Surging Idle Problem After Header Install Need Help

[Torched]

This problem was first noticed after I installed LG long tubes complete exhaust system and GHL bullets. Since the headers, i've put on heads,cam,polished throttle body and underdrive pulley. I need to make clear this problem occured before the heads and cam job. I believe the LG'S use only the rear oxygen sensors moved to the front position. I was using 2 oxygen sensors to fill the old front position.Since I had the Z tuned they disabled those 2 front sensors but thy still remain in the car. I took her out today and the car almost stalled with the idle going as low as 500rpm. I had the climate control on as well but I don't think that really effects it. I does it i noticed when comming off the gas at higher RPM'S then cruising in neutral to a full stop. I need some help with this please as i'm stumped. MTI tuned my car and I live in Los angeles. I talked to Jayson about this he told me to send him the PCM and he would smooth out the idle.He brought the idle up from 875 to 900 RPM'S.This did not have any effect on the surging idle problem also no codes are being thrown.Please post here or e mail me direct with your suggestions.Thanks again Greg. ggest@adelphia.net

[IT L GO]

Sounds like you have the O2 sensors crossed. Check that first. Many folks have made the same mistake.


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[IT L GO]

From LG's instructions

O2 sensors:
This is very important. When you remove your old headers, you will remove all four 02 sensors. Set the old front sensors aside and do not use them, the wires are too short
Install the 02 simulators and plug them into the car harness, where the rear 02 sensors were attached to the wiring harness. The car harness has a square plug and so does the 02 simulator.
Next, take the original REAR 02 Sensors, and plug the LGM adapter into them. That will give you a long wire, with the LGM adapter which will allow this 02 sensor to be used as your main front 02sensor. Install the long 02 sensors in the collectors of the new LG headers, and make sure to route them away from any hot tubes. You must install the 02 wires one side at a time to not mix them up. The sensor on the right header (collector) gets plugged into the right side (Passenger side) and the one on the left collector gets routed to the left side plug in the car harness.
It is important that the 02 sensors go to the correct side of the car. If the 02 sensors are not hooked up correctly, the car will not idle correctly. This should be the first thing you check if a problem arises after the install. Just hook the driver’s side 02 to the driver’s side wiring harness, and do the same on the passenger side. Our 02 sensors angle across and can easily be confused. We drill a 1” hole in the upper heat shield to help route the wires, but this is not mandatory. But extra care must be taken to avoid the hot pipes so not to melt the wires.

Please call us if you have any install questions. 972-272-7753
Hope this makes your job easier.

[Torched]

Originally Posted by IT L GO

Sounds like you have the O2 sensors crossed. Check that first. Many folks have made the same mistake.


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Since i'm not throwing codes could this be crossed sims? The car runs very strong except for this idle problem. Greg

[dpd]

the problem wouldn't be crossed simms.sounds like the 02 sensors are crossed.if you plugged in the o2's the way "it looks like they should be",they are crossed.the left header o2 plugs into the left harness,right to right.if you plugged them in the way the originals came out,they are crossed.if that's ok,look for air leaks,vacuum leaks,etc.

[jdk]

The car would barely run if you had crossed the o2 simms.

I too have had idle surging problems, but I've managed to work it out to where it's only a problem for a few minutes on cold startup. I didn't use o2 simms, so I just deleted the codes for the rear sensors. Just to clarify, the LG setup uses the rear sensors, but they plug into the harness where the front sensors used to connect. This is what I've done:




increased timing 2 degrees in all tables between 400 and 1200 rpm (all g/cyl)

raised idle airflow vs engine coolant temp

raised IAC park position


Like I said, it idles fine once it's warmed up both with and without the AC on. It still has problems between engine coolant temps of around 150-185, but I'm not too worried about that. If I putt around at too low of an RPM when the car is first warming up it will also throw a codes (HO2S insufficient activity, etc). It's possible there is a leak between my MAF and throttle body, or perhaps a leak with the headers somewhere I guess, but I think it's just a bug that needs to be worked out in the tune.



Just my experiences.

[Gman2002Z06]

I idle down the 1 mile long dirt road I live on every day...My car stumbled and stuttered even before I did the LT headers...Some of it is due to the cam...Although not a radical cam...It is radical compared to the smoothness of a Caddy's engine...

I like how the engine has a little roughness to it...

After the LT's the stumbling was slightly more, but not to the point where it is causing any problems...

Occurs at normal driving, at rpms of 1200 and lower...

Peace...Gman

[Torched]

Originally Posted by IT L GO

Sounds like you have the O2 sensors crossed. Check that first. Many folks have made the same mistake.


.

I do not believe the 02's are crossed i believe that car would missfire and run horrible which it is not.I have a thought could it be a MAF problem with a blackwing on a 02 Z.I just read some old posts and some 02's have been reported to have surging idle issues with a blackwing. Is this possible? would a dropping idle be concidered "Surging"? Greg