# rpm drop while accelerating in 2nd gear.



## Robby (Mar 1, 2013)

edlloyd said:


> hello all. i have asked this on the facebook cruzetalk page, but just wanted to get opinions of you on here that don't get on that page. new 14 cruze ls auto. noticing a weird acceleration issue. start out and it shifts from 1st to 2nd fine. while in 2nd and still accelerating, the rpm drops a few hundred rpm momentarily then jumps back up. it almost feels like it is shifting again, but is still in 2nd. it is much more noticeable while going up a steep hill or while accelerating hard. i have been told that it is the torque converter locking and unlocking but it just doesn't seem normal to me. any thoughts?


Current mileage please?

Rob


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## spacedout (Dec 7, 2010)

Though the torque converter can lock/unlock on hill grades I wonder if your seeing the ECU detuning the engine when knock is detected? What octane fuel are you running? If your running 87 octane regular might try 89 octane midgrade to see if this behavior disappears. 

The reason I would suspect the fuel/octane being the issue is since your noticing it on hills, not just under normal acceleration. Hills add a significant load to the engine, especially when accelerating.


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## edlloyd (Nov 25, 2014)

2000 miles. i see what you mean on the octane thing, but it ONLY happens in 2nd gear.


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## Robby (Mar 1, 2013)

OK....still a youngster mileage wise.

I doubt if torque converter.....it is designed to lockup in 3rd, at shift, if at light throttle......none of which describes your observation.

This type of concern has not, in my memory, ever been posted.
At this time, I will WAG that the air control valve in the intake manifold is misbehaving.....possibly opening too much momentarily causing a torque/power drop off.

Usually sets a code but if the valve is responding to command, the ECM is satisfied.

Soooo, if you feel slightly mechanical, remove the negative battery cable to erase most of the ECM memory.
Reconnect and give it a few hundred miles of normal driving......it may just be a fluke that keeps repeating itself because it is being held in the memory.

Try it......can't hurt a thing......unless you just hate resetting clocks and radio presets.

Rob


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## edlloyd (Nov 25, 2014)

strange that it only happens in 2nd gear though. acceleration in all other gears is perfectly normal. and if i am on level road, there is no drop in acceleration. seem like only when there is a load on the engine. if it is a slight uphill it will drop barely 50 rpm. a steep upgrade it drops 300+ rpm and the steeper the grade the longer delay till it jumps back up


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## spacedout (Dec 7, 2010)

edlloyd said:


> strange that it only happens in 2nd gear though. acceleration in all other gears is perfectly normal. and if i am on level road, there is no drop in acceleration. seem like only when there is a load on the engine. if it is a slight uphill it will drop barely 50 rpm. a steep upgrade it drops 300+ rpm and the steeper the grade the longer delay till it jumps back up


You never did mention what octane you are running? Really doesn't matter if it only happens in one gear, that just happens to be the right amount of load for the given RPM to cause some engine knock. Using the torque app and a OBDII bluetooth dongle I register knock exactly when I see the drop an RPM as you describe. Higher octane even mid-grade makes the engine much less prone to this occurring, with premium I never see these RPM drops anymore. 

This is also why I will never buy less than midgrade for my car, and if above 80F outside nothing less than premium.


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## edlloyd (Nov 25, 2014)

i have been running 87. and here is something really strange. it happens when it is in normal automatic mode. if i put it in manumatic and shift, it does not do it. weird, huh?


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## spacedout (Dec 7, 2010)

edlloyd said:


> i have been running 87. and here is something really strange. it happens when it is in normal automatic mode. if i put it in manumatic and shift, it does not do it. weird, huh?


I'm going to assume the reason you aren't seeing it in manual mode is because you can use as much throttle as you want without causing a downshift, so in D your probably easier on the pedal, on hills causing more load at a lower RPM with less throttle open. 

I would say switch to midgrade or better yet premium & I suspect you will no longer have this issue on hills. I live in a very hilly area of SW Wisconsin and dealt with this behavior allot before when I wasn't consistently using higher octane fuel. Remember these engines are actually designed to run premium, GM just lets the ECU detune itself to allow use of regular fuel. 

The way this works is when running regular 87 octane gas the engine rely's heavily on the knock sensor to save the engine from harm. Any time the ECU detects knock it will dial back the power(the RPM drop you have noticed). My car its a night and day difference the power I have in hills with 91-93 octane premium vs regular 87.


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## LulzT1 (Aug 24, 2015)

Gonna bump this thread.. I'm experiencing the same exact thing. Last time the car went in for service, the tech said my P2002 issue was compounded with this and that everything is fixed (replaced cat converter). Go out of the parking lot and issue still persists..

2014 Cruze Diesel, 19k miles on the clock. Issue has occurred since day one.

I'm skeptical of the octane thing. If the car is sensing knock, it will retard timing which will give you a less powerful explosion for the power stroke. I don't think that would cause a direct drop in rpm. Also, I'm experiencing this with a diesel, not gas.

To the OP, have you had any resolve? I think I'll post a video later.


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## obermd (Mar 3, 2012)

edlloyd said:


> i have been running 87. and here is something really strange. it happens when it is in normal automatic mode. if i put it in manumatic and shift, it does not do it. weird, huh?


What RPMs are you seeing this at?


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## jblackburn (Apr 14, 2012)

Some Fords lock up the torque converter in 2nd gear. Not enough experience with the Cruze automatic to say, but that's what it sounds like. Looks almost like a gearshift, but it's not.

Our Toyota will occasionally lock/unlock the torque converter between 2nd-3rd.


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## obermd (Mar 3, 2012)

I'm thinking possible spark blowout on one cylinder. This is why I asked about the RPM. I know when my ECO MT starts having spark blowout I can see very small dips (~50 RPM) on the tach.


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## LulzT1 (Aug 24, 2015)

I have no spark and I'm still getting the same symptoms.


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## obermd (Mar 3, 2012)

LulzT1 said:


> I have no spark and I'm still getting the same symptoms.


The CTD also has a different transmission. The solution for OP may or may not work for you as a result.


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## LulzT1 (Aug 24, 2015)

obermd said:


> LulzT1 said:
> 
> 
> > I have no spark and I'm still getting the same symptoms.
> ...


I am aware, could be two different things. However, the description sounds exactly like what I am experiencing, so it could be a common link, too.

I think a single cylinder misfiring would be very obvious. Atleast when I burned a plug wire you knew it, then again that's a "V" motor so one cylinder out of balance is obvious. In my case, you're still accelerating but you see and hear the drop and it's only ever in 2nd under the same conditions.

Seems like we are the only two with this problem?


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## obermd (Mar 3, 2012)

LulzT1 said:


> I am aware, could be two different things. However, the description sounds exactly like what I am experiencing, so it could be a common link, too.


Definitely a possibility.



LulzT1 said:


> I think a single cylinder misfiring would be very obvious. Atleast when I burned a plug wire you knew it, then again that's a "V" motor so one cylinder out of balance is obvious. In my case, you're still accelerating but you see and hear the drop and it's only ever in 2nd under the same conditions.
> 
> Seems like we are the only two with this problem?


All the other gas Cruzen that have reported this type of issue have been spark blowout due to too much gap in the plugs. But when this happens it's in all gears, not just second.


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