QuestionThank's for the reply HT, it was the timing chain , the Hyundai tech said was slack (apparantly the opposite end to the timing belt (which has been replaced) my engine is the 16 valve twin cam 1.6, also i was thinking it could be the exhaust touching somewhere underneath the body, just to clarify HT, does the diagnostic test pick up every possible solution , like plugs , wires , sensors, and idle acuator and throttle body leaks ect....also what he said is it might be a start of a problem with a TPS sensor forwhich isn't severe enough to be picked up by the ECU, and he said sometimes what they can do is unplug the connector to the TPS and rev the engine a few times and this helps, i asked him if perhaps i could do this at home my self if the problem developed and he said you could but the ECU would need clearing afterwards, and that can only be done by them,( only i thought removing the ECU fuse for 5 minutes wiped the ECU, but he said the ECU has a memory that cant be wiped by removing the fuse...is he telling the truth?
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Followup To
Question -
Hi i have just taken my car in to a Hyundai dealership because my car has a very annoying vibration flutter felt through the steering wheel at idle (traffic light's), and i can feel it through the seat, i thought it was a fault with the engine Sensor something like that, but they hooked it up to their diagnostic machine, and no fault codes came up and they said everything was normal and running within normal specs, at this i said "well what about the vibration?" and they said just a characteristic of the car, and said it might be the engine mounts it might not , and to replace them would be cost and it still might not solve the problem.
Is their anything that might be the cause that wouldn't show up on the diagnostic machine, i have a Hyundai Lantra 1.6 1999 Manual transmission with 45,000 miles on the clock (genuine)........the one thing they did tell me was that the timing chain was slacker than it should be, and recomended that being done, could that be the cause?
Answer -
I'd seriously doubt they checked the timing belt tension, since that would require removing the timing covers, and unless they were doing other work you haven't told me about, there'd be no reason for them to do that. And it wouldn't cause the vibration anyway. By the same token, if it's never been replaced, it should be. It'd be about seven or eight years old by now, so you should be concerned that it might break and cause engine damage.
Not having felt the vibration, it's difficult for me to tell you whether it's normal. If you've got an Alpha or Beta engine, it does have some characteristic high frequency vibration (about 2x engine rpm).
Presuming for a moment that it isn't normal, there are two basic possibilities: the engine either isn't running correctly, or the motor/trans mounts are excessively transmitting normal engine vibrations to the body. In the former case, there are many things the ECM would be able to pick up, but still some it cannot. You should be interested in whether the idle RPM is correct and whether the engine seems to be misfiring (even just a little). In the latter case, the ECM and diagnostic equipment will never be able to find problems with motor mounts. Typically what happens is the rubber cracks, breaks, or sags, causing an increase in vibration.
If there's another dealer near you, perhaps get a second opinion. If they say it's normal, too, then it's a pretty good bet it won't go away no matter what you do.
AnswerOkay. I forgot about that chain. You can hear it when that chain is loose. It makes kind of a rattling/knocking noise. But it shouldn't cause engine vibration. And it's also not a serious issue. I doubt you'd be able to wear it enough to cause it to jump a tooth or otherwise come off.
A technician will perform certain diagnostic tests depending on what the problem is. If you've got a check engine lamp or the engine isn't running properly, this will likely involve the technician plugging in a diagnostic scanner-- I presume this is what you're talking about-- and reading stored trouble codes and data in the relevant computer (engine, transmission (A/T only), ABS, air bag, or body control module). But this limits the technician to those things the computer can see. In the case of the engine, that's the data the computer reads (from sensors and actuators) and in some cases how it's interpreted.
On the other hand, if you were to have, say, a problem with the interior illumination on your car, the technician would check that particular circuit, probably starting with the fuse, and then the rheostat. And he'd be using basic electrical test equipment such as a test lamp and a voltmeter. No computer in your car controls or monitors the lamps. If you had a noise, he'd begin by investigating what makes the noise happen and trying to pinpoint the noise to a certain area of the car. Then he'll look for the things in that area that might make such a noise. He'll probably not have any diagnostic equipment to help him determine the cause of the noise.
Furthermore, trouble codes stored in a computer tell the technician the nature of a problem, not the cause. The technician still must check to find the cause. Let's say the technician checked your car and found code P0304, a misfire on #4 cylinder. That would certainly explain a vibration. But it doesn't tell him what's causing the misfire. All the computer knows is that it doesn't get the same power out of #4 cylinder as it does from the rest. It can tell this by monitoring the crankshaft position sensor. What it cannot tell is whether the condition is caused by a coil, plug, wire, fuel injector, or low compression. The technician must then start checking these items individually to find the cause.
It'd be odd for a TPS to cause a vibration issue. And I'm not sure what the point is behind the technician's exercise. I'll agree that operating the throttle can clean the contacts of the TPS, but I don't see the point of unplugging it. I believe you'll be able to clear the ECM (Engine Control Module) on this car by pulling the appropriate fuses, but I believe there's more than one. I find it much easier to just disconnect the battery for 30 seconds.
