Newbie

[chevybb2005]

Hello All new to the Colbalt scene having problems with the car heres the lay out has a 2005 ls colbalt auto with AEM instake with dry filter and mega flow full catback exhaust with 57K on the car with 18s not lowered.

The problem started a few weeks back after putting octane 91 in the car for the first time gave it some gas coming out of the gas station to beat the on coming traffic was kinda a slopping curve wheel chripped a little bit and then around 4k the car went in engine reduce power mode and was bogging bad drove a little while down the road so I could pull of to the side the engine check light came on as well as the T/C traction control light. Let the car sit for a while and it ran fine with the engine check light still on and the TC light went on to autozone to get the codes. when they ran the codes game me a P0068 and a P0105 and a traction control malfunction code which I didn't get. had the traction control code cleared wanted to see if it would pop back up later. So I took it easy on the car and been putting octane 89 in the car since. Every so often when Im at a dead stop and it to test it out when it hits 4K the car boggs aganing and engine reduce power light signal comes on as well as the engine check light and the T/C let the car sit starts up fine the T/C light go out put the engine check light stays on when I get it checked out same code P0068(Throttle position and engine load do not agree) and P0105 MaP(Man. absolute Pressure)/ Baro or Maf/VAF(Vane Air Flow) sensor condition. Did a through cleaning of the Air Filter and dried it with a blower dryer and let it sit reinstalled and later same issue. Only does it from a dead pull when rolling around 4k doesn't do it at all or when I was caught in a dirt patch was able to get it all the was to around 6k before the car pulled out any idea what could be causing the problem

 

[Florida 76]

91 octane is not ment to go in a LS.. only use 87

 

[BankDude]

yea your car might be bogging because you're not tuned for a higher octane and your flooding the crap out of it when your MAF doesn't know what's happening. put 87 back in and beat the crap out of the car for a half a tank or so. or you could try some seafoam too

 

[chevybb2005]

Thanks I'll give that a try figure the higher octane would give better performance with the setup I have I'll give it a try since it will save me money at the tank anyway just weird how higher octane would cause the problem I do here a little value ticking as well

 

[YelloEye]

91 octane is not ment to go in a LS.. only use 87

that's like saying that your body isn't meant to drink purified water, just drink the stuff out of the tap.

Effects of octane rating

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Higher octane ratings correlate to higher activation energies: This being the amount of applied energy required to initiate combustion. Since higher octane fuels have higher activation energy requirements, it is less likely that a given compression will cause uncontrolled ignition, otherwise known as autoignition or detonation.

It might seem odd that fuels with higher octane ratings are used in more powerful engines, since such fuels ignite less easily. However, detonation is undesirable in a spark ignition engine, and is signified by audible "pinging" or in more extreme cases "knock".

A fuel with a higher octane rating can be burnt in an engine with a high compression ratio without causing detonation, as such fuels are less prone to detonation. Compression is directly related to power and to thermodynamic efficiency (see engine tuning), so engines that require a higher octane fuel usually develop more motive power and therefore do more work in relation to the calorific value of the fuel (BTU) being used. Power output is a function of the properties of the fuel used, as well as the design of the engine itself, and is related to octane rating of the fuel. Power is limited by the maximum amount of fuel-air mixture that can be brought into the combustion chamber. When the throttle is partly open, only a small fraction of the total available power is produced because the manifold is operating at pressures far below that of the external atmosphere (depression). In this case, the octane requirement is far lower than when the throttle is opened fully and the manifold pressure increases to almost that of the external atmosphere, or higher in the case of forced induction engines (See supercharged or turbocharged engines).

Many high-performance engines are designed to operate with a high maximum compression, and thus demand fuels of higher octane. A common misconception is that power output or fuel efficiency can be improved by burning fuel of higher octane than that specified by the engine manufacturer. The power output of an engine depends in part on the energy density of the fuel being burnt. Fuels of different octane ratings may have similar densities, but because switching to a higher octane fuel does not add more hydrocarbon content or oxygen, the engine cannot develop more power.

However, burning fuel with a lower octane rating than that for which the engine is designed often results in a reduction of power output and efficiency. Many modern engines are equipped with a knock sensor (a small piezoelectric microphone), which sends a signal to the engine control unit, which in turn retards the ignition timing when detonation is detected. Retarding the ignition timing reduces the tendency of the fuel-air mixture to detonate, but also reduces power output and fuel efficiency. Because of this, under conditions of high load and high temperature, a given engine may have a more consistent power output with a higher octane fuel, as such fuels are less prone to detonation.

 

[chevybb2005]

Well I guess that would rule out the issue with higher octane gas with my setup like I thought after reading that and thanks for providing the info on higher octane gas ratings but still no idea what is causing my problem from a dead launch and the car hitting 4k in first year and going into limp mode and throwing those codes listed above because that is the only time it does it trying to get an idea before I start replacing the MAF and the Barometer

 

[YelloEye]

You mean p0106? I don't show a p0105 in the service books. Chances are your map sensor is dead.

 

[chevybb2005]

maybe that's the print out they gave me from auto zone but it describes the same thing "MAP/Baro or MAF sensor condition. if its my Map was dead would it cause the issue across the whole range besides just from a dead launch in first up to 4k with the pedal to the floor and slow rolling in first doesn't cause the problem. but I'll do some more test on pulls and any way I can test the map senor to see it its wrong or if its an issue with MAF

 

[YelloEye]

maybe that's the print out they gave me from auto zone but it describes the same thing "MAP/Baro or MAF sensor condition. if its my Map was dead would it cause the issue across the whole range besides just from a dead launch in first up to 4k with the pedal to the floor and slow rolling in first doesn't cause the problem. but I'll do some more test on pulls and any way I can test the map senor to see it its wrong or if its an issue with MAF

Nothing should be just 1st gear unless it's the ecu. I'll have to look at the diag process from the service manual.

 

[wardzach2007]

Nothing should be just 1st gear unless it's the ecu. I'll have to look at the diag process from the service manual.

Look at him getting all nerdy and stuff