No codes but something is def wrong!
 

Episodes of strong hesitation (like rapid, tiny fuel cut-offs under acceleration or even just cruising) and bad idle, accompanied by backfiring under deceleration. Engine light flashed then stayed on today, but getting "N/A" codes. Also, when it happens, I get a burnt smell coming from the vents even with the air off.

When I say "episodes' I mean that it can go for days without seeing symptoms or I can have symptoms for days. It's random, which makes me think it's electrical, but then it tends to increase with engine temp so I have no idea.

Where should I look?? Recommend any tests before I give up and take it to the shop??

Try cleaning your MAF sensors.

Dirty MAFs can cause all sorts of weird problems. Luckily, they are very easy and cheap to clean - the rawest weekend mechanic can do the job in less than thirty minutes and not get their hands dirty.

Edit: The N/A DTC is weird. You may have a CAN problem or need to reset the ECM.

Check you oil level also. If it is too high, it can cause major issues down the line.
I overfilled mine last year and the idle got so bad, that the ECM rest my idle to over 1100.
I had developed major foaming/bubbling in the oil. If this happens, the only thing you can do is drain the oil and refill. I let mine drain for a really long time. After I changed the oil, I had to pull the negative battery cable for 15 or 20 minutes, then reconnect.
The idle was so bad it sounded like it was running on 3 or 4 cylinders.

Do you happen to know how much you over filled the engine?

Just barely over the full mark.
When this happens, you can actually see small bubbles on the dipstick.
It is a progressive issue, meaning that it gets worse as time goes on and can severely damage the engine if not corrected.

Thanks for the replies, guys. I'll try cleaning the MAF sensor tomorrow.

BTW, I tried running the codes via bluetooth OBD2 and it gave me "P2a00," is that 02 sensor??

That's weird. I have overfilled mine by just a tad and I didn't have the issue that you said you had. I've seen cars overfilled by anywhere from 1 to 6 quarts here at work and they all ran rough. Just doesn't seem that overfilling it just a tad can cause the issue that you had seeing how oil will be in the oil galleries in the block, heads, oil returns and pan when the vehicle is running. Just saying.

Was your oil level at the H mark when cold?

No codes but something is def wrong!
 

It's when the oil gets up into the crank that the issue arises.

I had a crap load of bubbles when I drained it.

No problems since.

I think the level may have over H when cold. I honestly got sloppy about checking it.

I'd like to revamp my thread real quick. I'm still having the same issue intermittently. I took it to the shop twice and they have no idea what it is.

The mechanic did mentioned that it could be either my aftermarket intake or lack of backpressure (have deleted mufflers and a Takeda short ram air intake).

Could that be the cause? Thought I would check before trying to go back to stock intake.

To reiterate, it feels as though I have spurts of fuel cut off. It's as if the gas doesn't burn for a cycle or two and then ignites in the exhaust pipe (explains the loss of power and backfiring). All this happens randomly and on random days. Are ram intakes known to cause issues like this, or does the MAF need replacing...or something?

Take it to a different mechanic/shop. P2A00 (Air Fuel Ratio Sensor Circuit Range/Performance Bank 1 Sensor 1) is a one-sided problem. Unless you have a leak, intake or exhaust problems would affect both banks. Which leads me to suspect an intake leak.

It's easier to find out what's going on if you have a scan tool you can look at the short term fuel trim that's will tell you what the ecu is telling the motor to do(add or take away fuel) depending on if your running lean or rich. This should help eliminate a few variables

Actually shortly after getting the Bank 1 CEL, I got the Bank 2 as well... He said it was very unlikely that my cat is going bad at 50k. Does that help narrow it down?

By scan tool, do you mean OBD2? I use the Torque app although I'm not an expert at it.

I know you said the cats shouldn't be going out but are you sure it's not the sensor at the header? What is the code that was thrown? just wanna be positive we're talking about the same sensor.

Deleted mufflers won't be significant enough to cause issues with back pressure especially since your still running stock cats. (Which adds a lot of backpressure) it could possibly be the short rams, as many posted before a bad/dirty maf causes a lot of weird issues

Sorry, the recent codes were different. P0420 and P0430 ("Catalyst System Efficiency Below Threshold" at Bank 1 and Bank 2). He said it's unlikely that both sensors went out, which makes sense.

Gotta be air/fuel mixture...?

Yes he is right it is unlikely both went out at the same time. If it is a issue with air fuel ratio it should be throwing a different code saying rich or lean. I suspect either electrical issues with those sensors or maybe (even though unlikely) both cats went out. I agree with trying to take it to a different mechanic maybe he will know.

Change bank one Oxygen sensor #2

reset car, by unplugging battery for 10 min, start, drive for 5-10 min, turn off, turn on look at CEL if no, then turn off, turn on, look again.


if codes come back, its probably the MAP sensor always keep receipt to get ur $ back.

Is this normal??? (pics)
 

Hey guys, I wanted to post an update and something new that I may or may not have discovered. So, I cleaned both MAF sensors and went out for a drive, no issues. After a few hours, drove it again, and it was so bad I almost didn't make it home. Just like before, the problem is still there and still intermittent.

I haven't looked at anything exhaust side yet but I'll check the MAP when I'm done checking intake side.

Recently it's been throwing a new code: random/multiple misfires! And I can definitely feel them. So, before attempting new MAFs, I thought I'd swap out the plugs. I took out the intake manifold and noticed what looks to be oil in 3 out of the 6 airways... is this normal???(for some reason can't get the images to show, but it works if you right-click the icon and open in new tab). (Also..where are the spark plugs located?? :icon17:)

https://c77i.imgup.net/2017-03-15118b.jpg

https://v48i.imgup.net/2017-03-151435.jpg

https://a03i.imgup.net/2017-03-10a425.png

https://q31i.imgup.net/2017-03-1016da.png

Wait, really?

You'll see 3 coils with looms coming from them on each valve cover. Take those off and you'll see them..

Thank you, I'm blind!! Also, I've driven older Saabs my whole life and they're very different haha.

Still wondering about that oil though. It's only coming from one side which makes me think something's up...

We've all been there, you just have a much nicer platform to learn on than I did back in the day lol

Someone posted a similar thread on this site. Even has pictures, IIRC. I don't remember what the conclusion was. If you can't find the thread using the site's search, try any of the web search engines and add "site:the370z.com" to your search string. Eg, "oil in manifold site:the370z.com".

The conclusion was that he replaced all his O2 sensors and cats to get it to work. That's way too expensive for me at the time, so I'm thinking of starting with the most likely cause.

Which one should I try first? To reiterate my original problem, I'm getting P0420/P0430 with random episodes of hesitation/no power, coupled with backfiring, rich-smelling exhaust, and now misfiring. I tried: cleaning the MAF sensors, cleaning the air filters, and changing the spark plugs already. Should I start with the upstream oxygen sensors or is it definitely the cats?? Any other ideas?

Oil in the manifold sounds really bad. Only 2 ways I can think of for that one. Over oiling the air filter or too much blow by in the block. Blow by would be the worst, happens from scratched piston walls or messed up rings. You could do a compression test while you have the spark plugs out. I'd guess it should be somewhere around 160. All pistons should be within 10psi range. Also look at your spark plugs. They should all look the same. A bad cat should not be intermittent. None of the really major issues should be intermittent. Good luck!

When I replaced the spark plugs, I noticed the old ones were not that worn and had all been worn evenly. I replaced them anyway.

You said a bad cat should not be intermittent and I agree, so could O2 sensors be intermittent? What about blown rings?

You mentioned that you haven't checked for exhaust leaks.

I had a P2A00 and my car was running sluggish and chugging gas, no misfires but just bad. I came on here to try and find a solution, everywhere I read it said that it was probably an intake leak, turned out that I had a crack on both catalytic converters. The crack was downstream the O2 sensor on the exhaust manifold and upstream the O2 sensor on the cat. I had aftermarket cats so I put the stock ones back on and it solved my problem.

I understand that you have stock cats and it is very difficult to damage them, but try and rule out an exhaust leak in that region.