CHALLENGING ALL MECHANICS to figure out this problem

[slicksystem]

Okay guys this is not going to be your simple fix kind of thread. I am a mechanic myself and i cant figure this out.

Problem: Car starts and runs rough (misfiring). Then after car warms up(5-10 min) it shuts off and wont restart until i let it sit overnight. Im running out of possibilities and i cant figure this thing out.also the car shutting off happened after letting the car sit for 2 months.two months later when i came back this problem was here. Im thinking it is a bad ecu.

car: 2000 toyota celica gts (automatic)
engine: 1.8L 2zzge (new re certified engine was recently put in)

1)new fuel pump
2)new thermostat
3)new coils and spark plugs
4)new MAF sensor
5)new water pump
6)new air filter
7)new coolant fluid
8)1 new oil pressure sensor of 2 total
9)new crank position sensor
10)new alternator

any answer you give me please also give me the way to test it. for example if you say it might be a bad iac sensor tell me how to test the sensor to see if it is good or not.

[snshddog]

A plugged up exhaust like a bad cat can do that. Had a corolla that acted like that with a bad cat. Loosten off the exhaust before the cat to see if it runs right as a test. A vacume guage addapted in the O2 sensor port can also tell you. Any pressure is bad. With a long stored vehicle I have seen a massive mouse nest in the muffler do it. Many other possibilities too. Keep us updated.

[slicksystem]

i have no cat i cut it off awhile back and put a o2 sensor simulator to take away the code.

im thinking its gotta be the ecu or the neutral safety switch, but idk how to test either of these and both are very epensive.

what do you think, or do you know of any ways to test these.

[SCJake]

it does sound like it could be the ecu. honestly id go/call in to ur nearest junkyard/crazy rays and see if they got one. if they do its gonna be like 25 bucks. been there done that. tested it and it worked, so i bought a new one and kept the old one as an emergency. sounds like a pain in the ass, and it is, but its worth it if it fixes it

[jdmccright]

The only other thing I can think of might be the engine coolant temp sensor. If it senses the wrong engine temp it will feed the wrong amount of fuel.

[Coralie4grace]

[quote=slicksystem;6851703]Okay guys this is not going to be your simple fix kind of thread. I am a mechanic myself and i cant figure this out.

Problem: Car starts and runs rough (misfiring). Then after car warms up(5-10 min) it shuts off and wont restart until i let it sit overnight. Im running out of possibilities and i cant figure this thing out.also the car shutting off happened after letting the car sit for 2 months.two months later when i came back this problem was here. Im thinking it is a bad ecu.

car: 2000 toyota celica gts (automatic)
engine: 1.8L 2zzge (new re certified engine was recently put in)

1)new fuel pump
2)new thermostat
3)new coils and spark plugs
4)new MAF sensor
5)new water pump
6)new air filter
7)new coolant fluid
8)1 new oil pressure sensor of 2 total
9)new crank position sensor
10)new alternator

any answer you give me please also give me the way to test it. for example if you say it might be a bad iac sensor tell me how to test the sensor to see if it is good or not.

Hi,

Sounds like a timing problem bro....


CG:

[Moppie]

Has to be something temp related.

Either the ecu failing once it's warmed up, temp sensor failing, or an electronic part that fails when it's hot.

E.g. I had a problem with a prelude that would start when cold, but not run once warmed up. A small electronic bit in the dizzy had cracked, the crack expanded when it got hot and the car wouldn't run. Once it cooled down it would run again until it was warm.

[Scrapper]

[quote=Coralie4grace;6873607]

Originally Posted by slicksystem

Okay guys this is not going to be your simple fix kind of thread. I am a mechanic myself and i cant figure this out.

Problem: Car starts and runs rough (misfiring). Then after car warms up(5-10 min) it shuts off and wont restart until i let it sit overnight. Im running out of possibilities and i cant figure this thing out.also the car shutting off happened after letting the car sit for 2 months.two months later when i came back this problem was here. Im thinking it is a bad ecu.

car: 2000 toyota celica gts (automatic)
engine: 1.8L 2zzge (new re certified engine was recently put in)

1)new fuel pump
2)new thermostat
3)new coils and spark plugs
4)new MAF sensor
5)new water pump
6)new air filter
7)new coolant fluid
8)1 new oil pressure sensor of 2 total
9)new crank position sensor
10)new alternator

any answer you give me please also give me the way to test it. for example if you say it might be a bad iac sensor tell me how to test the sensor to see if it is good or not.

Hi,

Sounds like a timing problem bro....


CG:

i never seen where you changed map sensor and are you getting gas and good blue spark all the time? have you done compresson test on all cylinders? i came accross a car that ran good until it set for awhile and it ran good pulled tank down and it was pluged inside tank on the screen and or sock.

[mannasugar]

When the car does not start: are you getting spark out of the coil/ plug wires?

[jgabranski]

Do you have a scan tool? If yes can it watch PID's? (can it see what the sensors are sending the ECU) My money is on the ECU. Sounds like as it warms it goes into closed loop "ECU controled" then drops the ball and stalls. That would also explain why it wont restart. Also, check and ECU relays and fuses for corrosion or defects.
Another thought, what is your fuel pressure look like at key on engine off and at idle?