JakePSD
Well-Known Member
- Joined
- March 25, 2010
- Messages
- 402
- Reaction score
- 1
- City, State
- Ohio
- Year, Model & Trim Level
- 2003 Mercury Mountaineer
I'll give you guys my symptoms and we'll see if you all think I'm right. For a few months now my 2003 4.6L Mountaineer has been having a hesitation at certain RPM and throttle input. It first started a few months ago, shortly after I got it back on the road after an engine swap. I know little about the history of the truck prior. I bought it cheap because the engine was tied up. Anything over about half throttle it would hesitate real bad and just had no power. I attributed it to old gas since it'd been sitting for well over a year. I filled it up from empty with premium fuel and dumped a container of injector cleaner in it and took it out for a good ol' Italian tune up. It seemed to get better but never fully went away. No SES at this time. I just decided to drive it until it got worse so I could actually pinpoint the problem. Since then I have changed the fuel filter also.
Since then it would intermittently run rough for a minute or so on a cold start, along with still having some hesitation at mid throttle. WOT usually will hesitate for a second or so, then smooth out and run fine. Some days though it runs perfectly fine with no miss or hesitation.
Fast forward to last week. Finally got an SES, P0152. Reset it and went about my day. This morning I was able to learn a bit more about it. I had no SES on last night when I parked it. This morning when I started it, it idled rough for a minute or 2, then smoothed out. Put it in gear and started driving and within seconds the SES came on.
This is where you guys come in. My thinking is that I have a weak coil(s) on bank 2 causing an incomplete burn and loading the manifold up with partially burnt fumes, then when I start driving, the added exhaust flow forces all of that past the the O2 sensor showing a rich condition. Once I clear the SES it stays off for the remainder of the drive. Am I on to something? Or am I dumb and it's something else?
What is a good way to test coils? I'd rather not spend a bunch of money on new coils if it's only one or 2. Plus I have a parts truck I can yank coils out of to replace the bad one(s). Fuel pressure has also ran across my mind a few times. Is there any special fitting to temporarily hook a fuel pressure gauge to the schrader valve on the fuel rail? Is there any reason while doing this I couldn't use an oil pressure gauge since that's what I have laying in the shop? I mean it just shows pressure right? The only difference would be that one says "oil" and the other says "fuel" right?
Since then it would intermittently run rough for a minute or so on a cold start, along with still having some hesitation at mid throttle. WOT usually will hesitate for a second or so, then smooth out and run fine. Some days though it runs perfectly fine with no miss or hesitation.
Fast forward to last week. Finally got an SES, P0152. Reset it and went about my day. This morning I was able to learn a bit more about it. I had no SES on last night when I parked it. This morning when I started it, it idled rough for a minute or 2, then smoothed out. Put it in gear and started driving and within seconds the SES came on.
This is where you guys come in. My thinking is that I have a weak coil(s) on bank 2 causing an incomplete burn and loading the manifold up with partially burnt fumes, then when I start driving, the added exhaust flow forces all of that past the the O2 sensor showing a rich condition. Once I clear the SES it stays off for the remainder of the drive. Am I on to something? Or am I dumb and it's something else?
What is a good way to test coils? I'd rather not spend a bunch of money on new coils if it's only one or 2. Plus I have a parts truck I can yank coils out of to replace the bad one(s). Fuel pressure has also ran across my mind a few times. Is there any special fitting to temporarily hook a fuel pressure gauge to the schrader valve on the fuel rail? Is there any reason while doing this I couldn't use an oil pressure gauge since that's what I have laying in the shop? I mean it just shows pressure right? The only difference would be that one says "oil" and the other says "fuel" right?