Hi everyone,

I put in a speedtech exhaust with 200cell cat. After a 100 miles or so, I got a CEL while light city driving. Bought a prometric and see P1144 and P1145 codes.

After some searching it seems a # of things can be occurring:

• backwards reinstall- which sensor is precat and which is post. I see another post about grey/black wires but also "color coded"...
• O2 sensors are bad- any way to test via durametric?
• MAF- i pulled it out to clean it prior to exhaust install after hesitations as noted in other threads. Seems to run better- no codes other than 1144/1145.
• Bad lifters- seems to be other problem...hopefully not the case.

What am I missing?


thanks.
Scott

 

Scott,

We have not produced exhausts with 200 cell cats for quite some time other than a couple of special requests on our X-cellerator system. You must have purchased our older generation twin can system, however, either way, I do not believe the codes are exhaust related.

My guess is the Bank 1 02 sensor before the exhaust may have become damaged during the installation - that code points to a precat 02 sensor problem with heating, which means it's not working properly or it points to an MAF issue, too.

My advice is to switch the primary 02 sensors from one side to the other and clear the code. If it comes back as bank 2, then it's the 02 sensor...

 

+1 agreed

 

Hi John- i think I mispoke- looks like I picked up 100 cells. Just got around to installing it.
https://www.6speedonline.com/forums/...ross-flow.html

Thanks for suggestion I will give it a go this weekend.

Scott

 

Please keep us posted! I picked up a SpeedTech 3.0 with cat bypass pipes about 6months ago and just like you, after 100 miles of light driving I got a p1145. I made a very lengthy post about it on 6SO. I've tried everything short of a different exhaust but I still get a p1145 every few days. The car runs great and I don't blame the exhaust which I am still very happy with, but your case was so similar to mine I had to respond.

 

^ No cats will get you O2 sensor codes no matter how you look at it. It's the nature of smog equipment. You can get it tuned out by EPL but I don't think you'll pass smog.......

 

It's not the lack of cats. I ran an ebwerks before this, also with cat bypass pipes, and never received any CEL. The secondary O2's are installed with bung extenders and even if they were the problem that is a different code.

 

Are you catless swappable ? I've had issues in the past with a bad weld or a poor seal in the exhaust flow that caused the codes at idle or low rpm driving causing the CEL. When my occured it was discovered a crack in the weld at the flange to cats that expanded when it got hot and changed the flow of exhaust gasses, resulting in the code.

 

you can log o2s see if you messed them: if they dont respond under boost and stay at lambda 1 or so then you know its the o2s.. but in most cases both do not go bad at the same time...
check for exhaust leaks...
if this is a new exhaust talk to John, Im sure he will make it right..
markski

 

No they're not but there are no exhaust leaks before or after the primary O2's. Chances are my case is an intake lifter that is starting to fail on bank 1 but my shop could not confirm or deny that after running the tests for small valve lift indicated in the shop manual. Since it is not impacting performance I just clear the CEL right when it happens with my PLX gauge that is attached to the ODB port. I'm not going to spend 5 grand on a CEL after my shop told me it was safe to ignore. It is just an annoyance I've learned to deal with.
I really am curious to see what the OP's issue turns out to be though.

 

I had the same thing with my Milltek 200 cell and I tried O2 sensor extenders/bungs and it would not go away. Only after I got the FVD tune that disable the O2 sensor readings did it go away.

 

Does the rear O2 sensor provide any input for the tune, or is it only emissions stuff?

I just threw on some of the spacer/mini-cat things to stop my CEL from coming on (catless exhaust). Car has a tune though I don't know what.

thanks

 

Again...these codes are for the pre cat sensors, not the post cat sensors and have nothing to do with cat efficiency.

 

i installed bung extenders and i still kept getting cel's, after a couple of months it stopped happening though, knocking on wood right now

good luck op

 

I used to think they were only for cat efficiency but my tuner (EPL) informed me that they do play a role in fuel trims. I was skeptical but when I removed the rear O2's from the bungs while leaving them connected so I could use them for standalone wideband sensors to feed my AFR gauges I quickly realized that the rear sensors do more than just see if the cats are working. The mixture would slowly get richer until it went from 14.7 to 11-12 when idling. Pulling the battery would reset it to 14.7 and then within a couple days it would get rich again. When I put the rear sensors back in there was no more problem with the mixture getting rich.
Regarding the extenders, I use them as well and so do many people with cat's removed. They seem to provide just the right amount of exhaust flow to the sensors to keep the mixture just right while preventing CELs so you should have no problem with them.