ThatOneIS

Hi everyone,

First off, I have a 2015 IS350 (yes I know I posted in the 2IS forum) I’m doing this because this forum is far more active and I’m hoping this can get more exposure to get help. I’m having an issue where at WOT, the car will either completely cut out (RPM stops going up too) with no throttle response and go really lean (usually 18-22 AFR) before 3.5K RPM, or if I ease past 3.5K and floor it the car will jerk violently until I let off the gas. Both issues stop as soon as I get off the gas. I also recently noticed that from a dead stop if I give the car too much gas there will a jerk, like a misfire and the car will go lean. So it’s not just at WOT that the car is running weird. The jerk isn’t as violent as when I got WOT, however.

I got the supercharger installed two months ago and the car was fine initially after the install. I decided a week after to run ethanol to an E30 blend and the car was still running fine. At this point, I didn’t have an ethanol gauge yet (it was on the way) so I might’ve been a little over, and one night the car completely went into limp mode when I floored it. I had a code for the car running too lean and cleared it as well as filled up a little on pump gas. Afterwards, the car was able to pull again, but I noticed sometimes that at WOT in the upper RPM’s, the car would hesitate briefly before pulling hard again. After another week, the night this issue started happening, I had just added more ethanol to exactly E30 because I got the ethanol gauge installed. It was at E23 before I added more and it pulled amazing up until I added the extra 7%. I’m certain the extra ethanol did something but I don’t know what.

Initially, I thought it was the tune so I got multiple tunes from Rafi and none of them fixed the problem. I even went back to pump gas and the base supercharger tune, which worked before and STILL had the same problems. This leads me to believe it can’t possibly be the tune.

I had new spark plugs installed when I got everything done and I changed them out again today because I thought that was the issue. The old ones I took out today were gapped way too small (.022). The new ones were gapped by Rafi at (.025) but the problem is still there. I also verified the compression on my engine and it’s above specs (210 in five cylinders and 200 in one cylinder). I have no CEL. I asked Rafi about potential fueling issues and according to him, the stock fuel pump and injectors should be more than enough to run ethanol. Strangely, the car will have no problems going to redline with some boost at quarter ish throttle

I have attached some logs that are short because they are only of WOT pulls (about 6-8 each log). The first pull in the log will be the violent jerking. The few pulls afterwards will be the cutting out followed by the throttle closing after the cut out.

I just don’t understand why the car was completely fine before and now I can’t do more than half throttle. Even Rafi is perplexed by all of this. The only thing I haven’t done yet is check my fuel pump, filter, and injectors. Did the ethanol mess up one of those components since the problem is still present even with pump gas? I did notice the chargepipe was extremely loose when doing my plugs so maybe there’s an install error somewhere, or a vacuum/boost leak? But if so, why would the problem show up weeks later? I’m not sure at this point.. I really hope someone can help out or point me in the right direction.


Thank you.

jrule2

I'll chime in since I was supercharged. The car registering as lean is a strange one and it almost sounds like you're describing a misfire with the jerking sensation - if you've changed the plugs it could be a coilpack. Seeing if there are any codes would be a good start here as you might be registering a misfire on a particular cylinder.

If you can rule out spark and the engine is healthy the next bet would be fuel injectors, fuel system in general, fuel leaks etc. Also pretty rare but sometimes fuel cap. Might also be worth double checking the wiring around the injector controller as well.

Only other thing I can think of which would have no correlation to the car running lean, would be belt slip. The superchager belt slipping would give you a jerk or misfire feeling.

Hope something here helps.

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2013FSport

iTrader: (2)

^^ but it probably wouldn't go lean if the boost were low.

Lean + boost + Ignition advance = potential damage.

You monitor the knock sensors yet? They should attempt to protect the engine by pulling back the timing and if it continues, chop the throttle. If damaged, they could limit potential from the engine.

I'll peak at the csv file later...

AMIRZA786

I'm no expert on this, but previous to my IS350 I owned a 2018 Civic Si. As you know this is a highly modded platform, and on the forum I was previously on (CivcX) there were three things that many times led to lean AFR's:

Aftermarket intakes
Not being able to push enough fuel while trying to push too much power on the stock turbo
Ethanol

Ethanol use was usually the contributing factor to lots of issues, including misfires, fuel trims being off, and blown engines, especially when using water/meth injection

ThatOneIS

Yes please review my logs whenever you have the chance and let me know what you think.

2013FSport

iTrader: (2)

I'd suggest you add a data point that includes engine load so during review of data you have a sense of what work was being done. I know the ingredients for calculating load are MAF flow, MAF temperature, Amb pressure, vacuum, TPS, stroke volume, RPM, and yada yada yada.
What I don't know is what happens to an NA engine ECM when vacuum becomes pressure. More important is what the Tune does to the weighting of the Vacuum that now becomes boost. The OEM MAP for weighing the value of vacuum varies by manufacturer and application, so we are completely in the dark here with both OEM and Tune and what it impact it has.

What are some of the questions you raised and the answers to those questions regarding the current drivability? We don't see too many boosted 2GR's here. Any data on them boost #'s? What do you have going on over there?

GrizzlyMan

Did you ever find out what was wrong with the lean condition?

Dealarr

The big issue with O2 sensors and alcohol is that the alcohol fuel will mix with the zinc from the oil that isn't removed by the piston rings...the chemistry of alcohol + zinc = a substance which is known to very quickly kill the actual sensing junction in the O2 sensor itself.

This is not my answer, suspected there was something like this. And found confirmation. If your oil is zinc heavy. Not sure if you could clean it. Only suggesting this because the GR engines have larger than normal ring gaps. Otherwise the zinc would be mostly cleaned off so other engines may not suffer the same. Clean your MAF as well, it honestly feels like a sensor thing. Because this sounds like a gradual problem, and over time of degradation. So sensors most likely.

Armadous1

What is your spark table or spark map whichever you want to call it.

jizz4jazz

iTrader: (1)

looks like a sensor issue, mass airflow? a dirty or bad mass airflow will cause jerking like you described.

B_390_LU

Have you been monitoring your KCLV? If you have, what are the figures lately, since you begun having issues.

Armadous1

Well there is a good chance with your mixture that may or may not have been correct and dead on you cooked the upstream sensors as well. Need more data to truly see