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Lack of throttle response upon slowing down/re-accelerating (running ECUTEK)

444 Views 13 Replies 5 Participants Last post by  240Z TwinTurbo
Hey guys,
I'm experiencing some serious throttle response or lack thereof when slowing the car almost to a stop, then re-accelerating again. The acceleration unresponsiveness seems as long as 1-2 seconds sometimes. I mean I will really hit the throttle to the ground and there is no response. I installed a pedal commander today thinking that would alleviate the issue however it didn't

My car has the following specs **(Tuned on Ecutek)
2015 Premium
AAM Competition Stage 3 Tune (COBB)
3 in Boost Logic Intakes
Downpipes (AAM Competition R35 GT-R 3" High Flow Catted Downpipes (GESI HFC))
Tanabe exhaust
1300 IDX injectors
Upgraded fuel pumps (AEM’s 340lph)
Visconti speed density kit

I'm not sure what the issue could be, this wasn't an issue for me really when I was on COBB but started after switching to ECUTEK for some reason.

My tuner ran a log on my throttle vs my pedal depression and it wsa the following (You can see the blue line (throttle) lags the red line (acceleration):

Rectangle Slope Plot Line Triangle

This has been discussed in the following thread: Getting some serious hesitation from engine throttle (Post #36)
The issue was resolved by COBB via some Launch Control map update? However, that does me no good as I'm on ECUTEK.

Any thoughts on what this could be, has anyone seen this before running ECUTEK?

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I have seen the same issue a few times. I am pretty sure its transmission related, it feels like the transmission was about to downshift to 1st and then when you engage throttle again it delays. Log transmission and ask your tuner. The throttle won't engage until the shift is finished and at slow speeds it takes extra time.
I have reached out to my tuner and provided numerous logs. He even had a ticket out to ECUTEK as he had not seen this issue previously. ECUTEK didn't provide any resolution unfortunately.

He spoke to Paul Blamire, the lead developer at Ecutek. Paul said
he believes the behavior you are seeing is completely normal and related to how the car is being driven. He said a stock GTR will do the same thing.
In other words Ecutek is not going to “fix it” because they do not see a problem.

This does not seem normal to me at all as the car was not doing this when I was on COBB, so I am stuck between a rock and a hard place as not even ECUTEK will acknowledge this as being an issue....just that it's "normal" 😒
It can be adjusted, you just need to delay when it shifts to 1st gear. It's all in the shift tables.
Yeah, wish I knew how to update the shift tables correctly. Unfortunately, I am unknowledgable in making those types of updates.
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Agreed and I had a similar issue, but mostly when slowing to a stop on a downward slope. However, I did also see it from time to time when going up the driveway at an angle. I would log all TCM parameters ending in "flag" and also log line pressure.
What year was your R35? I can try and get those TCM parmaters posted from a data log. If I posted them here would you have an idea if something was off?

What did you end up doing in your situation that fixed your issue?
So I took a TCM data log just now. Apologies, but I included all parameters and highlighted the "flag" and "line pressure" parameters yellow for easier identification. I also got the no response behavior to repeat at the end of the log. I highlighted the area orange where I think it was happening as my Accel Position Sensor 1/2 % shows around 100 at that point. This is where I had the pedal to the floor and no responsce. Not sure if anyone here has any ideas?


When this occurs, is the car going slow enough to the point where the clutch needs to re-engage and negotiate the friction point again?

I do notice some similar behavior if I try to get on the throttle while it's doing that. Same thing happens if I quick shift into 2nd and try to accelerate. Power gets cut pretty abruptly (maybe due to excessive clutch slip) and acceleration won't continue until I let the clutch fully engage. I've just learned to let the clutch fully clamp then accelerate. This works 99% of the time but it does become intrusive in certain situations.
Basically it's to the point where I'm slowing down in 2nd gear and I'd say the car is about to get into 1st gear...or actually hits 1st gear before I re-accelerate again. So, I'd say that seems accurate.
I can see it happening in the log, but don't have enough experience to say why. Line Pressure and Line Pressure Target are both OK. As you slow down the trans may or may not have shifted into 1st gear, but you press the accelerator and the car doesn't go. One Gear parameter says it is in 2nd and the other three say it is in 1st. I will assume the ECU cut the throttle because you did not log that parameter. Clearly you have a gap where neither gear is selected as both Clutch A Pressure and Clutch B pressure are at 0psi despite accelerator being 100%. After a second or so Clutch B pressure rises and the car starts to accelerate. I took a screen shot of the graph and added comments, but for some reason I can't find where I saved it. Because you logged 4,000 parameter, I don't feel like going through you log again to recapture the image. Could be tune related and when I had the issue I ended up going back to the stock shift map and have not had an issue since. Must be an issue with the tranny not knowing what gear it is in and the TCM won't allow the throttle to open under the scenario.
@240Z TwinTurbo Thanks so much for looking into this, I truly appreciate it! I'm assuming going back to the stock shift map is something only my tuner would need to do, it's not something I could just update myself?
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