I read a lot around the forums and found many similar problems, but none quite exactly like mine.
It all started with a slight stutter when the engine was running at low rpm's or when idle. I noticed that sometimes while driving on a highway at around 60 mph, if I stopped accelerating (just let go of the pedal), the engine would sometimes stall completely (shut off).
The problem was random. Sometimes the engine would stutter when idle, sometimes it would run smoothly. Every once in a while, when the engine stuttered, it would stall completely as well.
When idle, tapping on the accelerator once to make the rpm's increase would increase the chances of the engine stalling when the rpm's decreased again.
The problem seemed to be less occurring when the A/C was turned on, as the rpm was slightly higher than when it was off. The engine would still stutter, but rarely stall.
Eventually, the problem got worse to the point that every single time the engine is either idle or at low rpm, the engine stutters heavily and often stalls, unless you accelerate it even if just a tiny bit.
Last Thursday, I was checking out the engine with my dad. We were thinking about uncovering the air filter when two pricks mugged us
Right before that, we had disconnected a cable from the air filter. I have no idea what it is. I saw two connectors close together, we had removed the upper one.
After the incident, we decided to move the car back into the garage and just quit checking it. At the moment, we didn't realize the engine didn't stutter...
Next morning, after realizing the above mentioned, I did some testing. The engine would stutter with the cable connected, but not with the cable disconnected. I was happy because I thought I had found a workaround.
Later, we noticed that even though the engine didn't stutter, once in a while it would suddenly stall completely. When it did, it was hard to turn the engine back on, and when it did, it would stall again in less than 3 seconds unless we revved the engine a bit. Then it would work "normally" again at either idle, low rpm or high rpm. I did notice that when trying to start the engine, sometimes (rarely) I could hear a loud, deep and somewhat hollow thud coming from the engine. It seemed to come from the air filter, like something was exploding in there.
The engine was making a rattling noise. We checked the oil and it was very low, so we bought some and filled her up. I'm pretty sure I poured a tiny bit too much oil (oops). A few miles later, the engine began stuttering VERY heavily (more than ever) at low rpm's and almost always stalling when idle.
At this point, whether or not the cable from the air filter is connected makes no difference at all. Again, this ONLY happens at low rpm's or when idle. Otherwise, the engine runs pretty darn good and pretty darn fast.
I tried tapping what I think are the IACS and TPS, as I read something about that, but no change is noticeable.
Another question: The O/D function is not working. Thankfully, I can't switch it off (it would be bad if I couldn't switch it on, eh ?
). Any ideas on this ?
I've seen how great you guys are at giving advice. I can only hope for the best. I love my Sephia, and I hate that it's going through this. I am aware I haven't given my car the maintenance it deserves. I've given it NO maintenance actually, for economic reasons. This only shows me how great this car is. No maintenance and yet this is the only major problem it has.
Thank you all in advance. I'm sorry I made such a long post, but I'm trying to give as much detail as possible to get more accurate answers.