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Discussion Starter #1
This is the second time I've experienced this. Same circumstances, same hill, same part of the day, same temperature outside. But only twice out of the month I've owned it commuting on the same road daily.

I have no experience with turbo cars, so I don't know if this is what is called "lag".

Manual transmission, 90 degrees Fahrenheit, about 6pm, sunny, low humidity, uphill about a 6% grade, about 2 miles from starting the car, 60 miles per hour speed limit, car is using 91 octane, about 1500 miles on the odo.

Typically I leave work, hop on the bypass and set the cruise to 62mph. About 2 miles down the road as the grade is increasing I need to shift into second as the rpms are dropping fast. I shift into 5th and flip the cruise back on and keep heading up the remaining 3 miles of uphill until I head down the other side of the mountain. Once the car hits 5th, it maintains speed going up the hill at 63.

Today, and this was the second time, I shift into 5th and the car keeps decelerating as if it is losing power. Revs drop to about 1600 so I shift to 4th. WOT. Revs pop up to about 2k, then continue to drop. I am now at about 45mph when I shift into 3rd. Now the car finally wakes up and I start to accelerate back up to the actual speed limit.

Both times that this happened I was not using the cruise control. This is a 1% instance that I am not using the cruise while commuting. I am not sure if that has anything to do with the issue, but should be mentioned in the parameter set.

What the heck is going on? I feel like I should be taking it back to Chevy since it has only happened twice since I've had the car. It is obviously not a problem with the road since I commute this same section daily. It is something going on with the car. Problem is, again as it has only happened twice and it is a specific set of circumstances, I know I'll take the car in and they will not be able to recreate it. Then they'll tell me nothing is wrong. It has been hotter than this in the past, so I have a hard time believing it is the heat, but it does feel like the car is pulling timing. But again, I don't know if I am just hitting the specific instance of where the lag is on the turbo?
 

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I have the same problem with a hill in my town...car doesn't have enough balls to make it up the hill...just shift it into 3rd everytime and I bet you never see the problem return
 

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:sigh:

Ditto. I have a hill like that during my commute 5th and 6th being overdrives, it just doesn't have the power at 60, have to set the cruise at 65 or 70 to maintain enough power up the hill and stay in 6th.

If I remember correctly, the turbo (just forces more gas and air into the engine) kicks in around 1850 rpm. My general impression is don't expect power unless the rpms are above 2k.

Sadly the price we pay for the fuel economy. Too bad there couldn't be another couple cylinders that only engage (not rotating thus not even dragging the engine when not in use) when the pedals 3/4th of the way to the floor thus giving a tiered horsepower and yet maintaining otherwise miserly gas consumption.
 

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60ish and in 6th your in the wrong gear to start with

If i'm sub 60, 5th is rarely used. The car just isn't asking for it, thats about 4th gear range. 6th gear is 70+ mph only gear unless your sporting a trifecta tune. THEN you can use 6th in the situation your talking about.
 

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60ish and in 6th your in the wrong gear to start with

If i'm sub 60, 5th is rarely used. The car just isn't asking for it, thats about 4th gear range. 6th gear is 70+ mph only gear unless your sporting a trifecta tune. THEN you can use 6th in the situation your talking about.
A lot of guys go into 6th around 40mph, if it's flat... I tried it after reading on here, and mileage is through the roof, but of course, you have to downshift if there is a hill or you need to speed up...

Driving normally, I'm usually in 5th above 40, and am in 6th above 60...

Having said that, if there's a steep hill, I will downshift to 5th or 4th at that speed, to use the turbo...

Doesn't make sense that OP would have to be in 3rd gear to get up a 6% grade at 60mph, though... 4th gear is the lowest I could see that that speed, because that's, what? 3000rpm or something in 4th?

ETA: wait... OP was down to 45 when shifting to 3rd... Sounds like you're letting it get down too far before you downshift, then because you let it get down so far, the gear you downshift to is doing the same thing as the gear you just came from...

But it normally pulls this hill in 6th just fine, but you had to go down to 3rd a couple times?

Mike
 

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Discussion Starter #7
Normally if I get out of flat land, I watch it until it gets to right around 2k before I shift. I will let it cruise down a flat section of road below 2k, but if I know it is getting hilly I'll shift to 5th which is usually all that is necessary. It was at 2k when I shifted to 5th, and still around there when I shifted to 4th, and still there when I finally hit 3rd.

Normally the car will pull just a tad at 2k, nothing extraordinary, but just a tad.

And to the guy saying "What do you expect?" I expect to not be required to shift into 3rd going up a 6% grade. I don't care if it's a 4000 lb car with 140 hp. My Focus was 130hp in stock config weighing 2700 pounds and I was able to take this hill in 5th during my every day commute for 3 years. This is not normal, since as I stated, I usually hit this hill in 5th with no problem so they are isolated instances.

:)
 

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I agree with what the guys are saying. You need to get the RPM further up in the cars power band. Try keeping the RPM around 3 - 4K when going up hills. Otherwise, you're putting too much load on the engine and it wont pull the 3000# car up a hill.
 

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60ish and in 6th your in the wrong gear to start with

If i'm sub 60, 5th is rarely used. The car just isn't asking for it, thats about 4th gear range. 6th gear is 70+ mph only gear unless your sporting a trifecta tune. THEN you can use 6th in the situation your talking about.
And based on your diving habits your avg mpg would be.................?????
 

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60ish and in 6th your in the wrong gear to start with

If i'm sub 60, 5th is rarely used. The car just isn't asking for it, thats about 4th gear range. 6th gear is 70+ mph only gear unless your sporting a trifecta tune. THEN you can use 6th in the situation your talking about.
This is ridiculous. 6th gear is for any speed over 40 where its not dogging the engine, especially on flatish surfaces. I would never be in 5th above 50 unless I was taking hills greater than a 3% grade or accelerating and that is without a tune.

Now if I had to pass I would downshift, but with the exception of that I am in 6th gear when driving at least 70% of the time. Of course I like getting 40mpg city as well.

As to the OP, this actually sounds like the cruise control is not reengaging. I have noticed since I upgraded the CRuze steering wheel for cruise control over the aftermarket that some times it just doesn't engage and continues to slow down. I actually think the wheel cruise control is the most poorly made part of this car.
 

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As to the OP, this actually sounds like the cruise control is not reengaging. I have noticed since I upgraded the CRuze steering wheel for cruise control over the aftermarket that some times it just doesn't engage and continues to slow down. I actually think the wheel cruise control is the most poorly made part of this car.
FWIW, this was happening when he was not using cruise control, and was WOT...

Mike
 

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FWIW, this was happening when he was not using cruise control, and was WOT...

Mike
I misunderstood it, I understood he stopped using it as he shifted though gears.

That being said, I have found if you start losing power going up a hill, especially a steep one, you have to downshift even more than if you had been maintaining speed.

Seeing that it rarely happens I am more likely to think the operators slight variances in manually accelerating are what is causing this to happen. He isn't giving it as much gas when shifting or while in 6th as the cruise control is, the engine isn't spooled, and it starts a slowdown cycle that takes him to 3rd gear before he can snap out of it because he is constantly playing catchup.
 

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I misunderstood it, I understood he stopped using it as he shifted though gears.

That being said, I have found if you start losing power going up a hill, especially a steep one, you have to downshift even more than if you had been maintaining speed.

Seeing that it rarely happens I am more likely to think the operators slight variances in manually accelerating are what is causing this to happen. He isn't giving it as much gas when shifting or while in 6th as the cruise control is, the engine isn't spooled, and it starts a slowdown cycle that takes him to 3rd gear before he can snap out of it because he is constantly playing catchup.
Yep...

Mike
 

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And based on your diving habits your avg mpg would be.................?????
That's what I was thinking. I'll engage in 6th as low as 32 MPH. If I need power to accelerate, I'll down shift. I like to keep my RPMs around 2K or below for gas savings.
 

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Discussion Starter #15
Seeing that it rarely happens I am more likely to think the operators slight variances in manually accelerating are what is causing this to happen. He isn't giving it as much gas when shifting or while in 6th as the cruise control is, the engine isn't spooled, and it starts a slowdown cycle that takes him to 3rd gear before he can snap out of it because he is constantly playing catchup.

This is highly probable. As a slight refresh, I only have noticed the problem when I am not using the cruise. I'm going to drive this hill in full manual mode a few more times and see if it is strictly related to not using the cruise. If so, then there is something I am doing as the operator. Your explanation makes quite a bit of sense and is sort of what I was wondering. I know with the NA cars I've had, it was just push the pedal and go. But adapting to a new power band is taking me a bit.

I'll give it a few more shots without the cruise control on and see if I can get it to occur again. :)
 

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Same thing happens to me daily, I have some very steep hills around me, thus I'm only getting 37.1 on my ECO right now. But I've also decided babying it around everywhere just wasn't worth the extra 3 mpg I was getting.

According to GM, they've calibrated the ECOs (not sure if manual only or what - I think it is) to delay peak boost. I believe this was for two reasons (at least on the manual).

#1 Keeping out of boost at lower RPM will improve fuel economy (this is the primary reason)

#2 (speculation) At a very low RPM with a manual it's actually possible to get real compressor surge. Wide throttle angles, in a high gear, going up over a grade causes my car to surge, both in feeling and on the compressor. I believe the surging is an attempt to limit boost. Several times now I've been able to get the bypass valve to flutter at like 85% throttle and above at very low rpms 1500-1800. It's a very obvious noise coming right from that ole turbocharger.

only we have an internally bypassed turbo so I could hear that flap open and slam shut in a very rythmic somehwat fast paced repetition.
 

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Quazar

I actually think the wheel cruise control is the most poorly made part of this car.
As the wheel controls are only switches that feed information onto the CANBUS what else could be done to make them better?
 

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I get 52mpg 90% of the time, 6th gear is good at 40mph under lite load.I have a vacuum/boost gauge and watch what is happening with loads. Below 2000 rpm boost does not help much and wastes fuel. You have to get the engine reving to enjoy the benefits of the turbo. I have seen 15 psi out of the turbo before the waste gate opens. The surge you are feeling is the waste gate opening and closing, limiting the boost. I pull a mile long hill and try and hold the boost at 5psi in third gear, I still can increase speed, but slowly as the boost climbs to 10psi+. I have found that if I use second gear and stay out of boost, I can gain 3-4 mpg up the same hill.
So guys if you want power keep the rpm well over 2000 and let the turbo work for you. BTW I set my cruise on 60mph and hit a hill, it just kept slowing down by itself because the turbo could not handle the load and gear of the incline, the cruise finally kicked off and I had to downshift and boost to continue.
 

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That's what I was thinking. I'll engage in 6th as low as 32 MPH. If I need power to accelerate, I'll down shift. I like to keep my RPMs around 2K or below for gas savings.
X2! (Fuelly to show it works!)

Sounds like some are revving the piss out of these....
 
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