Hey guys, first off I want to apologize for the length of this, I want to try to cover everything up front. Also I am a complete LS noob, this is my mother-in-laws car. Its a 2004 LS v6(3.9?) with right at 100k miles. I've been trying to tell her the mechanic she trusts so much was robbing her blind! Now that it's apparent, its my turn to fix everything lol. Im not 100% certain he replaced everything he said he did, but I can tell a few parts are new.
First off, im from the mustang side of things, so im blind to the electronics of "luxury" cars. Her now former mechanic(which be referred to as "he") has been telling her that nothing can be worked on unless its hooked up to a "computer" or it will wipe out(she called it "reset") the pcm. That's a new one to me, as we always want to reset the pcm after a mod or replacement part. Everything from changing spark plugs to changing the battery. I want to call bs, but these newer electronics have come a long way. I also noticed a dealer reflash update sticker under the hood warning not to reflash it. So can I unhook the battery to clear the codes and replace parts without killing anything? This is the first thing I'd like to know before anything.
It started with a cop problem about 3 yrs ago. She took the car to her mechanic, and there have been ongoing problems ever since. All of them being cel, bad gas mileage, and rough running in general. Every so often it would mess up, and she'd take it and he would say it was something else. I could tell there was a root of it all when she cleaned her windshield at the gas station, and 1/2 mile later it started running bad. The mechanic told her it was the cats/o2 sensors this time. He cut the cats out and welded in some universal ones, but can't tell if the o2's were changed. He charged $1700 for that. Shortly after that I noticed that the coil covers were completely taken off(prolly so he could keep taking her money). She took the car to a decent general repair tire shop to have some put on. She didnt have them check anything, only went in and said, I need new coil covers put on."
It was around 40* when I started the car. It idled low and horrible. It doesn't stall out, but gets dang close. Throttle input does nothing, doesn't even make a change in rpm's. After a minute or 2 it smooths out some, but still rough at idle. Once in drive, after u manipulate the throttle to where it would go, it smooths out. Only does this when the engine is cold(and cold outside). After i got home i let it cool, then went out to start it. Not near as bad as when it was cold outside, throttle input worked, just had a rough and low idle for about 30 seconds. Once warm it is alot better, but still has a misfire at idle, and sounds a little rough accelerating. Terrible mpg's
When I scanned for codes, there were a total of 14. The 2nd set of codes repeated the first 7. The guy at the autoparts store said they couldn't clear them. I dont know if his scanner wouldn't do it or a company policy or what. Heres the codes as listed:
P0300- Random misfire
P0301- cyl #1 misfire
P0316- misfire on 1st 1,000 revolutions
P0420- bank 1 cat below threshold
P0430- bank 2 cat below threshold
P2195- bank 1 upstream o2 function
P2197- bank 2 upstream o2 function
Im not going to just start throwing parts at it hoping to fix something. If I can unhook the battery, I want to reset the pcm, and have them scanned again. The misfire codes makes me think there's a bad cyl #1 cop. If there is, Im going to replace all of them, and replace the plugs. Don't know if it's the same with the LS, but in the mustang world new cop/old plug always causes problems later. The fact that it runs worse when cold outside make me think the cop is straining. I can test those without problems. I will replace the VC gasket at the same time just because. Am I right by thinking that's where I should start? Would it be bad to get generous with dielectric grease in the plug holes and boot lip? I also planned to seal the coil covers really good with silicone. Good or bad idea? Which plugs should I get, and should I gap them on the lower end of recommended plug gap? The next codes are o2/cat problems. Her shady mechanic replaced that about 3 months ago. I've heard of rich/lean conditions and misfires killing them, but would it be that fast? Possible those codes were triggered because of the misfire problem? What should I be looking for with that? Can anyone point me in the right direction to get this thing back right. Im fixing this while she's on vacation as a surprise. Not even gonna tell her I fixed it until after a few days. I have a week to fix it before she gets back! Anything else that suggested to replace or check out while Im doing it? Here's a list of parts that I'm 100% sure were replaced:
Catalytic converters with universal weld in cats. The weld is right up to the upstream 02 bungs(possibly a problem?)
MAF sensor
Coil covers
Im on the fence about the o2's, they somewhat look new, but at the same time there looks like way too much rust/buildup where they thread in the bungs. Once again, sorry for the length post, i just wanted to be detailed about it. Any suggestions and LS specific things i should know are appreciated. For those of you who take the time to read this and reply, thanks a bunch!
First off, im from the mustang side of things, so im blind to the electronics of "luxury" cars. Her now former mechanic(which be referred to as "he") has been telling her that nothing can be worked on unless its hooked up to a "computer" or it will wipe out(she called it "reset") the pcm. That's a new one to me, as we always want to reset the pcm after a mod or replacement part. Everything from changing spark plugs to changing the battery. I want to call bs, but these newer electronics have come a long way. I also noticed a dealer reflash update sticker under the hood warning not to reflash it. So can I unhook the battery to clear the codes and replace parts without killing anything? This is the first thing I'd like to know before anything.
It started with a cop problem about 3 yrs ago. She took the car to her mechanic, and there have been ongoing problems ever since. All of them being cel, bad gas mileage, and rough running in general. Every so often it would mess up, and she'd take it and he would say it was something else. I could tell there was a root of it all when she cleaned her windshield at the gas station, and 1/2 mile later it started running bad. The mechanic told her it was the cats/o2 sensors this time. He cut the cats out and welded in some universal ones, but can't tell if the o2's were changed. He charged $1700 for that. Shortly after that I noticed that the coil covers were completely taken off(prolly so he could keep taking her money). She took the car to a decent general repair tire shop to have some put on. She didnt have them check anything, only went in and said, I need new coil covers put on."
It was around 40* when I started the car. It idled low and horrible. It doesn't stall out, but gets dang close. Throttle input does nothing, doesn't even make a change in rpm's. After a minute or 2 it smooths out some, but still rough at idle. Once in drive, after u manipulate the throttle to where it would go, it smooths out. Only does this when the engine is cold(and cold outside). After i got home i let it cool, then went out to start it. Not near as bad as when it was cold outside, throttle input worked, just had a rough and low idle for about 30 seconds. Once warm it is alot better, but still has a misfire at idle, and sounds a little rough accelerating. Terrible mpg's
When I scanned for codes, there were a total of 14. The 2nd set of codes repeated the first 7. The guy at the autoparts store said they couldn't clear them. I dont know if his scanner wouldn't do it or a company policy or what. Heres the codes as listed:
P0300- Random misfire
P0301- cyl #1 misfire
P0316- misfire on 1st 1,000 revolutions
P0420- bank 1 cat below threshold
P0430- bank 2 cat below threshold
P2195- bank 1 upstream o2 function
P2197- bank 2 upstream o2 function
Im not going to just start throwing parts at it hoping to fix something. If I can unhook the battery, I want to reset the pcm, and have them scanned again. The misfire codes makes me think there's a bad cyl #1 cop. If there is, Im going to replace all of them, and replace the plugs. Don't know if it's the same with the LS, but in the mustang world new cop/old plug always causes problems later. The fact that it runs worse when cold outside make me think the cop is straining. I can test those without problems. I will replace the VC gasket at the same time just because. Am I right by thinking that's where I should start? Would it be bad to get generous with dielectric grease in the plug holes and boot lip? I also planned to seal the coil covers really good with silicone. Good or bad idea? Which plugs should I get, and should I gap them on the lower end of recommended plug gap? The next codes are o2/cat problems. Her shady mechanic replaced that about 3 months ago. I've heard of rich/lean conditions and misfires killing them, but would it be that fast? Possible those codes were triggered because of the misfire problem? What should I be looking for with that? Can anyone point me in the right direction to get this thing back right. Im fixing this while she's on vacation as a surprise. Not even gonna tell her I fixed it until after a few days. I have a week to fix it before she gets back! Anything else that suggested to replace or check out while Im doing it? Here's a list of parts that I'm 100% sure were replaced:
Catalytic converters with universal weld in cats. The weld is right up to the upstream 02 bungs(possibly a problem?)
MAF sensor
Coil covers
Im on the fence about the o2's, they somewhat look new, but at the same time there looks like way too much rust/buildup where they thread in the bungs. Once again, sorry for the length post, i just wanted to be detailed about it. Any suggestions and LS specific things i should know are appreciated. For those of you who take the time to read this and reply, thanks a bunch!
