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Amedee, Saturn Technician
Category: Saturn
Satisfied Customers: 26643
Experience:  ASE certified Technician advanced level specialist. Wisconsin certified emissions state inspector
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Getting a p0174 and a P0221 code. When they come on the

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Getting a p0174 and a P0221 code. When they come on the transmission cycles hard
JA: Just to clarify, what's the exact code? And have you tried to reset it?
Customer: P0174 and P0221 yes I have reset them and they come back
JA: What is the model/year of your Saturn?
Customer: 2001 L300
JA: Are you fixing your L300 yourself? What have you tried so far?
Customer: Yes I hg Ave changed the mass air flow sensor and the throttle body
JA: Anything else you want the mechanic to know before I connect you?
Customer: There was a loose wiring harness behind the engine that I respected that has seemed to make the car run better

Hello and welcome!

My name is ***** ***** I can assist you with your question.

I am very sorry your having this issue with your vehicle.

I will try my best to answer all of your questions.

However, before we get started, please let me mention a few things.

1. If at any point you would like to speak on the phone, please feel free to request a phone call on your end and I can call you right away.

2. If you dont understand any technical terms or anything that I mention (component tests or theory or operation), please let me know and I will provide you with a more in debt explanation or answer.

3. Please understand that I am here to help.

How does the engine run? Does it idle OK? Does it stall at times?

Does it have plenty of power under a load while accelerating?

Customer: replied 1 month ago.
Some times the engine runs fine. Intermittently the idle will fluctuate and then die. It can be restarted and driven again. The check engine and service look lights both come on. I feel like it lags under acceleration and load

Thank you for that information sir.

What is the engine vacuum at idle?

Are you aware of the TSB for related to P0174?

Customer: replied 1 month ago.
I have read the TSB for P0174. That is why I changed the mass air flow sensor. I don't have a vacuum gauge at the moment

Got it! Thank you for that information, sir.

Have you checked the valve timing?

Customer: replied 1 month ago.
No I haven't

Ok, thank you for that information. one moment while I type.

If the engine is stalling at times, I bet this is related. 9 times out of ten, this is caused by an air/vacuum leak. This is very common. If you have done a visual inspection and have not found any vacuum leaks, the intake system NEEDS to be smoke checked for vacuum leaks using a smoke machine. I have a feeling it might just be that simple.

Another cause would be incorrect valve timing. The timing belt is loose or it could have jumped time which can cause these codes.

Have you checked the signal from the new mass air flow sensor with the engine running? If not, this also needs to be done.

Customer: replied 1 month ago.
It will take me some time to rule these things out. I have done a visual/ audible check of the vacuum system

Let me get you the readings on the MAF sensor.

One moment

Customer: replied 1 month ago.
The Smoke test equipment is not cheap

I understand that sir. I am just telling you what needs to be done. Just because it is expensive does not mean I should keep it a secrete from you. That would be unfair to you and unprofessional of me to do so.

I have worked with many people in the past in your shoes. You could pay a shop a small fee to smoke test the intake for you rather than purchasing a NEW smoke machine or improvise your OWN smoke machine to check the intake for leaks. Trust me, it has been done before.

Here are the correct MAF readings.

At 600 RPM, it should show about 3.5 Grams Per Second, 1200 RPM 5 GPS, 1800 RPM 8.5 GPS, and 2500 RPM 13.5 GPS.

Keep in mind, if these readings are not accurate from the NEW sensor you just installed, that does NOT mean the sensor is faulty (although it could be).

Base engine mechanical issues or a vacuum leak can all affect the MAF readings.

I am glad I can help!

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Thanks and have a great day!!

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