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Discussion Starter #1
It's time I make a post to try to figure out what is going on with my wife's 2005 Mercury Sable. I'm at the point where I am afraid I am throwing money at it and don't want to go further down that rabbit hole unless necessary.

(Quote from another post I made asking questions about a vacuum line) For a little bit of background information: She has had the car for a few years now but recently started throwing codes P0302 & P0316. If I clear the codes it doesn't throw them again unless it's been sitting, usually after sitting all weekend. You can feel it misfiring and running rough at cold start but once it warms up the misfiring goes away and runs/accelerates very smoothly. I had to change the valve cover gaskets so I also replaced the coils, plugs, intake manifold gaskets and cleaned the EGR while everything was apart thinking that would solve the problem. Everything runs smoother than before, almost like new, but after sitting it's the same problem, 302 & 316.)

Fast forward to the last few weeks it was running rough randomly. Usually when I first start it up after coming out of a store. Yesterday I got a code P0171, which I read was Fuel Trim System Lean Bank 1. Cleaned the MAF with MAF cleaner. Reinstalled the MAF this morning and the car started fine. We drove to the gas station and it started fine afterword, but the idle was a little rough. Went to the grocery store on our way home and when we came out and started the car the idle was very rough. If I gave it any gas it would die. It would start back up but idle really roughly and die. I let it sit for about ten minutes then started it again to find that it had a rough idle but would run. Drove home fine with no CEL on at all.

I really figured with it running that rough and stalling it would have thrown a CEL for something but no. I could not find any visible vacuum leaks but plan to spray some MAF cleaner around once the rain stops. My next step was going to be ordering new fuel injectors but I wanted to hear some feedback before I keep throwing money at it. Any help you can offer would be greatly appreciated.
 

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How old is the battery and what is the voltage BEFORE starting the car in the am?
The battery is less than a year old, but I will check the voltage after it has sat overnight and report back.

I'm reading another post about the idle air control valve now. Starting to wonder if that might be a possibility.
 

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Discussion Starter #5 (Edited)
I replaced the upper but not the lower because I never removed the lower intake manifold when I did the valve covers.

The voltage was at 12.48 this morning. I cleaned the IAC valve this morning, it was a little bit dirty but not too bad. The plunger moves smoothly.

As soon as I started it CEL came on. Code P2195. Cleared it to make sure it wasn't a fluke but a quick five minute drive and it came right back.

Looks like the O2 sensor is no good, this indicates bank one position one correct? That's the one between the rear valve cover and the firewall right? I have fused vertebrae in my neck from a previous surgery and really am not looking forward to pulling the upper intake manifold again.

Edit: I just noticed that it pushed power steering fluid out of the reservoir for some reason during this short drive.
 

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Discussion Starter #6
Cleaned up the power steering fluid and took it for another ride. It didn't push any fluid out of the reservoir so I think that is just from when I turned the wheel while it wasn't running the other day when I was stuck in the parking lot of the grocery store.

It was running a little rough though and Code P2195 came back so no more running it until I change the O2 sensor. I think I am going to order the fuel injectors since I have to take the UIM off again anyway. I just hope that it fixes the problem.
 

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Cleaned up the power steering fluid and took it for another ride. It didn't push any fluid out of the reservoir so I think that is just from when I turned the wheel while it wasn't running the other day when I was stuck in the parking lot of the grocery store.

It was running a little rough though and Code P2195 came back so no more running it until I change the O2 sensor. I think I am going to order the fuel injectors since I have to take the UIM off again anyway. I just hope that it fixes the problem.
P2195 Cause
  • Frayed oxygen sensor circuit wiring/connectors
  • Faulty heated oxygen sensor bank 1
  • Malfunctioning fuel injector
  • Vacuum leaks
  • Fuel pressure too high/low
From the internet quote.


-chart-
 

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Discussion Starter #8
P2195 Cause
  • Frayed oxygen sensor circuit wiring/connectors
  • Faulty heated oxygen sensor bank 1
  • Malfunctioning fuel injector
  • Vacuum leaks
  • Fuel pressure too high/low
From the internet quote.


-chart-
Thanks. Too many things are suggesting that the injectors could be the culprit, so they are going to be changed along with the O2 sensor. I don't know how old they are anyway so it's just a good idea.

If the fuel rail pressure is reading within the proper range via obd2 can I assume that the fuel pump is okay?
 

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Thanks. Too many things are suggesting that the injectors could be the culprit, so they are going to be changed along with the O2 sensor. I don't know how old they are anyway so it's just a good idea.

If the fuel rail pressure is reading within the proper range via obd2 can I assume that the fuel pump is okay?
Fuel pump issue will cause both banks to have the same problem.


-chart-
 

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Discussion Starter #10 (Edited)
So, I am getting frustrated.

Removed the UIM again. Replaced the O2 sensor and all six injectors. Drove it for a week now.

Results: CEL for the O2 sensor has not come back. In fact no new CEL since this last service. Twice now though I have had it drop RPM's really low and almost stall. Once was just after putting everything back together on the third start, RPM's dropped low for about two seconds felt like it was running out of fuel then cleared up and idled fine so I thought maybe just a fluke. Then again yesterday after coming out of a shop. Started fine then RPM's dropped really low felt like it was going to stall for about three seconds or so then back to normal (weather was hot and dry at the time). In between all of this everything felt pretty good. No CEL still.

It's the random nature of it that is driving me nuts. If it was a vacuum leak I would imagine it would do it all the time, not just randomly then back to normal. I could be wrong though as it would be far from the first time.

I screen captured a few LTFT from the OBDII app on my phone at idle and around 2500 RPM and noticed bank one and bank two are a bit different but I don't know what they should be at when running properly. What should my RPM's be at idle?

So far I have:

Replaced: Injectors, Ignition Coils, Spark Plugs, EGR Pressure Feedback Sensor (Plastic hose connections broke), EGR gaskets, UIM gaskets, PCV valve, Fuel Filter and probably more that I am forgetting

Cleaned: EGR, MAF, Throttle Body and IAC

I also sprayed MAF cleaner all around the engine bay while at idle with no changes in RPM that I could notice.​

:unsure:
 

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Discussion Starter #11
I did some further searching and reading on here (what a great resource) and discovered a post explaining the smoke test procedure and decided to give it a try. From the best that I can make out I had smoke rise from two locations, from under the UIM and from under the battery tray.

I tried my best to see where the smoke was coming from exactly but couldn't tell if it came from under the UIM or LIM. I have changed the UIM gaskets twice now in the last few months so I am assuming that it is coming from the lower since I didn't change those yet.

Before I tear everything apart again I have a few quick questions, I'm hopeful that this will be my last time doing this.

1. How difficult is it to remove the LIM?

2. Can I get away with re-using the fuel injector seals? I normally would replace them but since I just put new seals on with the injectors about two weeks ago I figure they may still be fine.

3. At the part store they sold me AGSF-32WM as the suggested plugs when I did the tune up a few thousand miles ago, but I just read that I should have used AGSF-32FM, should I pull them and replace them with the AGSF-32FM instead?


Thanks for taking the time to answer my questions. I'm finding a lot of great information on here but I am learning as I go with very little time to actually work on things.
 

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If you have done the UIM, you can handle the LIM. I would also inspect very carefully for cracks in the manifold, in the vicinity of where you spotted the smoke. There is a good chance the new gaskets will fix your problem.
 

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Yea, the LIM isn't too much harder. Just have to purge the fuel line first by disconnecting the fuel pump fuse and running the engine until it dies. Disconnect the electrical to the fuel injectors is easy, but mine were brittle and the tabs had chipped off. The hardest part for me when I changed the LIM gaskets was I also pulled the fuel injectors to flush them and check them for leaks. Getting them out of the LIM was tricky. I ended up using a 12" clamp (like a wood clamp) to clamp onto one to get more leverage to pull it free. There's videos online that show how to hookup a plunger type ear syringe with some hose and clamps to flush and back flush the injectors. Just need a 12 volt battery pack and only flick the injectors on briefly or you'll burn out the solenoids. There's professional pulsers you can buy, but they're about $50 too.



*But*, have you tried renting a fuel pressure and volume tester gauge? If you have the schrader valve on the fuel line, it's very easy. You mentioned reading it off the OBDII port and I only have a $20 code reader, nothing fancy, so not sure how that compares. But you mention doing errands and coming out to a rough idling and starting car after being in the store briefly in this hot weather - hot soaking - a recipe for vaporlock. Keep in mind it's both pressure *and* volume flow rate that are needed. I had that problem last year, and new fuel pump helped tremendously, but this year replacing the alternator that was just about not wanting to turn anymore (and thus throwing way more friction at idle than the ECU would expect) was the other piece of the puzzle. So maybe renting a serpentine belt tool, and quickly removing the belt so you can hand test the pulleys to see if some are sticking. Doing both of these tests should be a lot less time than tearing down to the LIM.


Not leaking any power steering fluid either? Sounds unlikely for your symptoms, but it can cause it to buck more than be rough at idle.
 

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*But*, have you tried renting a fuel pressure and volume tester gauge? If you have the schrader valve on the fuel line, it's very easy. You mentioned reading it off the OBDII port and I only have a $20 code reader, nothing fancy, so not sure how that compares. But you mention doing errands and coming out to a rough idling and starting car after being in the store briefly in this hot weather - hot soaking - a recipe for vaporlock. Keep in mind it's both pressure *and* volume flow rate that are needed. I had that problem last year, and new fuel pump helped tremendously, but this year replacing the alternator that was just about not wanting to turn anymore (and thus throwing way more friction at idle than the ECU would expect) was the other piece of the puzzle. So maybe renting a serpentine belt tool, and quickly removing the belt so you can hand test the pulleys to see if some are sticking. Doing both of these tests should be a lot less time than tearing down to the LIM.


Not leaking any power steering fluid either? Sounds unlikely for your symptoms, but it can cause it to buck more than be rough at idle.
Thanks for the replies! The Haynes manual says I have to check the fuel pressure via OBDII port on the 2005 so I checked the fuel rail pressure previously and it was always within the limits that I found on the internet. My code reader is an inexpensive one as well that connect's via bluetooth but it works great, I bought it for my Nissan back when it had an OBDII compatible engine still in it and I am glad I held on to it as it's been very useful so far. The alternator was replaced about a year and a half ago, but when I have the car apart next I will check it. That's a great idea that I wouldn't have thought of.

Here's an update: I haven't done the LIM gasket yet, but the set is in the mail from amazon and should arrive soon. Even though the IAC did't show signs of leaking during the smoke test I decided the gasket looked a bit old and since it was a cheap gasket I pulled the IAC and replaced it. I read about oiling the plunger in the IAC after cleaning it and since I didn't do that previously I did it while it was off.

For about 900 miles everything was great, the rpm's at idle were a little bit higher (felt more stable) and the miss was gone. Until yesterday. Just before I dropped my wife off at her work I mentioned to her how great the car was running and less than five minutes after I dropped her off it started to misfire again. While sitting at a light I quickly connected my phone to the OBDII connector and had it monitor the drive home. Once home I let it idle and within a few minutes the misfire started again and felt as if it was running out of gas and stalled. I let it sit a minute started it back up to find it had thrown CEL.

Codes P0171 and P0174. I had ruled out the fuel pump because it was always on bank one, but for the first time after this stall the codes indicate lean in both banks. Cleared the codes and started up, and for the last day everything, including idle, feels smooth again. That's strange to me because from personal experience either worked or didn't, but I am reading that intermittent fuel pump problems are not uncommon.

Then while I was looking around in the OBDII app I realized that as long as I was connected it recorded all sensor data! So, I am including a screen capture of my LTFT for both banks and fuel pressure during the event. I should have plenty of other sensor data if anyone thinks anything else would be useful to see. I am also keeping the connection going every time I drive it until this is figured out that way if an event happens again I will have data to review.
 

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fuel pressure always jumps around a few psi so I dont see an issue there. From the LTFT numbers it looks to me like you have a vacuum leak that effects both banks you havent found yet.
 

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Fuel pressure seems normal but fuel trims way too high usually 5% or less. Agree with above on vacuum leak. PCV or any hose that connect to manifold near the throttle body. Those affect both banks.
 

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Fuel pressure seems normal but fuel trims way too high usually 5% or less. Agree with above on vacuum leak. PCV or any hose that connect to manifold near the throttle body. Those affect both banks.
Chart of a well running '01 DOHC as example. What is important is at idle the trims should be similar and equal to or less than under power trims. This the opposite of a vacuum leak chart. Leak will cause much more positive at idle than under power.


-chart-
 

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