bonza
29-11-2012, 01:27 PM
for some time my cruise control has felt odd when travelling along a smooth road at 100 KMH or whatever it is set to. it would surge up and down and you could see the speedo fluctuating 5 KMH or so and looking at my Scangauge II the TPS was also surging in unison
I dont have much experience with cruise but thought maybe a vacuum line to the servo control was damaged. checked out all the lines and all seems ok. besides the air con vents were all working ok to whatever was selected, a sure sign a line is damaged if the blend doors dont work.
spoke to one of my electrical guru peers and he suggested that it could be the Throttle Position Sensor that's causing the surging, even though there was nothing to suggest it was faulty. the Jeep idled nicely and revs were smooth. but ordered a new one anyway, about $60 to my front door and got around to fitting it last night.
after fitting the new TPS started the heep up and the idle started to hunt up and down slightly and I immediately thought maybe I have just fitted a dodgy unit and will have to refit the old one back in. then took it for a test drive and the idle revs were high for a few seconds then would settle down to 750 RPM confirming that maybe the new sensor is dodgy. however, after driving around for about half an hour the idle revs settled to where they should be and there was no engine hunting and all seem to come good
maybe a new TPS has to be adapted to the ECU? who knows, I'm a nuts and bolts spanner man that likes to hit things with a hammer, not a sparkie or computer geek.
anyway, today had to go on a 150K trip, some freeway and plenty of stop and go in traffic
the cruise worked perfectly, no surging and at stop lights idle was a stable 715 RPM with either aircon running or not. no signs of stumble or any problems at all
so it seems a faulty TPS in its early stages can show up on cruise control and it also seems they have to adapt to the ECU before being fully functional
I dont have much experience with cruise but thought maybe a vacuum line to the servo control was damaged. checked out all the lines and all seems ok. besides the air con vents were all working ok to whatever was selected, a sure sign a line is damaged if the blend doors dont work.
spoke to one of my electrical guru peers and he suggested that it could be the Throttle Position Sensor that's causing the surging, even though there was nothing to suggest it was faulty. the Jeep idled nicely and revs were smooth. but ordered a new one anyway, about $60 to my front door and got around to fitting it last night.
after fitting the new TPS started the heep up and the idle started to hunt up and down slightly and I immediately thought maybe I have just fitted a dodgy unit and will have to refit the old one back in. then took it for a test drive and the idle revs were high for a few seconds then would settle down to 750 RPM confirming that maybe the new sensor is dodgy. however, after driving around for about half an hour the idle revs settled to where they should be and there was no engine hunting and all seem to come good
maybe a new TPS has to be adapted to the ECU? who knows, I'm a nuts and bolts spanner man that likes to hit things with a hammer, not a sparkie or computer geek.
anyway, today had to go on a 150K trip, some freeway and plenty of stop and go in traffic
the cruise worked perfectly, no surging and at stop lights idle was a stable 715 RPM with either aircon running or not. no signs of stumble or any problems at all
so it seems a faulty TPS in its early stages can show up on cruise control and it also seems they have to adapt to the ECU before being fully functional