DarenW Posted December 12, 2016 Share Posted December 12, 2016 Last week my battery was flat. After recharging the car would start but wouldn't idle. It was the same whether cold or hot. My throttle body has a stepper motor attached and it would appear that this is the cause of the problem. If the car is running, by holding the throttle open, when you disconnect the stepper motor it then idles fine. As soon as you plug it in again and rev the engine it stalls. Could this be a battery related issue or a stepper motor problem. Any help would be appreciated. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted December 12, 2016 Member Share Posted December 12, 2016 Like this?Jonathan Link to comment Share on other sites More sharing options...
DarenW Posted December 12, 2016 Author Share Posted December 12, 2016 I have read that. I was going to get a new battery tomorrow. I have dismantled the throttle body and have given it a good clean too. Have also tried the reset but that doesn't make any difference. It has to be either the stepper motor or the battery - that's what I think. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted December 12, 2016 Member Share Posted December 12, 2016 Why do you suspect the battery?Quick battery tests: what's the voltage across the battery: At rest, everything off? Minimum during cranking? At 3,000 rpm?Then I'd disconnect, inspect and clean all the relevant connections, including the engine earths and the connector(s) for the TPS.Jonathan Link to comment Share on other sites More sharing options...
Englishmaninwales Posted December 13, 2016 Share Posted December 13, 2016 May be a TPS problem. The early K series TPS associated with the stepper motor TB wear out the internal electrical connections. They are very difficult to obtain but I was informed that Redline have them at £80 I was lucky to pick up a complete TB with a TPS on eBay. Link to comment Share on other sites More sharing options...
TomB Posted December 13, 2016 Share Posted December 13, 2016 £80 isn't too bad for a part that doesnt seem to exist anywhere! I remember seeing them on eBay a few years ago for £120. Im sure I had that problem, but sorted it by fitting a set of SLR throttle bodies! Link to comment Share on other sites More sharing options...
RyCliff Posted December 15, 2016 Share Posted December 15, 2016 I've just had the same problem (1.4K Road-Sport), though it also led to some running problems earlier on too.Took the car into a local specialist who put it down to the same stepper motor. He took it apart and cleaned it up, now it's running perfectly.I had already refurbished the alternator and replaced the battery whilst I was mis-diagnosing the problem.Used to hunt at idle too but that's also fixed with the cleaned up stepper. Now starts quicker than ever on the ignition. Link to comment Share on other sites More sharing options...
TomB Posted December 15, 2016 Share Posted December 15, 2016 Ryan - I bet your both annoyed and relived it was go simple. I bet he just took the TB off (4 bolts, 2 minutes) and gave it a good blasting with carb cleaner. Hope he didn't charge too much! Link to comment Share on other sites More sharing options...
RyCliff Posted December 15, 2016 Share Posted December 15, 2016 I was very relieved- but a bit gutted that I'd missed out on the car running for all that time when all it needed was that.Charged for a couple of hours labour which is reasonable considering it was a bit of fault finding which I haven't got the tools for. He'll have had to mess around unloading it from the trailer too.Got a multimeter at the top of my Christmas list to sort various lights out, going to make a few changes to LEDs I think. Link to comment Share on other sites More sharing options...
DarenW Posted December 15, 2016 Author Share Posted December 15, 2016 I did take the stepper motor out and cleaned it. I also cleaned the throttle body. I think it's a stepper motor related issue as when the car warms up and I can get it to sit around 1k rpm, I unplug the stepper motor and it runs fine without cutting out. I am fitting a new battery (which some say have cured the issue) anyway as mine keeps going flat. If that makes no difference then I will get a new stepper motor. Not sure it's related to the TPS but I will try and borrow one from a mate and swap it over to see if that makes any difference. Link to comment Share on other sites More sharing options...
RyCliff Posted December 15, 2016 Share Posted December 15, 2016 If unplugging the stepper seems to solve the problem, you've probably found the source there. Other symptoms that my car had as well as not idling were struggling to start and the engine cutting out in the manner of the fuel supply being cut. I'm not sure if it's related but the car also used to smell as if it was burning a little rich on the odd occasions I got it running, and fuel consumption was noticeably higher.If the battery has been drained to low capacity levels at any point then it could well be damaged, which won't help the problem. Worth a quick check of voltages if you have a multimeter to hand (though this won't tell the full story on the battery state). Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted December 16, 2016 Member Share Posted December 16, 2016 I am fitting a new battery (which some say have cured the issue) anyway as mine keeps going flat. If that makes no difference then I will get a new stepper motor.I's check the charging (as well as the other voltage tests) before fitting a new battery. That's both because the new battery might not be needed and to make sure it doesn't repeatedly run down the new one.Jonathan Link to comment Share on other sites More sharing options...
DarenW Posted December 23, 2016 Author Share Posted December 23, 2016 Quick update. I managed to find an old Rover throttle body on eBay. It came with the stepper motor and TPS. Replaced the whole unit and it solved the problem. It was more than likely the stepper motor. Link to comment Share on other sites More sharing options...
RyCliff Posted December 23, 2016 Share Posted December 23, 2016 Brilliant, glad you got it sorted. The issues sounded very similar to my car. Hope you can enjoy the car over the Christmas break now! Link to comment Share on other sites More sharing options...
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