Techtech

Tue Jul 16, 2019, 06:51 AM

Many thermostats? (car question)

I own a Chevy Sonic that is about 5 years old. Recently (6 months or so) it started acting up. Mileage went to hell, engine racing, check engine light coming on and off, air went out. Took it in a couple of days ago. I found a great shop.

Anyway, I got called yesterday, they can't really make sense of the diagnostics. But they are sure they need to replace the? a? thermostat. The mechanic was sure that would fix all the problems except for the air. And he was 50/50 on the air. $250 so sure replace it.

I haven't worked on a car for 30 years. The only thermostat I am familiar with is the radiator thermostat. So how the hell could the radiator thermostat cause so many issues?

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Response to def_con5 (Original post)

Tue Jul 16, 2019, 06:59 AM

1. the "throttle body" is similar to a choke on the old carbourators

change your air filter and clean that throttle body (probably real close to the air filter.) with spray "choke cleaner." the computer read out might be "throttle body sensor defective" or some such rot, but if the butterfly valve is moving freely in that throttle body your sensor will follow it.

then give it a few miles to see if there is something wrong with the thermostat or if that is an artifact of the improper fuel/air mix.

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Response to def_con5 (Original post)

Tue Jul 16, 2019, 07:40 AM

2. Do you know the number of the problem code that the car is giving?

You can look the code up online and it will suggest different remedies.

For 80-90 bucks you can purchase your own device that reads error codes. The investment can pay for itself many times over. My neighbors are always borrowing mine.

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Response to oflguy (Reply #2)

Tue Jul 16, 2019, 07:56 AM

3. mine reads out on my smart phone

plugs in under the dashboard somewhere. i was upside down when i installed it.

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Response to rampartb (Reply #3)

Tue Jul 16, 2019, 07:59 AM

4. As a part of your phone, I would think it updates automatically

I have to plug mine into a laptop if I want to check for updates

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Response to oflguy (Reply #4)

Tue Jul 16, 2019, 08:04 AM

5. it is an ap i have to enable to read out.

then it gives me a list of every code since the last time i checked. i get a lot of those throttle body codes usually in winter.

works pretty good.

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Response to rampartb (Reply #5)

Tue Jul 16, 2019, 08:07 AM

6. The cost is coming down on monitors

But vehicles are too damn complicated these days.

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Response to oflguy (Reply #6)

Tue Jul 16, 2019, 08:18 AM

7. the computerized automobile is too complex for most diy mechanics

i do very little of my own work anymore. i can not buy oil and a filter for the price of a "speedy oil change." and the boy vacuums my interior.

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Response to oflguy (Reply #6)

Tue Jul 16, 2019, 10:51 AM

8. " vehicles are too damn complicated these days " - as was the plan . . .

The Big Three et al were miffed, but not overly concerned with independent garages siphoning off business from their dealerships,

until it got massive . . . . .

There is no "basic" car anymore - one that any owner with a smidgen of mechanical skills and the ability to read a manual could fix, albeit with lots of cursing and time involved . . .

(sigh)

CC

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Response to def_con5 (Original post)

Tue Jul 16, 2019, 11:24 AM

9. how the hell could the radiator thermostat cause so many issues?

ok

if the thermostat stays open when it shouldn't, then the engine runs colder than it should, 'puter will richen the mixture to compensate - ergo gas consumption goes to shit (like leaving the choke half-closed sorta thing)

some check engine lights (whatever happened to the old fashioned temperature and oil gauges/lights they had for decades?) are connected to engine temperature (too cold/hot)

Air conditioning?

coincidence methinks -

Ya - know - if now ur brakes start squeaking and ur brain tries to connect dots . . . .



CC

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Response to akaConcernedCanuk (Reply #9)

Tue Jul 16, 2019, 11:36 AM

10. Thanks CC

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Response to def_con5 (Original post)

Tue Jul 16, 2019, 02:19 PM

11. There is a temperature sensor

 

on GM cars/trucks that tells the computer how hot the coolant is. The fuel/air mixture is adjusted based on the reading from this sensor. If the sensor is telling the computer that the engine is running too hot then it could shut off the AC compressor to relieve drag on the engine.

This sensor is separate from the sensor that sends signals to the Temp Gage/Idiot Light. I've fixed many problems with friends' cars/trucks by simply replacing that sensor. Hard starts/no starts/sudden bad fuel economy/AC not cold.

The sensor costs $20-30 and takes ten minutes to replace. Make sure the engine is cool or you'll get a face full of hot anti-freeze -- learned that from experience and being in a hurry.

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Response to def_con5 (Original post)

Wed Jul 17, 2019, 11:21 AM

12. Sound to me more like a Mass Air Flow Sensor, or MAF.

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