I finished up the install of my LG Motorsports Street Series headers with no cats this weekend. The car is a '97 6 speed if it matters. I followed the instructions and used the rear O2 sensors in the front. I have cleared the codes a few times and they come back. Any help on figuring out which of these codes are for the missing rear sensors and also what are the remaining codes telling me? Thanks for any help!

Here are the codes:
P0131 H
P0140 HC
P0153 C
P0160 HC
P1133 C

 

...also, I had to remove the intake for the new AIR pipe. I swapped the original for an "LS6" intake while I was at it. New gaskets. New plugs TR55's.

When I first started the car after the header/intake install, the car ran very rich (burning eyes). I took it for a spin and while cruising the car was surging pretty bad. I drove it around this weekend and the surging has calmed down a lot but its not gone and the car isn't real rich "burning eyes" at idle anymore.

 

1st the codes are as follows---P0140-P0160 are for both REAR 02 sensors--You have to have the" DTC Enablers" / "MIL lites" turned off via a tune to keep these from coming back on--even if you clear them they will return unless you have them permanently disabled via a tune
2nd ---code P0131 is for low voltage on the front drivers 02
code P0133 is for slow response on the front drivers 02
code P0151 is for low voltage on front pass. 02
code P0153 is for slow response on front pass 02
These other codes are for the front 02's--you can try to clear them with a scanner 1st and see if they re-appear--often when changing the front 02's they will pop up briefly---If they come back-- you need to check to see IF the are working
To check them---you need a scanner--
See if after starting the engine the ECM goes into "closed loop"this will show on the scanner it hould say "closed loop" or "open loop" or maybe "open loop fault"
Then also with a scanner see if the 02 voltages are oscilating (bouncing very rapidly from around .050 millivolts to around .950 ---If they are not and are flatlined at .450 millivolts they are NOT working-- This could indicate a burnt 02 fuse heater but more than likely a junk 02
Often the rears will be fouled when just moving them to the front--It is a good idea to use the rears i the front location as they are more sensitive and work better with LT's If you need new ones get new rears-) 02's can fould easily---once fouled they are no good-
This is just the beginning of the header issue--get this solved 1st--Then---- with LT's a tune IS required for any serious performance gains-- also they can cause issues like surging-etc as you describe--
Reason being the LT's 02 bung locations are further back then the stock maifolds---This re-location causes the 02's to get erroneous voltage readings and also act slowly or with low voltage--The Stoich. commanded AFR in closed loop of 14.68 becomes much richer--something like 14.2--( as drescribed by you as a rich fuel smell)
There are ways to fix with tuning-- Closed loop is for part throttle operation mostly--You should have the CL operation dialed in before you work on the PE/WOT stuff--How the LT's affect WOT is directly connected to the CL fueling------Reason ?? The LT's will create positive fuel trims as the ECM is trying to correct for the added airlow in closed loop---BUT when going to WOT-- whatever the + trim is just before going to WOT will be ADDED to your fueling making it way rich (as an engine safety system) LT's will often cause 10-15% + trims at WOT making your engine lazy and down on power--
--- Bottom line--- You need to get it tuned to get rid of all the codes and to getthe full benefit of your LT's--
PS: there are also several other codes that haven't popped up YET that need to be disabled with a tune with your LT's----hope this helps---

 

I dont have codes P0133 or P0151.

 

The car should be tuned after a header install.

If you moved the rears to the front, what did you do for rear 02 sensors? Are they shut off in the computer? If not it will not hurt performance but you will for sure get codes for the rear sensors.

The surging, does this start after it warms up? Sounds like a front 02 sensor wire might be crossed if that is the case.

H codes are history codes, C codes are current, and HC means it happened before and it is currently going on.

I think the other post above me pretty much explains what is going on with each code.

 

The rears bung holes are plugged with the provided plugs. I expected the codes for the rears. It is the other codes I am trying to figure out.

 

Could just be a lazy sensor and they need to be replaced. Hard to know without seeing the response of the sensors on the scanner though.

 

sorry --P0133 is a typo --I meant P1133 -------- also P0151 is the same code as P0131---just for the other side---even if you don't have it it may show up as it's for the same issues you are having on both sides--- i included it for reference----


""I think the other post above me pretty much explains what is going on with each code.""

Thanks Anthony--a nice compliment from a respected tuner/vendor----

 

Thank you sir! I really appreciate the help!

 

OK, got it scanned last night. The guy that scanned it said that the o2 sensors seemed to be working (maybe lazy) but he said something about fuel threshold on bank one seemed to be a bigger problem. He showed me on the scanner at idle it would go up to 50 and then when he revved the engine it would go down to zero. He said he thinks there is a leak around the intake manifold. Remember these are my codes:P0131, P0153, and P1571. Do these codes indicate a vacuum leak? The car surges when I have the cruise control set at 45-50, but when I set the cruise at 70 it does fine.

I have an appointment at the chassis dyno on Monday for a tune. I really want to get any issues I can sorted out before I go there. I don't want to end up paying the dyno shop to do something I could do myself. What is generally included with a tune? Do shops typically help diagnose problems for the price of the "tune?" Can they even do the tune if the car isn't right? I wouldn't think so.

 

....SO, I took the intake back off and replaced it. I used a torque wrench thins time! The car doesnt surge anymore and the only code now (other than the missing rear sensors) is P0153.

Should I replace the O2 sensors before going in for a tune? The dyno shop had to re-schedule.