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Is350Engine power reduced. Potential pinging/rattle at full throttle.
My is350 one day seemed to suddenly lose it's power and now throws a P0300 and misfires when I do a full throttle pull. I've datalogged some pulls through obd fusion, and I noticed the fuel pressure is dropping when the misfires begin so I'm assuming it's creating a lean condition bcz of the lack of fuel??? Also the car will stay misfiring heavily until I turn it off, then when I start it back up it's normal again. What terrifies me is I'm pretty sure the car only uses direct injection when under the heavy loads it misfires at, so I'm praying my HPFP isn't going out bcz it's so expensive. I'll attach some files here, any help or opinions are greatly appreciated Here's a 3rd gear pull. It won't let me upload csv files for some reason. 4th gear pull
Here's a pull where it pulled the consistent misfires.
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My is350 one day seemed to suddenly lose it's power and now throws a P0300 and misfires when I do a full throttle pull. I've datalogged some pulls through obd fusion, and I noticed the fuel pressure is dropping when the misfires begin so I'm assuming it's creating a lean condition bcz of the lack of fuel??? Also the car will stay misfiring heavily until I turn it off, then when I start it back up it's normal again. What terrifies me is I'm pretty sure the car only uses direct injection when under the heavy loads it misfires at, so I'm praying my HPFP isn't going out bcz it's so expensive. I'll attach some files here, any help or opinions are greatly appreciated Here's a 3rd gear pull. It won't let me upload csv files for some reason. 4th gear pull
Here's a pull where it pulled the consistent misfires.
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That's incorrect, WOT activities use PI 90%. DI is for cruising. Order up a tank filter and pump and start there. One bad fill up can fill the tank and filter with sediment.
Take a look at your long and short term fuel trims as well as well as actual Air Fuel Ratio which should display 14.7 while cruising and dip into the 11 12 at WOT. If you see it at 16:1 vs 12:1 you can bet it's running out of fuel.
That's incorrect, WOT activities use PI 90%. DI is for cruising. Order up a tank filter and pump and start there. One bad fill up can fill the tank and filter with sediment.
Take a look at your long and short term fuel trims as well as well as actual Air Fuel Ratio which should display 14.7 while cruising and dip into the 11 12 at WOT. If you see it at 16:1 vs 12:1 you can bet it's running out of fuel.
It's all here on this site most of posted by Redspencer. Could i have turned that around, yes! I had screen shots from Fusion at RPM of the duty cycle of PI and DI and the DI rates dropped substantially. IIRC it showed calculated load as 100% but they may not have been enough to switch to full DI?
Could I have caught it at some crossover point, certainly.
Still I'd be suspect of pickup filter before HPFP.
Pull up the AFR and STFT & LTFT and they will tell you if it's fuel starvation.
It's all here on this site most of posted by Redspencer. Could i have turned that around, yes! I had screen shots from Fusion at RPM of the duty cycle of PI and DI and the DI rates dropped substantially. IIRC it showed calculated load as 100% but they may not have been enough to switch to full DI?
Could I have caught it at some crossover point, certainly.
Still I'd be suspect of pickup filter before HPFP.
Pull up the AFR and STFT & LTFT and they will tell you if it's fuel starvation.
The Air Fuel Ratio, bank 1 and 2 lambda are in the datalogs.
1. What maintenance has been done prior to this happening? When is the last time a basic tune-up has been performed?
2. Any mods the car has been altered with recently ,or has currently?
Judging by the data you've provided. It looks to me. The misfire issues are more prevalent on Bank 2 of the engine.
No mods, had ported manifolds for months. Sparks and valve cover gaskets changed months ago along with intake valve cleaning and BG 109,44k treatment
Might I add, bank 2, the one with the more prevalent misfires does have scored cylinder walls and they fouled the bank2CAT , but I stopped the oil burning months ago by soaking the pistons. This happened about 1k miles since my last time I soaked my pistons, and might I add, the pistol soak I do does help the car a whole lot. Here's a video of exactly what I've done the last 3 oil changes. It made me go from burning a quart every 100-300, to burning nothing for basically 3k which is my oil change intervals.
It's all here on this site most of posted by Redspencer. Could i have turned that around, yes! I had screen shots from Fusion at RPM of the duty cycle of PI and DI and the DI rates dropped substantially. IIRC it showed calculated load as 100% but they may not have been enough to switch to full DI?
Could I have caught it at some crossover point, certainly.
Still I'd be suspect of pickup filter before HPFP.
Pull up the AFR and STFT & LTFT and they will tell you if it's fuel starvation.
Found a post redspencer shared and it states in high rpm 100% direct injection is used
Not trying to fight a battle to be "right", but just trying to pinpoint what is actually going on with my car. Hell I hope I'm wrong and you can provide a source that shows it's port injection at high rpms, because I'd rather have something wrong with my port injection system than my direct injection system
The articles are correct and my recall is wrong. Just saying that when watching my car, the PI duty cycle is often higher than DI under load but the two are constantly on the move as is the HPFP PSI. I've seen that as low 800 and high 3800 PSI.
Yours appears to be hitting 11.9:1 AFR which is what mine does when fueling at WOT but my B1 B2 fuel trims mirror each other 99% of time. And at steady cruise, the LTFT zero out.
IMO the 4th gear load creates the most work and work being cylinder pressure loading is subject to ignition failure.
Are those Denso Plugs and Coil Packs? If not, I would start there as it's getting fuel based on your data. I was simply too lazy to go look it up.
Only use the AFR data on the left next to the value.
Last edited by 2013FSport; Jul 14, 2023 at 01:26 PM.
The articles are correct and my recall is wrong. Just saying that when watching my car, the PI duty cycle is often higher than DI under load but the two are constantly on the move as is the HPFP PSI. I've seen that as low 800 and high 3800 PSI.
And you forced me to go look it up a converter for Lambda to ratio percent. lol
Wow you've seen 3800psi?? It seems the highest I get is typically around 1500kpa/2200psi. That has me concerned now and leaning back towards it being a fuel delivery issue. How come you don't think it is a fuel delivery issue anymore though??
Also for lambda to afr for gasoline, just multiple 14.7 × your lambda number and you get the AFR 👍
14.7×0.81=11.91
Because both banks are fueling as shown by those 12:1 AF ratios. Could those cylinders go lean and cause a misfire under load? Absolutely. But now I need to compare my ignition advance with the stuff you posted and see if detonation is a possible factor?
If yes, it would pull back the timing and that would kill power.
Add KCLV to your Fusion gauge and give us a snapshot where it rides. It should be > 21
This is old data from 2017 but the ignition advance is in line with your numbers. Any chance those holes have a vacuum leak?
Because both banks are fueling as shown by those 12:1 AF ratios. Could those cylinders go lean and cause a misfire under load? Absolutely. But now I need to compare my ignition advance with the stuff you posted and see if detonation is a possible factor?
If yes, it would pull back the timing and that would kill power.
Add KCLV to your Fusion gauge and give us a snapshot where it rides. It should be > 21
This is old data from 2017 but the ignition advance is in line with your numbers. Any chance those holes have a vacuum leak?
I'll be checking for a vacuum leak this week when I install my headers. I'm starting to suspect my intake manifold gasket might be leaking a bit since I hear hissing along bank 2s runners. Thanks for your help and I'll post an update soon
I'll be checking for a vacuum leak this week when I install my headers. I'm starting to suspect my intake manifold gasket might be leaking a bit since I hear hissing along bank 2s runners. Thanks for your help and I'll post an update soon
Update, just took off my manifold and checked, but I guess it wasn't that
What is your exhaust setup? I had something similar happen with my car and it turned out that one of my cats broke internally and the piece turned and it was pretty much like my driver's side exhaust was plugged up. I would check short and long fuel trims while doing some light driving and see where they are. If you see where the combined fuel trims are close to matching from bank to bank but are more than +a few a% then clean your maf and see what happens. If the fuel trims are off by a bit between the banks then investigate the side that is furthest off from what the car is calling for. I'd also replace all spark plugs and see how each cylinder looks. Also don't dismiss the possibility that you might have a bad O2 sensor. Maybe you have a bad oxygen sensor which has caused you to run rich on one side, ruining your cat until you ended up where you are now. You should be able to see this when looking at your plugs.
Is350Engine power reduced. Potential pinging/rattle at full throttle.
