Exhaust Question

[WS6 L98]

Heu guys. I am potentially picking up an LS1 T/A that has no exhaust from the y-pipe back and according to the owner, is causing the check engine light to go on. He also said that the car bogs/stumbles between 3-4K. The car recently had only 7 spark plugs changed (couldn't get the last one) and I am wondering if the exhaust (or lack of) plus the one dirty plug are contributing to this?? Any insight would be greatly appreciated.

[JunkyardZ]

I would try to get codes scanned first. I don't think that the exhaust being gone downstream of the o2's would cause a check engine light. If that one plug is bad, then yes, it could be the problem but really need the codes read first. Alot of autoparts stores will do it for free. Why did he take the exhaust off anyway?

[RyanJM]

Having no catback exhaust will just make the car loud basically like having a cutout installed and shouldn't affect the way it drives at all. Now with GM's one bad plug will make the car run bad but not sure if it will throw a code. I would agree and take it somewhere to have the codes scanned like a parts store. If you don't know much about motors there are alot of shops that will charge you like $40 to 50 and check the car for you. My friend used to do it a his place. Would do a test drive, check the fluids(see if there dumb enoght to sell a car with old oil and burnt tranny fluid), and put if on the lift to check for any other under car issues. Neve know whats banged up from people driving up curbs and may other things they go over.

[AM35thZ28]

If the 2nd set of 02 sensors are not connected to the headers that will make the engine light turn on. That bad spark plug will affect the performance of the car, but not by alot. I too have a very hard time changing that last plug cause its hard to get to.