99 grand prix 3.8l p1133 and kr @ wot

[davez28]

HI, any input would be greatly appreciated. I have a 99 grand prix gt stock .. my gas mileage has not been as good as the last 99 grand prix. car has 78k miles on it.i decided to change out the o2 sensers to see it it would help as it did on my old one. got bosh sensors and started getting p1133.took them back and changed them and again intermittent p1133. took them back and put in ac delco and still getting intermittent p1133. checked all wiring. heater circuit seems to be working with no voltage drop. switching circuit bounces from 200-800 mv as it should. started scanning with hpt and found a lot of kr at 80%-wot. at wot o2 hangs steady at 850mv. i found some corroded terminals on the coil packs on #1 & #3 so i replaced all 3 coil packs, plugs and delco wires. no change in the kr. put in 10 gal of 93 octane and my kr seems a little better. kr would go as high as 8 and with the better gas not going over 4 much. do i have a fuel problem? I am stumped on the p1133. should i just turn off that dtc with hpt? I want to figure this out on my own so i can learn but im stumped. Thanks, and sorry if i posted in the wrong section.

[5FDP]

I had the 1133 all time when I installed headers, but it soon went away forever after a month or two. It's not really a emission code and does not effect anything, more or less just annoying.

As for the KR, thats completely normal for a stock vehicle. Been around enough 3800's to say that seeing 8-10 on a NA car is normal and with adding 93 octane the kr goes way down.

The stock exhaust in restrictive. Front manifold has poor flow and the stock downpipe with u-bend is the biggest factor. It goes from 2.25 down to like 1 7/8th pipe and then back to 2.25, and it's just for the o2 sensor clearance. Most people will either cut the u-bend out or just buy a 3in downpipe. Both of those will reduce the knock retard.

[davez28]

Thanks, good to know on the kr. the p1133 wont put it in open loop then? Should i turn off the p1133 with hpt? funny thing is i didn't get the code with the old sensors. Im interested in the exhaust work. does it help fuel mileage much? could i scrap the cat all together? its not all bad because i would not have found the corroded coil packs if i had not been digging around from the p1133..

[5FDP]

I found this for the code.

http://www.ls2.com/boggs/dtcs/DTC%20P1133.htm

But really it just sees if it switches enough time within a given time and if it does not it sets a code. It will still stay in closed loop and run as normal.

If you have no emission testings and dont care about the smell of catless exhaust you could get or make a catless downpipe and run it. 97-00 grand prixs do not care at all about what the rear o2 sensor has to say, it's just there to say yes or no on if the cat is working or not. On 01-03 cars they added a cat test and the rear o2 plays a part in fueling.

Thats why you can remove the rear o2 sensor altogether and turn all the codes off for it.

[davez28]

Thanks a lot for the info..