Hi all, new to the forum and have a quick question. I've done a search on this site and haven't found any info so maybe this will help me out. I got the SES light and pulled the codes (P0120 and P0505). changed the TP sensor, erased the codes and drove for a few seconds and the SES light came back with P0120. The P0505 cleared. The engine also surges by about 500-1000 RPM's without trying to accelerate hard (from 2000 to 2500 or 3000) just about immediately after shifting from 1st gear and seems to drive fine after that. Anyone have any ideas on this?
1999.5 QX4 3.3L with 130K mi.
thanks
99 QX4 P0120 engine code
Re: 99 QX4 P0120 engine code
P0120 TP (Throttle Position) Sensor
The TP may have a loose connection, remove the cable and the connector without breaking it. When removed both the male and female sides need to be cleaned with 1- brake cleaner then 2 contact cleaner and 3 blow both dry with compressed air.
With everything clean and this may take more hands to manipulate the meter probes test all the connections to see that:
The potentiometer is moving up and down.
The switches work for the WOT controlling the transmission.
That all surfaces are clean.
Then re attach the cable and the connector after attaching can you pull it off, if you can make a lock with tie wraps or wire. If the connector has a bad junction the ECU will interpret it as bad solenoids in transmission, bad WOT, bad ratios in speed.
Remember the ECU is not very bright, it just reads what it is given.
The TPS when not stable will cause many reactions and many erroneous readings and will cause you the real interpreter to scratch your head.
All sets of contacts must be secure, must be closed and must not be intermittent.
The TP may have a loose connection, remove the cable and the connector without breaking it. When removed both the male and female sides need to be cleaned with 1- brake cleaner then 2 contact cleaner and 3 blow both dry with compressed air.
With everything clean and this may take more hands to manipulate the meter probes test all the connections to see that:
The potentiometer is moving up and down.
The switches work for the WOT controlling the transmission.
That all surfaces are clean.
Then re attach the cable and the connector after attaching can you pull it off, if you can make a lock with tie wraps or wire. If the connector has a bad junction the ECU will interpret it as bad solenoids in transmission, bad WOT, bad ratios in speed.
Remember the ECU is not very bright, it just reads what it is given.
The TPS when not stable will cause many reactions and many erroneous readings and will cause you the real interpreter to scratch your head.
All sets of contacts must be secure, must be closed and must not be intermittent.
Re: 99 QX4 P0120 engine code
Thanks ARKQX33V6! I'll clean and check.
Re: 99 QX4 P0120 engine code
Sorry for not catching this until i went looking for it, but what/where is the cable and connector located that i need to clean? i only see the two electrical connectors on the TPS. Is this what you are referring to?
Re: 99 QX4 P0120 engine code
By memory, the TPS connector is close to the centre of the engine it is fairly large grey with 3 separate sets of wires.
1-WOT for transmission
2- 3 wires for throttle position,
3- on/off switch
If you have never had this connector off, there may be dust that mixes with other atmosphere pollutants that create havoc with electron movement.
When you remove the plug you may have to break the retainer. If you do you will have to make or buy another retainer. DO NOT OPERATE WITHOUT A RETAINER. The plug will work loose. The 3 different connections can be dislodged and the ECM will indicate a real handful of meaningless warnings.
From your original post these warnings or alarms may be taking place as we write.
When you have the electrics apart, do yourself a favour and examine the Throttle plate for relative position, amount of carbon, clean and check out the EGR and IAC valving for carbon. A good spray with carb or brake cleaner will help.
The EGR may need to be shocked to free any carbon
1-WOT for transmission
2- 3 wires for throttle position,
3- on/off switch
If you have never had this connector off, there may be dust that mixes with other atmosphere pollutants that create havoc with electron movement.
When you remove the plug you may have to break the retainer. If you do you will have to make or buy another retainer. DO NOT OPERATE WITHOUT A RETAINER. The plug will work loose. The 3 different connections can be dislodged and the ECM will indicate a real handful of meaningless warnings.
From your original post these warnings or alarms may be taking place as we write.
When you have the electrics apart, do yourself a favour and examine the Throttle plate for relative position, amount of carbon, clean and check out the EGR and IAC valving for carbon. A good spray with carb or brake cleaner will help.
The EGR may need to be shocked to free any carbon