How to check fuel trims on OBD1 cars?
01-03-19, 10:29 AM
#16
Driver School Candidate
DRC10 You are the man, I guess I found the problem. As you mentioned in your post about fuel pressure regulator that has internal diaphragm. I went ahead and checked the vacuum line that is attached to diaphragm, I followed that vacuum line and other end is attached to VSV solenoid . I believe that diaphragm is good but the vacuum solenoid that provides vacuum to the diaphragm is dead.
91 LS400 has two vacuum switching solenoids. One is attached to the EGR system and the other is attached to fuel regulator that has diaphragm.
The part number written on the VSV for fuel system isn't readable. Any one knows the part number?
Regards!
Thanks a lot again DrC10!
91 LS400 has two vacuum switching solenoids. One is attached to the EGR system and the other is attached to fuel regulator that has diaphragm.
The part number written on the VSV for fuel system isn't readable. Any one knows the part number?
Regards!
Thanks a lot again DrC10!
OOPS just saw the last post. I bet it's off to the salvage pool or FleaBay...NLA from my vendors.
Last edited by DrC10; 01-03-19 at 10:31 AM. Reason: added info
01-04-19, 01:14 AM
#18
Intermediate
Thread Starter
Ok, so I did perform the OX1 and OX2 tests but the numbers that I was getting were way higher than 0.9 volts, it was jumping up and down from 45 to 25. Then I looked at FSM which explained how to test O2 sensors while they are installed.
According to factory manual measuring voltage between terminals VF1 (VF2) and E1. VF1 is for left bank and VF2 for right bank. If the voltages is more than 0V then replace the 02 sensors, if not then their is further diagnostic procedure explained for troubleshooting the problem.
What I am getting when I measure the voltage between VF1 and E1 is 0.2V on both banks. When I fired the car, it started showing random numbers. In the FSM, it isn't mentioned if I should perform those test while the car is on or off but anyway I tested it both ways.
According to factory manual measuring voltage between terminals VF1 (VF2) and E1. VF1 is for left bank and VF2 for right bank. If the voltages is more than 0V then replace the 02 sensors, if not then their is further diagnostic procedure explained for troubleshooting the problem.
What I am getting when I measure the voltage between VF1 and E1 is 0.2V on both banks. When I fired the car, it started showing random numbers. In the FSM, it isn't mentioned if I should perform those test while the car is on or off but anyway I tested it both ways.
Now I am confused that how can these two aftermarket Denso sensors can be simultaneously faulty. I replaced those 5 months ago. I wasn't getting any check engine light with my old OEM O2 sensors but I replaced them anyway. I still have those old OEM sensors and I tested the resistance of those with multi meter, from test I found one is bad and other one that was on right bank is giving me 6.3 ohms resistances which indicates that it is still good.
I guess denso aftermarket parts quality is going down the toilet because not too long ago my brand new desno spark plug wire failed, Parts that Denso makes for Toyota are of great quality but their aftermarket parts aren't.
Now one more option is left to make myself completely sure that the sensors I installed are in fact faulty by doing resistance test and for that I have to get under the car in freezing cold weather.
Is there any other way to test 02 sensors without getting under the car?
I guess denso aftermarket parts quality is going down the toilet because not too long ago my brand new desno spark plug wire failed, Parts that Denso makes for Toyota are of great quality but their aftermarket parts aren't.
Now one more option is left to make myself completely sure that the sensors I installed are in fact faulty by doing resistance test and for that I have to get under the car in freezing cold weather.
Is there any other way to test 02 sensors without getting under the car?
01-04-19, 06:40 PM
#19
Ok, so I did perform the OX1 and OX2 tests but the numbers that I was getting were way higher than 0.9 volts, it was jumping up and down from 45 to 25. Then I looked at FSM which explained how to test O2 sensors while they are installed.
According to factory manual measuring voltage between terminals VF1 (VF2) and E1. VF1 is for left bank and VF2 for right bank. If the voltages is more than 0V then replace the 02 sensors, if not then their is further diagnostic procedure explained for troubleshooting the problem.
What I am getting when I measure the voltage between VF1 and E1 is 0.2V on both banks. When I fired the car, it started showing random numbers. In the FSM, it isn't mentioned if I should perform those test while the car is on or off but anyway I tested it both ways.
According to factory manual measuring voltage between terminals VF1 (VF2) and E1. VF1 is for left bank and VF2 for right bank. If the voltages is more than 0V then replace the 02 sensors, if not then their is further diagnostic procedure explained for troubleshooting the problem.
What I am getting when I measure the voltage between VF1 and E1 is 0.2V on both banks. When I fired the car, it started showing random numbers. In the FSM, it isn't mentioned if I should perform those test while the car is on or off but anyway I tested it both ways.
Now I am confused that how can these two aftermarket Denso sensors can be simultaneously faulty. I replaced those 5 months ago. I wasn't getting any check engine light with my old OEM O2 sensors but I replaced them anyway. I still have those old OEM sensors and I tested the resistance of those with multi meter, from test I found one is bad and other one that was on right bank is giving me 6.3 ohms resistances which indicates that it is still good.
I guess denso aftermarket parts quality is going down the toilet because not too long ago my brand new desno spark plug wire failed, Parts that Denso makes for Toyota are of great quality but their aftermarket parts aren't.
Now one more option is left to make myself completely sure that the sensors I installed are in fact faulty by doing resistance test and for that I have to get under the car in freezing cold weather.
Is there any other way to test 02 sensors without getting under the car?
I guess denso aftermarket parts quality is going down the toilet because not too long ago my brand new desno spark plug wire failed, Parts that Denso makes for Toyota are of great quality but their aftermarket parts aren't.
Now one more option is left to make myself completely sure that the sensors I installed are in fact faulty by doing resistance test and for that I have to get under the car in freezing cold weather.
Is there any other way to test 02 sensors without getting under the car?
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