VetteRedLS6Z28

Hey guys I've been trying to search for this all day yesterday with all different answers but it seems I can't find the answer to my solution.

I put pacesetter LTs in (no air fittings) and tsp true duals a few days ago, there's no cats and no rear o2 sensors. Now when I put them in I ripped out all of that air stuff and threw it away. Now my problem is this, when I put the car in gear it stumbles to get going like theres a misfire going on then there's a loud backfire.

What could be causing this problem? I didn't cap off that vacumn seal behind the manifold when I took the air system out Which Im going to do today.. Could it be that? Would it be that I just need a tune? My mechanic said that the only codes that the computer is spitting out is the rear o2 sensors because they're not there, he said since the computer is reading they're not there it's telling the PCM to dump more fuel because it's running lean. He told me to put the rear o2 sensors in and the problem should go away, is that true?

Jon@Texas-Speed

iTrader: (18)

If the car has an SES light on scan it and post up the codes or give me a call. The vacuum leak could be causing an issue with the MAP sensor which will cause the car to add a bunch of fuel. It could also be the O2 sensors are bad or plugged in wrong. Either way, getting the codes read will give us a better idea of what is wrong.

Jon

VetteRedLS6Z28

Im not sure the exact code # off hand, but my mechanic told me it was the code for the rear o2 sensor(s). I bought new bosch 13111 o2s and they were installed with the headers. Maybe they are not in tight enough as you said, ill check them. Thanks for the reply Jon

I capped off that little vacumn tube on the drivers side of the intake manifold, and it didnt help the problem

Anyone else have this problem in the past?

Jon@Texas-Speed

iTrader: (18)

Have him get the you code numbers with the scanner and post them up. Rear O2 sensors don't cause that.

Jon

TheSilverOne

iTrader: (22)

the rear O2s have nothing to do with fuel. what about the spark plugs and wires? did you replace them when you installed the headers? are the wires properly seated on the plugs?

Delgoat

Def needs a Tune after header install and this will fix the issues.

VetteRedLS6Z28

I'll get the codes soon.. And I made sure the wires were on the plugs good today. I didn't change the plugs or wires when I did the install. Would putting the wires in different locations effect anything?

Delgoat are you sure the tune would fix it? My buddy swears that's all it needs

SF 1HOTLS1

iTrader: (24)

what vacumn seal are you talking about? i deleted my air system as well and also have a bad misfire.

Delgoat

I had same issue and found a bad plug. Loose wires could also be an issue. I took it in for a street tune, replaced the plugs and wires and the car is running great now.

lt1pwr1

iTrader: (1)

Get rid of those POS Bosch o2 sensors. You have those in the fronts right? I would get the Denso ones instead.

VetteRedLS6Z28

Late reply but I found the problem, must have cracked a plug when I was getting the header in the passenger side, replaced plugs and wires and she runs like a champ now ,and so far no issues with my Bosch o2s..

01ssreda4

iTrader: (96)

Glad you found the problem...btw your mechanic is an idiot.

crainholio

iTrader: (2)

Expert advice fail.

J-Train

No kidding, my car runs just fine after LT's, O/R Y, catback, lid, filter, MAF and bellows.

It will be getting tuned after my cam and convertor, but it runs fine like it is, way stronger than stock thats for sure.

crainholio

iTrader: (2)

It's great that you followed up and posted the solution, possibly somebody with similar problems will find it useful!