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View Full Version : 2000 4runner hot re-start issue


Gerdo
02-12-2012, 02:11 PM
I have a re-start issue. It starts perfectly when the engine is cold. If it sits a day, week or month, it fires right up. When I drive it and get it up to normal operating temperature, turn it off and try to re-start it 10 minutes to an hour later, it will crank for 6-10 seconds before it sputters to life. The work-around is to crank it for a couple of seconds, let it sit for 5 seconds and crank again. Most of the time it'll fire right up.
Not bad gas. I've put over 1000 miles on and multiple tanks of gas from different stations and brands.

Things that I have done are: (some was normal maintenance)
New fuel filter twice
Not running hot.
Replaced battery
Cranking normal speed.
cam position sensor
clean MAF
cleaned the IAC
changed the spark plugs
cleaned TB
fuel injector cleaner in gas
sprayed seafoam thru TB while running
plug wires are fairly new
swapped coil packs with a friend's

Yesterday and again today I get a CEL code of P0171
1. Exhaust system leak.
2. Improper fuel pressure.
3. Fuel injector restricted.
4. Defective heated oxygen sensor No. 1.
5. Defective Manifold Absolute Pressure (MAP) sensor.
6. Defective Engine Coolant Temperature (ECT) sensor.

Any thoughts?

TIMZTOY
02-12-2012, 08:26 PM
it sounds like heat soak.
which means that its an electrical issue.. :gaah: most likely ignition related

Gerdo
02-12-2012, 09:34 PM
it sounds like heat soak.
which means that its an electrical issue.. :gaah: most likely ignition related

It definitely has to do with heat.
Today I packed snow on my crank position sensor and it definitely shortened the cranking time.

Corbet
02-12-2012, 09:58 PM
Sounds similar to my neighbor's 96 Tacoma that is suffering from some sort of warm/hot start flooding where the ECU is calling for too much fuel.

The shop has not been able to determine exactly what is causing this. Sensor/ECU/other? Just that it gets too much fuel.

Gerdo
02-13-2012, 07:38 AM
I don't think mine is too much fuel because when it fires up it doesn't blow smoke out the exhaust.

SteveH
02-13-2012, 11:27 AM
I would try to measure the fuel pressure under various temperature conditions and see if you can find a case where there is no/little pressure during a hot start.

thefatkid
02-13-2012, 12:50 PM
The P0171 is, more often then not, caused by a dirty mas airflow sensor. It is easy to remove and clean so it should be your 1st line in diagnosis. Make sure you clean the 2 hot wires inside the sensor as they are the most important, just cleaning the temp probe will not do the job. Next, 4runner and Tacoma vehicles are common to have high milage fuel pump failures. As mentioned, inspect fuel pressure with a gauge. Find the root cause of the p0171 1st, I doubt there any other issues. If you can get a scan tool on the vehicle, check the data list and inspect ECT and IAT.

TIMZTOY
02-13-2012, 11:39 PM
check for vauume leaks. cold motor and also after heat soaking, several ways to check. visual and spray some intake or starter fluid.. bla bla bla

i also would reccomend getting ahold of a lazer thermometier and after the car is hot while running normally, check the temp of the exhaust infront of and after the cats.. and also check after heat soaking when the car is acting up..

in a jist cats might be bad

Gerdo
02-14-2012, 09:07 AM
I probably have fixed the P0171.
I cleaned the snot out of the MAF, it was visibly dirty.
Also I noticed that I MAY have left the breather/vac line off the intake when I was last working on it. (OK, I did leave it off by mistake, my bad).

Po Boy 80
02-20-2012, 09:33 PM
Hello,

I am the neighbor Corbet mentioned. I have had a certified Mechanic tell me that the ECM is commanding 9 milliseconds of injector pull when hot. This is causing flooding. The MAF has been cleaned as well. It was really bad thanks to a K&N. Next thought is to check the Carbon filter for me. Fuel pump has been replaced prior. Not that... According to some reliable info there are 2 sensors to check too. One for the gauges and one for the computer. I have not checked these yet but need to. Guess it is time to find a FSM for the Taco now................. Any one know where?
This has been very frustrating and apparently well documented on line, according to my mechanic. People have spent fortunes chasing this. I can't bring myself to writing a blank check to the dealership, which was where I was told to go. I have been dealing with it now for a year.:confused:
Mine will start just fine when cold or has sat for 2 hours. It will restart most of the time if I turn it off for just enough time to fill the tank. If I wait for 20 to 30 minutes though, forget it. :rant:

JadeRunner
02-20-2012, 10:36 PM
Sorry to hear about your troubles. I haven't had those issues. I do remember having to replace my MAF sensor. Over oiling my oil filter really damaged it early on. Cleaning it wouldn't resolve code issues permanently. Can't remember if it was a PO171.

Good luck.

TIMZTOY
02-20-2012, 11:14 PM
It definitely has to do with heat.
Today I packed snow on my crank position sensor and it definitely shortened the cranking time.

if what you say is true. Then start there. You need to get a DVOM and prob into the crank sensor and read the signal when cold. Then let it heat soak and read signal. Compare the two. If out of spec. Replace the sensor.

Gerdo
02-29-2012, 09:47 AM
I replaced the fuel pump yesterday. I gave it a 5% chance of success. So far so good.

Red_Chili
02-29-2012, 09:52 AM
You may also need to clean your IAC unit on the bottom of your throttle body. (Idle Air Control).

thefatkid
02-29-2012, 10:44 AM
I replaced the fuel pump yesterday. I gave it a 5% chance of success. So far so good.

Were your fuel pressures off? Drop pressure when you shut the truck off? That is a lot of money to throw at a problem without knowing for sure.

TIMZTOY
02-29-2012, 11:47 AM
Were your fuel pressures off? Drop pressure when you shut the truck off? That is a lot of money to throw at a problem without knowing for sure.

agreed

Gerdo
03-07-2012, 10:49 AM
After a week or so all is good, it fires up instantly everytime!