Just installed AR 1 3/4" headers with catted x-pipe. Car sounds great and drives great. however, i now have pretty rough vibration when at idle. It only happens when the car is in drive and i am at a complete stop. when im at a stoplight or sign, and i put car in neutral it is fine. The car vibrates so hard that it rattles the windows and mirrors. Please help.

Thanks
Neil

 

Maybe you cracked a plug during the install? Fires at high RPM's, but mises at idle..

 

I would re-tighten the header bolts and go under the car and make sure the exhaust system doesn't make contact with the car, especially near the rear.


---Matthew Hicks

 

Or maybe broken spark plug wire/ bad connection. What is the idle rpm? How long have you let it sit at idle post header install?

 

Check two potential pinch points.... one is right by the heat shield where the headers pass the frame. Generally this is on the passenger side. You can remove one of the rivets holding the heat shield in and it will give you and extra 1/4 of an inch which will, surprisingly, eliminate the vibration. You do not have to remove the heat shield. Just get underneath it and chip out the rivet. It takes 1 minute. The heat shield remains in place functional.

The other place is the rear pipes: what you are describing may not be in the rear.

A header rubbing the frame will radiate and vibrate the entire cab of the vehicle. Pipes rubbing in the rear will just be annoying.

Check the plugs and wires as well.

 

Idle RPM is the same as before header install. 500 rpm. Keep in mind that the car only vibrates when at a stop in drive. if moving or car in neutral, it is fine. We double checked everything after the install to make sure that nothing was touching anywhere. We also took all plugs out before install and checked for cracks before we put back in. Any other ideas?

 

You are probably aware of this... you must check while the car is on a chassis lift to simulate driving conditions. Mine was fine on the drop lift until it was on the ground.

 

One other thought is that the computer just need some time to relearn.

If you do not hear it in the or feel it cab in the shifter, it may just be a slight engine vibration. Hard to tell over the board.

 

Going to tuner tomorrow for dyno tune. Maybe he can figure it out. If anyone has any other thoughts please post. The more ideas the more likely i am to fix issue.

thanks

 

Is the engine running rough, or is there just a vibration/noise coming through the chassis? If is it a vibration/noise issue then I'm in agreement with Retrotech, its probably exhaust system component contacting the body somewhere. A few have had the passenger side header touch a spot at the rear of the front wheel well.

 

Not sure but if i had my guess it would be its the engine running rough. I am positive there is nothing touching underneath my car unless things have shifted since i have taken it off lift and driven car.

 

Mine did. Once we had the car tuned on the dyno, we had to put it back on the lift to recenter the xpipe and over axle pipes. If you lift the hood while the car is idling you should be able to tell..If its shaking, its missing.

 

Could be the computer is trying to adjust to a new air fuel ratio w/o tune? Is this system with or without cats?

 

You reversed the rear oxygen sensors. They are wired to cross over to the opposite pipes.

 

can you please explain to me why this matters? I do not remember if we crossed them or not, but I would assume that if they are plugged in they would be fine. do you have pictures of an example? Thanks for your input.

 

When I had headers the only way I could get a decent idle was to run Open Loop. Have your tuner try OL and see if that helps. The 02 sensors are too far away and may not be getting warm enough.

 

What is Open Loop?

 

Your idle should be 700rpm. 500 is too slow, I think you have a cracked plug.
Put on some rubber gloves and pull them 1 at a time. The one you pull with no change in idle, is the bad one pull the plug and inspect
looking for a line is the insulator.

 

Basically you are programming to bypass the front two 02 sensors and running off the MAF. Your tuner should know how to do this.

 

This has been done and when people had them reversed it fixed the problem. Each O2 is specific to that side and they adjust independently of each other. Why would you think a left bank O2 would be ok in the right side???

Why it matters is that info used for each bank is specific to that bank. A rear 02 sending back info on the wrong bank makes it not adjust when the PCM commands a fueling event. If the O2 says its too hot on that side and the PCM commands more fuel to cool the cat with no response, it then commands more fuel. As its doing this the O2 on the wrong side isnt going to get any response for that side since its not reading that side.

There are countless people running headers in closed loop without issue. Closed loop is the way it supposed to run and open loop only is for people who have it hooked up wrong.

Your symptoms are exactly what happens when you have the O2's reversed. You dont use band-aid fixes such as running in open loop. You fix whats wrong so it works properly. Take the O2's out and reverse the pipes they are in. Common symptoms will show ok perofrmance for WOT since its not closed loop. Its got messed up fueling though because it uses a long term fuel trend to act as a base for PE mode.

You dont need a picture; reverse the O2's. Since you say the car sounds great and runs great you are definitly not running on 7 cylinders.