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Misfires badly while idling (cold/warm start, or hot start)
Application is a 2.7 EcoBoost, stock tune or performance tune (doesn't seem to matter). I ran VCM Scanner just to see what was going on, and the misfire count racks up to over 300 but the Misfire detected PID shows no. I know this correlates to the OBD Mode 6 data showing misfires for individual cylinders but not bad enough to set off a DTC (P030x).
Spark Source is Torque Control and Fuel Source is Stoich. This is during a cold (ECT at 32F) start, warm re-start (120F-150F ECT), and hot re-start (170+F) but mostly cold and warm.
Final spark advance zig zags/switches rapidly from -10* to +30* or so, MBT/Borderline looks fine like my old datalogs. But whenever the final spark advance switches like that, the engine sounds like it is missing and wants to stall. When I shift into gear (Reverse or Drive), the spark advance smoothes out. Since the roads are covered in salt, I don't want to take the car out of storage to go on the road. But in the months prior to winter storage, upon a cold start, the car has/wants to stall out when braking after the first near-WOT run. Any ideas?
No coolant is missing or being burned. No visible smoke from the exhaust at all. No smell of burning oil, no loss of engine oil, etc...
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Advanced Tuner
I get the same thing with the misfire detected PID, I watch the misses since start up, works good if you fire up the data logger before you start the car. Most I,ve ever had was 67, most times when I was having the issue with mine it was only 20 or 30 tops. I changed tunes a few times and it went away, I,ve looked at timing, fueling, even torque demand. Never could figure out the reason for it, but I went back to a tune that was know to cause the miss, and it did. Switched it back, and the next morning it was fine, no miss.
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I even used the stock tune and it still does it just idling. During a 15 minute idling session, it counted over 300+ misfires. No DTCs set because it was spread throughout all the cylinders but mostly on #4. In the past, #6 gave me the most issues. I am suspecting a fueling issue or something like that since the tunes don't have any impact. Once spring comes around, I plan to run some PEA injector cleaner.
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Advanced Tuner
Be careful with the injector cleaner, I,ve had guys that know the D.I. system pretty good, said not to use it because the injectors are touchy. I,ve heard this about the newer Diesels too with the common rail fuel systems, One thing I liked about my old dinosaur 7.3 you couldn't screw it up if you tried, LOL. Other thought would be bad gas, how long has it been sitting ? The tank life on currant gas is like non exsistant, and I,ve heard people say winter gas is even worse.
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It was kind of exhibiting these symptoms with the fresh tank of gas at the time. I've run the cleaner through the SHO system before and the injectors never had a problem.
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So I was playing with the CSER spark tables and about 2 years ago I added some spark in the Adder tables for low temp / cold starts which helped. Now for some reason if there's too much spark, it causes bad misfires just idling. So I went back to stock (0*) and it seems to have helped. However, when I shift into Drive and idle, it doesn't exhibit any misfires or spark hunting where it cycles between 0* and 30* rapidly which happens when the engine shakes and a misfire count is added.
Here is the log screen capture from beforeMisfire Before.JPG
and then after
Misfire After.JPG
It seems to be a bit better now. I already put some injector cleaner in the tank so maybe it is doing something.
I noticed injector pulse width used to be 1.0 ms when the misfires were bad, and now it is up to 1.2-1.3 ms which is what I saw with the car brand new and idling fine. I don't know why LTFT is so lean though at 10%-14% for both banks.
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Advanced Tuner
I was getting that for a bit cold, idle it was running -15%, touch the gas peddle and it went up to center, let off and back to -15% till it got warmed up. Keep in mind, if it's running lean enough, it will miss. Even at idle. I ended up adjusting my trainsient fueling for acceleration, and it seemed to fix it. I also played with timing too, though it didn't seem to effect it
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What I don't understand is that I haven't done any modifications that would require adjusting anything beyond stock values, especially for this RPM/load (basically idling). I could understand different cams/turbos causing issues, but it's basically/physically stock at this point in that operating region.
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Advanced Tuner
Yeah, doesn't sound right. Have you bumped up torque demand down low at all ? I raised mine all the way from 600 to wide open, 10% and then hit the upper cells a bit more. I changed my table back too stock at one point and just hit the upper cells, still did it. One thing I,ve seen with my tuning is some tunes will hold 8 to 10 degrees of timing at idle, and another one will show -5 to 7 degees. Odd part is I never touched any timing tables between the two tunes. What I was thinking is there is a fine line there with timing that at idle you dont get fuel burnt, it reads rich, so the system goes bonkers trying to lean it out, but then the deal with the gas peddle is odd too. Wondering if it's a air flow issue, touch the gas and the flow comes up.
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Would a crank relearn be necessary or maybe KAM reset? I've never used either function in HPTuners before.
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Advanced Tuner
KAM reset wouldn't hurt, only bad thing is you loose your trans learning, it will have to relearn your driving habits. Which isn't a huge deal, drive it about ten miles and it should be good. the trans relearn process I use is, Kam reset. Start it, go gear to gear four seconds each minimal, then back to park. Drive it keeping the RPM's under 2000, then stop, back to park and do the gear to gear thing again. Go drive it like you stole it, and see how it is. They claim your suppose to do this every time you do a reflash changing the tune, but I'm kinda bad about doing it every time. Big thing I notice is the first 3 or 4 times it shifts into 3rd its a bit harsh, but then smooths and feels how you tuned it.
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The relearn for my 2018 Explorer is brutal. Takes like 3 weeks of driving regularly. Fusion Sport isn?t too bad. I did more testing today and I think it is carbon buildup in chambers and or injector tips. CKP and CMP seem to be in sync and no faults for injectors Or CMPs.
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I have a 15 X-sport that had cold start misfire issues. Adjusting the cat warm-up tables toward normal really got rid of the rumble.
Last year I noticed a misfire and strange fueling at idle and found that the evap solenoid on the intake manifold was messing up badly. Sometimes it did not set a code but it was the cause.
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My evap purge valve hasn?t set a code but I can see it flowing between 30% to 50%. What did you do with the cat warm up tables? I don?t think it is right to have to modify stock values to fix an idle misfire issue on an otherwise stock vehicle in stock conditions.
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Also what cat warmup tables are you referencing?
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Fist I'd like to thank you for all that you have shared on here. I have learned A LOT from you.
My evap purge valve was not setting a code most of the time. Maybe just 1 time in 2 months, but when I finally took it off and tested it...yep, not sealing well at all compared to a new one.
I would like to think that factory tables were engineered with our priorities in mind but GM's GEN5 warm up tables really make a racket (and make your eyes water) in a race vehicle as they add so much fuel, double-pulsing and what not. But a little time and attention resolve that too. I realized that some companies pump in extra fuel during cat warm up and some companies retard the timing a lot and some do both in order to get the cats hot. That is what gave me the idea to look into the warm up tables on my X-sport. Spark>Advance>Emissions Reduction 3 tables. It was noticeably smoother after a few small/gradual increases to timing on the colder end.
I am sure the cam tables can help too but I haven't dug into them on Fords yet.
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Advanced Tuner
I've replaced the purge valve on a number of cars, my 13 being one of them. It has a thing for causing a weird issue, you go to the gas station. Shut the car off , and fill it up. Go to start it back up and it will crank for a while, when it does start it acts like a motor that's loaded up with fuel. You tap the gas peddle a few times and it's back too normal. I,d have to go look for the definition, but it basically says the system can't release the vacume in the tank. I,m still not sure what's gong on there, if its a lack of fuel or too much pressure and causing it to over fuel, though I dont see how that is possible the way our fuel system works. At any rate, you replace the purge valve and your good as new again. Might be worth while to replace it, and see if it fixes the issue. Could be what people are fighting, and keep looking at the wrong part.
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It starts up just fine, never had a problem with startin. I took off the purge valve and used compressed air as well as lung pressure, no leaks.
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I've seen a cat that is starting to plug up cause a mis at idle. Are your full throttle performance numbers still what they were?
Carbon buildup? That will show lean/random misfire during a startup until the carbon sucks up all the fuel it can hold.
Otherwise how is your fuel pressure? High pressure pump might be worn enough to reduce output at a low idle. It should set a code if the high side is not meeting the specs though.
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Cats seem fine. When my cats broke apart and clogged up the system on my Crown Vic, no codes were set and it never misfired at idle but the car has 17k miles on it, so I'm not sure how much carbon buildup there'd be.
Low side pressure is about 70 psi during idle, and HPFP is 300-500 psi at hot idle (600 RPM).
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