hard time starting the engine up?

Here are the images from the scanner.

With the p0171 more then likely you have a vacuum leak somewhere.The best way to find a vacuum leak is by injecting smoke in the intake manifold.You could watch short term fuel trim to spike and spray carburetor spray around all vacuum sources.But smoke works the best by far. THis guide can help us see what's going on.


https://www.2carpros.com/articles/engine-cranks-excessively-before-starting


Please run down this guide and report back.

I did spray carburetor cleaner, but no luck.

Smoke is truly the best spraying around is a hit and miss. smoke is truly the best way.

Where would I hook up the smoke machine?

To the brake booster hose that goes to the intake manifold.

Okay, I will keep you posted.

Sounds good.

So, I did a smoke test today and I couldn't find any vacuum leaks. So I reconnected the hose to the break booster and scanned for codes, this time it gave me 2 codes. P0171 and p0113 which is intake air temperature sensor. So I cleaned the maf/iat sensor with carb cleaner, cleared the code and drove it for a bit and check engine light came back with p2196 o2 sensor signal biased/stuck rich. So I cleared it again and drove it till the light came back on again, and this time it gave me the p0171 again

What did you use to clean the mass air flow sensor?What did you use to inject the smoke?

The maf is actually new but I still cleaned it with maf cleaner. As for smoke test, I used the cigar method. Maybe not good enough?

I see I just read your answer again you used carb cleaner to clean the mass air flow sensor.Carb spray is oily you should only use maf sensor cleaner so get a can and do it that way.Also the cigar method doesn't really work effectively.I built a smoke machine from a old metal paint sprayer.I drilled a hole in the bottom center of the paint cup.Installed a glow plug from a 80's diesel K1 Chevy blazer.Then installed two nipples on top of the paint cup one on each side.One for the pump and the other to inject the smoke.I use a old nebulizer pump they use for kids asthma.I block off the throttle body before injecting the smoke.I use unscented mineral oil in it I got from a feed store.I attached pics of it not pretty but have used it many times to find vacuum leaks Evap leaks exhaust leaks etc it works amazingly well.

Ok, I'll try the paint can smoker

Make sure you use a fuse and the paint cup gets very hot when using it be very careful.Only handle it by the handle of the sprayer.

Ok, so I did a smoke test using a pint can and little compressor hooked up to it on the side and on top another house going to the break booster. I found a leak near the pcv on the valve case. I used jb weld and tested it again, no leak at all but the code came back again and it's still having hard time starting sometimes. Btw, I replaced the upstream o2 sensor and still no improvement

How would I test the fuel pressure? Where would I hook up the gauge to?

I used maf cleaner and I found this video on YouTube showing how to make a smoke machine using a paint can and small compressor. Charcoal inside and cardboard which produced a lot of smoke. Compressor hooked up to the inlet on the paint can and another hose hooked up to the outlet going to the intake

Yeah charcoal would make a lot of smoke I like the unscented mineral oil it's smoke on demand.So when it runs down the road does it have good power?If it does then I wouldn't suspect low fuel pressure.You would have to check the fuel pressure at the banjo fitting at the fuel rail.There is no nipple on those to hook to.They rent a gauge at auto zone to check fuel pressure.Also have you checked the coolant temp sensor that feeds engine temp to the ecm?

So what should the fuel pressure read as? Also where is the coolant temp sensor

E2 in the diagram is the coolant temp sensor the pressure should be 44-50 psi

So I did some research and found out that only denso sensors are good with Toyota. The new maf was purchased from advance auto. I scanned the live data and the IAT was reading 132 when the temp outside was only 83. So took the new one out and put the old one in, IAT read 100. But gave me MAF code. Also the ECT was reading 199. Here are some pix of the live data. I'm thinking about getting a denso maf

The coolant temp read 199 but what was the actual coolant temp?Sounds lie you have to do something about the maf if the iat is reading that far off.

How would I get the actual coolant temp compared to the scanner reading ?

With a infrared temp gun I usually measure where the top radiator hose goes into the head.Within 10 degrees of what computer says.

Update. So I cleaned the maf and tested it with a multimeter and it's all good and car starts right a away with no problem. I still have the p0171 code and on the ready page on the scanner, everything has a green check mark except the cat and o2 sensor with have red x mark. Could that be causing the p0171? The upstream o2 sensor is good and new. Could the downstream o2 sensor be causing this?

The down stream o2 sensor monitors the health of the cat.By comparison of the upstream o2 readings verus the downstream o2 sensor readings .I would say ove 90 percent of the cars I have seen with a code p0171 have been caused by a vacuum leak somewhere.

So then do you suggest that the vacuum leak or p0171 is causing the cat and o2 sensor to not read ready ?

The o2 sensor is effected so that could effect the cat from being ready since it has to use the o2 sensor readings to tell the computer how its working.

Ok so I put a new maf sensor and still the same. Did a vacuum leak test and nothing. But, I put my hand under the catalytic converter and there is hot air coming out from a very small hole at the front side of the converter. Not the joints. Could that be causing the problem since the scanner showes cat and o2 sensor not ready ?

No that won't set a lean code the upstream o2 sensor monitors that.From what I saw intake manifold leak number one by far and second place is mass air flow sensor and O2 sensor is way down on the list for causing that code.

Did you ever get this resolved? Having similar symptoms with a 2007 Camry - P0171 code running very lean. 45% LTFT. It won't start when engine is hot until it cools off. Have done smoke tests, intake manifold gasket, valve cover gasket, plugs, fuel injector service, MAF, upstream O2, and a number of other things. Fuel pressure and crank sensor next I guess.

Hey JEREMY,

This sounds like a weak fuel pump, if there is a filter replace that first, if not I would suspect the fuel pump int he tank.

Do a fuel pressure test first to make sure here is a guide that will show you what you are in for.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Best, Ken

very hard to start, some time 3 or 4 times need to try but some time starting smoothly
I checked pugs all are OK

Check fuel pressure and coolant temperature sensor then comeback

as you said, I checked coolant temperature sensor then found loose connection on the connector.
after I connected properly, the probles is solved
Thank you very very much

sir.

This car has a unique problem as it does not start once engine is cold. it requires a long key-self to start. Immediately after starting its starting is okay, but a second attempt even just 30 minutes after parking it requires a long starting. and immediately after starting when the engine is either cold or hot.
I have changed spark plugs,fuel pump, salf, heat sensor and battery. Everything seems okay.
Your kind suggestions please.

Furthermore i have checked it at many mechanics including the dealership, but so far problem still exists. I also had a complete tune up done. but it still requires a long starting after being parked. Second start immediately after engine switches off is okay.

scan for codes and check fuel pressure with a gauge in US auto parts rent it. it may be losing fuel pressure due to many things should be 44-50 psi and not drop after 5 minutes.

Sir, fuel pressure i just checked with a guage. it is not losing the pressure, it remained normal even aftr 30 minutess. your kind view please.

we really do not have Toyota's with that size of engine here in USA, so the spec I gave may be incorrect, but it has to stay at minimum pressure otherwise it is too low. scan for codes as well.