Need help asap please. Wicked misfire.

Start by ditching the Diablo tuner and get the MPVi3 from HP Tuners. This will allow you to data log and see where the misfire is occurring. Then send that log to someone like Pat G for a real tune. It’s expensive but worth it…

Vwlove56 said:

Start by ditching the Diablo tuner and get the MPVi3 from HP Tuners. This will allow you to data log and see where the misfire is occurring. Then send that log to someone like Pat G for a real tune. It’s expensive but worth it…

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Right. In the middle of switching to HPT now. I have the MPVi2 myself. Problem is I can’t scan it at the moment.

The best way to explain what is going on is if you were in 5-6 going 30mph and try to punch it without shifting. Then throw in some stuttering. BUT it’s intermittent. And no codes

My guess is that the MAF is out of whack and needs adjusting. You're going 30mph in 5th gear???

No that you are getting proper fuel pressure, LT and ST trims are out of whack, my guess? Needs retuned

Jim said:

My guess is that the MAF is out of whack and needs adjusting. You're going 30mph in 5th gear???

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No but it acts like that. It’s really sluggish almost like it’s dumping too much fuel


Now I can’t really get it to duplicate. Do you think it’s possible air could have got into the fuel system or something from the catch can? I also noticed after a day of driving that I am getting oil in the can.

Yeah, probably got some bad fuel. Not the catch can; it’s doing what it’s supposed to

Well, I am leaning that direction. It hasn’t done it this morning. I’ve only had this car a few weeks and I am still combing it over.

if u get some better fuel into it and it goes away all good, if not then id say the vve needs some more fuel in the low load areas, alot of tuners dont bother in such low rpm/load areas, see what ur 02's are showing at the time is splutters might be a lean spot

Last video. This is a perfect example of what happens:

Ablackcts said:

I noticed yesterday that idle was a little rough. Now under low to mid throttle, it sputters and chokes like it’s getting too much fuel. I used 91 in it, would it have anything to do with the catch can I installed or turning off the rear 02 sensors?

2012 coupe with full exhaust, CAI, Diablo tuner smaller pulley

it seems to be intermittent as well but it’s happening a lot more now. First thing I plan to check is the plugs. I am not getting any misfire codes. Also I’m running my first full tank of gas since I fixed the leak on the elbow.

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I had a misfire which obviously threw a CEL and auto start wouldn’t work. Then I cleared the code and started the car up again and it ran for a few min, misfired, and just shut off. When I tried to auto start it after , no luck. Had to fix the misfire and all that for it to work again. I’m sure this isn’t going to help much, but just figured I’d throw it out there since it had to do with the auto start not working. 😅

I had this same problem way back with my first V2. Being new to the platform, I as well used a Diablo tuner. After much troubleshooting I took it to Dr. Phil here in Michigan. He's a well know LS tuner. He put on a better tune, yet the issue was still present. After much troubleshooting the issue was still there. Coincidently I happened across another V owner who had the same symptoms. He stated his diablo screwed up his ECU and he swapped it out. I relayed this to Phil and he was very skeptical that it was the issue. Suffice to say, we swapped out the ECU and the issue was completely gone.

Oh joy, that is not great news

not sure what they charge compared to getting a new ecu but u could try get the dealer to flash a fresh tune into your ecu back to stock which should fix any issues caused by a tuning device, then read that fresh tune with hpt and then copy over all your changes to it from your last old working tune to the new read and then flash the new file back to it and should be ok, that should fix any background issues without doing ecu, and if all the numbers are the same it shouldnt cost any more credits hpt, then delete all your old tune files so they arnt accidently used and start with the fresh one

Looks like you're missing a spark plug and an O2 element.

I chased a spark plug with a cracked insulator for a weekend. I cracked it while installing it. Let's say I'm more careful now.

Where did the 8th plug go?lol Is the end of that O2 sensor jammed against your cat or did you remove it already?

The 8th plug decided to hide somewhere I looked but it never hit the ground. The MSD wires also decided to separate when we were trying to remove them. I have no clue how the front O2 did that. Is that what the factory front O2s look like? The replacement had more holes