Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Engine misfire?


I have a 2002 Nissan Altima 2.5S with about 86,000 miles on it. Since '02 to mid '08 the car was used in the Detroit area. Now, I live in the Atlanta area.

A couple of weeks ago, just after I started my car, I noticed it shaking. As I was just going to a place that is about a mile from my home, I ignored it.

I haven’t had any issues until Thanksgiving Day when it happened again. This time the shaking was even worse and the “Service Engine Soon” light came on. I looked under the hood and noticed the engine shuddering. Just the previous night, I drove the car more than 50 miles to my cousin’s home and did not have any problems.

On the day after Thanksgiving, the problem disappeared but the light was still on, so I took the car to the dealer. They connected my car to their diagnostic device, but couldn’t find a problem. They reset the computer on the car and the light turned off.

Yesterday, when I was on the highway and was driving at about 70 to 75 mph, the “Service Engine Soon” light started blinking, but the shaking was not serious. I slowed down to about 60 mph and the light turned off!

I am clueless as to what is going on :frowning:

Please help!

Thanks a million!

When the light comes on the computer stores a code, or codes, indicating the nature of the problem or the area in which a malfunction is occurring. For the dealer to say they couldn’t find a problem is pretty BOGUS, in my opinion. There must have been at least one code stored. Even if the light goes off by itself there should still be a code.

Has all required maintenance, according to the owner’s manual, been done on this car? Maybe something simple, like a clogged fuel filter or worn spark plugs, is causing the problem.

I suggest you get a second opinion from an independent mechanic if this problem continues, which it probably will. Something is going bad, and it won’t fix itself. The diagnostic computer should at least give a mechanic an idea of where to look.

Thanks for taking time to comment.

The dealer had his hands full that day, so I doubt if they looked into the problem closely. I should have asked them what codes showed up, but I didn’t.

All the required maintenance has been done, at least since I bought the car in '05. But, the last time I had the oil changed it was about 4000 to 4500 miles after a previous oil change.

FORGET the dealer, they obviously don’t care or are morons. You gave a serious ignition problem (bad spark plug, plug wire, ignition coil, OR a dirty fuel injector. Codes have been set that will point a COMPETENT mechanic in the right direction. The BLINKING CEL will have set codes that can be read even though the light goes off. Most autoparts stores will read those codes (for free) and tell you what they were…Post them back here and you will get more informed advise.

Thanks for the comment. I will take it to an autoparts store (Napa? Autozone?) and find out what codes have been recorded.

4,000 to 4,500 miles is well within the factory recommended oil change interval. I don’t think the oil has anything to do with the problem. Find someone who will read the codes and tell you what they mean. Auto parts stores often do this free, although they might just give you the code number, which won’t help you much. Mechanics have books or on-line reference materials which tell them what the code means.

I went to not one but two auto parts stores and they couldn’t read any codes. One of them said the diagnostic device can read only when the “Service Engine Soon” light is blinking. The other guy said it is a water condensation issue in the fuel line and recommended a cleaning additive (I was not impressed by the additive he recommended). So, I guess I’ll have to go straight to an auto parts store the next time I see the light blinking?

When the check engine light comes on, go to the auto parts store for a scan. Since the problem is intermittent, if you keep driving, and the problem doesn’t recur, the code will erase in a certain number of short, trouble-free, “trips”.

It sounds like a TPS is going bad some times the sensors will start going bad intermitently .have the TPS (throttle posistion sensor) checked.

Thanks for the advice.

Is that something that can be checked using a diagnostic device or is that something only a mechanic can check (expensive?)?

A mechanic can check the tps (throttle position sensor) with a multimeter quickly and easily. It’s not difficult to change, either. You would, probably, be charged for an hour of labor plus part cost.

Your first step should be getting the codes pulled. AutoZone, O’Reillys, Checkers, Advance Auto, etc. will do this for you free and it only takes a few minutes.
Get that done first and post the results for further discussion.

Just offhand, sounds like an ignition miss related to a coil or possibly a crank sensor problem.
If the spark plugs have never been replaced then I would leaning very heavily towards a coil problem.

I have a feeling the problem has something to do with cold weather (we are dealing with freezing temperatures since a couple of days).

Yesterday morning, the light started blinking again and I went straight to an auto parts store (of course, the light stopped blinking when I was 500 ft from the store!). The mechanic connected a diagnostic device and the code was P0304 with “Cylinder misfire detected - Cylinder number 4” as the definition and “powertrain control module monitors the crankshaft speed and has detected a misfire condition” as the explanation.

Per the mechanic’s recommendation, I added SeaFoam Motor Treatment to the gas tank when I probably had about 10 gals in it.

Today the light is not blinking, but is on all the time.

How major is this misfire issue? Is it expensive?

Please help!

So have the spark plugs ever been replaced? This kind of thing is cumulative.
A subtle plug misfire becomes a not so subtle misfire and this in turn can knock out the ignition coil. (You have 4 coils; one for each cylinder)

The plugs should be changed about every 40-50k miles as faint misfires often develop before then. Age and moisture can also corrode the end of the coil where it attaches to the spark plug and this can also cause a poor running engine. A poor connection here can also knock out an ignition coil.

You can try a set of plugs and see what happens but it’s possible a coil could be needed.
Try an independent shop for this as the cost could be less. Wild ball-parking here I would say a couple or three hundred dollars or so depending on where you live, type of plugs used, and if a coil is needed or not.

I think the spark plugs I have are original.

Another possibility is that your engine control computer is failing. It’s always one of the many possibilities.

Since the misfire on #4 cylinder is intermittent, I doubt that the cause is the spark plug. The cause could be in what triggers the spark.
Each cylinder has its own ignition coil on top of the spark plug. Exchange #4 ignition coil with another. Erase the check engine light code – usually by disconnecting the battery a couple of minuets. Drive the vehicle until the problem recurs. Have the code read. If the code indicates another cylinder, the ignition coil was the cause. If not, the secondary ignition system needs more testing.

I have to respectfully disagree that a plug cannot be intermittent in nature because I’ve run across it a few times.
The most glaring example was a gentleman who was an architect from Tulsa and was employed in this area designing a retirement village.

He owned a Subaru (very low miles, super clean, etc.) and made the 125 mile one-way trip back to Tulsa each Friday evening. The car would run like a champ but would take spells, usually after about 50-60 miles, and would act like it was running out of gas. Every time I looked at the car it always ran fine and nothing appeared to be out of line; plugs burning normal, etc.
He would drive it around town all week long without a hiccup but on the open road after an hour it would start acting up. The plugs had recently been replaced in Tulsa with the proper NGKs, correct heat range, etc.

Anyhoo, I made the decision to replace the plugs and the problem went away. The owner was a bit of a DIYer so I suggested that sometime he might try installing the old plugs back into the engine just to see what happens. Later on he dropped by and told me that he had done this and the problem resurfaced. Back out with the old new plugs, in with the new new plugs, and problem gone again.

On the day after Thanksgiving, I vaguely remember the dealer mechanic saying something about exchanging coils to see where the issue was coming from (but they said they were not able to read any codes at that time).

Now, if I go to a different mechanic, can he figure out which coils were swapped?

BTW, this morning the light’s not blinking (temperature is about 50 F right now!); how safe is it for me to keep driving for a week or so without getting the problem fixed?

Just want to point out that usually when a misfire get severe enough, (that is so many engine revolutions per misfire) the check engine light will start to blink. This is because running the engine with such a severe misfire will destroy the catalytic converter if the problem is ignored, and vehicle is continues to be used. So this is something you want to fix ASAP.