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Po300 302 304 306 And po171

Customer Question
Po300 302 304 306 And po171
Submitted: 2 years ago.Category: Toyota
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Customer reply replied 2 years ago
Sorry! This was a Toyota question 99 solara 3.0
Answered in 58 minutes by:
3/2/2016
Toyota Mechanic: Juan Crespo, Tech Trainer replied 2 years ago
Juan Crespo
Juan Crespo, Tech Trainer
Category: Toyota
Satisfied Customers: 1,532
Experience: A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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Well, everything here points out to lack of fuel - misfire codes are caused by lean conditions and P0171 reinforces that argument.

Start by checking fuel pressure. If not 44-50 psi, fuel pump is not doing its job and needs to be replaced. If within specs, the we'll need to test the MAF. Let me know about fuel pressure first and then we'll continue if necessary.

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Customer reply replied 2 years ago
One of my concerns is the plugs were all carbon.
Toyota Mechanic: Juan Crespo, Tech Trainer replied 2 years ago

Duly noted and will be taken into consideration for the overall diagnosis. In the mean time, what about that fuel pressure reading?

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Customer reply replied 2 years ago
Need to get back to u
Toyota Mechanic: Juan Crespo, Tech Trainer replied 2 years ago

That's OK. Based on your replies I don't think I can work with you. I'll opt out so others may try. Don't reply until another expert responds or the system will revert your request back to me.

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Toyota Mechanic: Skyvisions, ASE Certified Technician replied 2 years ago
Skyvisions
Skyvisions, ASE Certified Technician
Category: Toyota
Satisfied Customers: 14,994
Experience: Toyota Master Diagnostic
Verified

Are these the only code you've ever had in the system? Or have you had a VVTI malfunction code ever set This would be something in the 1300 series number P1346 and so on.? Have you checked for intake leaks? I wouldn't worry about fuel pressure at this point fuel pumps rarely fail on this vehicle and you wouldn't have just 2, 4, 6 misfiring you would have all six misfire codes.

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Customer reply replied 2 years ago
I only saw those codes . I changed the plugs! And I put an air fuel sensor in b1. My concern is carbon. I keep thinking egr? Or plunged cat?
Toyota Mechanic: Skyvisions, ASE Certified Technician replied 2 years ago

An EGR valve won't cause this problem. Have you checked your intake leaks that would be common to the front bank of cylinders? I'm on my mobile device and have limited access for the next hour and a half. A plugged catalytic converter could theoretically cause this but would be extremely unlikely. Did you check the vacuum on the engine while it's idling? It should be at about 20 inches and if you do a snap throttle test it should drop down and instantly come right back up if it lags then it could potentially be restricted exhaust.

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Customer reply replied 2 years ago
I did a smoke test ! Saw no leak other than air intake hose! I tighten clamp . Would explaine lean code ! I'm sure the misfire was the carbon'd plugs .
Toyota Mechanic: Skyvisions, ASE Certified Technician replied 2 years ago

Do you have a picture of the three spark plugs from bank two? Do you have an active testing scan tool that will active test the VVTI controller for bank two? Is it currently running rough right now? If you clear the codes do just the cylinder misfire codes come back each time or is it intermittent that it runs rough?

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Customer reply replied 2 years ago
Car runs fine for awhile when plug carbon up it will miss a little and chec engine light sets. This car does not have a vvti controller I think the belt just has a spring or hydraulic tensioner down low on front of engine.
Customer reply replied 2 years ago
It clearly has a carbon issue !! Black soot on plugs, Air fuel sensor and even tail pipe is pretty black
Toyota Mechanic: Skyvisions, ASE Certified Technician replied 2 years ago

Do you have the VIN available? Is the excessive carbon on all the plugs or just the front bank and when was the last time they were replaced? Do you have a picture of them?

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