Engine light came on, it shut down to 4 cylinders, message read reduced power. i got fuel at a place i regularly dont get fuel at. so i went and put 30 dollars worth of good fuel on top of that and the ligjht cleared and it ran great. 2003 chvy suburban. it did not get hot , checked fuel cap to make sure it was on good,could have been bad gas, 4 or 5 days later the engine light came on again and read reduced power down to 4 cylinders turned it off and checked everything again but didnt find anything .started it back up about 5 minute later and light cleared and ran fine but still sluggish at take off .the last month or so when starting it would turn over real slow so i put in new battery, the other battery was 6 1/2 yrs old. had it put on computer scan showed nothing. it hasnt happened again since i put in new battery but when i first start it up and put it in reverse it seems sluggish but the computer scan shows nothing and it is still doing it. can you pleas help me ? should i put some kind of a fuel additive in it?
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The reduced power light is most likely responsible for the stabilitrack light to illuminate as it will shut it down as a safety feature. The reduced engine power light is normally set by a defective throttle control motor. In some cases, the sensor on the gas pedal can also cause this message to display, but, in my experience, the throttle control motor is most likely the problem.
Are you sure it's actually a plug?
Are you getting oil on the plug?
The plug may be firing but you may be losing compression which gives the symptoms of a misfire. As you've changed the plug, lead and coil this points to to a problem elsewhere.
Your first course of action should be to get a mobile mechanic carry out a diagnostic check for you.
To put your mind at rest, do a 2nd compression test using a light oil squirted into the bores:
Doing a Compression Test
Warm the engine. Remove all the spark plugs.
Get a pencil and piece of paper to note down the readings.
Put the compression tester into the No1 cylinder and crank the engine for 10 seconds.
Note down the compression reading.
Repeat process for all cylinders.
Here's an illustration of what you may expect on a 4 cylinder engine:
Cylinder 1 2 3 4 psi 125 122 120 124
125 is the uppermost figure for that engine. Here, this engine is fine. There's a slight variation in psi figures, but that's perfectly normal.
Here's the same engine:
Cylinder 1 2 3 4 psi 110 112 114 112
The psi reading is down. However, as all the figures are pretty much equal it doesn't indicate head /gasket problems. It may point towards worn pistons or burnt valves.
Now consider these psi readings:
Cylinder 1 2 3 4 psi 125 84 86 124
There's more than a 10% drop - a difference - between cylinder 1 and 2, and cylinders 3 and 4.
The compression readings for cylinders 2 and 3 is down; low. There's something clearly wrong.
It suggests that there is a defective head gasket between cylinders 2 and 3 or a crack in the cylinder head. The rising piston compresses the gases which escape into the adjoining cylinder via the defective gasket or cracked head.
However, it could also mean that there is a problem with the valves (burnt/not seating properly) or perhaps piston / ring problems.
A burnt valve - it's usually the exhaust valve as they bear the brunt of the combustion - can cause a reduction in engine power simply because the combustion process isn't occurring properly. Compressed air/fuel gets squeezed out of that cylinder because of the damaged valve . There even may be a misfire - a surge as the car runs.
Worn or broken piston rings allow compressed gases to leak past into the crankcase. A compressed crankcase can force oil out of the dipstick tube. The pressure in the crankcase will leak to atmosphere anywhere it can find an outlet.
The 2nd Compression Test
The second compression test is known as a 'wet test'. The first compression test was the dry test because no oil was added to the bores. The second 'wet' test can give an indication of whether it is the rings or valves at fault (though bear in mind rings and valves do not cause overheating or water in the coolant symptoms).
Spray a liberal amount of light penetrating oil into each cylinder - aim for the cylinder walls, not the centre of the piston. You want the oil to run down the cylinder wall and around the piston to form a seal.
Place a rag over each spark plug hole and spin the engine to eject the surplus oil.
Then carry out a full compression test noting down the results.
Here's the previous results with the 2nd compression readings added:
Cylinder 1 2 3 4 psi 125 84 86 124 Wet 128 112 110 126
The readings have increased. This because the oil sprayed into the bores has formed a temporary seal around the piston, thereby enabling the compression to be raised. It also indicates that the bores/rings are worn on cylinder 2 and 3 - the 'oil seal' has increased the readings but is still low in comparison with cylinders 1 and 2.
This could also indicate that in addition to worn rings there is also burnt valves. Oil cannot form a seal around a valve. A worn or split valve will cause a low compression reading and misfiring symptoms.
Compressions readings should be taken in conjunction with other symptoms. It will help you identify the problem:
Low compression readings between two adjoining cylinders point towards a head gasket/head fault if your vehicle has shown signs of coolant loss, coolant in the oil system - mayonnaise, overheating, rough running and lack of power.
If those symptoms are not present it points towards burnt valves/piston rings. A worn engine may be difficult to start and pressurise the crankcase, but it doesn't cause overheating problems.
Jerry, Drive to a good shop. So many things can cause reduced power light unfortunately. The first step would be to get the truck hooked up to a scanner/computer and have the computer scanned for trouble codes. One thing that you could try is to drain the water from the water separator that is mounted on the frame under drivers front door. If the PCM picks up on water, power is reduced until water is removed/drained. It could be an exhaust sensor that is reading faulty. Unfortunately from here its impossible to tell you exactly what the fault is because there are just so many engine sensor inputs that could cause your problem. Check the attached links, forums,instruction and guides, Good luck
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engine power reduced means that the CPU has placed the ECM in a safe operating mode and reduced power to lessen the risk of serious engine / transmission damage. Stop and check oil level and coolant level at the radiator cap. have the fault codes read urgently so as to prevent damage to the units
Some or most cases the throttle body has a air charge temp sensor built on it or your throttle positioning sensor is going bad. Most engines that size operating oil psi is 40to 60 depending on the type and weight.
GM's power strategy will reduce power if it doesn't see proper charging. It does this to conserve battery power by shutting off non-essential electrical accessories. It can also mean that the traction control system is reducing engine power to avoid a skid. The traction control system gets input data from the wheel speed sensors to figure out if you're entering a skid or the wheels are locking up. One way to get you out of the skid is to reduce engine power or pump your ABS brakes. In your case you should get the trouble codes read. An ABS or traction code code could be a C, U or B code which can't be seen by a cheap scan tool or the tools they use at auto parts stores. GM had major problems with the ABS wheel speed sensors built into the wheel bearing hubs in these vehicles. The fix involved replacing the hub. So get the codes read by a pro scanner to find out which wheel sensor is setting the code. Then do the fix. Also, the P0128 is usually caused by a bad thermostat. Fix that first, because if the engine doesn't get up to operating temperature, the computer can limit some features.
Read these posts for more trouble code information http://ricksfreeautorepairadvice.com/p0128/
Only way to be sure what is wrong is to have the computer scanned with a code reader or scanner to retrieve the trouble codes. They will direct you or a technician to the proper sensor, control, or circuit that is malfunctioning. Many national parts stores provide code reading for free.