Black91Vette

I'm running long tube headers and had some closed loop idle issues. I installed a heated O2 sensor which solved my problem.

Now I noticed the closed loop timers ($8D). Cold and warm timers are 3 mins and hot is 54 sek. Should I decrease 3 mins to eg 1 min? Or should I leave as it is? Is there a good reason for those 3 mins when you have a heated sensor?

Kevin91Z

iTrader: (1)

Yes, when the engine is cold it needs those 3+ minutes to warm up and get into operating temp. You can set the hot O2 timer to 30 seconds, but definitely leave the cold timer alone.

carls1982z

are thos #s correct ???----------i started here new at the tuning thing this pas spring, and i had added a 4 wire heated 02, and it goes closed loop aroung 135 degrees.---------with my tuner pro and 7747 ecm is the timer listed as closed loop timer warm sec, AND cold secs, ??? and theres a listing of warm thres, ???---------my stock #s are cold-47 secs AND warm 10 secs, You say 3 min on the cold, but mine doesnt list that high ???----i would like too get mine too warm up more before going cloosed.

HaulnA$$

The long timer numbers are to allow a non heated sensor enough time to fully warm up and become active. Now that a non heated sensor has been replaced with a heated one, the timers can be decreased. If you look at .bins of applications with heated sensors from the factory, some of them have the warm and hot timers at 15 sec. or even less and the cold timer can range from 30 to 90 sec. With long tube headers and a heated sensor, I typically set the warm and hot timers to 30 sec. and the cold to 60 sec. HTH

3.8TransAM

Another note I have found.

When doing applications other than stock, shortening the cold timer can lead to increased knock counts whether the 02 is hot enough to osciallate or not.

Again this is something that I have found and it might be 100% possible to eliminate all cold start/driving concerns another way, but I havent found it yet.

I do agree on it being wholey possible to shorten the warm and hot 02 times, as long as the 02 is active, you should be fine.


later
Jeremy

Black91Vette

I was assuming the "O2 ready" bit shown in Datamaster would show that the O2 sensor was fully warm and ready for operation but that was just my guess.

I noted that both commanded AFR=14.7 and O2 ready=1 long before those 3 mins so I figured the timers could be decreased a little bit.

I tried 50 sec and 120 sec which worked just fine and I'll try your numbers 30 and 60 too.

Thanks for all the comments!

Black91Vette

One more question, I was thinking that the ECM will not enter closed loop operation as long as O2 ready = 0, right? At least that is how it seems when I look at my logs.

carls1982z

so, then whats warm thress,--------min temp 02 is alowed too go closed ??????, mine is 60degree c, in stock bin with 7747 ecm.