QuestionQUESTION: My 98 Elantra (81,900 miles) started having trouble last week with no power when I pushed the gas to go. On hills, I have to start in 2nd gear; when I'm already going, it doesn't accelerate well. The Check Engine light keeps blinking or staying on. They said it was the coil pack and spark plug wires (spark plugs were already changed-twice in last 3 months). The exhaust pipe broke off and is hanging on by a hangar. They say that needs to be fixed to recreate the back pressure that's needed. I spent $274 to get the coil pack and spark plug wires fixed and my car is worse than when it went in. They also mentioned the ECM (computer). Any ideas of what it really could be?
ANSWER: While the ECM is a possible cause, it's not very likely. Since your check engine lamp is flashing, it's clear that you've got a misfire issue. It's more likely that you have an issue with one or more spark plugs or fuel injectors, or with the wiring harness, or an internal engine problem. You don't need to fix a leaky muffler for the engine to run right.
The first step in diagnosis is to determine which cylinder is misfiring. Probably the best way to do this is to check the diagnostic trouble codes (DTCs) that are stored in the Engine Control Module (ECM). Once the misfiring cylinder(s) is/are identified, individual components can be inspected. If it's unclear whether there's a plug or wire issue, the plug or wire can be switched with another cylinder to see if the misfire moves to that cylinder. A similar approach can be used with the fuel injectors. To check the internal condition of the engine, a compression test would need to be done.
It's my suspicion that the shop which did the repairs on the car didn't really do any diagnosis-- they simply identified that the car was misfiring, knew it had already had the spark plugs replaced, so they figured the problem was with the coil or plug wires and replaced both. It's also clear that whoever looked at your car doesn't have the knowledge necessary to diagnose and repair a misfire if they think the issue is caused by your leaky muffler.
If the shop is willing to perform further repairs for free so that your car runs properly, I'd recommend taking it back to them. If not, you should try to get your money back-- they didn't fix the problem with your car-- and take the car to a good driveability shop or dealer to be repaired.
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QUESTION: Thank you! I'm going to rate you excellent, I just wanted to ask this follow-up first...
I actually did take it to the dealer-World Car Hyundai. They had it for 2 days b4 even diagnosing. They said it was spitting out so many codes, they didn't know where to start. This is from the actual receipt:
"Misfire P0301. P0302 misfire on 1-2 cylinder. coil pack misfire, need spark plug wires. replaced coil pack and spark plug wires. also needs drive belts, manifold, convertor, pipe exhaust, tail pipe muffler, ECM" (which is $773).
Their original driveability diagnosis was "customer states vehicle has no power." It didn't when I drove it off the lot either, plus when I turned on the a/c, it sounded like something was going to fall off!
I asked what should/could be fixed first just so it will drive and he said there's so much wrong with it, it all needs to be done. I told him if he could fix something for the $274 I already paid and make it driveable, I'd pay off the other part in payments. First I have to get it back to them.
I don't know which state you live in, but what do you mean by "driveability shop"? Is that where they do the driveability diagnosis? Do you know of any good places in Texas, San Antonio specifically?
Thank you so much for your help!
B
AnswerI must say that I'm very surprised that you had this problem at a dealer. Most dealers have at least one technician that's good with driveability problems (check engine lamps, vehicle running poorly, transmission performance issues). I'd recommned speaking to the service manager if necessary when you take the car back in. If what you're telling me is an accurate representation, it's clear that the service advisor wasn't accurate about the things that would make your car run poorly. Whether that's because he was lying, the technician for whatever reason told him such, or he just didn't know is hard to tell.
P0301 and P0302 are a far cry from enough codes that it's unclear where to start. P0301 indicates a misfire on cylinder #1, and P0302 indicates a misfire on cylinder #2. You have one coil assembly which has two coil packs. One coil pack fires cylinders 1 and 4, and the other fires cylinders 2 and 3. While it's not necessarily the case that you didn't have a coil problem, misfiring on cylinders 1 and 2 doesn't suggest a coil problem since they're on different coil packs.
The condition of the drive belts and leaky exhaust won't affect the way the car runs. It is possible, however, that the exhaust (including the converter) will make the car lack power, run poorly, or not run at all if it's clogged or partially clogged. But it won't make the car misfire. Since your check engine lamp is flashing, it's fairly obvious the car is still misfiring.
Why does the shop say you need an ECM? I realize you probably don't know this answer, but it's important that they not be guessing with this amount of money. There should have been some sort of diagnosis completed that shows there's a problem with the ECM.
Hopefully, they'll fix the misfiring for you for no charge. I don't know anything about any places in San Antonio, so you'll need to operate off word of mouth. And by driveability, I mean the types of problems described as driveability above. Shops will need special equipment and their technicians will need extensive knowledge of fuel management and transmission operation systems in order to do a good job with this type work. Most chains that do maintenance type work (quick lubes, tire and front end places, brake and exhaust chains, etc.) won't have the necessary tools and technicians to do a good job with the type of diagnosis you'll need to ensure a quality repair.
