Stutter in boost that goes away when warm

heres a short video of it happening, hesitation and stutter.
right after this video it actually shut off on the highway so i had to get out disconnect the battery and reconnect it, then i started it and it was fine and made it to work after babying it for 10 mins then back to normal and can do a 20psi pull no problem.... driving me nuts.

https://youtube.com/shorts/4WinX2MbVkk?feature=share
 
Look at the wiring harness to the coils I suspect you have a poor connection or failing wire there
 
Ok I will go over the harness. My map is started to act up too now, when I had my intake manifold off I sprayed it out pretty good with chlorinated brake clean but forgot to pull the MAP off so it got soaked and definately sprayed directly so I’m guessing I damaged it. On the way home it was reading 15-20psi of boost on the Accessport when I wasn’t even on the gas at all, very erratic and of course running like crap. I have to find a new map tomorrow, and I will inspect all the wiring I can.
 
This car is driving me nuts lol…
New map installed today, fixed that issue boost readings back to normal/ looked over coil harness and everything looks good, no loose or broken or bare wires. Wiggled the harness best I could while running and no change. Problem is still there. Start of the drive as soon as it gets into boost hard cut, like head almost hit steering wheel cut. Drive it for 15 mins and back to normal
And also, now it has developed a stalling issue. Started the car after sitting for a few days and it died after 5 seconds or so of idling. Did that 5 times in a row. Got out and jumped the fuel pump resistor on the frame rail and I started it and it actually stayed running. Drove 5 mins down the road to the gas station and it stalled out twice on the way there. On decel/ coasting both times. Power steering quit same time car died. Key off then it would start back up no problem. Risked the drive home 45 mins away and it made it without issue, after the normal warmup made a WOT rip and it was completely fine. Good fuel pressure, AFR, no knock, MAF readings good. It’s solely issues when the car is cold. It was even super hot out today, car started with a 100 degree coolant temp, but still needed the usual 15 mins to shake out the crap.
Would a failing ignition switch cause the car to stall mid drive? Noticed lately taking the key out car would beep with the door open telling me key is still in the ignition but clearly wasn’t. Put the key In and out again and it stopped so I’m guessing the switch is on its way out. I’m almost ready to fire the parts cannon at it again, do the crank position, ignition switch, 02’s. never had an issue such a pain to diagnose.
 
That would be a weird fucking cause but would kinda explain why it doesn't show up in the log.
Not exactly sure how 15 mins of driving does anything at all to the ignition though.
 
Enki said:
That would be a weird fucking cause but would kinda explain why it doesn't show up in the log.
Not exactly sure how 15 mins of driving does anything at all to the ignition though.
Click to expand...

No idea why it stops stalling when it drives awhile…
I’m starting to think it’s not ignition or coil/ plug related and it’s either in the ECU or a sensor working better as it warms up. Car is cursed…
As for the boost cut, If it was a single coil or a general misfire it would be a lot less violent when it happens. I know the video I posted makes it look mild, but it’s usually much more pronounced. but its boost/ fuel cutting hard.
 
How old is your battery. The stuttering etc on decel is usually a dying battery. The cold behavior could be the battery being charged back up
 
Easter Bunny said:
How old is your battery. The stuttering etc on decel is usually a dying battery. The cold behavior could be the battery being charged back up
Click to expand...

battery is the one that came with the car when I bought it. No idea how old it is but it looks pretty old. corrosion/ white buildup on the negative terminal. I was watching voltages today since it crossed my mind and I’m only pulling 13-13.2 volts around town running/ highway it can hit 13.8 but it’s a bit erratic and moves from 13-13.8. Could the battery really cause all this?
 
Probably. IIRC, float voltage should be 13.8 with >14 being recharge voltage on a cold start. Maybe clean the terminals and take it to a local auto parts store; they should be able to test the battery and alt for free.
 
What's the Voltage on the battery when the car is off?

My car started and idled fine with a bad cell in the battery but acted weird in certain situations while driving
 
I went out this morning and did a video of a cold start after sitting all night. Shows voltage and I went through my trouble codes. Something is up with my downstream o2 but don’t think that would cause anything it just watches cat efficiency right? Other codes are probably from my SWAS connector being disconnected, and VTCS delete.
The P2251 has me puzzled though. Never seen it before today. When I was messing with the car yesterday I was missing a few downpipe bolts. I didn’t use studs when I did my downpipe, but I did tq bolts properly.no idea how they backed out. I replaced the missing bolts yesterday and everything is good and tight now.
https://youtube.com/shorts/y9x4wNwM7q0?si=bsNBoa3D4JPZbQME
 
Last edited:
Update:

I replaced the primary oxygen sensor with a new OEM one, just for maintenance/ was planning on doing it anyway, sensor was original, and replaced the MAF with a Denso 604 off rockauto and issue seems to be completely fixed. I drove it for a day and a half so far and it doesnt stutter at any temp, idle and part throttle is smoother too. The car ended up starting to crank no start, so I took a guess the MAF just quit completely especially with the other symptoms and suspecting the MAF before. Car drives perfect. Its such a relief to be able to get in the car and just drive it without worrying about about it. Thanks for the help everyone.
 
You must log in or register to reply here.
Back
Top