Originally Posted by dbturbo2

Post flash, my car feels like it responds instantaneously when I press the throttle whereas before there was a slight lag. The hesitation I'm describing happens occasionally shortly after pressing the throttle, there is a momentary hesitation anywhere between 1-4K rpm's. You can see the tach needle drop slightly and feel/hear the hesitation when it happens. That hesitation is the same pre and post flash.

Originally Posted by dbturbo2

Post flash, my car feels like it responds instantaneously when I press the throttle whereas before there was a slight lag. The hesitation I'm describing happens occasionally shortly after pressing the throttle, there is a momentary hesitation anywhere between 1-4K rpm's. You can see the tach needle drop slightly and feel/hear the hesitation when it happens. That hesitation is the same pre and post flash.

Originally Posted by dbturbo2

Post flash, my car feels like it responds instantaneously when I press the throttle whereas before there was a slight lag. The hesitation I'm describing happens occasionally shortly after pressing the throttle, there is a momentary hesitation anywhere between 1-4K rpm's. You can see the tach needle drop slightly and feel/hear the hesitation when it happens. That hesitation is the same pre and post flash.

Originally Posted by chrismgiro

I own a '15 RCF with 800 miles and have the same exact issue with the hesitation, for lack of a better term. It is a drop in RPM, which causes a noticeable "jolt" 1-2 seconds after shifting into gear at the lower rpm range, as you describe. It usually only happens in Sport, Sport+, or Manual mode. Doesn't seem to do it in Normal mode or at least it is not as noticeable. I had the TSB performed on Friday, but that drop in RPM is still present, but the throttle response was definitely improved. The Service Tech and Service Manager both made mention of the modifications I have done and said they may be causing the issue, since messing with the intake and PCV system may throw off the ecu (insert comment here, lol). I obviously don't believe this is the case, but maybe we can rule that out here by comparing mods and everything else we put into our vehicles, rather than putting everything back to stock to prove them right or wrong. I have the RR Racing Titanium intake pipe with their K&N valve cover breather hose modification, The RR Racing Air-Oil Separator (The tech mentioned the PCV system has no issues in the RCF, but we all know this is far from the truth), and a Borla Cat-Back (secondary cat delete). I changed my oil at 500 miles and used Mobil 1 5w-30 conventional. I only use Shell 93 octane fuel and add mystery oil (to the fuel only). For the life of me I cant recall if this issue was occurring prior to all of the mods, as I did all of them around the same time and the car was so new that I may not have noticed the issue right away. Please feel free to chime in here. Hopefully we can get closer to a cause and resolution to this annoying problem, which seems to be affecting quite a few Lexus vehicles.

Originally Posted by Davew77

You may want to consider a tune from RR Racing.

IMO, all of the performance shortcomings of the RC F (other than the weight) is in the tuning of the ECU and the transmission. I don't see Lexus doing anything about it anytime in the future. They have purposely held back the car in a lot of ways. Probably because they are more concerned with reliability than they are with the actual performance of the car. It could also be because they want the car to be as tame as possible for novice sports car enthusiasts. They specifically mentioned wanting to build a car that "everyone" can enjoy. Compared to every other sports car I have ever owned, I would have to really try to lose control of this one. Something that should not be true of a car with 467 hp and 389 tq. (This entire paragraph is my opinion)

Aftermarket fixes are likely going to be the only fixes. It's likely that the only reason the ECU flash for the fuel pump was implemented was because people could hear a noise. A Lexus shouldn't make unwanted noises.


But I love my RC F and I will turn it into the beast it should have been.

Originally Posted by chrismgiro

I agree with all of the above, but this issue with the hesitation/lag is a real problem, not really a performance short-coming or something I would call a hold back by Lexus. There should be no drop in RPM ("The Jolt") unless the car is shifting or I let off the gas. It may be computer related, but it is very hard to diagnose with a "fly by wire" setup. I would just like to know if people with this issue have mods done, are they bone stock, or a mixed bag. I have the apexi controller and the harness finally shipped today after being back ordered for over a month, so I am curious to see if that will resolve the issue. I will report back in the next couple weeks, as I can easily reproduce the issue. In the mean time, I would love to hear from others with the issue and whether they have any modifications done or not.

Originally Posted by Davew77

Well, I am completely stock and have not noticed any hesitation after shifting. With one exception; If I take a corner in 1st gear and shift into 2nd gear at 3k-4k RPM, then attempt to go WOT in 2nd gear I get about a second delay before the throttle actually kicks in. So I punch it earlier to compensate. I attribute this to "novice loss of control prevention" tuning by Lexus. This is also with Expert mode activated (which I use exclusively along with manual mode, unless I want to use cruise control).

Is this what you are talking about?

If I am running straight line, I have not noticed this delay. But I have not specifically tested for it. In a straight line if I'm going to nail it, I do it in 1st anyway. Then I'll shift to 2nd at redline. No hesitation.

Originally Posted by chrismgiro

I am not talking about the delay after stepping on the throttle. That issue was fixed (or should I say, made much more responsive) after they did the Fuel Pump noise TSB. Night and day difference. The issue I am talking about occurs mostly at low speed and seems to be most noticeable after shifting into 2nd gear and occurs around 1200-2000 rpm. Try this...in manual mode, sport or sport+, doesn't matter, shift from 1st to 2nd. Just normal driving, not getting on it ( I am talking 10-20 mph). After you shift into 2nd, about 1-3 seconds after you shift, see if you feel the jolt, due to the drop in RPM I am talking about. As others have mentioned, you can also watch the tach to see if the needle drops. This happens to me in Automatic mode as well, so test it out in Automatic mode too. It is easier to feel in manual, though, since you know when the shift into gear occurs and know there shouldn't be any hesitation after you shift. It should be smooth increase in RPM, with no pauses/jolt/rpm loss...whatever you want to call it. I could probably get a passenger to make a video of this from inside of the car, as it is that noticeable.

Originally Posted by chrismgiro

I am not talking about the delay after stepping on the throttle. That issue was fixed (or should I say, made much more responsive) after they did the Fuel Pump noise TSB. Night and day difference. The issue I am talking about occurs mostly at low speed and seems to be most noticeable after shifting into 2nd gear and occurs around 1200-2000 rpm. Try this...in manual mode, sport or sport+, doesn't matter, shift from 1st to 2nd. Just normal driving, not getting on it ( I am talking 10-20 mph). After you shift into 2nd, about 1-3 seconds after you shift, see if you feel the jolt, due to the drop in RPM I am talking about. As others have mentioned, you can also watch the tach to see if the needle drops. This happens to me in Automatic mode as well, so test it out in Automatic mode too. It is easier to feel in manual, though, since you know when the shift into gear occurs and know there shouldn't be any hesitation after you shift. It should be smooth increase in RPM, with no pauses/jolt/rpm loss...whatever you want to call it. I could probably get a passenger to make a video of this from inside of the car, as it is that noticeable.

Originally Posted by SmurFPwr

I have the same hesitation when I manually shift from 1st to 2nd with light steady throttle around 2100-2400 rpm while increasing speed.

Originally Posted by Davew77

I made numerous attempts to replicate your issue. I could not. I tried shifting at 2000 and at 3000 rpm from 1st gear to 2nd gear (I can't see a point in trying to shift at less than 2k rpm). I kept the throttle constant during the shift and there was no hesitation. I was in Sport+ mode, as always.

Perhaps it is your mods. It also could have something to do with the ECU flash that you had done. I have not had the ECU flash since I have not had any issues with my fuel pump.

That's all I got. But this issue is clearly not one that everyone has. However, I don't believe that any of the known issues are experienced by everyone. I have been one of the lucky few that have not had any issues (if I don't count my disappointment with the ventilated seats).

Originally Posted by chrismgiro

I am not talking about the delay after stepping on the throttle. That issue was fixed (or should I say, made much more responsive) after they did the Fuel Pump noise TSB. Night and day difference. The issue I am talking about occurs mostly at low speed and seems to be most noticeable after shifting into 2nd gear and occurs around 1200-2000 rpm. Try this...in manual mode, sport or sport+, doesn't matter, shift from 1st to 2nd. Just normal driving, not getting on it ( I am talking 10-20 mph). After you shift into 2nd, about 1-3 seconds after you shift, see if you feel the jolt, due to the drop in RPM I am talking about. As others have mentioned, you can also watch the tach to see if the needle drops. This happens to me in Automatic mode as well, so test it out in Automatic mode too. It is easier to feel in manual, though, since you know when the shift into gear occurs and know there shouldn't be any hesitation after you shift. It should be smooth increase in RPM, with no pauses/jolt/rpm loss...whatever you want to call it. I could probably get a passenger to make a video of this from inside of the car, as it is that noticeable.

Originally Posted by estoyf

i have this same hesitation. theres no abnormal noise to indicate the fuel pump issue, but this hesitation is apparent in my rcf. i've noticed it for a while, but haven't really paid too much attention and only feel like posting to let OP know his rcf is not the only one. the hesitation is apparent after the transmission gets into 2nd gear, whether in auto or shifting manually and occurrs around the low 2k rpm mark. i can feel it as well as see rpm tach drop.

and the only mod i have is a Joe Z exhaust. i can't remember if this hesitation was around before i had the system put on. usually put in gas from BJS, and only have 3200 miles on it.

Originally Posted by chrismgiro

Hey, thanks for testing. What do you use for fuel, how many miles are on your RCF, and what are you using for Oil?

The ECU Flash was done to try and resolve the hesitation, since some folks that had the hesitation said the fuel pump TSB update resolved their hesitation issues. I had the hesitation prior to the ECU update. Unfortunately, the update did not fix the issue. It may very well be the intake mod or PCV mod (highly doubt it is the exhaust). Still waiting to hear from others with this issue.