Still trying to track down a driveability problem with my 93. Although no code (ODB1) I want to back probe the throttle position sensor while it is plugged in and check the voltage from idle all the way up to wide open. Got my t-pins ready but don't know exactly which holes to probe.

I stripped away a little bit of the weatherproofing and my TPS plug has these wires:
Green (with what looks like a White stripe)
Red
Yellow (with what looks like a White stripe)

I think I need to probe the red wire with the positive probe on the multimeter with the ignition key on, but not sure which one of the other wires to put the negative probe on. Checked some other threads but there are several other color wires mention. Black, Blue, etc. Confused.

edit: make the TPS

 

you can ground out the negative probe to a chassis or battery but with the positive you can try guessing and try it on all 3 wires to check which one gives off voltage.

 

http://hondaswap.com/~pills/obd1guide.html


How to Check the Voltage on your Throttle Position Sensor

After performing a swap, many times the throttle position sensor on the engine is broken, forcing you to use one from your old d15 or d16 (or whichever you pulled). The Honda TPS has three wires coming from it: green/white , a red/blue , yellow/white. Your primary focus will be on the red/blue wire, as this is the one that sends a voltage to the ECU telling it how open or closed your throttle is. The ECU expects .5 volts to be closed throttle and 4.5 volts to be Wide Open Throttle (WOT). The red/blue wire goes to pin D11 at the ECU. Rotating the TPS will change the voltage, when you take it off, you'll notice that the holes are slotted so it can move. If you are fortunate enough to have Hondata Datalogging or an Apexi V-AFC you can use their inbuilt functions to read the TPS voltage. If you do not have such a device, you can use a Voltmeter or similar device. Ground one lead on the chassis somewhere and use touch the (+) lead to the pin on the TPS (should be the center pin) and measure the voltage. Rotate it until it reads .5 volts, then tighten it down. Have a friend press the gas pedal to the floor and also check that WOT reads 4.5 volts.



For those interested with the other two leads, and I know there has to be someone out there. The green/white wire ties into a braided wire with the Intake Air Temp Sensor and the Heated Oxygen Sensor and they all run to Pin D22 on the ECU which is a sensor ground that reads less than 1 volt while the car is started. The yellow/white wire goes to pin D20 on the ECU which is a reference voltage, where it gives about 5v with the Key on and engine off.

 

Thanks much. Finally got it done. Unfortunately, the TPS is not causing the trouble. I put the meter in the windshield and pressed pedal and watched it go from 0.50v all the way to 4.60v in damn near .10v increments as I feathered the gas pedal through the range. Time to focus elsewhere. Next is the EGR valve.

In addition to learning how to check it, one other good thing I learned from fooling with the TPS is that the little T-bar pins I bought from office supply store (Staples) are perfect for back probing. Shove the pin into the round opening beside the wire as far as it will go and it touches current. Then just clip the meter alligator clips to the other end. No need to buy costly special back probe pins.

 

haha i always used the T-bar pins.. never even knew special back probe pins existed. what exactly is the car doing when you say drivability problems???

 

Yeah, they sell them. They have a thin pin that goes into the back of the harness and then a shielded alligator clip on the other end. My multimeter has pins, but they are too big to work on a small plug without damaging it, so I just rigged some small radio shack alligator clips to the tips and then clipped those to the T-bar pins. Had to buy 100 t-bar pins to get 2, haha, but still better than paying $25+ for back probe pins.

Car is bogging when pulling off from a standstill. Disabling kind of bogging. The kind where you have to let it buck along and drift it over to the shoulder because it won't do more than say 10mph while bucking. It doesn not cut off, though. Sit there and rev it up a while and it seems to come out of whatever mode it's in and run okay. I can tell when the car is about to bog because the idle becomes a bit rough and even in neutral revving the motor reveals what feels like a miss but becomes crippling under load. I have driven the car for some miles with no problem and then all of a sudden pulling off from a light, bam, it starts bucking and refusing to go. First I thought it was the cat' converter (original) but had a shop inspect it and it's in good shape.

I think the EGR valve is getting stuck open but I just don't know. I have to get back under the hood and take that valve off and have a look. Got the new egr gasket ready to go but need to find time to take the coil off and make a little room to get to the egr with a wrench. Quite naturally there is no way to put a socket flush on the bolts from up top. The more I mess with this car the more I think a person is foolish to be working on a car without at least one air tool that can get into tight spaces and put some power to bolts that have been in place for many years.

Anyway, I've been reading up on probing and testing the EGR selinoid and stuff but don't yet have a grasp of the procedure, don't have a pump to create vacuum, etc., so I'm gonna just take the valve off and have a look. It's also an original part and if it's badly clogged cleaning it might do the trick. The car probably needs the EGR port plugs pulled and cleaned but I need to find a full day, or more, to try that procedure. I have never done that one before and would have to pull the IACV and FITV valves (I think), to get a clean shot at drilling the ports to tap them. Meanwhile, I try to take as many back roads as I can to get from place to place. Bogging down on a heavily traveled road is hellish. It's a safety risk no matter where it happens.