Can air cause a misfire?

[jumbojones]

Can air in the gas tank/line cause a misfire?

A couple of times now my car has started up sputtering like it was going to stall, the first time it went away after a few minutes. The second time it happened the cylinder misfired and the check engine light came on. Now both times I remember I had filled up the night before this happened. I told the dealership this and they said that air wouldn't cause this and that I needed to replace my spark plugs at 90K Kms for $600. I got them to turn the light out and I told them I'd get it done later.

So since I've always filled my own gas and cranked the gas cap on well over the recommended 3 clicks and it hasn't happened again. Just thought I would get a second opinion on whether the dealership was trying to fleece me or not.

Thanks.

[m4gician]

I told the dealership this and they said that air wouldn't cause this and that I needed to replace my spark plugs at 90K Kms for $600.


You're getting PWNED HARD by scumbags! Seriously, $600 to change spark plugs? How many hours of labour is that? My god, a monkey could change spark plugs.

What make/model car? The plugs are at most $20 a piece (most likely $7-$10) a piece. x4,6 or 8.

Let us know and we'll provide you the manufacturer instructions on how to change them yourself OR provide you a mechanic who can for more than half that price.

As for misfiring, for the most part they're caused by the spark plugs fouling and/or the spark plug wires/coil packs. Changing the plugs will more often than not fix your problem. Sounds like you are getting "fleeced" as you put it.

[mau108]

90k is late for plug change imho. I change mine (even with iridiums) at 50k for the best performance and fuel economy.

I change the cap, rotor and wires at 100k. If its a 4 cyl it can most likely be replaced easily in 30 minutes. If its a v8, some of them are quite difficult to get to and require a lot of labor time thus the 600 dollar charge.

[pitz]

90k is late for plug change imho. I change mine (even with iridiums) at 50k for the best performance and fuel economy.

I change the cap, rotor and wires at 100k.


"cap, rotor and wires"? WTF kind of car are you driving? Must be quite an old model if they haven't gone with coils and electronic igition . Most plugs installed on new cars are good for 100k+, the platinum or iridiums.


If its a 4 cyl it can most likely be replaced easily in 30 minutes. If its a v8, some of them are quite difficult to get to and require a lot of labor time thus the 600 dollar charge.

V6's can be difficult (I have to remove engine mounts on my car to change plugs), but most V-8's aren't transverse-mounted.

[KawaiiTentacleBeast]

$600 to change spark plugs? How many hours of labour is that?

He could be driving a W12 Phaeton, or Bentley Continental/Flying Spur. Bentley labour rates + need to remove intake manifold to get at spark plugs +12 sparkplugs, it might add up to $600.

"cap, rotor and wires"? WTF kind of car are you driving? Must be quite an old model if they haven't gone with coils and electronic igition .

Probably some kind of Honda, up to 2000 most Hondas still used distributors. The Accord V6 still used a distributor in 2002. :lol:

[Pete_Coach]

Can air in the gas tank/line cause a misfire?

A couple of times now my car has started up sputtering like it was going to stall, the first time it went away after a few minutes. The second time it happened the cylinder misfired and the check engine light came on. Now both times I remember I had filled up the night before this happened. I told the dealership this and they said that air wouldn't cause this and that I needed to replace my spark plugs at 90K Kms for $600. I got them to turn the light out and I told them I'd get it done later.

So since I've always filled my own gas and cranked the gas cap on well over the recommended 3 clicks and it hasn't happened again. Just thought I would get a second opinion on whether the dealership was trying to fleece me or not.

Thanks.

With 90,000 kms on the car I suspect that you have a dirty mass airflow sensor or throttle body. Your plugs could,be fouled and your cap and rotor could also be worn. It all depends on where and how you drive. if it is a lot os city stop and go, short drives (less than 20 kms) you could very easily be fouling up the car. You need an "Italian tune up". That is, a good long highway drive at high rpms to blow out all that bad stuff LOL. I am not sure what he is offering for $600 but I would get a breakdown of that.


90k is late for plug change imho. I change mine (even with iridiums) at 50k for the best performance and fuel economy.

I change the cap, rotor and wires at 100k. If its a 4 cyl it can most likely be replaced easily in 30 minutes. If its a v8, some of them are quite difficult to get to and require a lot of labor time thus the 600 dollar charge.
If you are changing your iridium plugs that often, you are wasting your time and money. The plug fires hotter, remaining clean longer and the wear on the iridium tip is far less than anything so far.

[jumbojones]

Thanks for the replies, its a Hyundai XG350, apparently they're hard to get at hence the $600 price tag.

Funny thing is Hyundai suggests that the spark plugs be replaced at 82K km, which was the Km's on the car when I bought it in February. I asked the Hyundai dealer where I bought the car "why wasn't this done before being released to me?" Surprise I have yet to receive an answer on this. Pretty sad when a dealership doesn't even perform it's own recommended scheduled maintenance before selling the car!

I bought a repair guide from ebay and I hope to replace them myself, I haven't done this since I owned a 92 cavalier, which was probably a simpler process.

[jumbojones]

You need an "Italian tune up". That is, a good long highway drive at high rpms to blow out all that bad stuff LOL.Funny you should say that, just took her up to Timmins and back with no problems. It's amazing the hwy milage I got compared to city/hwy combined.

Anyone change spark plugs on a V6 Hyundai? Just wondering the difficulty level.

[rchong]

from:
http://wiki.answers.com/Q/How_do_you_change_the_spark_plugs_on_a_Hyundai_XG3 50L


The front plugs are easy to get to, but the back three require removal of the intake manifold since the plugs are located in the cylinder head directly beneath it. This is not the easiest task. The first problem is that there are so many other things connected, including the wiring harness and lots of vac. hoses. Additionally, there are brackets along the rear of the manifold that need to be unbolted. Once you do that, the EGR valve will need to be disconnected from the manifold. Peek your head under the hood at that one before you jump in. If you do tackle this yourself, buy the best spark plugs that you can afford so that they last longer before the next time. Also, replace the ignition wire set at the same time. No point in saving the cash on those only to have them fail before the next plug change.

[jumbojones]

from:
http://wiki.answers.com/Q/How_do_you_change_the_spark_plugs_on_a_Hyundai_XG3 50LF me! Sounds like a PITA.

Next question, what are the "best" spark plugs?

[rchong]

F me! Sounds like a PITA.

Next question, what are the "best" spark plugs?

For the back ones, I'd recommend iridium spark plugs. Use whatever you want for the front.

If I have the right car:
http://www.championsparkplugs.com/results_app.asp?AAIA=1415887

I would pick:

Champion Iridium Plug 9001 9001 for the back


Champion Traditional spark plug 346 RC10YC4
or
Champion Single Platinum 3346 3346

for the front

[Pete_Coach]

Funny you should say that, just took her up to Timmins and back with no problems. It's amazing the hwy milage I got compared to city/hwy combined.

Anyone change spark plugs on a V6 Hyundai? Just wondering the difficulty level.
Wow, with old plugs?
F me! Sounds like a PITA.
Next question, what are the "best" spark plugs?
Seems to me that the ones that came with the car are relatively cheap and lasted a long time and performed very well, even with over 90,000 kms on them? Sound like pretty good ones to me.
Or, you can read the hype, pay $10 to $15 each and get what...oh the same mileage. Be careful, there will be lots of people who have drank the kool aid and will do almost anything to convince you that the tri tip, iridium core, blue cheese coated, high tension igniter is the only one to buy.
Be smart, think of what you had, how long it lasted (and is still working) and will you really benefit with the more expensive one? I think not.

[mau108]

"cap, rotor and wires"? WTF kind of car are you driving? Must be quite an old model if they haven't gone with coils and electronic igition . Most plugs installed on new cars are good for 100k+, the platinum or iridiums.



V6's can be difficult (I have to remove engine mounts on my car to change plugs), but most V-8's aren't transverse-mounted.


99 honda prelude...

[jumbojones]

Wow, with old plugs?Ya, 800km on 3/4 of a tank of gas, I believe it's a 60Lt tank. I only get about 550km City/Hwy combined for a whole tank.

[ES_Revenge]

First off "air" [without fuel] can certainly cause a misfire condition, but air doesn't just mosey on into the fuel system as you think. The fuel pump and injectors don't pump air, they pump fuel. Doesn't matter whether you just filled up your tank or not. :confused: If that were the case everyone would have misfires everytime they put gas in their cars, LOL.

So the stealership is right in the respect that unless you have a good reason to suspect air is getting pushed through the fuel system, your reasoning for the cause of the problem is way off.

"cap, rotor and wires"? WTF kind of car are you driving? Must be quite an old model if they haven't gone with coils and electronic igition .
LOL no kidding. And cars with [relatively] low-voltage old-skool ignition systems require more frequent plug changes by nature, which is probably why that poster said 90,000km was too late for a change. Higher voltage electronic ignition systems put much less wear on plugs, making for better plug longevity (this is aside from using different materials like platinum, etc.).

He could be driving a W12 Phaeton, or Bentley Continental/Flying Spur. Bentley labour rates + need to remove intake manifold to get at spark plugs +12 sparkplugs, it might add up to $600.
LOL I'd imagine on a Bentley he'd be paying like $6000 for that service; and likely not caring to hand over the cash either.

Probably some kind of Honda, up to 2000 most Hondas still used distributors. The Accord V6 still used a distributor in 2002. :lol:
x2. Honda--always years behind the technology curve. :lol: I mean other than VTEC (which at the time was innovative for road cars) and SH-AWD (the EM clutchpacks remain impressive to me to this day), I'm not sure what else Honda has really done that's anything special in terms of auto technology...