open loop problem

[map 87 gn]

Hey guys i need your help.
I have a mostly stock GN with the following upgrades. I am having problem with the car going into open loop idle after it is warm. The car has been set properly in idle when in closed loop. What happens is after a drive the car will be in closed loop but if left idling it will eventually go into open loop. I also noticed on the weekend while cruising on cruise control at around 68 MPH that the car was in open loop (as per the flashing light on the scanmaster). I checked the CrossCounts & they were still reading, though not as fast as usual. Below I have included the mods to the GN.

Scanmaster, 160 degree thermostat, 3 core radiator, Big Mouth cold air kit, LT1 MAF & Translator, 57lbs injectors, Extender Extreme chip, Hooker Super Competition headers & downpipe kit, Walbro GSS340M with Racetronix Hotwire Harness, RJC plenum plate.

I have already changed the O2 sensor from an AC Delco to a Bosch (which was not working very good) back to an AC Delco. Waiting to receive a Denso sensor delivered to see if this will help in any way.

Now I know that the Hooker Headers are not good for this car but they were already on the car when I bought it. I do plan to change them hopefully next year.

So just wondering on ideas on where to start to rectify the problem, or any suggestions. Thanks.

 

[Chuck Leeper]

Hookers forcing the O2 sensor to cool off and go OL???

 

[TurboDave]

Hookers forcing the O2 sensor to cool off and go OL???

That's the direction I was heading.

 

[TurboBuRick]

Which chip. Extender or T.T.?

Most of the newer T.T. chips are programed for open loop idle.

 

[TurboDave]

Which chip. Extender or T.T.?

Most of the newer T.T. chips are programed for open loop idle.

That's true, but if I read his post correctly, and assuming he's seeing it correctly, he stated that it is dropping back into open loop idle. I assume he meant that it had been in closed loop idle for a while and drops back after idling for some time.
And he also stated that it will drop back into open loop during a light load cruise.

 

[mikestertwo]

The problem is the headers. The O2 sensor is cooling off. Typical problem with Hooker headers. My son's car had the same problem with the Hookers. Took them off, problem solved.

 

[map 87 gn]

Yes the car does go into closed loop then afterwards will go in open loop.
The chip is an Extender Extreme.

Thanks for all the input/info. It's great to have more than one head trying to figure out a problem. I was also leaning towards the headers but wasn't quite sure. I guess I know what to ask for Xmas.

 

[TurboBuRick]

If it is an issue, you could maybe try to relocate the o2 bung. Get it closer to the heat.

 

[Steve V]

Until you get around to swapping headers get a heated o2 sensor kit,this is only a bandaid.

 

[map 87 gn]

Sorry for my stupidity but i am guessing that having a heated O2 would help in it not cooling down so quickly? Am i on the right track?

 

[delcowizzid]

heated o2 sensor is allways hot ready to read

 

[map 87 gn]

Thanks for the info. I might try this a "band aid" until I can buy & change the headers & up/downpipes

 

[mikestertwo]

You will be supprised how much faster your turbo will spool when you get rid of the Hookers and go back to stock headers

 

[map 87 gn]

You will be supprised how much faster your turbo will spool when you get rid of the Hookers and go back to stock headers

I can't wait....as soon as I have $$$ to buy some. Maybe even the reproduction ones would probably be better. Thanks for the heads up to watch out for whiplash once I change the headers.

 

[mo86gn]

i had the same problem. it may sound to easy of a fix but gm ecm's also need to see coolant temps higher than your 160 tstat can give. my car would not pass emissions because open loop fattens up fuel mixture. i had 160 tstat. changed to 180 and car would go in closed loop. its worth a shot. easy to swap.

 

[TurboDave]

i had the same problem. it may sound to easy of a fix but gm ecm's also need to see coolant temps higher than your 160 tstat can give. my car would not pass emissions because open loop fattens up fuel mixture. i had 160 tstat. changed to 180 and car would go in closed loop. its worth a shot. easy to swap.

Actually, the Temp. thresh. for C/L determination (degC)

In the stock chip (and most others because nobody messes with it) is:
76.1°F

The reason they're red is because I clipped them right out of my spread sheet where all the chip data lives.

There are of course other settings in the chip that decide whether or not or when C/L(closed loop) happens