Random Misfire Multiple Cylinders SEL Code

**davidz28** · 04-17-2012, 05:30 AM

During an autocross race my SEL came on and when I took the car to advance it displayed the "random misfire multiple cylinders" code. What could be the cause of this? I havent been able to check my plug wires physically but they look fine. Also I wouldnt think it would be very likely that multiple plug wires failed at the same time. I do have long tube headers and brand new spark plugs with the stock plug wires.

**Knight** · 04-17-2012, 05:46 AM

Check to ensure the plug wires are fully connected to the coils and plugs. Also check to ensure they haven't been in contact with the headers, causing them to melt.

**pajeff02** · 04-17-2012, 08:30 AM

^^ This. Two other thoughts -- your plug wires are at least 11 years old and they should be replaced. Also, when you re-installed the wires, did you hear/feel two "clicks" on the coils and one "click" on the plugs?

**1MileCrash** · 04-17-2012, 08:31 AM

What knight said. Disconnect your battery for an hour...clear the codes and then see if they come back while driving. Check all your coil and rail connectors and run a fuel treatment thru. If none of that takes care of it you may...MAY...have a bad ecm. Computer controls spark timing on the ls1 not a separate module.

**davidz28** · 04-17-2012, 02:29 PM

I probably need to go ahead and swap to new plug wires. The car only has 30k miles on it, any suggestions for new wires? also should I invest in some of those heat shields for the wires?

**pajeff02** · 04-17-2012, 05:52 PM

MSD wires work nice. You can also bend the boots and they will hold their shape for added header clearance. A set of DEI wire boots are not a bad idea on our cars in place of the factory metal pieces.

**cammed goat** · 04-17-2012, 06:14 PM

Keep us updated. Wires WILL throw a multiple miss code. Happened to me when my cyl #5 wire came off the spark plug. I also agree with Knight.

**davidz28** · 04-17-2012, 07:01 PM

Well i just checked all of my wires and everything looked fine except for the third plug back on the drivers side. The thick rubber boot had melted against my header but it didnt look like it affected the wire at all

**pajeff02** · 04-18-2012, 03:05 AM

If the rubber cover is gone or burned through, the spark may be arcing to the head, header or anything metal in the vicinity. Start the engine at night and open the hood -- take a look at the plug wires and you'll know right away if you are arcing.

**davidz28** · 04-20-2012, 02:23 PM

I just ordered some MSD super conductors and some protective heat sheild like the DEI ones but its on a roll and alot cheaper. Should I get rid of the factory metal heat shields to bend the boots for better clearance?

**cammed goat** · 04-20-2012, 02:54 PM

You could try that. Can't hurt.

**az gt eater** · 04-20-2012, 07:23 PM

unplug and replug in your coil pack connectors, i had the same problem. this took care of it.

**cammed goat** · 04-22-2012, 09:23 AM

Updates?

**davidz28** · 04-22-2012, 10:39 AM

I tried taking off and re installing the wires took it for a short drive, no code was thrown but it still missing quite a bit. Plug wires and boots should be in around the middle of this week and i will install those and see if it helps. Anyone got any tircks to reaching the last 2 plugs on the passengers side? ive had to get to them from under the car

**az gt eater** · 04-22-2012, 03:09 PM

Originally Posted by davidz28

I tried taking off and re installing the wires took it for a short drive, no code was thrown but it still missing quite a bit. Plug wires and boots should be in around the middle of this week and i will install those and see if it helps. Anyone got any tircks to reaching the last 2 plugs on the passengers side? ive had to get to them from under the car

Like the rest of us........ have fun.

**pajeff02** · 04-22-2012, 04:58 PM

I tossed the metal boots and just used the DEI sleeves on our car.

**davidz28** · 04-25-2012, 03:30 PM

What type fuel treatment would you suggest? i might as well do that too.

**pajeff02** · 04-25-2012, 04:57 PM

Only fuel treatment I use is Chevron Techron Fuel System Cleaner. Add it to about 12 gallons of gas. I also use TC-W3 2 stroke oil on a regular basis -- one ounce per 5 gallons of fuel.

**cammed goat** · 04-26-2012, 02:49 PM

What Jeff said. I have used Techron and it works. I also use Sea Foam. Let us know how you make out.

**davidz28** · 04-26-2012, 03:05 PM

Just changed the 6 plug wires i could reach, made certain i heard on click on the plug 2 clicks on the coil packs. started the car and it did the same thing. no arcing from under the hood. I did notice that when I would rev up a little the miss seemed to go away but when left to idle the car almost sounds like its about to cut off????? anyone got an idea? Ill put the car on a lift tomorrow and change the last 2 plugs.... but there was no arcing at all