Full Throttle Delay

[Bogie]

I've discovered at low RPM if I floor the accelerator (keeping in mind this is an electronic throttle) I will sometimes get a significant delay in acceleration and boost...like the computer is going "Damn....everything full power....engine..turbo..." and gets confused. It's almost like a FULL POWER command at low RPM isn't processed correctly. Or, it's possible the Traction Control is kicking in, but I don't get a TC message on the DIC.

If I give it 3/4 throttle and then take it to 100%, I get immediate response at 3/4 and take it to 100% without a problem.

Anyone else experience this?

[Celt03]

Yup - discovered that one pretty quick.
I had Saffy less than a week, when I punched it to avoid a semi trying to change lanes and I was where he wanted to go. Guess he did not see me even though I was doing right at the speed limit & he was going about 10 under - AND it was even a rare sunny day. .
Scared me a little that there was a slight delay for kicking in - so I played with it a bit & figured out how to handle it.

[WishfulThinking]

I wonder what type of throttle (pedal) position sensor it uses. If it is potentiometer-style, then they might have some filtering in the software to prevent accidental acceleration. (i.e. instant full-throttle might look like a potential electrical short.)

Just a thought.

[shabby]

At what rpm and in which gear is this happening?

[Bogie]

Originally Posted by shabby

At what rpm and in which gear is this happening?

I have an automatic, I would say I've experienced it in 1 through 4. Don't know the RPMs, but I believe they were on the low end for each gear in each case.

[Celt03]

I had dropped it into 4th gear - I have a manual.
Can't tell you the RPM - this all occured last August & I have not driven Saffy much during the last couple of months.

[California Skyway]

This is a really late reply...I just looked in on the site.
My manual Red Line pulls the same trick, and I have a theory that it's going overly rich...too much climate comp. It's especially pronounced when cold or when I've been stop and go. Immediately following, the engine runs rough (missing) until I get it over what would be the torque hump if it weren't direct injected. This idea fits with the fact that my tail pipes are sooty. I think the controler is supplying too much of a good thing (gas) in an overeager attempt to follow the command "GO VERY FAST". I also think the problem may be partly due to turbo lag when both gates first open. There's a fair amount of negative momentum that's inhibiting air flow rather than assisting it until those little props get twirling. At least that's my theory, and I'm sticking my foot in it.

[Bogie]

I've analyzed my problem a bit more, and I will actually get an RPM ramp up, a down shift, and turbo spin up (I'll have some good torque...for about 1 or 2 seconds)...the car is launching....and then....it's as if I pulled completely off the throttle...for about a second or two. And when this happens on the high side of the shift, I'm not just coasting over those two seconds but I'm getting trans braking. So I go from being pushed back in the seat on the launch to being pulled into the seat belt to the point my head tilts down...to getting slammed back in the seat once everything decides to go.

It's like full throttle for two seconds.....brake for a second or two.....then full throttle.

[sky 4 us]

I have a 2007 redline and have noticed the same effect and also the soot in the tail pipes. I have read that there is a fix at the dealer for this. they are putting hotter pluge in the 2008 cars and if you complain they are putting them in the 2007 redlines to cure some of this problem. I have yet to get mine back to the dealer to get these so I can't tell you if it helps for sure.

[mbeardsley]

Could the traction control be thinking it needs to do some braking to get you "under control" ?

Have you tried turning off the TC and see if it still happens ?

[Bogie]

Originally Posted by mbeardsley

Could the traction control be thinking it needs to do some braking to get you "under control" ?

Have you tried turning off the TC and see if it still happens ?

Haven't turned it off. If TC is kicking in, it should display on the DIC, right?

It might be a wastegate or a bypass sensor problem caused by the ECM commanded downshift. If the turbo is spooling up and then faced with a downshift, there might be some actuation of the wastegate and/or the bypass, which could be sensed by the ECM as an overboost, resulting in retarding of throttle. But I'm just grasping at straws here.

[lostcause]

It's not TC. I've had this happen to me with TC off. I'll start accelerating then suddenly it's as if I had taken my foot off the gas. Then in about 2 seconds it picks up again. Frustrating as hell. I'm not sure what it is.

[MidniteBlues]

Another minor problem I don't have with my oldie but goodie.. I stomp on mine it hauls ass, no hesitation, no BS until I let up on my foot.. Another minor issue looks like with the 2.0. Feeds it to much fuel all the time (soot), then when you want it, stomp on it WOT, it doesn't get enough fuel perhaps? Does this happen with updated, or tuned ECM's? I wonder..

[mbeardsley]

Originally Posted by Bogie

Haven't turned it off. If TC is kicking in, it should display on the DIC, right?

I'm not certain that the TC always displays a message. I suspect it only displays if it triggers for more than just a moment.

It seems that I get much better launches with it off, even though I don't normally see a message at launch when the TC is enabled. Though I only have my "butt-dyno" to judge that by, so I could be wrong.

[Nova-Exarch]

About the only time I get this is when I try to take off in too high of a gear after slowing down some.

I'll have to experiment some with varying levels of throtle.

Most of the time a quick down shift fixes the lag.

[lostcause]

Originally Posted by sky 4 us

I have a 2007 redline and have noticed the same effect and also the soot in the tail pipes. I have read that there is a fix at the dealer for this. they are putting hotter pluge in the 2008 cars and if you complain they are putting them in the 2007 redlines to cure some of this problem. I have yet to get mine back to the dealer to get these so I can't tell you if it helps for sure.

Any updates on this?

[Rob the Elder]

The way the motor is tuned, you are literally behind the power curve at RPMs below 2500. If you observe you can watch the boost curve on the DIC and feel it ramping up until you hit the magic RPM then the boost really kicks in. The little motor just will not pull tons of torque down low when the motor is not spinning up and the turbo is not able to blow much boost.

Its not a problem with the car, its the way its designed. Try keeping the revs at above 2700 when you start out and Oh yes try to keep the front end pointing forward. It is a real experience.

Its actually physics at work. With 2 liters available you can only do so much and the tuning puts the power at 2500 RPM

Both of my cars drive exactly the same, ok below 2500 - 2700 and Katie bar the door starting at 3000. No hesitation, no problems.

[Bogie]

Originally Posted by Rob the Elder

The way the motor is tuned, you are literally behind the power curve at RPMs below 2500. If you observe you can watch the boost curve on the DIC and feel it ramping up until you hit the magic RPM then the boost really kicks in. The little motor just will not pull tons of torque down low when the motor is not spinning up and the turbo is not able to blow much boost.

Its not a problem with the car, its the way its designed.

I'm not talking lag, or even slight hesitation. I'm talking about an engine reving up, boost building...acceleration kicking in....I'm feeling the g's pushing me back into seat, and then....nothing. ZERO torque....nothing from the engine...nothing from the boost....CLOSED throttle (even though I've got the accelerator floored). In fact, the transmission is still engaged, so I'm actually getting trans braking, and if the gear just dropped (I've got an auto) it can be a good bit of braking. And considering I was already pulling positive g's back into the seat, the trans braking flips me into negative g's enough to throw my torso against the seat belt and toss my head down. Then, about two seconds later everything lights up again, throwing me back into the seat..and off I go.

[kwayne]

Sounds to me like you hit the "REDLINE" sorry couldn't resist.
Seriously, what you describe is redline cutout; we lose ignition and fuel when you hit 6200rpm, so immediate no g's.
Listen for telltale backfire... then shift sooner.

[mbeardsley]

Nice idea, but he's got an automatic. So he's not shifting too late.

Unless of course that IS the problem and his auto is not shifting before he hits the cutoff...but that shouldn't ever happen.

[lostcause]

As mbeardsley said, it's an automatic. It happens exactly like bogie describes to my automatic too.

[mbeardsley]

I also have an automatic, but I've never seen this happen...though I don't really pound it that much, so maybe I've just never been in the right situation.

It would be interesting to see at what RPM this happens. Maybe it is hitting the redline before it shifts, or maybe the ECM THINKS it's hitting the redline when it hasn't yet.

I've never tried this, but what happens if you put it into neutral and floor the gas? Will the engine go to redline and then cutout?