Starting issue...misfire?

[elspectro29]

When leaving work tonight the car had a weak sounding start, and when it started it ran lower than it normally does and sounded poor, and the CEL was on, so I turned the engine off after a few seconds. When I went to start it back up it was fine for the rest of the night. The battery is pretty old (it's dated 4/07, so the previous owner almost certainly put it in with the H22 swap in June 2007), but other times the car had a weak start it cranked fine. Given the CEL coming on I'm speculating this was a misfire, but are there any other possibilities?

[RedRacer]

Was the CEL just on steady or was it flashing? Flashing CEL usually is indicative of misfire or multiple misfires.

By ran lower and sounded poor, I'm assuming you're saying the engine was running rough and sounded as if it was "missing"?

A weak battery could contribute to a misfire and hence the poorly running engine.

Definitely time to get a new battery - low power at start can bugger up all kinds of things if done repeatedly over a period of time .... It sounds like a misfire and the weak battery could have contributed, especially if there are other weak links along the way, like bad or going bad injector or old wires and/or plugs, etc.

Misfires come in all sorts of varieties and can be caused by different things. For those who may not know, a misfire is when the cylinder gets the fuel but doesn't get the spark to cause combustion to return the piston. Can be caused by faulty plug leads or a bad coil, plug gone bad itself, bad ground, etc. AND, a misfire can be also be on the opposite plane -- You get a good spark but no fuel or not enough fuel to cause combustion. This kind of misfire can be due to a faulty injector or injectors, loose injector wire, fuel filter or line blockage, computer problem. A misfire can also be caused by lack of compression, dead cylinder, and even insufficient valve clearance which causes the valves to remain open, causing misfire -- lots of variables when it comes to this particular problem.

I'd start with the battery replacement anyway because it's definitely at the end of its useful life and is going to leave you stranded somewhere, probably sooner than later, with it being winter time.

Then I'd get the code history read. You'll know more and can go from there. If it's running OK now and doesn't do it again or start becoming a noticeable event, I wouldn't worry over it too much.

Spiffy will most likely have more concise input on this than I've given, he's more of a motorhead than I am and is filled with vast and great knowledge. We're tempted to name hims Spiffy Yoda instead of Guido.

Let us know what you find out. Always helpful to others who might have the same problem to know what your resolve was.

[spiffyguido]

Hey elspectro. Great to see you on here again. Sorry to hear about your latest mishap.

RedRacer has given some great advice. I'd start with following up on his comments. Modest as he is, RedRacer is certainly a 4th gen expert and has provided some great tips.

I'll second the notion that you should have the battery checked out, and if needed, replaced. Most stores that sell car batteries will test old batteries for free. Take you battery in, get it tested. If it can't serve up the amps or volts that it should, pitch it and get a good one. Batteries have a great habit of going bad when you need them most. If your battery is on its last legs, just wait till a cold day comes and you won't be able to start your car at all.

Outside of potential battery problems, your issues sound like ignition problems for sure. I'd give your ignition wires and plugs a good once over to check for connectivity. If your plugs are bad, change them. It's one of the easiest and cheapest things you can do for your car and it makes a HUGE difference. If you engine was running roughly and slowly, I wouldn't be surprised if what was happening was misfires or you were running on 3 cylinders instead of 4.

Whatever the cause, I don't think this problem will be hard to fix. Since it starts and runs just fine (sometimes), the car probably just needs a little maintenance.

[elspectro29]

The CEL was on solid when it was acting up, but it did run rough and sound like it was missing. I got the battery replaced after work today, so if it happens again I'll looking at the ignition. Thanks to you both.

[RedRacer]

You're welcome. Keep us posted as to what happens ..... continuing education, as I like to call it, is what allows us all to learn.

[elspectro29]

It hasn't happened again since, but I've had a couple minor things since then: First, I noticed a small amount of ATF leaking from the transmission cooler. It turns out the clamp was on too tight, which caused a few small splits, but when the problem was fixed (used a different clamp and cut the offending end of the hose) there was still a little ATF oozing out, albeit a much smaller amount after a longer drive. Second, after the snow we had Sunday, and having to drive in it due to working that night, the serpentine belt, especially around the alternator, was making some noise it hadn't made before when i started it the day after. After I let it run for a few minutes it mostly died down and got better through the day. The oil light also came on again the next day. Same as it was before. I'm getting it inspected tomorrow so I have all of those issues checked out then too. I have a replacement belt and sensor ready to swap in if needed. I'll update the situation tomorrow.

[spiffyguido]

Are you certain that the noise was coming from the belt and not a bearing in your alternator? Belts will squeal more when they're cold, but so do bearings. If you're certain that the belt is tight, you can start to wonder about the bearings. Use the guidance in the service manual to check belt tension. The belt should fit according to the specification. Too loose, the belt will squeal. Too tight and you're straining the bearings in your alternator, power steering and air conditioning.

[elspectro29]

It wasn't a squeak; it was more just running louder than it should. The belt tension was fine; it just hardens a bit when it's cold, according to the inspector. Once the car is warm the noise goes away. The transmission cooler had the wrong kind of clamp on it (again), so yet another different one is on there now. The oil sensor has no problem; the post that holds it is a little loose, which means it occasionally wobbles the sensor around. The car passed inspection, so it's good to go now.