Okay, I posted this on same question on LS1tech.com but I haven't gotten to many answers. I installed race style Pacesetters and a TSP ORY yesterday and now my car doesn't run right. It backfires through the exhaust when I try to give it gas, and it surges a lot. After it ran for a while and I drove it on the highway, I wen to get gas and when I tried to start it I really had to step on the gas. I almost thought it wasn't going to start. I'm thinking that the car was running rich. What can I do without getting a tune to help this? Is there something that I might be missing on the install that would cause it to do this? I still have the front O2 sensors, I took off the AIR and EGR systems, the car idles fine, but it just won't let me open her up without coughing her *** off. What should I do? Thanks for any suggestions.

 

Go out an put it up on ramps, pop the hood and double check everything. What did you plug the intake manifold with? Is it sealed tight? Are all of the plug wires on tight/right? Are there any wires close to or touching the header tubes? Did you plug the front O2s to the right plugs? If you unplugged any vacuum lines are they hooked back up right? ect.

 

and double check for exhaust leaks around the flanges.

sounds to me like you forgot to plug something in.

are you getting any SES lights?

 

I'm getting the SES light, which I assume is coming from taking the EGR off. I think I didn't plug in the Temp sensor before I drove it, would that do it? How would the car sound if I had a gasket leak at the headers? I'm just confused as to why it surges, then backfires.

 

I found a leak, I'm trying to fix it at the moment, but I was wondering if this would cause it to backfire or sound like it was backfiring. The leak was at the driver's side collector where it hooked up to the ORY. The really loud backfires were about 30 seconds to 1.5 mins apart, but I could hear what sounded like a consistent backfire coming out of the rear pipes. Has anyone had this problem after a header install? I also listened to all of the cylinders at the header pipes with a tube and it sounded like it was firing fine on all cylinders. All plugs are connected and tight, everything is hooked up, O2 sensors are on. I'll get back and tell you guys if fixing this leak fixes the problem. Any other suggestions?

 

I bet it's something electrical/computer related.

When my friend and I did my spark plugs, we unplugged and unbolted everything to make the job as easy as possible.

After everything was completed we decided to fire my car up. Like an idiot, I forgot to plug this sensor back into the block and reattach the AIR pipe. The first time we started it, it would barely crank and the second time it started it sounded like it was running on 4 cylinders, backfired just like yours did, and blew gray smoke out of the pipes like an old car. When I saw my car doing that, I about sh** a brick and thought I broke the engine.

We rechecked all connections, found our mistakes and after testing the car on the road and making a WOT run, the SES light turned off.

The point I'm trying to make through my example is double-check everything. Even the most careful people make mistakes.

 

These motors will barely run with the coolant sensor unkooked.

And don't ever assume that one thing caused an SES you could have 2-3-4 things wrong and only one SES. Untill you scan and read the DTC you have no clue.