Free ACE study guide questions. Are these any good or real?

General Discussion
1

I thought I would share these. But after trying some it seems many of the questions are poorly worded.

Question 6 is confusing.
Question 7 incorrectly refers to Voltage as power.
Question 9 says there is a negative fuel trim and the ECM is adding fuel to the air fuel mixture. It seems poorly worded, because it should read the uncorrected ECM is adding too much fuel to the air fuel mixture. It’s confusing because the correct fuel mixture is being added due to the oxygen sensor’s correction. Is the ECM adding too much fuel due to faulty sensors, or is it adding less due to the oxygen sensor correction?
Question 11 says that a faulty engine temperature sensor and thermostat can cause the engine to run too rich according to a scan tool. A faulty thermostat would cause the engine to not warm up, and the correct amount of fuel for the engine temperature would be added. So the true problem is that the engine fails to reach operating temperature, and there is nothing wrong with the fuel mixture.
Queston 27 just doesn’t make any sense to me. Why would it backfire after the injector was replaced?
I haven’t been doing so well on the test, but I think it’s not entirely my fault.

2

OK , you don’t think much of this thing why are you posting it here ?

3

For me the best is the trouble shooting flow charts in the factory manuals are best. I think prolly written by engineers for the mechanics in the shop. But as they say can still have some errors and omissions.

4

Question 6 is confusing.

Probably supposed to be confusing, to make sure student is paying attention. Both statements seem correct to me.

Question 7 incorrectly refers to Voltage as power.

Technically you are correct, but pretty common to refer to a “no power at test point” situation when the problem is actually no voltage.

Question 8: says there is a negative fuel trim and the ECM is adding fuel to the air fuel mixture. It seems poorly worded, because it should read the uncorrected ECM is adding too much fuel to the air fuel mixture. It’s confusing because the correct fuel mixture is being added due to the oxygen sensor’s correction. Is the ECM adding too much fuel due to faulty sensors, or is it adding less due to the oxygen sensor correction?

It’s question 9 rather than 8. Negative fuel trim means computer is subtracting fuel beyond what engine intake air flow says would it normally require, subtraction of fuel necessary in order to satisfy O2 sensor. There’s no objective test data to indicate cat is overheating, although such a thing is possible. IMO neither tech is correct. What’s causing the negative fuel trim? That would require more detective work.

Question 11 says that a faulty engine temperature sensor and thermostat can cause the engine to run too rich according to a scan tool. A faulty thermostat would cause the engine to not warm up, and the correct amount of fuel for the engine temperature would be added. So the true problem is that the engine fails to reach operating temperature, and there is nothing wrong with the fuel mixture.

A faulty ECT could definitely cause engine to run too rich. A faulty thermostat (& correctly working ECT) could cause coolant to be too cold. Computer would richen mixture based on ECT. So it would be running richer than if thermostat was working, but not richer than it should be. That part of question seems ambiguous.

Queston 27 just doesn’t make any sense to me. Why would it backfire after the injector was replaced?

Backfire may have not been related to injector, so problem remains. Or gasoline has accumulated in cat due to leaky injector, and even though injector now working correctly, cat still has extra gasoline, so gasoline going into exhaust pipe, drawn by cat flow. Wording seems confusing, but I’d say both techs are correct.