Tech / Special Interest → Automotive > [Help] 2007 Chevy Uplander "Reduced Engine Power"

[Help] 2007 Chevy Uplander "Reduced Engine Power"

Earlier this summer I bought an 07 Chevy Uplander with a 3.9 V6 (No flex fuel). It broke down on us yet again tonight. My wife had started the car and was idling for roughly 1 minute when it stalled out and the display issued the warning "Reduced Engine Power". At which time it would no longer start. This is the 2nd time that the car has broken down in exactly this fashion.

Doing my own research I've found that this can be caused by the throttle body. The throttle body looks awful and could certainly do with a thorough cleaning, but I was more concerned that the butterfly is not completely closed when the engine is off. Or am I just confused and it should be partly open?

What other things should I check? I don't have access to a computer to see what code(s) pop, just the info on the dash. Check Engine, ABS and "Reduced Engine Power". Any help would be appreciated.
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The Goober (Formerly Mac Bridger)
Fight Cancer! Join DSLR's Team Discovery

Throttle body may not completely close if there is an actuator to set its idle position.

"Reduced Engine Power" usually means the computer is running in fallback mode as it sees invalid parameters from sensors.

Either get a code reader, borrow one or take it somewhere to be read (many auto parts stores will read codes for free or have tool loan service.)
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Scott Henion

Embedded Systems Consultant,
SHDesigns home - DIY Welder

Chevy has a lot of problems with their drive by wire system. It is normal for it to be partially open at rest. You will most likely need to replace the electronic throttle body because there are no serviceable items in it.
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LET FREEDOM RING

In that case it may be something else entirely. Electrical, corrosion, fuel line blockage... Gah... This pile of crap has broken down 5 times since we bought it in June. It's been in the shop more than its been driven.
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The Goober (Formerly Mac Bridger)
Fight Cancer! Join DSLR's Team Discovery

If it were me, I would certainly check the throttle body route. Everything so far you have mentioned points to this as being a very likely culprit. With it being dirty as you mention, the actuator opening and closing it likely isn't able to open to where it needs to be. Computer is seeing conflicting readings (actual open position vs what the ECU wants to see it at and is telling the actuator to open to) and is doing the reduced engine power fallback. And the stalling out is probably just the same reason and the throttle body is closing, due to the gunk, beyond where there is enough airflow to keep the engine idling. My educated thought is that under normal conditions when starting cold it runs at high idle to warm up. After the minute or so it drops back a bit and when the actuator pulls back too far, overcompensating, or is hitting gunk which is forcing the butterfly valve closed too far.

Have codes pulled and see if it makes a clear distinction. It should. At worse case, have the throttle body replaced and I am almost positive it'll be solid after that.
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I swear, some people should have pace-makers installed to free up the resources. Breathing and heart beat taxes their whole system, all of their brain cells wasted on life support.-two bit brains, and the second bit is wasted on parity! ~head_spaz

Hey guys, just wanted to post a follow up as this is FINALLY fixed. It had multiple issues, all of which was electrical. Four wires had been cut/melted which in turn blew out a number of fuses and relays. Also had to have a pigtail rewired and harness replaced.
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The Goober (Formerly Mac Bridger)
Fight Cancer! Join DSLR's Team Discovery

Obviously? What in the world tells you that?

With all due respect, you are not entirely correct. Wires can be damaged by heat sources and direct exposure such as a leaky exhaust manifold or EGR valve, plus several others. And I have never in 25+ years replaced a fuse "box" because a circuit failed.