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Reduced engine power in 2003 Suburban


military_deployed
06-17-2007, 07:10 AM
I am a Captain deployed to Baghdad, Iraq and need help determining the problem with my suburban, which we use to convoy personnel throughout the Baghdad region. I am by no means a truck expert, and the repair process over here is dreadful...help me!

Our 2003 suburban often gets a "reduced engine power" displayed by the computer and the RPMs drop to below 1,000. The vehicle will not accelerate and will not go above 1,200 RPMs no matter how much gas it is getting. Flooring the gas pedal has absolutely no effect and the truck continues on its merry way at about 20 miles per hour.

I have been told by various amateurs that it is the gas lines or electronics that regulate the gas flow. The reduction in engine power seems to happen randomly, but most often if the vehicle is idling for too long (and I'm sure the 110 degree heat doesn't help). I can get it fixed much quicker if I know what the problem may be. Any ideas?

Thank you
Capt Bill

MT-2500
06-17-2007, 09:20 AM
Welcome to AF

Does it have a electronic gas linkage or gas pedal?
That would be my first check on it.

And Always a good idea to check fuel filter?

If electronic gas pedal you will need a engine capable scanner to test it.
But have a look at the wiring and wiring plug in on it.
And if you can see the butterfly in the throttle body look and see if it is caked up with carbon.
If so try a little TBI/carb cleaner on scrub it with a tooth brush.
Do you have any check engine lights?
What engine does it have?
MT

military_deployed
06-17-2007, 10:57 AM
Engine is a 8100 Vortec and has a gas pedal. Will check the air filter and butterfly in the throttle body.

The check engine light is on, but these are government vehicles...they are always on. I asked this question because there is no one here who specializes in Suburbans or GMC/Chevy, only a general vehicle mechanic.

I appreciate your assistance.

Capt Bill

2000CAYukon
06-17-2007, 11:26 AM
It would still help to at least get a code reader and see what codes are stored.

Be safe other there!!!

//2000CAYukon

MT-2500
06-17-2007, 04:43 PM
Engine is a 8100 Vortec and has a gas pedal. Will check the air filter and butterfly in the throttle body.

The check engine light is on, but these are government vehicles...they are always on. I asked this question because there is no one here who specializes in Suburbans or GMC/Chevy, only a general vehicle mechanic.

I appreciate your assistance.

Capt Bill

8.1 Vortex
I am not up on it.
But fuel filters should be checked on it.
And as said codes read.
Post back any codes you can get.
From your description it sounds like the throttle body is not opening the butterfly.
Some use a electronic gas pedal instead of a cable to open the engine up.
Here is a link to a truck forum that may be able to help
http://www.batauto.com/Forums/index.php/board,6.0.html

Good luck and be careful over there.
MT

MT-2500
06-17-2007, 05:14 PM
On the 8.1
The electronic throttle body is controlled by a throttle actuator control module that is activated by the accelerator pedal position sensor.
Under the gas pedal.
All electronic.
If you can get any codes that may help pinpoint the problem.
MT

hrcslam
06-18-2007, 02:43 AM
I think the problem you are having is you engine is over heating. GM put in certain counter measures to prevent engine over heating and this is one of them. Also there have been some problems with the coolant use din those trucks they are the 100,000 mile type it should be red or orange. I am assuming you are already deployed so I recommend replacing the coolant with the coolant used in the HMMWV. After all the HMMWV is GM also. I also recommend replacing your thermostat with a much lower thermostat. I think the stock on should be between 190 and 210 degrees. I recommend using a 170 or lower version. Another fix you can do is there is a coolant line that runs in to the throttle body. It is designed to raise the temperture of the air coming into the engine. This is not good in Iraq summers. If you disconnect the two coolant lines from the throttle body and connect them to eachother it'll cool the engine down and give you a few more hp and better gas mileage to boot. If you Google "GM throttle body coolant bypass" it'll pop up some instructions. Ohh yeah I think MT-2500 is right it does have an electronic throttle based off of the sympotms you stated. Hope this helps.

Nukaya
04-25-2012, 01:37 PM
Did you ever get this fixed and what was it? I have the same vehicle doing the same thing. So far have spent about 2k and nobody can seem to fix it. I love this vehicle, comfy, roomy and has the power if needed...when its not reduced obviously. At one point I had to take it in to get a flat tire fixed, had them rotate them while I was there and it cured the problem for about 2 weeks, drove like a dream during then but I have continuously had this issue for about 2 yrs now. Thank you for anyone who can help.

gmtech1
04-25-2012, 01:41 PM
Any codes? If so, post them please.
There are problems with the pedal position sensor.

Nukaya
04-25-2012, 01:58 PM
It has a new one, didn't help at all. Mechanic said the machine was reading that the sensor to reduce power and the sensor to accelerate were fighting each other though.

Nukaya
04-26-2012, 02:25 AM
I don't remember the codes, but first it was the code for like an air sensor and then it still did it, then they said it was a fuel pump which was very expensive, didn't do the trick either, dealership said new battery and another air sensor of some sort, again didn't do the trick, the last thing now code said accelerator pedal throttle sensor so new one is now, problem still there but now if its not in reduced engine power, its accelerating on its own...the mechanic I have looking at it right now is trying to figure it out and hasn't charged me anything but is totally stumped. What I can find is a ton of gm suv's and pick ups are having this issue and a lot of them are 03's. Code did come back for a the throttle sensor again plus for the sensor basically (from how I understood) opposite of the throttle sensor. Grounds have been checked and all the little things like fuses, coolant change, ect have been done but its driving me crazy. Tomorrow I'm going to do the by pass thing as mentioned above. Mechanic also said that the whole brain could be messed up but cause some people have done that and it not have changed anything I will have to let the vehicle go, can't spend that kind of money for just another failed attempt. I'm trying to convince my dad to help me to just create a new engine all together, one with no sensors...computers...or gas haha. I love my ride though, really I do, would love even to upgrade to a new one but the price is pretty high and really can't handle that kind of price if its going to go through the same thing.

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