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Re: Throttle Lag
Hi Brett,
I have read about this mod too, but I don't think it's gonna fix or address the throttle lag issue, as it is more directed at performance gains.
BTW for an added 3-5 HP as a result of this mod (as being claimed) and the risk involved in stuffing it up completely, I don't think it's worth it.
Not unless you buy aftermarket throttle body that has already been made bigger.
HERE some info about this mod and how it is done.
My personal opinion about this mod. Don't go there! 
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18/Nov/2005, 12:20 pm
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Re: Throttle Lag
Hi Guys,
Reviving an old thread to throw-in a new gadget which I have come across recently which seems to address the delayed throttle response and the lag some of us are experiencing with the exy in lower RPMs.
It's called SPRINT BOOSTER
Basically this little gadget gets directly attached to your accelerator pedal and it has resistors which will fool the pedal position sensor so instead of the ECU only giving command to run the accelerator at 1/2 throttle, it will run at full throttle therefore achieving better response time.
Sounds simple enough, but I am not sure how effective it will be with the exy, although they do make one for us:
HERE is a video describing it.
Anyone come across it before and should we explore it a bit further?
Last edited by jalalski, 29/Mar/2008, 8:47 am
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29/Mar/2008, 8:44 am
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Re: Throttle Lag
Sounds ok, it's probably just a faster P&ID loop. I couldn't find the X-Trail in the compatibility list.... but it's pretty pricey. I hope there is a satisfaction guarantee!
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29/Mar/2008, 9:44 am
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Re: Throttle Lag
The UK site doesn't list the xtrail, but the manufacturer (Italian) site does. They're going from anywhere between 250-350 bucks per piece and I have no idea if it works with the exy. Would love to try one for sure.
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29/Mar/2008, 12:51 pm
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Re: Throttle Lag
I think it might work with cars that have a device where the throttle pedal measurement is digitised at the pedal and fed to the ECU. The Sprint thingy could conceivably digitise faster or add a bit of attack to rising values in certain situations, but even that seems a bit of a stretch!
The XTrail T30 series 1 and 2 both have an analogue measurement device at the pedal. It outputs two signals: one signal voltage rises as you press the pedal : one signal voltage falls as you press the pedal. This gives the ECU a double-check that the "pot" at the pedal is not faulty and giving an accurate reading. The analoge voltages are digitised in the ECU, all the secret Nissan stuff is done to with them and then the trottle plate moves if appropriate. And there's also the fact that some small cheap device is not going to be able to change these anologue signals from the pedal in some positive way - the signal from the pedal is raw and unadulterated. About all you could do is make things worse.
The movement of the trottle plate is double-checked by another dual pot in exactly the same way.
Yep, there's a lot happens in the ECU, and there's may be some scope for speeding things up, but we really can't tell! We can only assume that Nissan made the ECU with enough CPU power to handle it all.
In fact you can be assured of that:
Take for example the crank and cam sensors: The ECU adjusts oil pressure via a pulsed solenoid to the inlet cam timing mechanism and measures the timing of pulses from the cam sensor (it outputs 1 pulse for cylinder position 1, two pulses for cylinder position 2 etc) and also uses the crank sensor (many pulses per revolution, not sure if its something like 180 per rev) to determine if the cam timing has reached the desired value. There seems to be plenty of CPU power there as all this happens faster than most people would believe possible. In fact a person pressing down an accelerator pedal as hard and fast as they can takes an eternity in the computer scale of things, so there should easily be plenty of CPU power to process that.
Probably where the real scope for change come in is how the data is used to control the trottle plate, cam timing, fuel delivery etc. And I don't see us doing that very easily!
Curious effect of drive-by-wire I noticed while using the ELM323 and viewing some data in graph form:
1. You press the pedal 100% to the floor through every gear only lifting off for gear changes
2. In first gear the throttle plate only opens about 70% initially and opens more gradually up to about 80% as revs come up
3. As you go up gears (possibly the CPU detecting increased load on the engine as there is no gear position sensor in the manual) the throttle opens a little more and rises more with revs
4. so in the higher gears (say third) you're more likely to get 100% throttle opening when using 100% pedal than in the lower gears
Summing up, an interceptor at the pedal can't make the throttle plate open sooner or faster by my way of thinking, it would require feedback from the throttle plate position sensor. And the throttle plate opening is not entirely dependent on the pedal position. To do it properly you'd have to reprogram or entirely change the ECU.
It could however easily make things worse.
Although the apparent horsepower increase could be because of lightening of the hip pocket!
---
Shawn and Belinda Eggins
2003 STR, K&N, Strut brace, Ground wires, Dunlop LM702's, Tint, Mud flaps, Tow, Nudge, Spots, Mats, Rear scuff plate
http://eggins.synthasite.com/
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30/Mar/2008, 8:47 am
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Re: Throttle Lag
quote:
Eggins wrote:
Although the apparent horsepower increase could be because of lightening of the hip pocket!
The manufacturer is not claiming any horsepower increases as a result of this modification and I can't see where it would come from when all you're doing is enhancing the pedal response time.
I still wish to test it, but am not gonna part with 350 bucks to do the test, so I will try and find a local (Australian) distributor or stockist and see if I can test it on the exy.
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30/Mar/2008, 9:09 am
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Re: Throttle Lag
Sorry, I must have pulled that horespower bit from another post in this thread.
But still...
How can you improve the trottle response by changing the signal from the pedal? When you've already got it pushed to the floor or got it pushed down further than required because you want to accelerate? The pedal position is not the only thing involved in opening the throttle plate.
Just letting Jalal and everyone know I'm definitely not having a go at Jalal or anyone else, just raising some questions, debates, and putting my side forward.
Personally I think Jalal has already taken out a lot of the compromise that affects flat spots and throttle response - air intake and exhaust. These are things that the manufacturer can most easily compromise on and still produce "acceptable" performance, although maybe not perfect. He has been on the right track with his Cold Air Intake and super exhaust system.
I'd be interested to see what signals the piggy-back ECU of Jalal's reads and what signals it modifies.
---
Shawn and Belinda Eggins
2003 STR, K&N, Strut brace, Ground wires, Dunlop LM702's, Tint, Mud flaps, Tow, Nudge, Spots, Mats, Rear scuff plate
http://eggins.synthasite.com/
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30/Mar/2008, 9:31 am
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Re: Throttle Lag
quote:
Eggins wrote:
I'd be interested to see what signals the piggy-back ECU of Jalal's reads and what signals it modifies.
I have explained all this in the piggy back ECU report HERE
I haven't taken your post as having a go at me at all and that is the reason I put this subject here for discussion and exchange of ideas and opinions. There must be a reason for the manufacturer to design this gadget for the xtrail and I don't think they would give it a part number and specify the xtrail model in particular if they haven't done the testing and proved it to be working. I am coming across more and more reports which seem to be favorable of the immediate benefits of the sprint booster, but as with any other new gadget that I have come across, I would like to see that for myself before making the final decision about it.
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30/Mar/2008, 9:45 am
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Re: Throttle Lag
I'm sticking with the PID theory. Although I can't explain exactly how it works in basic terms, the best example to use is that of a cars' cruise control. Check it out here
All the sprint booster will do is take an input signal from the pedal adjust the gain and response of the signal, then output it to the ECU.
It doesn't matter whether the signal is digital or analog. It might convert it somewhere in the sprint device, but at the end of the day, whatever is fed into it, is fed back out in the same format - otherwise it just wouldn't work.
There's no doubt this sprint device will have some affect on your acceleration, its more 'how much' affect it will have and to justify that to the price you have to pay for it.
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30/Mar/2008, 10:22 am
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CervantesXavier
Date Registered: 04-2009
TOTAL POSTS: 7
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Re: Throttle Lag
Hey, speaking of reviving old threads... 
I just recently got my Exie, so I thought I'd check and see... it's an '06 auto, and when I floor the pedal, it takes a solid 2-3 seconds before my RPMs ramp up and it gets going. Is this normal for this car, or indicative of some sort of problem (that hopefully has a solution )
It's got about 50,000 km on it, I've put on about 20 of that in the 5 months I've had it, and as far as I recall it's always been that way. I don't know how the lady who had it before me treated it though...
Anyways, just wondering if anyone has this same issue. Thanks!
---
Edmonton, Alberta, Canada
(But an aussie at heart!)
2006 XTrail SE
Auto, Black. K&N, needing many more mods. ;)
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27/Apr/2009, 10:49 pm
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