Running lean after CAI and muffler delete
 

Hello all,

I recently installed stillen CAI on my z, it ran beautifully! but after 50 miles I get a CEL. I decided to buy some MAF cleaner and do my diligence, I reset the ECU again. It ran beautifully again! another 50 or so miles the CEL pops up again and idles at 1k and runs like a limp donkey half the time. This time I run a scan and I get P0174 for bank 2. I clean the MAFs again, reset the ecu, and spray some maf cleaner to see if I can detect any vacuum leaks. I couldn't find any leaks, and after the reset it runs beautifully again. Here we are another 50 miles later and the CEL is on, idling at 1k, and wondering if I made a mistake by putting the CAI on after the muffler delete and wondering if I absolutely need a tune. Any ideas?

thanks,
Keith

Intake mods only - no tune needed, the ECM will adjust.
Exhaust mods only - no tune needed, the ECM will adjust.
Intake + exhaust mods - a tune is needed.

Keith you are at the border line of actually “needing” a tune. You could also have other issues with your Z as well with the CEL you currently have. I’ve seen lean conditions several times from intake manifold gasket/s leak,faulty MAF’s,vacuum hoses leaking,faulty 02 sensors etc.not related to any of your mods. First I would have a mechanic or shop you trust diagnose your CEL to see if they can find anything like a vacuum leak etc. before doing anything else. In the worse case scenario hope that you don’t have a plugged up internal fuel filter (result from using cheap gasoline),faulty/weak fuel pump,plugged fuel injector/s.

You most certainly, definitely, need a tune.

I just had no idea that something as small as a muffler delete would affect it that much. I didn’t think it would count as an actual exhaust mod. I figured I would be safe as long as I didn’t go full cat back or mess with my cats. I think I’ll take it into my mechanic and have him check for vacuum leaks just Incase, but I doubt that’s the issue since this started happening right after install, unless I myself ruined some vacuum line somewhere.

It’s not just the muffler delete. It’s the combo of both the Gen3’s AND muffler delete. To much for the ECU to handle.

I would check the vacuum for a piece of mind, but you really want it tuned anyway. You won’t be sorry. Trust me, it’s money well spent.

I’m still running stock manifolds with stock cats with the Gen3’s and the Fast Intentions Cat Back. With a tune she’s at 320 WHP. 50 WHP over stock!

I know it’s nothing compared to what the FI guys are pulling, but it’s my daily driver and I can tell you, you will IMMEDIATELY feel those 50 extra ponies. Not to mention there’s no more throttle lag.

I had Z1 do the installation and uprev tuning. All in price with parts and labor was just north of $2000.

Major improvement for minor money. Your already ahead of the game by doing your own wrenching.

i have beluga test pipes and axel back installed just for the sound until i go to fast intentions plus a tune

the CEL came up after 50 miles just like yours...i used to remove it via my obdII reader but said screw it and just ignore the light

i check periodically just to see if the error changes

the error just mentions an issue about the catalytic converter which is normal because they are gone now in my case

Well, what do you guys think, I plan on getting test pipes to augment my muffler delete before the tune. Is the mid pipe restrictive? Or would I be fine with the test pipes and y pipe with the muffler delete before the tune?

did the CEL put you in limp mode as well? or did the performance drop while the CEL was on?

Asking the same question a different way to get the answer you want is not helping. Anything you change is going to effect the tune. Do it all before the tune to save you time and money.

If you don’t have a vacuum leak, and I’d bet the farm you don’t, You need a tune. PERIOD.

Even if you HAVE a vacuum leak, you're going to need a tune.

Get a tune.

Did I mention you need a tune?

So, I think what youre saying is he probably needs a tune. Maybe.

Maybe

Hi Keith, if you want me to take a look at your car I can help, just send me a Pm. Some simple data analysis can help answer your question about needing tuning or not. I can help you collect and analyze the data and also provide tuning if needed.

Car felt sluggish at first until the ECU adapted after several miles

Felt similar to how the Z acts after a ECU reset.