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4K views 27 replies 14 participants last post by  trukk 
#1 ·
I've had my 06 V for a little more than a year now (!!!) and I've thought I sensed this on occasion but saw it for real the other day.

It only happens once in a blue moon, and when it does it's when I'm breaking. Tthe engine feels like it's still at 2k rpm when I'm in neutral or have the clutch in. The times when it's happened, I've looked at the tach and it's down around 1k, so I've thought "must be me".

Never having had a V8 before, let alone a 400hp beauty :bonkers: I thought "maybe that's just the way she rumbles, and I'm feeling things that aren't true.

But yesterday I thought I felt it and looked at the tach and - whoa - it was momentarily "hovering" at 2k with my clutch all the way in and my foot clear off the gas. It was only for a sec, maybe a little longer, then it continued it's usual drop down to 1k.

Is that normal? I was thinking maybe something isn't right with the throttle control (getting stuck?) but I've never felt it any time other than when braking/clutching, if the throttle control was going I'd expect something occasionally funny on acceleration too.

Comments/ideas/sanity-checks welcome!
 
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#2 ·
Mine has done this a few times too. Maybe not to 2K but 1500 for sure. Sometimes it just takes an extremely long time to rev down. Sorry I don't know why or how to fix it.

I do occaisonally get a little ping at WOT too. This is with the stock PCM.
(I need to send Rick the other one as his is pinging really bad.)
 
#3 ·
It could be a couple of things. First of all, when emissions controls hit hardcore, one of the things automakers tried to do was limit the number of scenarios in which excessively rich conditions could occur. One of those conditions that you'll sometimes see on carburated cars is that when you slam the butterflies closed, the mixture that had already made it through the venturiis is now in the intake (since all carburated cars are wet-intake) and is pushed into the system, but the air column that is usually pushing it along is cut off, so you get the wrong mixture of air and gas. It's not off by a ton, but it can be enough to cause a backfire due to excessive lean-ness or richness.
So what some automakers did (Ford on their EEC-IV applications) is turn off the injectors when the throttle is completely closed and you are above idle RPM. That was actually a pretty good approach because then if you were coasting down a hill, you'd literally be using zero gas. My C5 Vette did the same thing - when you were coasting down a hill in gear with the throttle closed, it would read "99mpg" on the DIC, which basically means "infinity", cuz you're using no gas.
For whatever reason when they tuned the V, they did it differently. Instead of shutting off the gas when you are coasting in gear with the throttle closed, they keep the throttle body cracked slightly, and actually keep the injectors firing as well.
I have no idea why they did this - makes no sense to me. They also tuned in some weird transitions in there. If you're ever coasting down a hill in gear with your foot off the throttle, listen to the engine and watch the instantaneous MPG readout as the engine slows down past 2700rpm or so. You'll hear a very pronounced difference in the engine note, and the milage displayed will drop down pretty miserably.
To me, that's a mistake in the tuning, and I suspect it's one of the thing Stealth-V tunes out when he does the tuning, but I don't know for sure because I have't had mine tuned yet. You *should* be able to close the throttle body and turn off the injectors when you're coasting down hill in gear, and it would significantly increase your milage. I live a really hilly part of Mass in Winchester, and i have to go down some pretty steep hills every day where i'm totally dragging the engine, and it always pisses me off to see the milage drop to 16mpg when I'm coasting down a hill off the throttle:tisk:, even if the burble from the Corsa exhaust is kinda cool. :thumbsup:
 
#5 · (Edited)
:yeah: I asked Brent at EPP why our engines took so long to get back to idle after you rev it, and he said it was in the tune, and you could get rid of it if you wanted. But supposedly it helps with emissions, and the chance of stalling.
Cuz when you hear an old muscle car with good compression rev up, it goes right back down to idle. I want that!
 
#4 ·
I am having the same issue now - I think I will have to add all my issues to the tune also. The issue of RPM hovering, bucking, rich fuel smell, gas mileage around 9 mpg around city and overall perf. Still battling with the local guy to help with the tune and maybe try to find a good tune in Va area.

Razl my car is 06 also and has the same problem and since I had my headers installed and a tune - The car has never run the way I think it should + with maggie.

MOD HELL - sometimes wish I never went down that slippery slope in today's economy :thepan:

Mick
 
#7 ·
My 'hovering' issue is when I'm coasting. If I bring it into neutral and have my foot off of all pedals, the car comes down from wherever it was cruising at, and often stops and hovers around 1500 RPM. If I push the clutch in, but leave it in neutral, and take my foot off the clutch (pump the clutch essentially), it drops back down to 900 or whatever. Just doesn't want to settle back at idle RPM unless I tell it to.
 
#8 · (Edited)
EXACT same thing here. My tuner doesn't know what it is and it is ANNOYING!!!! I'll be sitting in traffic going 1mph in 1st, engage the clutch and the rpms fly to 1.5k-2k until I come to a complete stop...then back down. :banghead:

Does anyone know how to stop this???? Is it a tuning issue? Mine didn't start doing this till I moved to Dallas. Then again, I hadn't modded the car until I moved to Dallas...hmmmm :hmm:
 
#9 ·
I would guess that all might have to do with some safety "feature". Newer saturns will engine brake with automatics to coast more safely, I'm thinking they might purposely not close the TB or let the injectors stop so there's more compression (if the TB is closed and injectors are shut off there's no, or at least significantly less, molecules to compress) so engine braking works better. And with the TB/Injectors open the rpm's wouldn't drop back to idle. I notice that a lot myself driving in the hills/mountains of new england, there's a huge hill every day I drive over to get to or from work, and every time I'm heading down it I'll shift a gear or two higher than normal because it engine brake's too much for me over 2krpm.
 
#10 ·
I would guess that all might have to do with some safety "feature". Newer saturns will engine brake with automatics to coast more safely, I'm thinking they might purposely not close the TB or let the injectors stop so there's more compression (if the TB is closed and injectors are shut off there's no, or at least significantly less, molecules to compress) so engine braking works better. And with the TB/Injectors open the rpm's wouldn't drop back to idle. I notice that a lot myself driving in the hills/mountains of new england, there's a huge hill every day I drive over to get to or from work, and every time I'm heading down it I'll shift a gear or two higher than normal because it engine brake's too much for me over 2krpm.
Uh... Isn't engine braking basically the pistons pulling against the vacuum in the cylinders because the throttle body is closed and there's no air charge in there? My V has less engine braking than any other car I've ever had, but I always thought it was a mix of the throttle being open and the car being really really heavy...
I guess to prove that engine braking is actually increased if you completely close the throttle body butterfly, you could start with your foot off the throttle complete when going down a hill, and then gradually add a bit of throttle. If you speed up at all (before you get to the RPM where the engine is turning at the same speed as the transmission input shaft) then it's the throttle being *closed* that is causing the engine braking, not the throttle being *open*.
 
#12 ·
Yeah, I think Jake's work by engaging the exhaust valves through another cam or something to release the air in the cylinder as it approaches TDC so it doesn't act like a spring and force the piston back down.
Or something. :)
I think Jakes are necessary because deisels don't have throttle bodies, so never really have vacuum in their intake manifolds like we do.
 
#13 ·
This is in the tune and I forget what they call it, my tuner told me once. I think it's a Cadillac thing because I have run many HPDE's with my Corvette and the CTS-V. This is especially noticeaable when I brake, and downshift going into a turn. The corvette doesn't hang, the CTS-V will stay at a higher RPM for a second or so, scared the hell out of me the first time I had the V on the track.
 
#18 ·
Hey guys.

The PCM has to see 0 miles per hour before the idle circuit/alogrithem kicks in fully.

That's why you will notice the rpm "drop" when the car comes to a halt.

This has been explained before.....
Hey Heavy - what's the change around 2700rpm?

As the car decelerates under engine braking, the exhaust stops popping around 2700rpm like it's going from stoich to lean or something. Any idea what that is?? (Obviously I haven't spent the money for tuning software or I could find out myself...)
 
#19 ·
Change occurs under 1200-1500 (I believe).

I have my idle reset (Stealth tune) to 700 rpms.

Mine drops from about 1000 to 700 when I come to "0" on the MPH readout.

I also had the "burble and pop" turned off (again via Stealth tune) so the car sounds like a slot car when you let off the gas/decelerate, which I kind of like on the Cad, but not on Mr. Vette.
 
#21 ·
I am having the same issue with my '06 and are wondering if anyone knows of a tuner in Northern Cal that is good with the V's. My idle hovering/surging is so bad it has finally triggered the check engine light so it's off the St. Claire on Monday but I think they have to stay with the stock tuning.
 
#22 ·
I have the same issue thought it was part of the tune since I have a cam + maggie, Car has stalled a couple times on HARD turns (at slow speeds) with clutch in. I just mash the brakes or pop the clutch to start the car again. I find the 2k idle while coasting real annoying as I am use to coasting down the road to save mpg. I noticed the issue is not nearly as common after I reach operating temps.

With the aggressive cam profile I fear removing this higher idle will cause more frequent stalling and another reason I have avoided the lighter flywheel (though I would love to add one) Only one way to find out though.....
 
#23 ·
I dont dare leave my neighborhood if my car is still cold. Pulling out into traffic would be suicide with my Maggie/Z06 Flywheel combination if it isnt warmed up. I have to push the clutch in, jam the gas and ride the clutch out to keep it from stalling but after only a couple minutes at idle it runs fine.

I think the heavy stock flywheel may be part of the hangup at 2K, I will try to pay more attention to mine.
 
#25 ·
Once the weather dropped into the 50s my car didnt like to run from a start. I let it sit for 4-5 minutes and its all good. Ill try to pay attention to coolant and oil temps this week.

I have never noticed the RPMs hanging up but this is also the first manual I have owned in about 12 years.
 
#26 ·
bpitas said:
Also, the way it revs now makes it pretty hard to do rev-matched downshifts. When I first got the car I couldn't figure out why I could never do a smooth rev-matched downshift until I realized it was because the car stays at high rpm way too long.
It just takes practice. I rev match all day everyday.

-Chris

P.S. My car has the 2k rpm hang as well :(
 
#27 ·
It just takes practice. I rev match all day everyday.

-Chris

P.S. My car has the 2k rpm hang as well :(
Yeah, me too - I never really use the brakes until I'm down into first gear, it just took me a while to figure out why I wasn't doing it smoothly. The cars I had before the V (WRX and C5) both revved much more freely so I kinda had to re-learn how to do it I guess.
Can't wait to get the lightweight flywheel in though - then I'll have to re-learn it again!
 
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