Built boosted engine idle/pulsing

xsamis

Hey guys i have a really wild issue going on.

i get the p0300 code when the engine is warm and i try to hold RPM. The motor will pulsate. Meaning the RPM's will go up and drop down within 700-1000 RPM. i logged it being weird but im not sure what to look for in the log.

I know p0300 is very generic but i have almost ruled out EVERYTHING. ill explain below my mods and whats done to the car.
Fully built motor, wiesco pistons, corrilo rods, ARP L19 studs, coated OEM bearings, ARP main stud kit.
Motor was built by some company but i lifted the heads so i rebuilt the motor myself following the FSM almost to a T except the clearances on the bearings and gaps on my piston rings.
Sparkplugs were also changed previously and gapped larger given im boosted (i talked to my tuner)

I took off the VVEL motors like an idiot and had to adjust them a total of 4 times to get them within spec. I have them at 5.5 degrees on both so i do not think its my timing. Also the timing was done by me, I've retimed the car before and it worked perfectly.

the car has been sitting for a few months with E85 but i added 93 (i have a flex fuel tune and sensor) and also added some fuel stabilizer. Its at about half a tank of this mix. (i think bad gas might be causing all my issues)

my Fuel pressure regulator stays at about 55-60 PSI when idling, when my car does the whole pulsing thing, the FPS does dip down and then dip back up with my cars RPM's. I checked for vacuum leaks/fuel leaks and found nothing.

also while idleing and the car does this pulsing, i have NO CODES. only when i try holding the rpm does it give me the P0300.

i have ID1050 injectors and a walbro 485 with the CJM return kit and billet top hat.

also when i hold idle my car doesn't hold idle very well. it dips and then comes back up, then MIL will start flashing.

ECUtek tune btw

Elmo370z

You’re going to lift the heads again. Just a matter of time. Might want to find someone who has a consult

Spooler

P0300 sounds like you have an exhaust leak. Search the code on here. As far as the idle hunt. It is normal when dropping your ethanol content. It can be annoying until the ECU figures things out.

xsamis

hopefully the L19's hold, im going for 700-750whp max. Anything over that my setup cant put to the ground.

xsamis

so if i just remove the exhuast after the turbo and have the 3 inch downpipe open then the p0300 should go away? I took off my recirc pipe. it connects the 2 wastegates to my Fast intentions exhaust. theres basicly a huge hole in the exhaust from where the 2 wastegates dump into the exhaust.

also i wasn't aware of the idle hunt, this is some real good information. I thought my timing was off because it kept moving up and down. My E85 gauge/flex fuel is tied into my ECU, i have it pinned in so my ECU does control my tune through the ethanol content coming in.

Spooler

Research the code on here. You are not even close.

xsamis

Sorry man im not understanding you. I tried researching the code, when you say exhaust leak, i have a B/P single turbo kit, the turbo attaches to the manifold and a 3 inch pipe comes off the turbo. There is no other exhaust that it could leak from once i take off the rest of the exhaust. How would it be an exhaust leak?

Spooler

Between the heads and the turbo.....

xsamis

Ill double check where the headers mount to the motor and the T flange on the turbo when i get home, im pretty sure they’re gucci. New header gaskets as well, but maybe i forgot something!

Ill keep you updated (: