FRP dropping, FDM failure? (w/datalogs)

[hawkeye93]

Today I went to datalog my latest Unleashed revision, and on both of my 2 runs, the car went into limp mode.  Didn't get a DTC until after I loaded an older tune, and I got a P0305 (misfire on #5) right on startup.  Looking at my logs, I see that my fuel pressure is dropping to below 1000 PSI.  Is this indicative of an FDM failure, or could it be related to my tune?  Bad gas?  I have noticed stumbles with this tune when I wasn't logging.

91 octane tune, running 92 octane gas

 

[ZSHO]

I would start off by checking the front middle #5 plug and check the electrode.. . are the plugs the the MC- Sp-534's ?any noticeable smell of gas?  Z

 

[FoMoCoSHO]

Have you noticed any FRP drop prior?

Did you flash back to stock and take a log to see if the behavior carries over?

 

[hawkeye93]

I would start off by checking the front middle #5 plug and check the electrode.. . are the plugs the the MC- Sp-534's ?any noticeable smell of gas?  Z

Plug looks OK (cell phone doesn't take great pictures), only the slightest hint of gas.  Plugs are NGK 6510s, which I understand are equivalent to SP534s.

Have you noticed any FRP drop prior?

Did you flash back to stock and take a log to see if the behavior carries over?

I have noticed "stumbles" under load.  I haven't flashed back to stock, but I did flash to a previous tune revision.  Haven't driven it hard since.  I'll go back to stock and give that a try.  When I first got the car, it did go into limp mode once while cruising on the highway.  I think that was with my first Unleashed revision.  Pulled over, stopped & restarted the car, and it was fine.

 

[ZSHO]

Did you check the relays,fuses by by the engine compartment....try swapping them around.  Z

 

[SHOdded]

How long (miles) have these plugs been in the car, and what is the gap?  More often we see a fueling issue than an ignition issue once plugs have been changed and gapped properly.  How many logs have you done on the latest revision prior to the limp home incident occurring?  If there are no codes, it could be the car adjusting to the tune, as it seemed to do before.

 

[hawkeye93]

How long (miles) have these plugs been in the car, and what is the gap?  More often we see a fueling issue than an ignition issue once plugs have been changed and gapped properly.  How many logs have you done on the latest revision prior to the limp home incident occurring?  If there are no codes, it could be the car adjusting to the tune, as it seemed to do before.

About 2K miles on the plugs, gapped @ .030.  These were my first recorded logs with the new revision, but a few days ago, I did notice (after one of the stumbles), that I had 10* of spark retard (see Min value in photo).  I assume that's a result of knock?

Did you check the relays,fuses by by the engine compartment....try swapping them around.  Z

Haven't swapped any fuses or relays yet.  I'll have to look up which ones are which.

 

[SHOdded]

could be really bad gas for sure.  same station as usual?  top tier?  OAR looks good tho ...

Load is hitting 2.0 after you reach 40 mph.  I remember AJ pointing that out as an issue, looks like Torrie will have to dial it in further.

 

[hawkeye93]

Gas is 92 octane premium from Fleet Farm, a sort of general store here in the midwest.  Don't know if it's Top Tier.  I've been buying there because it's hard to find 93 around here.

 

[SHOdded]

There are variances between LPFP pressure desired and actual upon demand.  Possibly a FPCM issue?  I haven't seen both the desired and actual logged before, at least recently, so I have nothing to compare against ...  Almost like the LPFP is in overdrive, shutting down the HPFP?

 

[ajpturbo]

I will try an ld look later but do your logs have wot in them?

You might not have anything wrong at all....if you are hitting 2.0 load then without looking at a log i would guess you are just out of fuel...if that 2.0 happens lower than 5k and or is a spike in load then your fuel system is simply taxed.

That is usually a symptom from having the throttle wide open during shifts

 

[hawkeye93]

The logs are WOT from a dead stop, no brake boosting.  Sport shift mode, AdvanceTrac off, climate control off.  For my datalogs, I generally try to get a 0-100 run at WOT.

What does load 2.0 indicate?

 

[ajpturbo]

The logs are WOT from a dead stop, no brake boosting.  Sport shift mode, AdvanceTrac off, climate control off.  For my datalogs, I generally try to get a 0-100 run at WOT.

What does load 2.0 indicate?

2.0 is more than likely over 20 psi..maybe 22 ish psi...too much boost basically....ive noticed that actually the fuel system is pretty robust and 20 psi at high rpm is not the problem but when there is fast load spikes and fuel demand goes up fast for some reason the pressure drops....if load is controlled better the fuel system seems to keep up better

Ive seen 1.7 load kill rail pressure when load spikes to 1.7 but if 1.7 load is sustained smoothly that is no problem for the stock fuel system 

 

[hawkeye93]

Just got an update from Torrie, said he took the boost down.  I'll give it a try tomorrow.

Sent from my HTC One M9 using Tapatalk

 

[ajpturbo]

Hawk you have a couple different things going on that can make it hard to isolate the problem from those logs...Your boost is kind of aggressive...In one log you had spikes to 240KPA or 20 psi. Couple that with a LAMBSE or commanded afr of .75 which based on the stoic of the fuel in your tune is like 10.5 air fuel ratio

That boost with that commanded afr will deplete the rail of pressure. When you command a rich afr it takes more injector duty cycle to achieve that and rail pressure falls because injectors are wide open and spraying as much fuel as possible.

You have some knock retard....Maybe from low fuel pressure.

also you have a discrepancy bank to bank as far as stft's and measured AFR. They are more different than what you should normally see BUT that could be a product of the super rich commanded afr and or the low fuel pressure

The stft for bank 2 is wonky and jagged.....Could be from what I said above and trims are adjusting rapidly because pressure is low OR the bank 2 primary o2 sensor is bad. But a bad O2 sensor won't cause bad fuel pressure.

Command lower boost and see if fuel pressure improves...That will tell you if there is a fuel delivery problem which I suspect there is not....Then once you have fuel pressure see if afr and stft balance from bank to bank improves, that will tell you If you have a bad o2 sensor.

That's all I got

 

[ajpturbo]

How long (miles) have these plugs been in the car, and what is the gap?  More often we see a fueling issue than an ignition issue once plugs have been changed and gapped properly.  How many logs have you done on the latest revision prior to the limp home incident occurring?  If there are no codes, it could be the car adjusting to the tune, as it seemed to do before.

About 2K miles on the plugs, gapped @ .030.  These were my first recorded logs with the new revision, but a few days ago, I did notice (after one of the stumbles), that I had 10* of spark retard (see Min value in photo).  I assume that's a result of knock?

Did you check the relays,fuses by by the engine compartment....try swapping them around.  Z

Haven't swapped any fuses or relays yet.  I'll have to look up which ones are which.

The spark you reference in that pic is not spark retard from knock....It's displaying the total spark advance and the min and max values could've happened at any time.

At one point you hit a very low spark value and who knows why...It could've been commanded for all you know...At startup, on an up or downshift due to tq reduction who knows really.

You are mistaken the spark advance PID for knock sensor I think.

 

[hawkeye93]

Yeah, I knew it could have happened at any time.  I wasn't sure the cause of the spark retard, I kind of figured any retard was due to knock.  But that's why I put the question mark...

 

[hawkeye93]

Update: New tune from Torrie fixed the issue.  A quick WOT shot only produced 18 PSI, instead of the 20+ PSI I had been seeing.  Wasn't datalogging today, but car ran strong, and no limp mode.  Thanks to Torrie and all who replied.

 

[SHOdded]

:thumb:  ENJOY!

 

[FoMoCoSHO]

Yeah, I knew it could have happened at any time.  I wasn't sure the cause of the spark retard, I kind of figured any retard was due to knock.  But that's why I put the question mark...

You might want to get rid of spark advance and use "knock sensor". That will give you a better idea of when your knock sensor is making corrections.