Adding 02 sensors to a tuned Mustang

[Enfield]

The car: 2007 GT convertible with 96xxx miles. Good compression on all cylinders. Completely upgraded suspension with square wheels/tires. Interior and top have been refreshed. No rust.
Engine mods: JLT3 CAI, UDP's, BBK long tubes, BBK catless X.
Why add cats?: Owner's recent physical issues prevent enjoyment of this car's manual transmission. In order to sell in the Mid-Atlantic, cats are needed.
Current tune: Car came with Diablo Predator v.9r07 with numerous canned tunes and an installed "87 octane street tune". The car starts and runs flawlessly, idles well, and delivers ~27mpg at 70mph, all on 87 with 10% ethanol. Plugs stay clean and there have been no CEL's.
Engine mods and tune were installed at AM back when they did that. I have called AM tech and they have stated that their BBK catted X can be added with no change to the tune needed.
As it seems likely that the current tune has disabled 02 response, I am concerned that the 02 sensors and the cat may not work well together in the long run: sensors too hot or cold -- possibly leading to problems with the cats.
So, what to do? The car will be sold by a reputable independent dealer, and neither of us wants to make the buyer unhappy. No shops around here have sniffers, but a local indy mechanic has a couple of current Snap-On engine diagnostic tools, and he has offered to look for possible problems after cats are installed. And there's the Predator. He knows how to reset parameters.
I have tuned and raced many cars from 1970 to now, but my last American sports car was a 1970 Z-28 back in that era. I know this car is not as highly modified as most other members' cars, but you guys have been very good at advising me on suspension upgrades - and in providing good, used parts, too.

All suggestions will be cheerfully acknowledged. TIA,

Enfield

 

[stkjock]

you "should" be able to add the cats & O2s, adjust the tune for the O2s being active, do a driving cycle and all monitors would typically reset

 

[GlassTop09]

The car: 2007 GT convertible with 96xxx miles. Good compression on all cylinders. Completely upgraded suspension with square wheels/tires. Interior and top have been refreshed. No rust.
Engine mods: JLT3 CAI, UDP's, BBK long tubes, BBK catless X.
Why add cats?: Owner's recent physical issues prevent enjoyment of this car's manual transmission. In order to sell in the Mid-Atlantic, cats are needed.
Current tune: Car came with Diablo Predator v.9r07 with numerous canned tunes and an installed "87 octane street tune". The car starts and runs flawlessly, idles well, and delivers ~27mpg at 70mph, all on 87 with 10% ethanol. Plugs stay clean and there have been no CEL's.
Engine mods and tune were installed at AM back when they did that. I have called AM tech and they have stated that their BBK catted X can be added with no change to the tune needed.
As it seems likely that the current tune has disabled 02 response, I am concerned that the 02 sensors and the cat may not work well together in the long run: sensors too hot or cold -- possibly leading to problems with the cats.
So, what to do? The car will be sold by a reputable independent dealer, and neither of us wants to make the buyer unhappy. No shops around here have sniffers, but a local indy mechanic has a couple of current Snap-On engine diagnostic tools, and he has offered to look for possible problems after cats are installed. And there's the Predator. He knows how to reset parameters.
I have tuned and raced many cars from 1970 to now, but my last American sports car was a 1970 Z-28 back in that era. I know this car is not as highly modified as most other members' cars, but you guys have been very good at advising me on suspension upgrades - and in providing good, used parts, too.

All suggestions will be cheerfully acknowledged. TIA,

Enfield

Hi Enfield,
I'll try to give you some info to use that will help to raise the odds of the cats working as best they'll do using the current specific BBK catted X-Pipe. Most will need to be done thru the tune file around the O2 sensor control. I'm using HPTuners VCM Editor software to ID the specific settings but this is similar thru other tuning interfaces.

1. Since the BBK catted midpipe moves those hi flow cats rearward from the engine's exhaust ports, there'll be potential issues w\ keeping both front\rear NB O2 sensors hot enough to maintain good engine feedback control & cat monitoring operation so the CL Sensor Temp setting should be reset to at least 700*F but no higher than around 750*F, than the stock 500*F to force the PCM to stay in OL cold start long enough to sufficiently heat them up before switching into CL. Then in the CL Sensor Temp delay table, from 20*F & higher, the delay time should be reset to at least 30 secs (60 secs is ideal) from the stock 15 secs to ensure that they get good & toasty before transitioning from OL to CL. Then in the Heaters Duty Cycle mapping, the DC needs to be set from the 15 sec scale & higher to 90% to use the O2 sensor's heater circuits to ensure that the O2 sensor elements stay hot enough to function properly if the heat from the engine exhaust isn't hot enough to maintain them (usually from idle to around 1,800 RPMs). This is usually stepped down to preserve the O2 sensor's heaters by allowing the engine exhaust to maintain proper operating temps......w\ the cats at the OEM location. Then turn the rear O2 sensors back on in the tune so the PCM will perform the cat CE ratio monitoring for IM Readiness\emissions. Then as long as the Stoich AFR target in tune is still set at the stock setting of 14.64 & you have a good, accurate calibrated MAF curve for the CAI's MAF meter for the PCM to use then this should give the best chance for good cat operation & pass emissions thru those BBK hi flow cats.

2. Outside of the usual physical engine operational checks, make damn sure that the car's EVAP system is fully sound (both CPV & CVS operate & CPV seals off when closed to prevent excessive unmetered air entry into IM & CVS seals off when closed so PCM can monitor EVAP system properly for any leaks when it runs leak tests on system). Excess unmetered air entry into exhaust will cause most cats to fail the IM Readiness emissions checks even if the cats are good (excess O2 will not damage a cat but if the cat can't use it all up it WILL cause the rear O2 sensors to mimic the front O2 sensor switching thus exceeding the CE ratio threshold & fail them.........The EVAP system is 1 of the most overlooked systems on these now 17+ yr old cars that can cause a good cat to fail emissions.

3. Keep the BBK catless midpipe & buy 2 good 3-way hi flow cats (preferably either EPA or CARB certified) that will fit the BBK midpipe's pipe dia & have a muffler shop (if you don't DIY) install them, then go thru what I typed above to ensure the best chance of operation to pass emissions.

Hope this helps you out.

 

[Enfield]

Thanks for responses. It's always comforting when your answers are in agreement. I probably should have added that passing emissions is of less importance than simply keeping the cats and sensors happy. So long as there are no CEL's or obvious malfunctions and the car continues to run well, I will feel good about the sale. The next owner can then take my old catless x and perform the upgrade described in #3 above if that is needed.
Will research how to troubleshoot EVAP system. On my last few Euro cars [newer than '07], the evap sensors were sensitive and the resulting codes were pretty easy to trace down; gas cap seals were often the problem.
Enfield

 

[GlassTop09]

Will research how to troubleshoot EVAP system.

Best way I've found to do this is to use smoke leak detection on EVAP system (if using air makes you queasy, use CO2 w\ a CO2 sensing probe to help detect the leaks) w\ some marker additive to make the smoke easier to see as it is the quickest, easiest & cheapest method to use.

From my experiences, the main areas to check are the CPV, the metal EVAP line from the canister to the engine bay (for rust spots\damage), the plastic corrugated flex line that connects the EVAP canister to this metal EVAP line (purpose is to allow the line to move\flex from cycling of engine vacuum into\out of system.....they'll tend to crack over time) & of course the gas cap seal. These are the areas where leaks will show up the most. The CVS is open most of the time & is used to run system leak tests only......but if it fails to seat off when PCM closes it to run tests, you can get faulty EVAP leak DTC's thus why check this solenoid 1st thru smoke leak detection to ensure it seals before validating any EVAP leak DTC. The CVS seats do go bad over time from fuel vapor\air wash drying out then cracking the rubber seats.

Just so you know, aftermarket replacement EVAP lines aren't available (only canister assemblies, some w\ the CVS, some w\o the CVS). All EVAP lines to date can only be bought thru Ford & Ford sells only the entire EVAP canister assembly w\ CVS, shield, rear shield mounting hardware (reuse front shield mounting hardware) & plastic corrugated flex line\plastic CVS vent line. The gas tank lines that attach the gas tank to the EVAP canister (also includes the fuel tank pressure sensor) & I believe the filler neck butyl rubber hoses that attach filler neck to gas tank & smaller plastic lines that attach the filler neck to EVAP side of gas tank lines & new hardware comes as another assembly (there are aftermarket fuel tank pressure sensor replacement kits to replace the sensor using the existing lines available) & they aren't exactly cheap so the next best option is the neighborhood junkyard or go full McGuyver.

Hope this helps you out as well.

 

[Enfield]

Re: EVAP leak detection. So how likely are there to be problems if no codes have shown up? Will still examine lines visually and check solenoid operation, and now I know to get the indy to run smoke tests. Just had shoulder surgery; there's only so much you can do with a big sling in the way. What I had fixed is typically called "mechanic's shoulder." Apparently amateur mechanics are not immune!

 

[GlassTop09]

So how likely are there to be problems if no codes have shown up?

The main problem is that enough unmetered air entry thru the EVAP system can cause cats to fail emissions & set P0420\P0430 Cat Inefficiency DTC's well before the leaks get bad enough to actually fail the initial PCM EVAP .040" Leak Down Test thus causing the PCM to start running the other 3 backup leak down tests before it will determine an EVAP Leak Failure DTC & light up the MIL (this is on Fed EPA cars......if a Cali CARB car there is an extra .020" Shutdown EVAP Leak test to run so 4 other subsequent backup leak down tests before PCM will set an EVAP Leak Failure DTC & light up MIL).

A lot of folks & mechs have replaced a lot of perfectly fine cats on these cars due to trusting the MIL instead of doing due diligence & physically test the EVAP system for these small leaks anyway when diagnosing a P0420\P0430 Cat Inefficiency DTC to ensure that the issue IS the cat before replacement. Now if the exhaust is FFE (I think I know what your intent is for this car) then this won't matter as far as the BBK hi flow cats will be concerned.......they'll just kinda be hanging out on their own.....present w\ all associated equipment but unmonitored, so to speak.

My car is a perfect example of the question you asked.......I had no EVAP codes but when I smoke tested the EVAP system anyway, I found the plastic corrugated extension line cracked & leaking (thus excessive unmetered air entry point downstream of EVAP canister to engine IM "hidden" by any fuel vapors from canister.....couldn't physically see the crack in the line but it was there), the CVS working but not fully seating off thus leaking (so any subsequent PCM EVAP leak DTC's would have been potentially flawed without backup physical testing) & 1 of the quick connects on the EVAP canister side of extension line under the EVAP canister shield that connected to the gas tank line assembly was found leaking (thus the 2nd unmetered air entry point but this point was leaking into the gas tank line side of canister which also was sending fuel vapors into canister so thus was "hidden"......again couldn't physically see the leak due to canister shield but the smoke said it was there). All else checked out good. These leaks were present but not bad enough to outright fail the PCM .040" EVAP Leak Detection tests (checked the EVAP passed test results in PCM's Mode 6 Self Check data) thus never threw a MIL light. Even though the 11 yr old original FoMoCo gas cap passed the smoke tests I replaced it anyway w\ a new MC replacement cause I knew it was gonna most likely be next so I nipped this 1 in the bud ahead of time. I ended up replacing the entire EVAP canister assembly w\ all new FoMoCo EVAP canister assembly w\ all new attaching extension lines to gas tank line, CPV metal line & CVS vent line to get my EVAP system sound (had already found\replaced the leaking CPV prior......which sent me down the path to smoke test the rest of the system......all original stuff over 11 yrs old at the time).

Some folks (and let's face it, some mechanics as well) assume that the EVAP system in the car is in good operating condition since the MIL hasn't lit up w\ a DTC yet saying it is bad..................but will blindly replace a cat on a P0420\P0430 Cat Inefficiency DTC because the PCM said it is bad..........without actually testing all systems prior to ensure that the cat IS actually bad thus validating the P0420\P0430 DTC before replacement.

Other issues include excessive lean\rich codes that most associate w\ other items but exclude the EVAP system due to no EVAP Leak codes present in Powertrain OBDII side. These cars are getting too old to not at least smoke test the EVAP system to know its in good shape......not assume that it is. I don't know how many times some have gotten these cars tuned w\ unknown vacuum leaks present (I've done that w\ my own car......the 1st 3 times it was on the rollers it got tuned w\ unknown vacuum leaks present....tuner thought I may have a leak present but all tuned OK & I couldn't see\find anything using all the "home remedies" so I broke down & bought a full smoke leak detection kit w\ all necessary attachments to test all systems (induction, exhaust & EVAP). Used it the 1st time on induction side & found a small leak in the brake booster check valve, small leaks out both TB butterfly shaft outer seals behind TPS sensor & ETC actuator (BBK 62mm TB........none where I thought they would be). Found EVAP CPV leak using my scan tool reading EVAP live data PIDs during a cold start then on 1st smoke leak test on EVAP system found all mentioned above in EVAP system.......all leaks were present on car when I bought it (was 8 yrs old then & all original under the hood & chassis) except the BBK 62mm TB.........none of them set off any DTC's or MIL's but thru the STFT\LTFT data you could see that something was off but the PCM could compensate enough to not notice it while driving the car & not set off any DTC's......until much later after getting some random P0420\P0430 codes show up on Kooks Hi Flow cats (which I finally found the issue causing the failures.....wasn't due to any leaks found prior but the EVAP system was involved.....had a known aftermarket IM installed at the time that has a EVAP port design that was causing the PCM to excessively purge EVAP due to uneven EVAP spread to all intake runners--ingesting excessive unmetered air thru it which caused the cats to fail IM Readiness over time cause they couldn't use up all of the excess O2 sent into the exhaust thus caused the rear O2 sensors to excessively oscillate & throw the P0430 DTC. Fixed this by reinstalling the OEM IM.....that took over 1 yr to find & fix after fixing all other vacuum leaks). Both smoke tests took no more than 10-15 mins time from start to finish & found all these leaks. All subsequent smoke leak tests since making all repairs (I do these now before any scheduled dyno sessions) have shown all systems to be sound so no issues & all tuning is clean & quick now.

Can have you chasing a LOT of rabbits otherwise w\o 1.

PS--Hope your shoulder surgery comes out successful. Been putting off carpal tunnel repair myself due to success rates being 50-50 at best so I put up w\ it from time to time until it gets bad enough that my hands don't work no more, then I have better odds of getting something out of the surgery as my hands still work Ok, just hurts if used a lot over time.

 

[Enfield]

Excellent analysis of EVAP-driven rabbit hole possibilities. Not sure what "FFE" means, but my primary goal is to keep the current level of performance while making the car capable of passing VA state inspection. In our part of the state it's merely required that cats/sensors be hooked up with no DTC's. My secondary goal is to make sure that the cats can live with whatever tune is driving them. The indy mechanic is a former certified Chevy shop tech with decades of experience in UPS fleet maintenance. Like most techs around here, he has nothing but contempt for emissions-related equipment. In explaining the relationship between sensors and cats he asserted that just about every vehicle in our rural county with more than 100k miles is worse off for having any emissions equipment; I would not disagree. He told a few horror stories about what happens to cats on vehicles with poorly-designed systems; his worst example is the design of the emissions system on early Ford 6.0 diesels. I posted on here to learn enough to be able to communicate meaningfully with this very accomplished mechanic. Fortunately, he likes to talk, as does his whole extended family, many of whom are old friends.

Healthwise, I had surgery on left wrist and hand about 50 years ago; full recovery [from pain] took about 4 years. Left shoulder just quit working about a year ago. PT on that starts today. Right wrist and hand work reasonably well with an OTC brace, but even with that the 1-3-5 shifts on the Mustang's Hurst are just brutal. New-to-me Volvo V60 T6 with exhaust and tuning mods is just as quick as the S197; it has a sport tranny mode with paddle shifters. It would be sweet to find a GT convertible with paddle shifters, but good luck finding one for even twice the money I can get selling the '07 GT!

PS. Have only myself to blame for getting into this pickle. When I went to look at the 'Stang, seller raised it enough with a floor jack that I could peek underneath. Saw an X-pipe with 4 sensors in place - little knowing that BBK made it that way to fool suckers like me. Still glad I bought the car, and I've been pretty well impressed by the design of just about every component except the rear LCA's [no toe adjustment] and of course the spark plugs. As stated before, running B12 Chemtool in the gas tank for about 100 miles cleans combustion chambers so the plugs come right out. LCA fix was J&M's, which can be a bit noisy, but only around town. Who wants to drive a car like this around town anyway?

 

[GlassTop09]

Engine mods and tune were installed at AM back when they did that. I have called AM tech and they have stated that their BBK catted X can be added with no change to the tune needed.

Ok, what I meant by "FFE" was due to this statement you posted from AM techs concerning the replacement BBK catted X-pipe to replace the BBK catless X-pipe.

You aren't seeing any P0420\P0430 DTC's is due to the rear O2 sensors being turned off in the tune, so the PCM isn't monitoring\checking for the cats, thus the term "FFE or free flowing exhaust". Now you can replace the existing BBK catless X-pipe w\ the BBK hi flow catted X-pipe, put all back as currently is & all will still be the same cause the PCM is still not checking for the cats due to the rear O2 sensors still turned off in tune, so all still operates just as all does now thus still "FFE" but w\ cats in the system so they're just hanging out (this is what I implied as to your intentions w\ BBK catted X-pipe....my bad)......w\ no monitoring\checking to test for emissions but also for health monitoring purposes as well (COT protection--to protect from overheat\substrate breakdown & cat CE ratio monitoring--operational health of cats to reduce HC & CO in exhaust as well as checking to see if the running operational CE ratio result doesn't exceed the max CE ratio threshold set in tune for emissions compliance....) as the rear O2 sensors need to be active for all of this to work. Once the rear O2 sensors are turned back on in the tune, then all this coding will become active, then its up to the condition of the cats ability to process the unwanted gasses in the exhaust.....but it is also important that ALL systems are in sound operational condition so to not introduce excessive unmetered air into the exhaust to defeat the cats ability to pass. This is also where the actual tuning comes into play......why I said to ensure that the CL Stoich AFR target is still set at stock 14.64 in tune (what the PCM uses to determine actual fuel type being used to apply a fuel index ratio to then determine BTU value to use in TQ calcs but also the CE ratio threshold for each bank based off the STFT data for emissions compliance.....this 14.64 AFR reps unleaded gasoline w\o ethanol. Technically we should correct this in the tune for current E10 unleaded gas @ 14.13 AFR but as long as the STFT's are properly switching around 450mv based off LTFT fueling corrections + MAF error corrections while in CL, this is actually Lambda 1.0 thus stoich thus the 14.64 AFR setting can be somewhat ignored due to ambiguity of meaning.....really reps fuel type\composition thru an AFR rating, not actual air\fuel ratio in engine) then the PCM will properly calc all thermal BTU energy in TQ calcs to efficiently calc HC%, CO% & NOx% output into exhaust from air\fuel combustion based on Lambda to then supply the necessary O2% into exhaust using the STFT's to assist the cats to properly convert all this to CO2, H2O, N2 & O2 at\below the EPA set emissions thresholds at the time of manufacture of car (for these S197's it's typically 75% reduction or CE ratio of .750).

Any excess O2 entry into the exhaust outside of PCM control doesn't help the cats at all to pass emissions...........it makes it harder.

Why the rear O2 sensors need to be enabled period if running cats in exhaust. And car was tuned previously thus the tune files have been touched so while in there to enable the rear O2's, check the rest to ensure all is set up well for optimal cat operations w\ the BBK catted X-pipe (if cats are put in the existing BBK catless X-pipe, they'll be put in the exact same section of the midpipe as the store bought BBK catted version.....only place in midpipe that has enough room for them so it's a cost toss-up either way).

So, what the AM tech said to you is essentially true, but in reality is a "half-truth"......you know what they say about half-truths............