CEL after new exhaust

[OGsohcHondaLOVE]

Just had my exhaust done Friday. Then sat my engine light pops on for the catalyst. I noticed right before that my fuel mileage had dropped extremely and when I did my 0-60car run earlier in the day that it was almost full 2 seconds slower than my last run without the new exhaust. Could this all be because of the rear o2 sensor getting too hot when welding on the new exhaust. It also seems like it is choking in the higher rpm a little and the light came on right after I made a pass around a guy today. I would think regardless of the downstream working properly I should see better 0-60 and easier in the higher rpm because of the new straight through and merge collector?

 

[LS5DodgeRam]

your truck is probably on "limp" mode.. which means your car wont run as well as now CEL since your computer thinks there is something wrong with the engine... at least that's what happened to my buddies genisis when he deleted his cat completely. that is what explains the whole slower 0-60 time and what not. its possible that the electric charge from the weld could have been messing up the sensor.

 

[OGsohcHondaLOVE]

When he welded it he did remove the positive battery cable. The CEL came on 2 times for the same thing. I went ahead and bought 2 of the o2 sensors seeing as they were only $27 each. I'm going to change Both of the rear ones out this morning when I get to work, and see from there.

From what I have always understood, the downstream sensor never has anything to do with gas mileage or runability. I also believe that it were to put the vehicle in a limp mode that I would be able to go over a certain speed or rpm and I have full range.

 

[LS5DodgeRam]

the downstream is what tells the engine if it is not running well. if the cats cannot change the gas to optimal level for the o2 sensor, it could set of a CEL saying the cat is bad, or that the engine is burning the gas incorrectly or some other stupid reason.

how many miles do you have on the car?

I ran into a similar problem with my dad's sunfire. the car has 180,000 and the engine and injection system has never really been cleaned. I seafoamed it and later on i got a CEL for the exact same sensor as yours. I will be taking it out and spraying it with brakleen, in order to clean the contact in hopes that the gunk that was cleaned just deposited on the sensor. if this doesnt work, then that means I need to replace the cat, since it gunked up the cat and will no longer change the gasses to where it needs to be

 

[SILVER_BULLET]

what kind of exhaust work did you get done?

 

[KGBIGCOUNTRY]

^Yep same question. If it was just a muffler swap sounds like they did something odd, if it was more indepth they might have unhooked or burnt something

 

[OGsohcHondaLOVE]

It was pretty much a catback with a custom y pipe in full stainless.

 

[OGsohcHondaLOVE]

I was able to put a few miles on after changing the o2 sensors. No CEL but still an 8 sec 0-60. Something seems off. The only things that have changed on the truck are the exhaust, new stock size tires, and added the trans running option on the SC but its tuning SC values since the advanced tuning isn't working properly and SC hasn't gotten back to me.

 

[KGBIGCOUNTRY]

What was the 0-60 before the exhaust?

 

[OGsohcHondaLOVE]

7.1 0-60 with the SC Vivid on 91 tune and AEM Brute Force. No advanced trans tuning which I have set on SC values right now because the advanced feature won't work for me.

 

[OGsohcHondaLOVE]

Came on again today. P0430 same as before.

 

[SILVER_BULLET]

weird thats the code i used to get but because i had longtube headers with no catalytic converters

 

[KGBIGCOUNTRY]

What brand name were the o2's?

 

[OGsohcHondaLOVE]

I don't think there is any way the cat went bad.

 

[truckin151]

down stream o2s don't do anything except tell you if your cats are not working right. the front o2s are the ones that need to remain in place for the engine to run right. I removed my rear o2s and before I had the tune to remove the code it still ran as hard as it did before they were removed.

For your CEL issue, If they made the new y pipe and had to drill and weld new bungs for the rear o2s they could have welded them to far back so the o2 sensor isn't reading right.

For the lack of power, how big of pipe is it? is it a y or h or dual? how big is the pipe the muffler is on? If you went to big on the pipe size it can drop your low-end and slow your times down Have you reset the truck to stock and reloaded the sc tune with the standard sc shift points?

 

[OGsohcHondaLOVE]

The o2 sensors were not moved. The pipe is 2.5-3" same area just a smoother merge. All the pics are in the exhaust **** thread in here. Ill try return to stock

 

[OGsohcHondaLOVE]

I tried to reload the 91 octane tune but didn't try returning to stock first.

 

[OGsohcHondaLOVE]

CEL is coming on every 25-30 miles. I decided to return it to stock on the SC VIVID today, because the program force closes all the time so I figured I'd try to update the unit and the tablet. When I get them inside to the computer it keeps coming up with a Code 43 saying that there is a problem with the hardware on both the vivid and the tablet. I'm beginning to think that these are the stem of my problems.

 

[OGsohcHondaLOVE]

CEL came on tonight on stock tune. Stayed off all night till I romped on the throttle. Then right after that it came on.

 

[truckin151]

alright, well how does it drive though? does it feel the same? better? worse?

as for the cel, you have already replaced both rear O2's right? have you traced the wiring all the way up? make sure there are no melted spots? checked the fuses make sure nothing was blown or shorted? how did your guy weld the pipe on? have you taken it back to the shop or called them to say that this issue is going on now AFTER they worked on it?