Flashing check engine light

[jimig1]

So last night I was doing some xmas shopping for my wife and on my way home I was getting on the highway and the check engine light came on an started flashing. I got off the highway and pulled in to a parking lot the car war running rough it was shaking the whole car. I took it slow and got it home. Today i changed the spark plugs and wires and it ran better but still not right at idle it runs fine for a few seconds then rough but not as bad. I got a code scanner and found the codes P0300(Random/Multiple Cylinder Misfire Detected), P1781(Engine Torque Signal Circuit), and P0700 (Transmission Control system Malfunction). I cleared the codes to see if after replacing the plugs it would come up with another code and nothing but it still not running right. I it an 04 Aveo with 71,000 on it and the timing belt and every thing was replaced just shy of 60,000. Any one have any ideas?

[petrified.rabbit]

How did the plugs look? Odds of 4 plug going at once isn't as likely as the coil pack going. (can happen in extreme cold) either that or the wires are shorting out...

But getting another code or checking the system is better then throwing parts at it, mist water on the wires and coil pack while it's running if you see sparks, replace that item.

[jimig1]

The plugs needed to be replaced after looking at them and it was cheap

[normburns]

Yeah, I have an idea, but you won't like it. That is pretty much what our 04 started doing, at 107K. Like you, I changed the plugs, I had changed them and the wires around 97K. They looked okay, but the plug in number 2 looked a little "different". Took it in to the dealer for diagnostics. They diagnosed it as a burned valve, and estimated the repair at $2500. Well, I did not like their diagnosis, and took it to my mechanic. He advises that there is a problem with a valve, but the real problem is the loss of compression in the number 2 cylinder. It reads 25psi, while the other 3 are reading 125psi. In my world, when you have a large disparity in cylinder compression, and you shoot some oil into the cylinder and the compression comes back up... that usually indicates a ring problem in that cylinder.

Pulling the motor right now, then disassemble and inspect, and plan to rebuild it. Based on estimates form my mechanic, and the machine shop, I can rebuild this motor, and have it balanced for less money than buying a surprise (surprise, I don't work!!!) engine off ebay, and installing it. Since she loves the Aveo, we are going to do it right.

Good luck, I hope your problem is different from mine.

[petrified.rabbit]

Oil in the cylinder account for rings yes, but the compression coming up does not always mean rings need replaced.

Although 25 is really low.

Putting the oil in helps account for the fact that a compression test does not account for running conditions. Rings can expand with heat to bring compression up, also if the engine has oil squirters then that can't really be accounted for during dry cranking. Etc

While it points to rings, a cylinder leakdown test should be done to point to the exact problem

For the op. I was stating if all four plugs looked bad then a common piece probably fouled them. Check your coilpack.

[paulsaveo]

So last night I was doing some xmas shopping for my wife and on my way home I was getting on the highway and the check engine light came on an started flashing. I got off the highway and pulled in to a parking lot the car war running rough it was shaking the whole car. I took it slow and got it home. Today i changed the spark plugs and wires and it ran better but still not right at idle it runs fine for a few seconds then rough but not as bad. I got a code scanner and found the codes P0300(Random/Multiple Cylinder Misfire Detected), P1781(Engine Torque Signal Circuit), and P0700 (Transmission Control system Malfunction). I cleared the codes to see if after replacing the plugs it would come up with another code and nothing but it still not running right. I it an 04 Aveo with 71,000 on it and the timing belt and every thing was replaced just shy of 60,000. Any one have any ideas?

From my experience 3 weeks after buying my aveo at 108,000 miles, I had a p0300 (multi cyl misfire), I had to to replace the ignition coil, while I was at it I replaced the plugs. due to having a multi cyl misfire though, it killed the air/fuel ratio sens (up stream o2) and it also killed the cat ($300 from discountconverters.com direct bolt on)

[jimig1]

I have not had a chance to really look at it nut from test driving it i notice that it only has the problem at idle if you have the car in park and give it a little gas less then 500 rpms the roughness goes away

[exodus0784]

+1 on the ignition coil. If you've changed the plugs and wires, next in line is the coil. Our '07 started throwing p0300 shortly after we got it and it turned out to be the coil.

Like Paul's experience shows, you really shouldn't be running around in it while it's misfiring, a $100 job can turn into $500 pretty quick.

[paulsaveo]

+1 on the ignition coil. If you've changed the plugs and wires, next in line is the coil. Our '07 started throwing p0300 shortly after we got it and it turned out to be the coil.

Like Paul's experience shows, you really shouldn't be running around in it while it's misfiring, a $100 job can turn into $500 pretty quick.

True, thruough my job, I got the coil for $100, the air/fuel sensor for $95 and as previously mentioned the cat from discountconverters.com for $300. Unfortunately, i didnt have the ability to just stop where i was, I was out of town so I had to limp it home, under low throttle it was fine, but under heavy acceleration is when it would misfire. I also had to limp it home so I could get my aveo to work to fix it, I wasnt about to take it to a shop and pay for something I could do myself for no labor LOL

[Daox]

I got a spare ignition coil if you're interested...