My wife was driving our 1996 Accent (with the 1.5 liter 12-valve motor, 5-speed manual transmission and 185,000 miles on the odometer) on the highway and after travelling about 15 miles noticed a rather sudden power loss accompanied with a flashing "check engine" light. She was able to drive several miles, at greatly reduced speed, to a place where I was able to pick her up. When she parked the car, she had put the car in reverse to back up briefly and noticed a very strong burnt-rubber smell, which was still very noticeably present in the car when I came to pick her up later. The car still starts and runs, and even runs relatively smoothly, but will not reliably idle - one must give gas pedal pressure - and produces very little power. I have crawled under the car but I can find no evidence of burnt rubber, and the source of the smell is still a mystery to me. I had suspected that perhaps the timing belt had slipped a cog which accounted for the power loss, but upon inspection I noticed that the timing marks on the crankshaft and camshaft sprockets seemed to line up properly with their respective timing marks on the motor castings. Recently replaced (within the last year) are the crankshaft and camshaft position sensors, coil packs, and spark plug wires, as well as the alternator. OBD-II readout shows codes referring to random cylinder misfires as well as misfires on cylinders 2, 3, and 4. Cylinder #1 is not specifically listed. There is also a code referring to idle speed misadjustment and one pointing to an oxygen sensor circuit problem. At this time I cannot remember the specific codes; if need be I can reassemble all the parts so I can start the motor again and check. My list of suspects currently include a possible fuel pump failure or other fuel delivery problem or perhaps a plugged catalytic converter. Or it may be either oxygen sensor. But it might be a lot of other things as well. The car has long idled with a bit of roughness, especially when the motor is warm - is the idle control valve at fault? Etcetera. I'm willing to "shotgun" a fix but would like to start on what is more rather than less likely and is cheaper rather than more expensive. Any help would be appreciated to get me started on the right track.
I must say that was quite a bit of info for the first posting of which I am grateful. Most questions are 3 or 4 words if that.
I guess my first question is how does the engine perform now ?
Have you drove it since you got it back home ?
The biggest hassle of driveability problems is the need to recreate the event in the shop. If you can't make the problem happen on demand, it is all but impossible to diagnose.
I would want to know what the trouble codes were/are, what the fuel pressure is, and where the smell was coming from to proceed.
There is a long list of possible causes.
I never admonish.
Understand the people on fixya like me who answer questions don't get paid for it.
I am here because I like to share my 40+ years of experience working on cars.
Doing this online is tough sometimes because I really need to be there in person, like a medical doctor.
When you reply again I will get a notice in my email.
(Hopefully these comments are getting through ok. This site's layout is confusing me.) I checked the coil, and the "half" that fires the numbers 2 and 3 cylinders was not sparking. I put the old coil back on - the one I replaced with the failed one - and there's good spark all around. Cylinders 2 and 3 had dry plugs before; now they show wetness. Car cranks and acts as if it wants to start, but won't. Maybe it's just flooded? I haven't checked the plugs themselves, as they appear OK and aren't eroded much. Perhaps I need to do that. Anyway, I'm going to stay away from it at least until tomorrow!
From my research, which includes reading the manual as well as checking on the web, I find that a flashing MIL associated with the P030x codes indicate possible "Catalyst Damage." This I presume is the catalyst in the catalytic converter, as I'm not aware of any other catalytic process being used anywhere on the vehicle. Since the coil appeared to have failed on the #2/#3 cylinder side, it might be reasonable to suppose that before the fuel flow was cut off to those cylinders - which it certainly appeared to have been - the catalyst might have been damaged, which threw the P0422 code. If only the car would just start now, I'd believe what I just wrote above, but I'm afraid there's something else in the mix that escapes me. I cleaned the plugs with toluene and hope to reinstall them soon and try to start the motor .... which makes me a liar, since I said I was leaving it alone until tomorrow!
Now I've got good spark but insufficient fuel flow. This is getting pretty wearying, first chasing down one thing and then another.
A gallon of gas and a match can feel like a good direction to go sometimes. I would suggest you slow down and take it one step at a time. If cyl 2 and 3 are dry but no spark, that would mean the injectors are not opening. Which could mean something is going on with the crank sensor or computer. You have to start at step one and work your way to step 12 while trying not to miss anything, or assume anything along the way. The flashing light usually means something is happening at the moment that COULD cause serious damage to the converter. It could be a more serious version of the same problem from the beginning.
Yes, you are right - the one step at a time thing, I mean. What I'm pretty sure I determined is that the coil I'd installed some time ago (routinely; the old one was working) failed. I could not and still can't get spark from the coil that fires the #2 and #3 cylinders. I BELIEVE (but don't know for sure) that this was what precipitated the whole thing. My old coil, which I never discarded, was installed and both coils work; all 4 plugs are getting spark. When I initially (re)installed the old coil, the plugs all got wet with gasoline; I cleaned them out with solvent and now they're no longer getting wet during cranking. It seems to me something has shut off the fuel flow; my inclination is to wonder if the ECU somehow needs to be "reset" or something. To recap: after digging around, cylinders #2 and #3 lacked both spark and fuel; cylinders #1 and #4 had both. Coil was replaced; spark all the way around. Initially had fuel, now there's none or very little.
I had also considered that something might have plugged the fuel injectors. Although this might still be a possibility, I kind of doubt it; I'd have thought the problem would have shown up soon after filling the gas tank; it's now at about the half-full level. Be that as it may, I'm tempted to inspect/clean the injectors, if possible, although I understand this requires a special tool and that they're easy to break; hence I'm hesitant to dig in there. I'm much more inclined to think it's a fuel delivery problem, by which I mean insufficient pressure, but I haven't verified this. By the way, I see I'm using the word "coil" in two different contexts, one meaning the whole coil pack and the other referring to each half of the coil pack. The pack seems to consist of two coils, which fire the #2/#3 cylinders and the #1/#4 cylinders.
A couple of questions that I'm sure you can answer for me: am I correct in thinking that the O2 sensors and converter are primarily there to "fine-tune" things for minimum emissions/maximum efficiency - that the motor would basically run right albeit at less-than-peak efficiency? If so, am I right in thinking whatever the underlying problem is that it must be addressed first before it makes any sense to consider doing anything on the sensor/cat end of things? If these questions are answered in the affirmative, at least things will be theoretically simplified, even if still a major pain in practice.
Yes you are correct in theory. The O2 sensors measure unburned oxygen in the exhaust, and the cat converts most exhaust gases into water. One thing to remember tho, if an O2 sensor fails, the computer will stop using the data and insert a pre-set reading that will usually make the engine run worse.
I think this is the longest conversation I have had with one problem, which is not good or bad. But not easy to keep up with. You may or may not know this, but to check a fuel injector you can test the resistance and also check for power and ground pulse with a low voltage test light. I would want to know if injectors 2 and 3 have both voltage and pulse.
OK, I might be able to do that, I think; I'll chase down a low voltage test light. I admit I'm a bit confused as to why the fuel flow ought to be a problem now. I'm fairly sure that the "original" problem was linked to the failure of half of the coil pack, which I'm currently strongly suspecting as causing the initial power lag. I surmised that the ECU might have shut off the fuel flow to the non-sparking cylinders. Replacing the coil with the old unit restored spark all around upon which all plugs were again wet with fuel. I cleaned and dried the plugs, reinstalled, and now am seeing very low or no fuel flow. Perhaps my brain got full and I overlooked something that may have shut off the fuel, but I thought I'd double-checked all the connections.
I think where you are confused is with the "why" part. Now keep in mind I am being a long distance doctor here and making assumptions along the way. The computer probably did not cut the fuel to cylinders 2 and 3. But the ignition module could have failed to provide a signal for both the injectors and the coils for those two cylinders. Or whatever component triggers both circuits. The injectors may be dead because of something that killed the ignition to those same cylinders.
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My thinking would be to further inspect the converter as when this plugs up excess pressure can cause multiple cylinder misfires and as far as the burning rubber smell, when a converter is plugged the lack of flow causes a build up of heat closer to the exhaust manifold possibly melting something nearby to cause such an odor.
I thought along exactly those lines, and I guess my follow-up would be to ask how exactly might I further inspect the converter? When I started it yesterday I observed the exhaust pulses coming from the tailpipe and those pulsed just like normal, whereas it would seem to me that a plugged converter would dampen those pulses considerably. And while you've got me on this train of thought, what might plug a converter so suddenly? This problem did not gradually come on but rather showed itself suddenly after about 15 miles of normal highway driving. Anyway, Mr. Mueller, I do appreciate your opinions and suggestions. I'll eventually get to the bottom of this.
best way to check converter is with a scan tool to monitor o2 sensor activity while reving motor. if rear o2 should flatline voltage instead of spiking like normal suspect faulty converter. as far as why so sudden a failure i am not certain. one would expect signs of failure before such a complete failure
Ok, that's good to know. But I can't rev the motor - at this point it will just barely run at all, and it runs slow and rough. One must keep pumping/fluttering the gas pedal wildly to keep it running at all.
if possible remove converter to inspect for blockage inside?
I suppose that would be possible. But I tend to think that's not the problem, simply because I would guess that the exhaust pulses would be noticeably damped were the converter plugged. Some time ago (before this problem) I had at one time blocked the tailpipe with my hand - I was suspecting some exhaust leak or another - and I was surprised how well the engine would run despite the heavy back pressure. Because of this little experinment and my current observations, I don't hold the plugged converter as a highly likely possibility, although anything is of course possible. I think there's a fuel delivery problem - by which I mean it's not getting enough fuel. MAF sensor? Low fuel pressure? Clogged injectors? ECM? I gather faulty O2 sensors will not cause the motor to nearly fail running, so I'm not suspecting those too strongly at this time. Thank you again for your assistance!
Chris, Today I decided to look at the spark plugs; I thought that the motor was receiving too little fuel. Cylinders #1 and #4 had sooty plugs; #1 was dry while #4 was maybe a bit damp. Numbers 2 and 3 were bone-dry-clean, as if any deposits were burned off completely. Although I realize that it's easy to get into a certain mental set and then ignore other problems, I cannot help thinking the problem is one of insufficient fuel flow, now obviously to the #2 and #3 cylinders. What could cause this? Coil pack? I don't know ..... it's here that I'm seeking suggestions. Thank you!
(Hopefully these comments are getting through ok. This site's layout is confusing me.) I checked the coil, and the "half" that fires the numbers 2 and 3 cylinders was not sparking. I put the old coil back on - the one I replaced with the failed one - and there's good spark all around. Cylinders 2 and 3 had dry plugs before; now they show wetness. Car cranks and acts as if it wants to start, but won't. Maybe it's just flooded? I haven't checked the plugs themselves, as they appear OK and aren't eroded much. Perhaps I need to do that. Anyway, I'm going to stay away from it at least until tomorrow!
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SOURCE: STARTING PROBLEM!! Have 2003 Hyundai Tiburon GT
try to get a wiring diagram it sounds like you have a rubbed thru or corroded wire in the circuit. haynes manual at autozone $20.00. Some local larger libraries have the wiring books also.
SOURCE: Hyunday Santa Fe 2008 3.3l Sudden
well, if check engine ligth on have the codes pull to find out the problem it may be mapp ,air ,sensor bad ..if engine ligth is on its picking up a a code..
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Thank you very kindly, Stephen,
The car is all but undriveable due to a major lack of power, so I haven't driven it. I'm in the process or changing out the timing belt tensioner, as the belt doesn't look any too tight - I did NOT replace the tensioner when I replaced the belt a couple of years ago, so I thought I might as well do it now while things are taken apart. When I get things reassembled, I'll start and drive it and read the trouble codes and get back here.
By the way, I don't know why, but the FixYa site's search function is much too broad, and in replying to your response I'm wondering if it will show up in the right place, so if I'm going about this all wrong, please feel free to advise or admonish.
Again, I thank you kindly for your willingness to assist. I realized a few minutes ago I need not run the motor to get the stored codes (duh...) so I went out and did it. Here's exactly what my OBDWhiz software shows from the ElmScan5 USB device; several of these are repeated.
P0304
P0300
P0302
P0422
P0506
P0303
P0303
P0302
P0300
The P030x codes refer to cylinder misfires, as you know. Looking P0422 I find it means "Main Catalyst Efficiency Below Threshold" while P0506 is listed as "Idle Air Control (IAC) System RPM Lower Than Expected."
Perhaps this will spark some insight.
I'm having difficulty with this website. Right now it won't let me format my comments at all. So my apologies. I did a couple of things: I checked the fuel pump by applying voltage to the test connector. This was with the fuel filter off, and fuel came shooting out of the fuel line. Then I connected everything up and started the motor. It ran rough if at all. Exhaust pulses seemed normal, so I'm suspecting a plugged cat less now. I personally think the problem is a lack of fuel - caused by what? I say this because the exhaust seems almost too clean, if that makes any sense. But I don't know. No new OBD codes. Fuel injectors? O2 sensors? Cat converter? I'm a bit baffled; the problem showed up all at once. Thank you!
You could disconnect the catalytic converter to see if it is at fault. Have you replaced the fuel filter ? The O2 sensor would not come into play until the engine reached normal temp. The coolant temp sensor could be faulty but you should have a trouble code for that. One injector could fail, but not all 4.
Yes, I did replace the fuel filter; I guess I failed to make that clear.
If the O2 sensor doesn't function until temperature is reached, that pretty much rules it out - for now, at least. I can barely start the thing and have it run for any period of time. The coolant temperature sensor is only a couple of years old; I tend to think that's not the problem; I had a code for that at the time. When I started it today I could, by wildly pumping/fluttering the gas pedal, make it run, albeit quite roughly, for perhaps half a minute at a time. My hunch is that there is a fuel delivery problem. Although the fuel pump delivers fuel, is it possible that pressure is insufficient?
Today I decided to look at the spark plugs; I thought that the motor was receiving too little fuel. Cylinders #1 and #4 had sooty plugs; #1 was dry while #4 was maybe a bit damp. Numbers 2 and 3 were bone-dry-clean, as if any deposits were burned off completely. Although I realize that it's easy to get into a certain mental set and then ignore other problems, I cannot help thinking the problem is one of insufficient fuel flow, now obviously to the #2 and #3 cylinders. What could cause this? Coil pack? I don't know ..... it's here that I'm seeking suggestions. Thank you!
I just now checked for spark. #2 and #3 are not sparking; #1 and #4 are doing fine. Ergo, #2 and #3 must not be getting any fuel, or else the plugs would appear wet. #2 and #3 are run off the same coil (dual pack) so does this indicate a coil failure? (Coil is a year old or less.) Would a coil or any other spark failure cause the ECM to shut off fuel flow to the affected cylinders? Or might the reverse be true? Thank you again for your assistance!
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