Hello,

About two months ago I disconnected my 12v battery and my hv battery in order to replace the hv battery fans (both fans had thrown error codes and I had had a couple of "stop safely now" incidents coupled with a complete loss of power that was resolved with a key cycle). Since then the vehicle's performance has been markedly improved - EXCEPT that when it is cold every 45 seconds or so it has trouble maintaining idle - rough sounds and rumbling with sudden rpm surges and drops. Sometimes stomping on the gas will help it through the rough spot - sometimes it does nothing. Maybe every other time or every third time it will stall (red triangle of death/stop safely now). It will also stall while traveling (at least a low speeds - I only really drive in a city - so basically like 20-40 miles per hour. More recently it has begun also doing it even when warmed up.

One positive thing is that when before I replaced the battery fans when it stalled the vehicle would lose all power. Now, while the engine shuts off, the vehicle retains electric power and I can at least pull over somewhat safely. A key cycle will resolve the issue (at least temporarily) and allows the vehicle to be driven again.

My supposition is that when I disconnected the 12v battery to replace the hv battery fans, the computer forgot strategies it had learned to compensate for sludge in the throttle body. I read about the re-learning process and spent 20 minutes idling with the defrost on to help it relearn. I also drove it a couple times a week for more than a month, thinking that that would help it relearn. However at the end of last week cylinder 2 and 4 misfired, and it threw these error codes: P1000-FF, P1A0C-FF, P2195-P, P0300, P0302, and P0304. Interestingly it was also idling worse in neutral than in park - I don't know why.

At that point I decided I needed to clean the throttle body - and I did that this weekend. It was very dirty and downstream from it was also dirty - black greasy sooty stuff - I wiped it out as well as I could with a rag before reconnecting the newly cleaned throttle body). I also cleared the computer memory by disconnected the 12v battery for a couple of hours. After I started it back up it purred like a beauty for 80 seconds then again couldn't maintain idle - jerked, rpm up and down, then stalled. P2195 (1st O2 sensor biased/stuck lean). Went through 3 more cycles of starting - idling fine, then stall. I opened the hood and noticed that when it has trouble idling the whole area near and above the throttle body shudders. Finally it started, ran fine, I put it on defrost and let it sit for 20 minutes, then drone it about a mile - no problems - ran great - in and out of ev mode appropriately (while driving), etc. No stalls. I thought that everything had been re-learned and the problem was solved.

Then I waited a few hours till it was cool, went out, started it up, waited ~ 60 seconds - jerking, cylinder misfire (P0302), stall. Cleaning the throttle body doesn't seem to have solved my problem.

I feel like my problem must be related to something the computer forgot when I originally disconnected the 12v battery to replace the hv battery fans (since that's when my current problem began - the problems I previously had with the hv system system seems to have been resolved by replacing the fans). Given the other information on this forum, it seems like the throttle body sludge compensation strategy is likely to have been it. But cleaning the throttle body doesn't seem to have solved it. Could I have damaged the O2 sensor by driving it with the throttle body issues? Do I need to replace the throttle body entirely? Could I have a problem with the mass airflow sensor? Something else entirely?

I'd appreciate any advice the experts here can give me. I thought that cleaning the throttle body would solve this, and now I'm confused as to what might be my underlying problem.

Thanks!

 

Step 1 with P030X is new spark plugs.
Step 2 is new coil on affected cylinder(s).

 

Thank you! I had been thinking that the misfires were caused by the problem I seem to be having with my airflow system (throttle body, O2 sensor, other?) screwing up the air/fuel ratio. Does that not make sense? Or is it possible that that problem then caused a problem with either my spark plugs or my coils? Or do you think I coincidentally have a spark plug or two going bad on top of my other issues? To clarify the sequence of events - I had stalling problems and code P10AC and P2195 well before I had any codes indicating a misfire.

Thanks for your advice.

 

Unless you're certain that the correct long-life plugs were installed at the proper maintenance interval, and you've visually confirmed that the plugs are not physically damaged or improperly gapped, then they should likely be replaced.

P030X in isolation is almost always a bad spark plug.

 

Thanks. That's helpful. I've been so convinced that it was an airflow issue that the spark plugs did not occur to me. Do you think that they could have been causing my stalling, and the P1A0C and P2195 codes that I was pulling before the misfires began? Or do I need to replace them to address the misfires, but will still need to track down the other issues?

If replacing the spark plugs resolves matters, I'll report back - although I probably won't get to it until the weekend.

 

P2195 - replace O2 sensor
P030X - replace spark plugs, maybe coils
P1A0C - engine disabled - may result from the above two or other issues.
P1000 - you get this any time you disconnect the battery.

Cleaning the TB may have been warranted, but the codes are telling you to replace the O2 sensor and spark plugs.

NTK 22012 is the replacement upstream O2 sensor, $30.
You might need an O2 sensor socket for about $10.
AUTOLITE XP104 are Iridium plugs for your car - $20 for all 4.

I would replace all of the above and then reassess the condition of the vehicle.

How are you reading codes?

 

Thanks for the parts list - that will save me some looking!

I was initially using Forscan, but my laptop charger broke last week so was using an old simple click through OBD-II reader this weekend (so everything I read after cleaning the throttle body). I've ordered a new charger and will run Forscan again once it's here.

I feel reasonably confident that this was all prompted by my having disconnected the 12v battery when I replaced the hv battery fans. But you've convinced me that it's worth replacing the spark plugs and the O2 sensor assuming that doing so is within my abilities (I'll need to look up how, but I've replaced them on other cars in the past so I imagine I'll be able to) and then, as you suggested, reassessing. Maybe the computer was previously compensating for a slightly bad O2 sensor or some change in how it operated put stress on a spark plug that was already on its last legs.

I'm grateful for your help.

 

You need to get back to Forscan ASAP. Something more may be lurking beyond P1A0C.

Your theory on the disconnected 12V is pure speculation and almost certainly incorrect. 12V disconnect typically forces re-learn of multiple systems and corrects issues, not introduces them. You may want to go a step further and hard reset the PCM:

 

The theory on the 12v disconnect was just because all of my current problems started when I replaced the battery fans yet all of the error codes changed, as did the physical signs of problems. Before I replaced the battery fans I had error codes for both fans as well as associated error codes for the battery control module etc. Plus the vehicle rarely went into EV mode, when it stalled just died (i.e. complete loss of power), etc. After I replaced the fans, the vehicle goes into EV mode regularly, I haven't had any battery-related error codes, etc. - instead I got all new error codes - P1000-FF and P1A0C-FF almost immediately, and then after a few drives P2195. P0302, P0304, and P0300 didn't appear until the end of last week.

My read of the evidence suggests that replacing the fans solved my battery-related problem but that something I did then caused my current problems. And since the only thing I touched was disconnecting the 12v battery, and then the repairs to the hv battery - it seems like I must have triggered my new problems by disconnecting the 12v battery. I focused on the throttle body because I'd read that sludge in the throttle body could cause the P1A0C error code and the symptoms I was initially having, and because when it has trouble idling the area near the throttle body shakes. I'd also read that Ford provided a software based compensation strategy that the PCM could learn to deal with sludge in the throttle body - so I thought that perhaps disconnecting the 12v battery had caused the PCM to forget that compensation strategy - and thus created the problem.

Otherwise it's just coincidence, or some underlying problem having caused both the problems with the battery fans, and my current problem.

 

Iridium spark plugs work perfectly, right up until the moment the work like garbage. They typically last 100K+ miles, and few people replace them on time unless they're paying out the nose to a dealership, who will make sure they get done, so they can get your money.

I have had half a dozen cars exhibit exactly the above behavior - perfect, perfect, perfect, GARBAGE.

Same with O2 sensors.

If you got excessive TB cleaner into the intake, you could have pushed marginal components over the edge, but these codes occurred AFTER "two drives per week for a month" and before TB cleaning. The car is telling you "I have a problem with my O2 sensor and misfires." Your response to the car was "ignore DTC and clean throttle body."

Again, your 12V theory is purely speculative. It just doesn't work that way. You have a 15-16 year old vehicle that's mostly neglected (two drives per week for a month? Poor thing!). Crap happens. It's important that you listen to what the car says and respond accordingly - not just start guessing and doing things. There are codes for TB problems.

Again, get Forscan going again. You may have more going on. MANY OBDII readers miss much that the FEH may have to say.

Moving forward:

1) Address DTC until no more DTC.
2) Assess any remaining symptoms.