Vy rough idle

[cody_muzz]

Hey guys, I’ve recently bought a vy v6 ecojet and have put a supposedly stroked out engine in it, put a new alternator on, new leads, hoses, full service on engine ect ect.

It was running a dream apart from an engine code that comes up, my mechanic friend hooked it upto a (correct me if I’m wrong) grade 3 scan tool to see what the code was, but was not coming up on the scan tool. Still ran fine either way but didn’t know what gear it wanted half the time (auto). Now, the other day I was half way around a roundabout sitting at maybe 2k revs just cruising and the Welch plug blew out, drove it the 3 mins up the road to my house and turned it off. Put a new plug in today, put everything back together, filled coolant back up and fully bled the system and put new ngk spark plugs in as I needed them anyway, BUT, it now has a very rough idle and is constantly over heating, slowly building revs the whole engine shudders and shakes and allmost sounds like it’s missing or at the least not firing right, give it a quick squirt or once it gets above 3-3.5K revs it’s smooth again. It ran fine even with the Welch plug out but now does this and I have no idea what’s causing it! Any advice, pointers, things to test/check is very much so appreciated!! Cheers fellas!!

 

[02VYSS1]

Could be head gasket or a cracked head. Being an ecotec they're both pretty cheap options if you go to a wreckers and you know what you're doing. Had a Vt where the lower RAD hose popped off on the highway and I had no idea until the temp gauge hit max. Ended up blowing a head gasket. Sounded exactly like you're describing almost as if it was cammed at idle.