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Ted Ritter
Ted Ritter, Toyota Master Tech
Category: Toyota
Satisfied Customers: 4179
Experience:  Toyota Master Tech, ASE Certified
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My problem has been check engine light on P171 /P174 codes

Customer Question

Customer: My problem has been check engine light on P171 /P174 codes brought to Toyota told me air intake control valve is faulty replaced it still has a problem especially when it is cold idles rough change map sensor smoke test was done, fuel pump pressure is fine I do not know anymore
JA: Thanks. Can you give me any more details about your issue?
Customer: Put some fuel injection cleaner in the gas tank seemed to help but not sure
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Submitted: 11 months ago.
Category: Toyota
Expert:  Ted Ritter replied 11 months ago.

Hello, I just saw this post, thanks for requesting me

I didn't see a year or model listed in your post, please provide that information and also what engine it has.

any codes besides the lean/rich conditions? Any misfire codes?

In most cases the misfires will cause these codes to come up due to the air/fuel ratio sensor's reaction to the overly lean mixture. Has anything been replaced to try to eliminate the misfire?

Customer: replied 11 months ago.
2004 Camry V6 3.0
Customer: replied 11 months ago.
According to Toyota it did have mis
fire codes
Customer: replied 11 months ago.
Map sensor was replaced , Air intake control valve was replaced PVC hose it had a crack in it
Customer: replied 11 months ago.
The air intake control valve does not seem to have any vacuum on it. I am not sure what conditions need to be met for that to happen!
Customer: replied 11 months ago.
what do you think? I spend plenty of money on it already, and still have the problem.
Customer: replied 11 months ago.
Hi,
Is anybody still there?
Expert:  Ted Ritter replied 11 months ago.

Yes, I'm still here

Please give me a moment to respond

Expert:  Ted Ritter replied 11 months ago.

Do you have the misfire codes that the dealer had, the misfire is the first thing that has to be dealt with.

Customer: replied 11 months ago.
Hi
They did not tell me, I would have to call them Monday
Customer: replied 11 months ago.
They cleared the misfire codes and then told me the Air intake control valve is faulty
Expert:  Ted Ritter replied 11 months ago.

I understand but I would like to have the actual code number so I can determine which cylinders are affected, also the Po171/174 codes should have a bank one or bank two designation You can get the codes read at most any auto parts store like Autozone for free, if it's not that urgent it can wait until Monday.

Customer: replied 11 months ago.
I went to auto zone again yesterday and results from the check engine light being on was just P171/P174 codes no others and said oxygen sensor should be replaced
Expert:  Ted Ritter replied 11 months ago.

The oxygen sensor is not the problem, how does the engine idle right now?

Does it seem to run normally , is there any loss of power?

Customer: replied 11 months ago.
The results from auto Zone is PO171 system to lean Bank 1 and PO174 system to lean Bank 2
Replace oxygen Sensor O2S bank 1 system is to lean for predetermined period of time
Customer: replied 11 months ago.
No when it is warm it runs fine no loss of power.
Customer: replied 11 months ago.
I was just driving it after it warmed up, it runs normal no loss of power.
Customer: replied 11 months ago.
What do you think ?
Expert:  Ted Ritter replied 11 months ago.

Ok, thanks, ***** ***** air/duel ratio or oxygen sensor is their standard answer which in most cases is wrong, since both banks are affected there may be a vacuum leak, have you checked for any vacuum hoses that may be disconnected? Is the air intake hose from the air filter to the throttle body on and no loose clamps? Try replacing the MAF (mass air flow sensor) it's the most common cause for these codes.

Customer: replied 11 months ago.
MAF sensor was replaced, and a smoke test was done on the vacuum system
Customer: replied 11 months ago.
maybe one of the vacuum lines is clogged
Expert:  Ted Ritter replied 11 months ago.

I don't think it would cause the problem, check the pcv hose coming from the valve cover near the firewall to the intake chamber, check the other large hoses that connect to the intake and the air filter housing.

Customer: replied 11 months ago.
PVC hose was replaced,, I guess will check other large hoses
Expert:  Ted Ritter replied 11 months ago.

And if you can't find anything there replace the MAF sensor.

Customer: replied 11 months ago.
I said MAF sensor was replaced, I put the old one back in
Expert:  Ted Ritter replied 11 months ago.

Ok, got that, let me get back to you in a moment.

Expert:  Ted Ritter replied 11 months ago.

There is a toyota service bulletin for those codes which is what the dealer went by, I will have to look into this a little more and see if I can come up with some more info and get back to you, are you sure you put in the gasket between the valve and the intake body?

Expert:  Ted Ritter replied 11 months ago.

The vacuum hose coming from the air intake control valve goes to a vacuum switching valve located under the engine cover, the vacuum applied should change with throttle position and rpm, check to see if vacuum is applied from the hose of the VSV to the AIC valve when changing engine speed, if not the vsv may be defective or disconnected.

Expert:  Ted Ritter replied 11 months ago.

Toyota Camry: Intake air control system (1MZ−FE/3MZ−FE ...

Click on this link for some good information

Customer: replied 11 months ago.
when I installed the Air intake control valve it appeared it had a gasket
Expert:  Ted Ritter replied 11 months ago.

Thanks, ***** ***** sure

The vacuum hose coming from the air intake control valve goes to a vacuum switching valve located under the engine cover, the vacuum applied should change with throttle position and rpm, check to see if vacuum is applied from the hose of the VSV to the AIC valve when changing engine speed, if not the vsv may be defective or disconnected.

20 Dec 2015, 10:57 AM

Me

Toyota Camry: Intake air control system (1MZ−FE/3MZ−FE ...

Click on this link for some good information

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