Leaking or Sticking Injectors, fuel system issues anyone?

[sbutler83]

I have a 2003 Mercury Marauder with 60,000 miles on it I am working on for a friend. He has a rhythmic rough idle, that almost feels like a bit of a knock. The engine is not detecting a miss, and the idle sounds good but the car shakes a bit.

After learning on these forums that this is a common issue with these cars, I am wondering if anyone has found issues with, or positively ruled out, a leaking injector, sticking injector, or any other type of fuel system problem as a cause or contributing factor.

The P1158 code was not locked in and the check engine light was not on, I had to use autoenginuity to extract it and i'm not sure exactly which test got it.

This is my first time working on a Marauder, but I have a wealth of experience on a lot of other FoMoCo Products, gas and diesel.

[SpartaPerformance]

That codes is for lack of switching HO2S bank 2 sensor 2 stuck rich, I don't think it would be an injector issue but I would follow testing procedures for that code and see where it takes you.

[sbutler83]

Trouble Code: P1158


Lack of HO2S-22 Switching, HO2S Signal High Input
Possible Causes:
-Check air cleaner element and air cleaner housing for blockage -EVAP vapor recovery system has failed (canister full of fuel)
-Fuel pressure too high, contaminated or leaking fuel injectors
-HO2S is fuel contaminated, or coated with silicone or moisture

A leaking fuel injector is a great way to fuel foul an oxygen sensor. If it plugs, it would cause it to read lean and overfuel, which would start attacking the cat and cause the downstream sensor to peg rich.

It is just hard to fathom that I have a faulty fuel injector or BPR at 60K miles if nobody else has had one, that's why I ask.

I request input from all on here because I really had to dig with a scan tool to produce this code. If you think about it, a leaking injector (or injector over-injecting due to higher than normal pressure upstream) would smooth out if you raised the idle speed, which I have seen a lot of people on here doing.

In addition, if it was due to a misfire to the extent it produced a rhythmic shake, it would be high enough that it should be detected by a threshold limit to trigger a bank rich code.

Now I do realize as well that this could be due to the high performance flow design and a possible design defect with too low of an idle speed to have sufficient air velocity in the intake runner to properly atomize the fuel in one or multiple cylinders. This is additionally a possibility that could cause similar symptoms and be cured by raising idle speed, especially if it is a cylinder that has the most restricted flowpath, but in either case the prolonged result would be a fouled oxygen sensor leading to a stressed catalytic converter, and a downstream sensor saying that the sytem is rich but possibly not to the threshold of setting a code yet.

[sailsmen]

Injectors are like light bulbs you never know when they will go out. I had one that was totally intermitten for 3.5 years.
It could do it 5 times a day and then nothing for 6 months. Finally it went out long enough to figure it out, fortunately while the tech was on a test drive and continued until he got to the shop.:)

[EMAS]

A rolling idle is usually caused by a idle air control motor that is failing. However the always rich code could mean that yes indeed there is an injector on that side that is leaking. However since it hasn't set a "hard" code that is suspect. What are the fuel trims? Have you watched th O2 data when it's acting up?

[sbutler83]

EMAS, I believe the fuel trim on the problem side (driver's side) was at 99.x and the other was around 0. I should have recorded the data but I could reverify tomorrow.
Although now that you mention it, I think you are on to something with the IAC, the car stalled twice while we were loading it onto the car trailer returning to idle while in gear. I'll have to do some testing with returning the car to idle, pull it off, and clean it and see what happens. I saw some threads on here that people have had success cleaning them, would you concur?

Thanks for the reply.

[EMAS]

Cleaning them certainly fixes them sometimes, other times it doesn't but cleaning it is definitely cheaper than replacing it.

[sbutler83]

This turned out to be the engine losing compression on Cylinders 6 and 7 due to a valve issue.