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SUVs Chevrolet Suburban & Tahoe 2007 and newer Chevrolet Tahoe and GMC Yukon
3125 messages, Last post on Nov 27, 2009 at 6:32 PM
You are in the Chevrolet Suburban & Tahoe Forum. Your Hosts are steve_ & tidester
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Replying to: gfraigun (Apr 23, 2007 9:23 am) Besides that point, idling is wasteful period. Better would be to add the mild-hybrid system GM has on some of their other small vehicles right now, that completely shut down the engine at a stop, and then use the modified alternator / battery system to get moving and restart the gas engine when needed. Secondly- you'd be surprised. I don't know exactly what conditions the engine computer is using to decide whether to use V4 or V8 mode on downhill grades, but it doesn't always do just one or the other on the single steep 6 mile stretch of interstate I travel daily. While I haven't figured out what makes it decide to use V4 or V8, I've paid close attention to the instant mileage readout on that mountain. What I've found is consistent with what I'd seen with the 2004 Silverado Z-71 5.3l 4 speed auto on the same hill in V8 mode: 1) The truck and my Avalanche both normally unlock the torque converter (seeming to almost completely freewheel), allowing the engine RPMs to drop to slightly lower than even a normal idle speed. 2) Fuel economy goes WAY up on the instant readout. Since this seems to be used for the average mpg readout, and since my average that I manually calculate at the pump every fillup is relatively close (no more than maybe 1 mpg off in either direction) to that readout, I assume the instant isn't too far off either. Gotta admit, 99mpg (max it can display) is a rush!  In V4 mode with the Avalanche, the same things seem to happen. However, the instant readout doesn't go quite as high, and I've noticed that fillups bear out a slightly *lower* overall average for tanks where the Av went into V4 on that steep downhill most of the time versus tanks where it spent most of the time in V8 mode. My Guess: It's been rumored elsewhere that there's some sort of coasting fuel cutoff (really, not completely cutoff, but only enough to keep the engine going). Mainly because the engine doesn't need to do anything to keep the vehicle moving. It appears that V4 mode doesn't use this, while V8 mode does, at least on downhill slopes. Result: V8 mode with the cutoff's lower fueling actually takes less gas than V4's four cylinders getting fueled more normally.. On more level ground, where the engine actually has to push to maintain the speed, V4 and V8 modes do as expected, with V4 being better than V8. Personally, I'd rather see it get the mild hybrid system added to the existing setup, and allow it to use it not only for situations where the vehicle's stopped in traffic, but also for any real downhill coasting (use regenerative breaking too for the battery, since it's free). After all, *really* shutting off the engine in that situation should best even the V8 fuel cutout scenario (assuming it's true). |
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 Got a special $4 basic carwash the other day and when I walked around my '07 Tahoe, I saw that the rear wiper was moved downward, below the stop. Sure enough, the bracket had snapped. A stop by the Chevy dealer resulted in a $43 replacement, which is the entire assembly arm and cover (but not the blade portion) that attaches to the drive motor with one nut. Yep, it was one of those "soft touch" car washes with the flappy foam strips, and No, the blade was not taped down, like some places do. I should have known better!  I had a Ford Explore in CA and ran it through one of these places every week without any problems, but they generally taped all wipers down. Anyone else use this type of carwash? Experience? The parts guy said they sell a lot of rooftop antennas caused by the same problem. Chuck
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Replying to: csprick (Apr 27, 2007 4:20 pm) 
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Replying to: rhame13 (Apr 27, 2007 7:33 pm) I'm due to take my Tahoe in for service on Monday so will ask the service rep about reimbursement. I'm sure that the carwash people would tell me to pound sand, since they have all kinds of disclaimer signs up. What's the considered opinion, Forum Members - warranty item or my loss 
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Replying to: csprick (Apr 27, 2007 9:52 pm) |
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Just rec'd a notice from GM that they were rebating $100 of my GMPP (ext warranty) due to the new 5 yr/100K warranty. The funny part is that when I bought it, which was after the new warranty came out, I got the salesman to knock $300 off due to the new warranty. I won't spend it 'til it's in the bank tho. 
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Replying to: csprick (Apr 27, 2007 9:52 pm) ____________________________________________________________ I would go back to the car wash. They can hang all the "disclaimer signs" they want but that doesn't excuse their liability for factory installed parts. There are thousands of Suburbans and Tahoes on the road and their equipment and staff should be able to handle anthing that GM puts on the vehicle. Owner installed after-market items are another thing entirely. Factory parts should be covered by the car wash. That's my story and I'm sticking to it.
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Replying to: rockman59 (Apr 28, 2007 5:00 pm) Besides, the worst that can happen is you ask for it to be replaced under warranty because you understand the situation to be as I stated, and they tell you 'No', then you pay for it yourself anyway. 
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Replying to: jerrywimer (Apr 30, 2007 3:52 am) |
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