more carbon

changed headers and exhaust system.the car runs fast at lights 1500-1700 searching for idle speed.is this a good indication she is runnin rich.????time for a re-tune

Honez

A tune will do you good but let the car run for a while so that it can do some learning, then tune it.

vettenuts

If it is hunting for idle, re-check all your connections and O2 wire routing. Mine was rich, but I have not heard of anyone having the issues you are indicating unless there was a problem. It should idle just fine with the installation of headers.

ArKay99

Also, check your intake for leaks after the MAF. Make sure the airbridge is not kinked underneath and that it's all sealed up properly. The other thing I would look at is to make sure all your vacuum lines are reinstalled properly

more carbon

thks for help.she idles good when cold.after the engine reaches NOT she goes fast idle.the header and cat back swap was to a way more free flowing system.i kinda think she is far too rich,but i could be dead wrong.need a tune guys advice.thks

vetpet

Putting a set of headers and an exhaust system should not cause the problem you're having. Did you do any other work besides the exhaust at the same time? When you start the car the computer is in a "open loop" mode meaning it is not relying on the O2 sensors for exhaust readings and it will run fine. Once warmed up and the system moves to "closed loop" the computer then starts using signals from the O2 sensors (particularly the rear two) to adjust the fuel mixture. If you have an exhaust leak anywhere before the O2 sensors the computer thinks the car is running lean and starts to put more fuel into the engine by adjusting the duty cycle of the injectors. This fattens the mixture but it is too much for the cylinders to burn and the car runs rich. Since pretty much everything is controlled by what the computer sees it also will try to increase the idle speed. In a carbureted car, a lean condition would make the engine idle faster because you're leaning out the fuel mixture but there's no compensation for fuel because there's no computer. Take a look at your spark plugs and see if they are black and sooty looking. Check all your pipe connections and also the O2 sensors where they thread in. If all you've done is an exhaust change I'd say you have an air leak that's allowing outside air into the system. Keep us posted and good luck.

T_Vert

since it runs fine in open loop but bad in closed, check your o1 sensors and for any unmetered air into the system.

Dave

more carbon

now we may have something.the rear 02's are not in the system and the fronts are now in the rear.the car had no cats to start with so the rears were taken out of the system in the old tune.with the new headers moved the rear cables to the front harness locations on the LG's and did not install cats,but no matter.does this sound right????

vettenuts

Rear O2's will not affect the way the car runs, it will set an error that you have a CAT problem due to inefficiency. They do not provide any direct feedback for system control to my knowledge. You need to check your wiring again, the left front goes to left front, the right front to right front. If not rears, I assume you are running SIMs.

more carbon

thks guys,jacked car up and checked o2 wires.i have R to R and L to L so thats ok.the rear o2 sensors are deleted from computer.i did not think a header and exhaust system swap would do this.gotta phone a tuner,looks like tune time.

Fastguy

Drive it for a while. Mine stalled and ran like crap for a day or two until the computer re-learned hiw to run right.

vetpet

You're correct Vettenuts. Sounds like more carbon has the wiring mixed up for the sensors. He'd have to install SIMS in the rear wiring harness to prevent codes. Looks like he'll have to get the wiring looked at or get an electrical schematic.

more carbon

ok,after a second 20 mile spin,the engine is only 1500 idle when hot.better from 2000 as before.it sounds and feels good.i think the systen flows better than the old and makes the car run on the rich side.the GHL bullets sound killer at idle standing outside the car,at 65mph they are quiet,full throttle you get the true sports car sound.thks for input.now for a tune and a cool-one.... peace