Losing engine power with no warning

10

Asked by Aug 10, 2014 at 11:38 PM about the 2007 GMC Yukon XL Denali 4WD

Question type: Maintenance & Repair

I recently took my Yukon (140,000miles) up to a local mountain(4000ft elevation) , it
drove up the curvy steep road fine. Engine ran a little warm, a smidgen above center, but
no problem till we approached a stop sign. When the break pedal was touched the
engine lost power-- with no warning lights or check engine light. The dash lights,
overhead lights, radio etc stayed on, then the engine temp gauge read close to red--still
no warnings, or check engine light. The car wouldn't restart. After a few minutes the
battery was dead too. 3 different people tried to jump us with no luck, finally two hours
later we successfully jumped it---drove fine down the mountain (no check engine light
still). Took it to a dealer, they didn't find any codes. Ended up replacing the oil pressure
sensor, thermostat, flushed rad & new coolant. We test drove it back up the mountain,
and the damn thing did it again. I'm at a loss, it seems as if it's not throwing any codes
the dealer won't fix anything. I'm worried about the potential danger this could be, a car
just losing all power! any ideas what's going on?

4 Answers

60,775

Sounds like the engine is either overheating or you're coolant temperature sensor is bad. Most newer vehicles will go into a "limp" mode when overheated to prevent serious engine damage. Some will even shut down. Get one of those laser thermometers. Check the actual temperature by zapping the thermostat housing (where the top radiator hose hooks to the engine) with the laser. Going up the mountain the engine is working harder than when coming down. Especially if you're towing a trailer or something. You can also try shifting the transmission into a lower gear when climbing the mountain so the engine doesn't work as hard. HTH. -Jim

1 out of 1 people think this is helpful.
10

Hi Jim, thanks for your response. Apparently, this Yukon is suppose to go into the "low power mode" where it shuts off the a/c, drops you down to <30mph or so when the engine overheats! But it appears there is a miscommunication occurring = no check engine light, no protective mode etc.. The coolant temp sensor seems like a good place to start! To my limited knowledge, it didn't appear to be overheating (no bubbling, steaming, hot smell etc) and the gauge read pretty normal till the engine cut out! But I will check on the sensor, thanks!

1 out of 1 people think this is helpful.
60,775

You're welcome. Glad to help. -Jim

10

My 07 Yukon denali shut down on me it seems like it's fighting for gas but I had gas in the tank is change the fuel pump but getting the same problem when I drive the truck regular I don't get that problem but when I drive it hard it start shaking and shut down and when the engine cool down it would start back can someone tell me what is that problem please

1 out of 1 people think this is helpful.

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