did trigger CEL or pop a code.
Edward