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Fourth cylinder misfire; car won't accellerate

Can anyone help with a question about a 4th cylinder misfire question? The engine light has been on off and on for about one year. I have not had any problems with performance until about one week ago. sometimes it shakes and the engine light flashes when it is idling. Today my husband drove it, and it would not accelerate when he put his foot on the gas, but it would pick up speed when he left his foot off the gas! Weird. This is an old car (2001 Ford Taurus station wagon) with 137,000 miles on it. We need this car.

I don’t actually consider an '01 Taurus with 137K on it an old car. I think its probably just about broken in.

First, a warning. A flashing check engine light is bad. If you need this car then you have to stop driving it until this is sorted out. Absolutely do not try to drive it while the light is flashing. And don’t keep driving around for a year with a check engine light - intermittent or not. Little problems often turn into big ones.

Second, if you want some help then you need to provide a lot more info.

  • discuss what your approach has been to maintenance including when the car last had things like new spark plugs, wires & filters.

  • discuss anything else that might be relevant such as whether or not you’ve been losing any coolant, how frequently you have to put oil in it etc.

  • get the error codes and post them. When the check engine light comes on error codes are stored in the computer. Many auto parts stores will read these for free. They look like: “P1234.” If you get them read, just write down the exact code and post that. Whatever words someone gives you for them will not help people here.

  • what if anything has anyone done to address this issue or any others related to the check engine light (or anything else).

  • a flashing check engine light is normally a misfire. There’s a good chance that you will end up with at least something between P0300 and P0306. One might guess that you have a P0304 - but then its something of as mystery why you wouldn’t say so. But either way you want to find all codes that are present. Many things can cause a misfire, but most people start with the ignition system (spark plugs & wires, then maybe coil pack).

When you report back folks might know where to start.

Thank you! It is in the shop now, and I will post the error codes when they check for them, and the history of problems for this car. I am pretty new to this. Thanks for your good advice!

How do you know it’s a 4th cylinder misfire?

Perhaps your timing chain slipped.

Thanks everyone for responding! I brought my station wagon in because it shakes when idling (like at a stop light), and the engine light flashes. The shaking and flashing stops a minute or two after I accelerate. I have read and been told by my (soon to be former) mechanic that I should not drive it when the engine light is flashing, and anyway, I was very nervous in a shaky car.

This is the information I have directly off the mechanics’ notes/bill for us:
PO304 cylinder misfire
B1318 low battery voltage at module
Notes:#4 cylinder running lean; causing rough idle sometimes. Unable to duplicate check engine light flasing condition. Recommend replacement of injectors to fix misfire condition.
FUEL INJECTOR- remove and replace-O.H.C.-DOHC- one
Replace all injectors
Fuel control system tune-up
Clean gum and soft carbon deposit from fuel delivery components and inside fuel pressure and volume test. Carbon deposits on valves causing engine misfires sometimes.

I don’t know how he could have failed to get the flashing “check engine” light. It flashed literally every time I came to a stop within 10-15 seconds at a stop light or even pausing to drop kids off at the school door first thing in the morning (no matter if the engine is hot or cold). Anyway, he charged us $662.75. Five minutes after I drove away (literally five minutes) the conditions that caused me to bring the car in in the first place started all over when I was in line at the cash machine. I took it directly back, and he said he would look into it some more. No charge for the extra day at the shop, but no improvement in the condition either.

The guy gave me a bottle of Techron and said to fill the tank (it was almost out of gas), then add the Techron. I followed his directions, but realized later that the bottle said to put the “juice” in BEFORE adding fuel. So next time I will read the lable and not listen to the mechanic, I guess. Nothing particularly significant happened as a result of putting the Techron in after fueling up, in any case. Well, it has been about two weeks since all that, and I have driven as little as possible. It starts up very well (a little hesitant, nothing terrible), and runs normally (compared to most old cars I have driven). When I come to a stop light, it shakes and the engine light flashes, but it is not as bad as before (less shaky). Very occasionally, the shaking and flashing has subsided on its own (maybe one time in ten) while I am stuck at the light. Could the Techron be working its way through the system and helping the situation? Thanks for any input, as it is much appreciated.

Take it to an autozone or other national chain and have them check the alternator and the battery for charging.

It is possible that a code could be sent with a low idle… but yes check the charging and battery. Also when was the last time the wires were replaced? Or spark plugs? Although new plugs can last many miles like 40k or more one can break down. i.e. number four. might have overheated because of the fuel issue and that alone could cause poor idling too. Mech or autozone. can check that too.

The engine light has been on off and on for about one year.

And what have you done? That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here.

As noted, have the battery and charging system checked.

The shop’s notes are confusing re: the potential cause of the misfire. One note says that the 4th cylinder is running lean. That’s why they replaced the injectors. But another note mentions carbon buildup hanging up a valve. I have no idea how this was figured. Perhaps it was a guess?

On the injectors, do you know whether they thoroughly checked the wiring/power supply for the #4 injector? The injector only works when it gets the right juice to it in the right way.

If nothing turns up on a check of the charging system, have the engine’s compression checked. The shop that did the work on it should have done this. If you end up having it done, write down the exact numbers for each cylinder (it will be in pounds per square inch - psi) and post the compression numbers.

Are all of the fluids staying topped up? I’m curious about the anti-freeze, specifically. Do you have to feed this car under the hood at all, or is everything stable?