Have you checked the timing curve both hot and cold, maybe the timing is way off when cold… just a thought… Doesn’t pull enough (retard) timing for boost when cold or something, maybe taking out to much or not enough, I think it is around retard 2 degrees per 1 pound of boost to start safely before dialing it in, up to a max of 50% of your total advance, or something like that, it still could be in the tune…
Are you running 93 octane or E85?? could it be something like an E85 tune for cold then swap over to pump gas when warm by mistake?? again, just thinking outside the box here…
I have seen the retard level on hondata. Before I dig into that. When it misfires and putters cold in park should the retard level be doing anything in park?
Then also what causes it to not missfire if it’s in gear?
For example, if I start the car, drop it in drive within seconds. And keep it under 2500RPM so it doesn’t spool I can keep the misfires at 0. Then once hot operating temp I can beat it with no misfires.
If I turn my car on, leave it in park to warm up it’ll misfire 5-8 times I can hear it putter while warming up. Then it’s fine once it’s warm in park.
You just need to watch live data or the tune data on a laptop, what a tuner looks at to make adjustments to see what everything is doing, at idle in park the RPMS are higher than at idle in gear, the difference could be adjusting the timing and or fuel trim in the wrong direction or too much/little when the idle is a tad higher in park vs idle in gear… The tune could have a - instead of a + or visa versa when cold vs normal temp… Again, have to be able to read all the data for the tune using a laptop, might be able to see some/most of it using a scanner live data…
Just thinking out load here, from my twisted left brain thinker… lol
You would probably get more out of the boost and run cooler cylinder and induction temps running E85, don’t need as big of a intercooler either, you just have to have a fuel system that can run on it… After it’s only money right?? lol
My guess, whatever is causing that too-lean spike in post 18 is also causing the misfire. The long term fuel trim at minus 7% is higher (in the negative direction) than expected. It means the engine computer is purposely cutting back on the amount of fuel injected. It computes how much fuel to inject for a particular situation based mainly on the engine coolant temp, throttle position, & maf/map sensor readings. It then adjusts the injection rate so the pre-cat cat O2 sensor feedback loop is at the optimum a/f ratio, neither too-rich, nor too-lean. In your case the computer is purposely decreasing the fuel supply to the engine by 7%. The puzzle is why the computer would reduce the fuel flow when it should know the mixture is going too lean at the time of that spike?
As you apparently have a sort-of custom configuration, the cause is most likely due to a problem in one of those components. Either that, or that the computer’s software is not expecting to have to handle that configuration. If I had to guess, it would be something about the turbo. Waste-gate, or boost control. Do you have a method to temporarily disable the turbo function? If so, then a good test would be to repeat the same experiment you did in the photo above, but with the turbo disabled.
You seem to be asking for opinions, and this just my opinion. I’m a diyer and have no experience w/turbos in any of my cars. No turbos, but plenty of opinions … lol … .
The computer was programmed to operate a naturally aspirated engine. Some software adjustments were performed in order to accommodate the turbocharger however the results seem to indicate that the software changes do not accommodate a full range of operation.
During open loop (cold start) the computer doesn’t rely on the air/fuel ratio sensor input to compensate for lean or rich variance.
These crude modification result in tailpipe emissions many times greater than the original federal standards. A Honda Civic Si turbo will have the correct “tune”, and 200 horsepower.
Yes, i can order Flex Fuel kit and not sure if need ECU upgrade. But yes the shop asked if I wanted to drop like 2k for all the work + tune. and just wanted the regular $600 dyno tune at the time not thinking I was gonna deal with this. Since original owner had premium octane tune before me and it was running good for years.
But as Nevada (and also IRL mechanic friend) bring your car in, take off the turbo, sell it stock, get SI thats built for modifications and you wont be dealing with headaches when you upgrade things. I warned you about this modification stuff, your cars not built for it.
Car I got to fix for headgasket issue has cold stumble for 10 sec and then smooths out. It is using no coolant. It did have a p0302 code but has no cel light. I think headgasket leak is in early stages. I bet a borescope to look at piston tops might be interesting.
The MAP is showing -21.8 psi under boost?? what-why?
2417 rpm and map showing -1.1 psi (cold side) and +7.1 psi boost (hot side)
Unless I am missing something (my head hurts now lol).
I would stop and find another tuner and just tell them that you just bought this thing as is and trying to figure out the misfire and have them look at the tune to see what they say about it… Don’t mention your current tuner, they could be BFF’s… lol… Or trash talk the other guy…
May need a fresh set of eyes, and your current tuner might not be able to see the trees for the forest…
The spool will start about 2500 RPM
The car runs -20 psi on idle, once im slowly pressing gas itll go -16 -12 -8 until 2500 RPM itll hit 0 and start spooling into + numbers.
Should I just find another tuner to do 91 octane or is it worth the money dump for E85 in your personal opinion. Cars old too might be time to SI and start modifying a car built for it lol
edit: That +7 PSI was at 5,400 RPMS -1.1 when it was trying to spool but was misfiring attempting to boost while cold at 2400 rpm
Original owner had it at 10 pounds, Got it retuned 8 or10 pounds since that’s the “safe” level for that motor.
2009 Honda Civic with the R18 engine has 140 horsepower at 6,300 rpm
Engine: 1.8-liter inline-four
Torque: 128 pound-feet at 4,300 rpm
because my car use to misfire all the time even while hot. Brought it in, swapped out sparks and plugs and went 1 step colder again, got it on the dyno, got it locked in. Went to pick it up and he said it’s tuned but during cold start it misfired once and we were unable to replicate the problem. If the car is warm it should be fine.
I was pissed at the shop being told that. But I had to get to work and couldnt really be chucking money and time into it, at that time.
So you are only making between 216 and 235 HP roughly, I would not mess with converting to E85 at that level…
Might just be better to leave it alone and just let the thing warm up before shifting over 2000 to 2500 rpms, kinda like having an old carb on it… Or spend the money for another tune…
I guess my last burning question is, if I choose to leave this problem and give up. (Which maybe the engine is tired and there’s no problem.) as you basically stated with the carb.
How fast am I gonna burn through plugs and coils ?
Will few misfires during warm up cause premature turbo or engine failure?
I’ve just never let a car intentional misfire so I just wanna be aware of what’s to come.
It sucks the tune is perfect while hot. Dang cars dude.
