I have 270k on my 2009 camry and for the most part it is still running reasonably well. I have replaced parts like motor mounts, alternator, radiator, ac compressor 2x, serpentine belt 2x, suspension parts, brakes, tires, all the good stuff.
I get an oil change every 5000 miles with full synthetic 0w20 and i have replaced spark plugs 2x, pcv valve 2x, engine air filter several times, cabin air filter every 12-15k. I clean the MAF sensor periodically, and most recently have a p0101 right after cleaning. I continue to get incredible gas mileage in my opinion, usually 27 to 30 highway, if all city 21-23, if mixed 23-27, for a 2009 with so many miles driven.
The acceleration is not as good as it could be and the idle is low in my opinion. There is shaking/rattling/knocking coming from the engine at idle, it smoothes out when it gets above 1200 rpm. The vibrations can be felt in the cabin and seen with the steering wheel shaking. It usually idles around 650rpm. I have had p0171 stored and pending for several months, but other than the poor acceleration and a hard starting condition, i have not been able to pinpoint the culprit(s) yet. I cannot find a vacuum leak but the LTFT is always +25% or higher and the short trim fuel trim is usually around 10%. Given the constantly high LTFT (now 35.9%) , when using my scan tool, the CEL has freeze frame data showing vehicle speed of 0 and 436 rpm, and tps of 18%. A local mechanic says the brake boost diaphragm may be leaking causing the p0171, and that the hard starting may be due to fuel leak down / poor fuel pressure. I'd like to replace the fuel pump assembly including fuel filter.
Any suggestions? Thanks!

 

Have you check for air intake leaks after the MAF sensor?

 

My mechanic checked for air intake leaks before and after the MAF sensor and found everything in good order. He thinks the catalytic converter is clogged. Wouldn't this throw a cat code instead of p0171? He said i should try cataclean, but it did not work yet.

 

Diagnostic work can be done.

The boost vacuum hose can be disconnected and plugged to take the boost diaphragm and its possible leak out of the air intake system. This is SOP if suspecting a defective booster.

A pressure gauge can be installed in line with the fuel line to check for fuel pressure when the engine is running (fuel pump on) and pressure bleed down when the fuel pump is off. There is check valve in pump to prevent bleed down. This pressure test requires a gauge and tap fuel off fitting to install. A good fuel pressure test kit should have all of these items. There is no direct way to monitor fuel pressure by the cars computer as in measuring actual PSI. The ECU measures exhaust air/fuel mixture from the A/F sensor.

A vacuum gauge can be installed on the engine air intake and with engine running monitored. A plugged exhaust system has a distinctive vacuum indicator pattern as the engine is running and exhaust pressure starts to build up. This is a very simple test and SOP when suspecting a clogged exhaust system.

Would think a plugged CAT would not result in a rich mixture.

The code for a bad CAT is P0420. This code is set by the 02 sensor after the CAT generating the same signal pattern as the A/F sensor before the CAT. This means the CAT is not working. It’s a comparison test of the two sensor signals and has nothing to do with fuel mixture.

There may be another CAT under the cars chassis.

If the fuel pump has never been changed might look into it as just preventative maintenance as they do fail over time.

The CAT issue becomes complicated as in CAT's are not low cost and depending you state can be very expensive as an approved CAT needs to be used. Here as suggested preform a few tests first.

I would stay away from cataclean type items. My understanding is the IF a CAT can be cleaned it needs to be removed and soaked in various solutions assuming this cleaning process actually works.

 

Thank you so much for the response. I asked my mechanic to diagnose these things and he did not give me a breakdown of what he did or did not do only telling me he does not suspect brake booster or fuel delivery for this. I am not at the DIY level yet to be able to pull hoses off and such yet and need to find a mechanic who will do these diagnostics in the order suggested so i can narrow down the problem. Joshua

 

Since the engine starting having issues has the brake pedal been harder to push down?

How is the acceleration? Fuel issues carry over into acceleration and maintaining speed when going up hill or engine under load.

 

The brake pedal feels like it goes down further than it should but that could be because when i press the pedal i don't tap lightly i am afraid it won't stop or hold unless i push it as far down as it goes, this could be my driving style or habit versus what's correct. Also, I have not had front brakes done since 210k and rear since 192k, but 80% of my driving is highway without traffic. I asked my mechanic to check my brakes and advise, but he did not do his job. I don't think he had any time to spare other than looking at my engine issues. The brake fluid level is slightly below the max line now, so i believe i am due for 2 brake jobs and a fluid flush. But, i asked a brake specialty shop owner his opinion, and he thought my pedal was fine and if there was a problem with the power booster then i would not be able to stop or stop well.

 

The acceleration seems weak and it is harder to maintain speed when going up hill. I want the fuel pressure to be tested to see if there is a drop in psi after shutting off engine. I would like to replace the fuel filter anyway, and it might make more sense to replace the whole assembly, but i need one that has everything i need built in to it. My vehicle supports California emissions and is north American built 08/08. I asked my mechanic to test my fuel pressure, but all he told me was he does not suspect fuel delivery. Maybe this is a difficult procedure with this camry because there is no Schrader valve??

 

Important to note that the shop that put down that there appeared to be a vacuum leak in the brake boost internally in the diaphragm and that suspected fuel leak down when i complained of hard start/extended crank, they said there was not enough time to further diagnose and they had already charged me an hour of diagnosis time. They claimed that the fixes could solve my check engine light but no guarantee. In that case if i told them to replace a brake booster and fuel pump assembly and the problem still existed, i would have lost a ton of money. So i went to a different mechanic i had used before, and he is the one who negates the findings of the first one. Every party says something different.

Now i have replaced the MAF sensor with an oem toyota one, and i would like to clean the throttle body myself to be sure. Using Live data on my scan tool I noticed that the voltage for O2 sensor B1 S2 (downstream i believe) is 0.000 volts all the time - at idle and at 1500 and 2000 rpm. Does this indicate a problem?

 

Try driving the car over 35 mph and checking.