Check Engine light is flashing, rough idle* solved (bad gas)

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Check Engine light is flashing, rough idle* solved (bad gas)

Postby Chadwick » Sun Oct 14, 2012 2:33 pm

It only does it once it is warmed up. I will be taking it to a shop to have them check the codes once I get my next paycheck. In the meantime, I'm just not driving it. Gas consumtion has seemingly doubled too.

I was wondering if anyone else has had this happen or not? And if so, what was the fix? I need to brace myself if the repair is something major.

Thanks folks.
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Re: Check Engine light is flashing, rough idle. Ideas?

Postby HenryJ » Sun Oct 14, 2012 2:42 pm

Plugged cat?

Most parts stores will read codes for you.

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Re: Check Engine light is flashing, rough idle. Ideas?

Postby killian96ss » Sun Oct 14, 2012 5:21 pm

A flashing CEL usually indicates a serious problem and is also a warning that catalyst damage may occur if not fixed soon. This can be from too much fuel being dumped into the engine or an extremely lean condition. If your gas mileage has dropped significantly your probably getting too much fuel or you have an ignition problem. I would get that code/s read right away before you end up with more problems. I had the CEL flash on 2 separate occasions when I had my CC. One was from leaking injectors and the other was NGK spark plugs that were misfiring badly.

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Re: Check Engine light is flashing, rough idle. Ideas?

Postby roadrunner » Tue Oct 16, 2012 6:59 pm

There can be several causes for the flashing light and high fuel consumption. You need to get the codes read to know a direction to proceed. I have even had this problem with a cracked/broken front y-pipe letting too much oxygen into the exhaust and throwing the O2 calibrations off not to mention many other possibilities.
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Re: Check Engine light is flashing, rough idle. Ideas?

Postby northsnoma » Mon Oct 22, 2012 6:55 am

I had a rough idle until I replaced the alternator. The weights were laying inside. That and head gasket kit. My MPG went from 14 to 17-20. With mine if i had it in park and pushed and held down the gas pedal in the same position the idle would jump around +/- 300-400 rpm. Maybe try that
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Re: Check Engine light is flashing, rough idle. Ideas?

Postby ApproachMedium » Thu Oct 25, 2012 5:24 pm

According to the manual the flashing light means a serious multiple cylinder misfire has been detected. And trust me, I know alllll about misfires... LOL. When mine starts flashing it means the spark plugs have fouled up again and I have to change them. Cyl #3 lasts about 10-15k for me since that's the cylinder that keeps misfiring at idle.

The constant flashing for me happened a lot at 200K when my fuel injector went and was just pouring fuel in to the engine. That plugged the cat up and there was nothing to make it go away but changing those two parts. Once that was repaired now I only get the flashing when the plugs get crappy like I said above.
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Re: Check Engine light is flashing, rough idle. Ideas?

Postby Lil-j » Fri Oct 26, 2012 8:16 am

Ignition coil?
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Re: Check Engine light is flashing, rough idle. Ideas?

Postby HenryJ » Fri Oct 26, 2012 11:19 am

Lil-j wrote:Ignition coil?

Either works or does not. Not usually a source for misfire. Look to cap-rotor-wire-plugs as ignition related misfire suspects.

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Re: Check Engine light is flashing, rough idle. Ideas?

Postby Lil-j » Sat Oct 27, 2012 8:33 am

My truck had this problem, engine would idle really rough, step on the gas peddle a little SES light would flash till you let off the gas. I took a spray bottle of water and sprayed down the spark plug wires with the engine running. Found nothing, sprayed some more, nothing. Revved the engine up from the throttle linkage and found the ignition coil was arcing from where the boot connects to the bracket, bright blue spark. It would it do it at idle, only when I revved it up. I shut the truck off, took the wifes car to autozone for a new coil, replaced it, truck runs fine.

So if by chance there is a crack where the plug wire boot connects to the ignition coil and the spark is jumping to the bracket, it will run like crap how chadwick describes, mine did with the coil still working.
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Re: Check Engine light is flashing, rough idle. Ideas?

Postby HenryJ » Sat Oct 27, 2012 8:38 am

Lil-j wrote:M... found the ignition coil was arcing from where the boot connects to the bracket, bright blue spark. It would it do it at idle, only when I revved it up. .. if by chance there is a crack where the plug wire boot connects to the ignition coil and the spark is jumping to the bracket, it will run like crap how chadwick describes, mine did with the coil still working.

The ignition coils also have an area on the sides that arc to the outer laminated steel of the coil. Many times you can see the ash on the side of the body. Clean it off and coat it with cheap hairspray. Cheap hairspray is an anti-static sealer that works great on the wires, boots, coil, and cap. An old mudbogger's trick.

Don't steal your wife's expensive hairspray! :oops:

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Re: Check Engine light is flashing, rough idle. Ideas?

Postby Chadwick » Wed Oct 31, 2012 4:51 pm

Thanks everyone for the replies.

As it turned out, the trouble was the fuel. Seems like a certain gas station the Missess got fuel at just closed down to replace their tanks. Once the bad fuel finished running through, problem disappeared.

The reason the SES light is one, per the shop, is that a heater that preheats one of the Oxygen sensors isn't working. They told me not to worry about it as it will be a costly repair and it will only slightly reduce fuel economy while the engine is cold. Once it is at temperature it has no effect.

My next concern will be to get those rear shocks replaced with some good quality units. After that I'll be tracking down the antenna issue on the radio. It seemingly isn't even attached, although I can see it is. Not sure where to start on that one. When I get to it, I'll create another thread.
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Re: Check Engine light is flashing, rough idle. Ideas?

Postby F9K9 » Wed Oct 31, 2012 5:25 pm

Chadwick wrote:Thanks everyone for the replies..................................The reason the SES light is one, per the shop, is that a heater that preheats one of the Oxygen sensors isn't working. They told me not to worry about it as it will be a costly repair and it will only slightly reduce fuel economy while the engine is cold. Once it is at temperature it has no effect......................
Yes, that is true but, you will not know what that CEL is hiding besides the O2 heater. Often the code can be thrown due to something besides a bad heater. Check the fuses and possibly a relay.
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