Left side of motor is not igniting.

**raynor139** · 12-21-2010, 08:40 AM

So been chasing this problem for the better part of a week. When driven the cars left side cylinders will not ignite under 2500 rpms or 60 mph. Every time we hook it up to a computer it tells us that we are getting multiple misfires. We have changed the plug wires, spark plugs, checked the coil packs over and they are working fine. We put in a new intake gasket thinking it was pulling air from a leak somewhere and causing the problems. Also pulled and cleaned the injectors. My mechanic is baffled and everyone he has talked to with experience on LS1s has said one of these items were the source but after going over them all we still have the same issue. If any of you guys have any insight we would really appreciate it.

**cammed goat** · 12-21-2010, 08:45 AM

Are there any loose electrical connections on the left side of the engine? Like maybe a main coil harness? Almost sounds like a bad ground for the coil packs.

**raynor139** · 12-21-2010, 08:51 AM

Gone through all the connections and they are good.

**Spaz** · 12-21-2010, 08:56 AM

do you have any friends that can swap out the PCM with to see if your pcm isn't shitting out on you???

**cammed goat** · 12-21-2010, 09:06 AM

Originally Posted by Spaz

do you have any friends that can swap out the PCM with to see if your pcm isn't shitting out on you???

I have never heard of coil packs on one side not working. O2 sensors, yeah, but not coil packs.

**Spaz** · 12-21-2010, 09:21 AM

the only other thing i can think of is if you've ever jacked the engine up (maybe to put headers in) that the wires might have been pinched between the firewall and engine...

**raynor139** · 12-21-2010, 12:10 PM

Originally Posted by Spaz

do you have any friends that can swap out the PCM with to see if your pcm isn't shitting out on you???

Pretty much what we are thinking of at this point. Just don't have easy access to one.

**raynor139** · 12-21-2010, 12:13 PM

Originally Posted by Spaz

the only other thing i can think of is if you've ever jacked the engine up (maybe to put headers in) that the wires might have been pinched between the firewall and engine...

Never done that myself but don't know about previous owner. We did find some cheap ass spark plugs from China being used in it so who knows what else he did.

**raynor139** · 12-29-2010, 07:52 AM

Mechanic called me back finally to go over everything since he wasn't in town when I got the car. Turns out the car had water in the computer.

**Smittro** · 12-29-2010, 08:33 AM

Originally Posted by raynor139

Mechanic called me back finally to go over everything since he wasn't in town when I got the car. Turns out the car had water in the computer.

Glad you got it figured out.. There is an under cowl drain near that area, I'd make sure that water can pass the PCM there. The area behind the PCM and along the fender and fire wall can fill with debris and cause water to not pass freely..