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Missfiring hyundai

97 hyundai elantra, 302 code, #2 CYLINDER MISSFIRE. mechanic put a new injector in. Still have the problem. Also have a evap code and o2. Could it be the coil? Car is now in the shop and if its a coil Ill take it home and do it and save some labor. Car runs like a top otherwise.

Car has all these codes but no symptons just the codes? You do say car “runs like top otherwise”

NO, the symptom that made me go get the new injector was rough running. The car was skipping and missfiring. The check engine light came on and I went to the gaRage. They found a 302, whitch is a #2 missfire, they replaced the injector and told me it was all set. Next day went to work, all well. On the drive home same thing, rough skipping. Went back and they found 3 codes, and there she sits.

JMHO, but the first step in an engine performance problem should be looking at the spark plugs and running a compression test. If compression is low one could throw parts at it all day long without fixing it.

An injector should not be a first step unless it’s actually verified that the injector is bad.
Spark plug, plug wire, coil should be first on the list if the compression is good.

I pulled all 4 plugs meself and they looked good, wires are fairly ne also. As far as I know, the shop just pulled the code and ordered an injector. They havent called me tonight so Im not sure what theyll do next.

Checking the compression is always a must IMHO and one cannot tell a good spark plug from a bad one by a visual most of the time.

I mention compression because it is usually assumed the compression is good; even on a low miles engine. This is often not the case as I’ve seen quite a few low miles engines (5k to 20k miles) with major problems.

Low compression means a misfire and early fouling of the spark plug. A misfiring plug will then kill off the plug wire, coil, and even the ignition module.
How many miles on this car?

148,ooo miles on engine, 165,ooo on transmission and new clutch. The car is in immaculate shape, oil changed regular by ME. Really a great car with no mechanical issues to date. She runs hard and fast and clean. MPG is in the 30s. Just got in to go to work and she was having troubles. Plugs are all the same, no irregularities. But I hope Im wrong.

148k on engine 165k on trans? Is this not the original engine? Sounds like this car has a little undisclosed history. And by the way, running an engine hard and fast as you put it is sure to shorten it’s life.

A '97 with an engine change already? And the current engine now has 148k miles?

If this was a salvage engine, etc then it would be even more important to check the compression. About half of the “guaranteed to be good” engines, transmissions, and rear axles I’ve dealt with seemed to suffer from some problem.

I would point out that a cylinder with low compression will often cause the engine to have a slightly rough idle and the engine may smooth out when off-idle. The spark plug in that cylinder may often appear to be somewhat dark in color if not sooted up. The plug may even appear to be somewhat wet (incomplete combustion) so is it possible that a wet looking plug was the criteria used in diagnosing a bad injector?

Not sure how their diagnosis went. Look, guys. Original engine, used tranny. Hard and fast is a figure of speech. The car runs very well. I take it to church and never ever go through stop lights with it. I dont slam the doors either and the radio only plays patsy cline. But it is misfiring. And that is what id like to figure out. Ill ask the mechanics to pressure test the engine. This diagnosis is a bit beyond MY capabilities. But having said that, Im not a greenhorn drifter. The car is loved and well maintained. But again is misfiring.

Original engine, used tranny. 148,ooo miles on engine, 165,ooo ??? The transmission when out at 17,000 miles and someone put in a used transmission ???

No, tranny went in at 144 and change. ITS NOT THE TRANNYS FAULT. How many times do you get to say that ?

Phil,what is happening is with the posting technique you are using,after you do this awhile you start to read between the lines,since what you post is all we have to go on we look at at everything you do post,when we see you mention a difference in mileage between engine and trans we take off on the tangent of the problem being caused by the infered work done,when we see someone post about driving the car hard we sieze on that as a cause,we we see a injector change out before more common parts we sieze on that.

It is a lot like detective work,you listen to not only what is being said but also what is not being said and you pay paticular attention to body language.

We/I will keep working on your concern and maybe come up with something.

Thanx guys. So Original engine. Used trans. Never beat on. Never stalls sputters, or caughs, until the other day. Started the car and it was misfiring. Then the check engine light came on. Drove across the street to the garage, left for work. They called and said its a bad #2 injector and I said ok to replace. Im not sure how they got 2 and 2. Next day drove to work, 4 miles, all good. On the trip home it happened again, misfiring and the blinking check engine light. As I was on the way home, I went straight back to the garage. There it is. Im assusming that its unlikely that my new #2 injector went bad after 6 miles. And Im wondering what to look for. As of now the garage has not called and Im trying to not call them. The car does have high miles but is well maintained and never beaten on. I get great mileage and at idle it sings nicely. Never had lights or codes of any kind. Only normal repairs to date. Trans was a blown bearing.

Ok, garage called and said they replaced the plugs and wires, no luck. They did a running compression test and he said 2 and 4 are a little low. Im not positive it was 4 though, two cylinders are a bit low. He is gonna get a different injector and replace the one he put in yesterday to see if its that. Now am I correct to assume if its not that then my engine has some internal issues? How about a fuel filter, its not been replaced. Or the evap code, could it manifest this way?

OK, got her back. They replaced the #2 injector again and she seems fine. Put 60 miles on it today and alls well. They arent positive thats what it was but are exceedingly accomodating and more than willing to help if it happens again. They recorded 3 codes; po1331 oxygen sensor
p0442 evapsystem small leak
p0302 misfire detected #2 cylinder
Could all this be from the evap system? I did wash the car just before this happened.

I have no idea what a running compression test is unless it is meant they were running A compression test. Without knowing the actual numbers I have no idea what’s going on.

They’ve already stated 2 cylinders are low and it only takes one to throw an engine out of kilter.
With low compression it’s pointless to replace much of anything; much less the same injector twice.

Any problems are not likely related to an evap code.