Car won't start one week after installing headers
 

Hi everyone,
So pretty much last Friday I had a shop install these catless EL headers. When I got home from the shop I did the stage 2+ tune from my OFT. Car was a lot of fun to drive and drove fine all week. This morning as I was coming back home, I was doing a 3 point turn and I braked.
As the car came to a full stop the engine just cut off. I turned it off and tried to turn it back on but no luck. I got a boost because I thought that was the issue but no. When I was under the hood I smelled a faint burnt smell, wasnt sure if that was from the header but when I looked I saw my 02 sensor seems to be burnt. Sorry if the picture isn't clear enough. I did search these forums but I found several different threads with people who had a similar problem to mine. I also found several different answers.
So I am no mechanic, but if the car won't start and I notice the 02 sensor is damaged, it would seem like I need a new 02 sensor. But before I spend money, I have a few questions: has anyone heard or had this issue before? Why would the sensor go bad, is this something that just happened or is it the shops fault? Im praying its just the sensor and nothing more like the wiring or I dont even know what.
Thank you all in advance for any help.

Edit: Car is a 2014 BRZ, added Skunk2 EL Headers

I don't see anything that would convince me (from the picture alone) that the O2 sensor is bad. Anyone know if the car will run briefly with no o2? Could help for testing if you just unplug it and see what happens.

Does it crank? Any other symptoms? Check engine light?

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I'm with you here. I've left an O2 sensor unplugged on occasion, it'll throw a code and stumble, but I've never had a car die due to emissions equipment. Worst case, limp mode.

Side note, that bung looks flat wrong, almost like the shop chopped the entire bung and sensor off before swapping. What header is this?

What's ur car year and model? Are u able to check the fuel trim on OFT? Cuz brz/frs they adjust the AFR through reading O2 sensors and send it back to the ecu to do the adjustment. I once had a catless uel header and sometimes it won't start well because of the ecu thinking it run too lean based on what o2 sensor reading. Then, it will flood the engine with too much fuel thus it will crank but won't turn over. That's my guessing ofc.

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If it wouldn't start because it was too lean, why didn't you just richen it up?

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The o2 senor tricked the ecu thinks it's too lean and enriched it too much. Thus, it did richen it but too much. In fact, it wasn't lean. It was just because of the catless header.

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Really? So its not the 02 sensor? It literally gives one crank and then just gives up, no check engine light

Im guessing the bung is that lip around the sensor? Thats why I thought it went bad to be honest, but it seems that the shop did that? This was a skunk2 EL header

Its a 2014 BRZ, sorry I should have said that in the original post

One crank then no crank? Any sputter? Or does the engine just spin? Definitely not o2 since there isn't anything for the sensor to measure until the car is running. Almost sounds like a battery or ground issue. Can you test your battery? Are there any damaged wires anywhere? Does you're fuel pump work? Can you test for spark?

I know it's a lot of questions but diagnosing a car is pretty complex. Especially over the internet


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Them your o2 sensor wasnt reading correctly. Or you had a big leak upstream from the sensor. If it's not reading what is actually there, then it's not doing it's job. Additionally, your o2 sensor doesn't do anything during cranking since the engine isn't running yet, there's no exhaust to measure. Sounds like your tune was just bad. Or there was another problem entirely. I haven't had cats in years. On the FA20 or now my LS. Never had an o2 cause a no-start. I've had numerous other things cause no starts. But never an o2 sensor

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Don't worry I welcome the questions as they can help narrow the problem down. Battery was changed in May actually so its fairly new. I can look again tomorrow for any damaged wires. Thank you.

What about the other questions? How exactly does it crank? Crack and sputter? Crank with no fire? Crank then no crank? Does it reliably crank right away when you turn the key? Any other symptoms at all?

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Fuel pump works, it gives one weak crank and sputter then just gives up, I will send a video tomorrow, its a push start btw, no engine codes no nothing, boost didn't help start the car. I can get the battery tested but like I said I just bought this battery in May.

Maybe it has something to do with the push start itself. This might be nothing but try disconnecting your battery and going it back up. Maybe replace battery in your fob too. Kinda thinking it might be an anti theft issue

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Actually I did that, I was searching the forums and I saw a thread where someone gave steps to calibrate the eco to the new tune. I tried that in case that was my problem, but no luck. The steps were to disconnect the batter for 10 minutes, connect the batter, turn the car on ON setting for 20 seconds, turn car off for 5, then turn car on. No luck. Maybe sitting over night will get it to start?

Since the engine cranks, starts, sputters, and dies quickly, it could be alternator as well.

Should still run off the battery though right? For a little while at least

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The sensor looks like it was installed with a mulching lawn mower rather than a torque wrench.
Is that their default shop tool?

I am not sure if the high pressure fuel pump would work with just battery. Otherwise, I would agree that another small engine would run with just battery for a short time. Alternator fail is not something we see frequently with twins but the problem sounds like that. It might also be the fuel pump itself.

Is the pump electric? I kinda wondered if the push start wasn't faulting out because of low voltage during crank. I've had that before with an after market push start. He said he tried to jump it and it's a fresh battery. Maybe not ideal circumstances but should still alleviate the issue if it's voltage related

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A bung in car context is the threaded opening for a sensor.

I just looked at some Skunk2 EL pics (Good one here: https://www.ft86club.com/forums/show...02&postcount=4) and what your image shows looks like someone drilled a small hole into your OEM header, grabbed a rotary tool, and started cutting away what they could when it didn't unscrew (If they even tried, no marks on the wrench flats is another odd visual). As @bcj said:
Back to the issue at hand. Other than a general feeling of unease from the work quality that would make me check everything the shop may have touched, we're back to the symptoms of "weak crank, sputter, die":

Is the sputter actually a sputter, as in the engine is sparking properly and turning over but failing to reach idle?

Personally I would be back looking at the basics. Fuel, spark, air.

For fuel you're already looking at the pump. I would test that the pump primes and holds the appropriate fuel pressure, and doesn't drop pressure when the starter engages.

For spark, the cheap shade tree method is to pull each plug and try to see the spark as someone turns it over. I actually wanted to bring this up: Have you ever had new spark plugs? They're a 60,000 mile replacement cycle and fresh ones have solved weird issues with starting/idling for me at various times.

For air, it's air. I'm not gonna bother, if your throttle body or valves aren't opening up properly we've got a whole lot more diagnosis to do.

Probably installed too many.

Hey everyone, sorry for being MIA. I wish I knew how to upload videos here, I sent a video to a NYC BRZ group im in and everyone there says its either the alternator or battery. So yes while the shop did a crappy job installing my 02 sensor, my car not starting has nothing to do with the header install which I am happy about. Seems to be coincidence that the battery or alternator died after bringing it to this shop. I wish I could upload the video here of it not starting to get an opinion from you guys.

I am going to take the battery out and bring it to my local pep boys to be tested, then I'll get the alternator tested as well. Thank you all for your help and troubleshooting. I know its not easy when you cant see the car. Will keep you guys updated.

Hope the simple thing is all you need, but since you said you tried to start it with a jump that didn't match the usual symptoms. Just did a fresh battery + alternator in the Matrix after it couldn't keep itself alive driving on the highway (Also the last time I disconnected an O2 sensor checking another issue and then threw a CEL driving home haha). Obviously there's a little "new parts bias" but it's definitely nice to have a more stable idle and slightly brighter headlights due to the proper amount of electricity flowing around.

Ok yesterday I took the alternator and battery out, had two different parts stores test them both and they passed. Today I put them both back in, started the car. The car struggles to start but it did start. It sounds super rough and has a lot of knocking noise on idle. I have no clue what’s going on but it doesn’t sound good. Can someone tell me how to upload videos here so I can show you all?

Ok, realized if I upload the video to YouTube I can just post the link here, I'm such a newb. Here is the video, this is after I put the alternator and battery back in the car.

https://www.youtube.com/watch?v=Yz8O4XW4CBA

I am literally praying that my engine isn't done. I have no idea what the issue is.

Do you have a datalog?

Sounds like a nasty leak from over here. Badly installed headers or maybe a loose spark plug, but the lack of CEL is confusing here. I know many tunes force the ECU to be quiet about exhaust codes with catless headers. You'd have a misfire and probably a real fire if the cylinder was dumping the A/F mix out the spark plug hole.

As such I'd be searching for an issue with the header install, say from a bad gasket or a badly installed O2 sensor. That would also explain the rough idle as it tries to compensate for O2 readings that don't represent what's actually happening.

Get CSG a data log though, I want his professional opinion!

Wow that sounds really bad. I would try going back to stock ecu file if you can.

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I don't think so?




Ok I am bringing the car to the shop tomorrow. I started the car again a little later and the knocking noise went away significantly but its still there. The squeaking was a lot more noticeable. I did an oil change after just to see if the old oil had any metal in there. I am happy to say it didn't. That alleviated my fears about the oil being done. Used my OFT tablet to see if there were any codes in the ECU and I had nothing, no codes.

Im wondering if the headers were loosely installed as well. My first thought was the 02 sensor but I was told earlier in this thread that the 02 sensors wouldn't cause that problem. I am happy that most likely my engine isn't done for. Just curious as to what the problem is still.

You think its the tune? I'm thinking about going back but now I'm afraid I may cause more problems?

I would also go back to stock headers if possible. Were you monitoring fuel trims etc... After the flash to make sure your were not tuning lean or watching your IAM to see if your car was pulling timming?

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The sensor may be fine, but if there's a leak anywhere from the valve to the last O2 sensor in a given exhaust set up, the ECU will compensate incorrectly, see other conditions change unexpectedly (like low RPMs from the now incorrect A/F ratio) and compensate for those, then cycle like that in a rough idle until the point where it can't recover and dies.

Along with the other guys, I'd go back to a stock tune and stock headers if possible. If you don't have the headers, definitely flash back to stock and make sure you're only throwing a P0420 Catalyst Efficiency code.
Maybe pick up a set of gaskets and start there too. I've seen many builds where the headers leak because of cheap or re-used gaskets. I'd also check that the flanges aren't warped if you have a good straight edge or a machinist friend.

Lastly, since it sounds like you're OFT so here's their article for logging: https://support.openflashtablet.com/...e-datalogging-

Some of the key channels to log are Air Fuel Ratio (AFR), Commanded AFR, Short Term Fuel Trim (STFT), Long Term Fuel Trim (LTFT), Ignition Advance, and Advance Multiplier (IAM). A normal log for a good tune at idle will have trims that are close to 0%, an AFR that's tracking the Commanded AFR almost perfectly, and an Advance Multiplier that's trending from 0.7 towards 1.

If you grab a log datazap.me is a pretty widely used site to chart and share them.

Thank you so much

Post up that log once you have one, and i'll see if anything is badly off

Will do. In the meantime, what do you guys think about this? Found this thread while doing research. I really should be sleeping but I am just so anxious.

https://www.ft86club.com/forums/showthread.php?t=107577

This fix he found, about the vacuum pump? Never heard of that before.

"Automatics have a special vacuum pump that is attached to the cam (instead of just a cover) on the passenger rear of the engine. This pump had gone bad causing stalling issues AND the metal knocking. Since it is attached to the cam, it was masking itself as potential rocker noise. Pump, O-ring and gasket maker was $170. Install was 20 minutes taking my sweat time. Fix is confirmed! She purrs like a kitten with no stalls or clanking noises! I've been chasing this over a year and have spent $12k in upgrades trying to get rid of it. Hopefully others can shortcut this"

Shop told me just now that the motor is blown, super bummed. Here is the log info though:

Engine blown from headers and a tune?
Seems suspect.

I am sorry dude, sounds just like the "rod knock" I had. I can't tell you what it was for sure since we never opened the motor up to find out. I found a well priced 2nd hand FA20 and threw it in over a weekend with a mate. Almost certainly the header install had nothing to do with your failure it is just coincidental that it happened after the install.

I'd hazard a guess that if you weren't comfortable installing the header you won't be looking to swap in a motor either. Make sure you get a few quotes whichever direction you decide to go. Given the hack job on installing your o2 sensor I wouldn't be rushing back to the guys that installed your header.

You fucked it up.