Idle problems on V8S but any rover V8 knowledge welcome.
Discussion
Hi
I've been having what I think I traced to overfuelling issues especially at start up for a while. Checked and Changed usual suspects and only fault or odd reading on Rover Gauge software was throttle pot. I change this and it seemed ok for a while. I even changed the ECU out for another working one during this process.
Then recently I've had trouble with starting and idling especially when can has been used and is up to operating temp. I used the Rover Gauge software to check the idle control valve and used it to retract it manually (i.e. overriding the ECUs control) to let more air in as an experiment. Its never idled and revved from cold better. So i thought its the valve. I buy a new one, install and reset ECU. It starts and idles fine so i think I've cracked it.
Then the last few weeks its been running terrible and on Tuesday (on way to important hospital appointment of course!) it stalled soon after starting and wouldn't restart. It may have flooded due to lack of air causing lack of ignition so I pulled injector impact sensor out, effectively cutting off the fuel and tried to start. It ran on the residue fuel and pressure for a few seconds then cut out as expected. I then pulled the idle control valve plug out (making it locked fully retracted to provide max air flow) and then it started first time. I ran like this for a bit but idle was at 2000rpm and then starting hunting all over the place. I plugged valve back in and rpm settled back at 950rpm ish which is good. After hospital I started it again and it was awful. Rpm at idle was about 400rpm and nearly stalling. I nursed it home with careful heel toe revving and braking with clutch.
Anyone had anything similar on their V8?
Thanks
Rob
I've been having what I think I traced to overfuelling issues especially at start up for a while. Checked and Changed usual suspects and only fault or odd reading on Rover Gauge software was throttle pot. I change this and it seemed ok for a while. I even changed the ECU out for another working one during this process.
Then recently I've had trouble with starting and idling especially when can has been used and is up to operating temp. I used the Rover Gauge software to check the idle control valve and used it to retract it manually (i.e. overriding the ECUs control) to let more air in as an experiment. Its never idled and revved from cold better. So i thought its the valve. I buy a new one, install and reset ECU. It starts and idles fine so i think I've cracked it.
Then the last few weeks its been running terrible and on Tuesday (on way to important hospital appointment of course!) it stalled soon after starting and wouldn't restart. It may have flooded due to lack of air causing lack of ignition so I pulled injector impact sensor out, effectively cutting off the fuel and tried to start. It ran on the residue fuel and pressure for a few seconds then cut out as expected. I then pulled the idle control valve plug out (making it locked fully retracted to provide max air flow) and then it started first time. I ran like this for a bit but idle was at 2000rpm and then starting hunting all over the place. I plugged valve back in and rpm settled back at 950rpm ish which is good. After hospital I started it again and it was awful. Rpm at idle was about 400rpm and nearly stalling. I nursed it home with careful heel toe revving and braking with clutch.
Anyone had anything similar on their V8?
Thanks
Rob
All of those things. All now fixed. Trouble is I have had so much changed in the past six in the past six months I am not sure what cured the high idle.
Hot stalling was the worst problem to solve, ie not being able to hold any sort of an idle with the engine warm. Tested everything else, had the car fully RR mapped by Mark Adams, guru of the Parish of Rover V8, but still had the problem. He suggested my new throttle might not be perfect in shape, and sent me back to the engine builder. He retested most things, reset one or two, scratched various parts of his anatomy, said "it HAS to be the stepper motor", rooted around in his stores and found a TVR original used one, swapped them over and cured it. Our diagnosis - heat sensitive faulty stepper motor. By the way, I did read on PH that the EBay Chinese import steppers can be faulty when new, so you might not actually have eliminated the stepper by changing it.
The 2000 rpm idle is a b
d when you are trying to crawl in heavy traffic, but when stuck in a half mile queue at roadworks the cycling up and down one is even worse, as everyone within 400 yards stares at you for being "impatient". You can improve the high idle by restricting the pipe that goes from throttle pot to stepper, but that's treating the symptoms, not curing them.
Hot stalling was the worst problem to solve, ie not being able to hold any sort of an idle with the engine warm. Tested everything else, had the car fully RR mapped by Mark Adams, guru of the Parish of Rover V8, but still had the problem. He suggested my new throttle might not be perfect in shape, and sent me back to the engine builder. He retested most things, reset one or two, scratched various parts of his anatomy, said "it HAS to be the stepper motor", rooted around in his stores and found a TVR original used one, swapped them over and cured it. Our diagnosis - heat sensitive faulty stepper motor. By the way, I did read on PH that the EBay Chinese import steppers can be faulty when new, so you might not actually have eliminated the stepper by changing it.
The 2000 rpm idle is a b
d when you are trying to crawl in heavy traffic, but when stuck in a half mile queue at roadworks the cycling up and down one is even worse, as everyone within 400 yards stares at you for being "impatient". You can improve the high idle by restricting the pipe that goes from throttle pot to stepper, but that's treating the symptoms, not curing them.Hi. No I meant the actual electrical plug that fits into the stepper that's fed from ECU. I see the way its written may make you think what you said.
Well I've cleaned it all up and have watched the stepper extend and retract as the ECU tries to control it with the car running and the stepper valve unscrewed so its not the stepper that's sticking as such.
I guess I could try a whole new stepper motor but I got one from here rather than the proper cheap ebay ones.
http://www.lrdirect.com/ETC6660-Stepper-Motor-Sole...
Well I've cleaned it all up and have watched the stepper extend and retract as the ECU tries to control it with the car running and the stepper valve unscrewed so its not the stepper that's sticking as such.
I guess I could try a whole new stepper motor but I got one from here rather than the proper cheap ebay ones.
http://www.lrdirect.com/ETC6660-Stepper-Motor-Sole...
Hi Idle problems on the v8 are common. Invest in an Ecumate from Steve Heath. http://www.ecumate.com/ It will tell you what is going on. I had Idle problems similar to yours and it turned out to be the throttle pot. It was faulty and not letting the ECU go into idle mode. Hence the symptoms you describe. Is your speedo working ok? as the other problem could be the speed sensor, if it thinks the car is still moving it will not put the ECU into idle mode. The ECU mate is a good bit of kit and there are downloadable instructions and an explanation of how the idle system works HTH
Hi
Yes I am familiar with that ECU mate and have read all the instructions as its a great source of knowledge about the fuel injection system and more.
I have rover guage which is similar and shows all the ECU readouts on the laptop. I think its slightly differernt in complete functionality but is still good at watching live simultaneous readout info.
check out this for a screenshot showing the data.
http://alum.wpi.edu/~colinb/images/rovergauge_0.4....
Ive just been out working on car for last 2 hours and playing with stepper motor position and watching its effect on the idling and stalling. Still was playing up after all fiddling had been done.. ah well.
I did find a loose brake servo hose jubilee clip though as it connects onto plenum. I though yes! Its an air leak all along. Tightened it. Same problem. But small mercies, at least the brakes should be better.
Yes I am familiar with that ECU mate and have read all the instructions as its a great source of knowledge about the fuel injection system and more.
I have rover guage which is similar and shows all the ECU readouts on the laptop. I think its slightly differernt in complete functionality but is still good at watching live simultaneous readout info.
check out this for a screenshot showing the data.
http://alum.wpi.edu/~colinb/images/rovergauge_0.4....
Ive just been out working on car for last 2 hours and playing with stepper motor position and watching its effect on the idling and stalling. Still was playing up after all fiddling had been done.. ah well.
I did find a loose brake servo hose jubilee clip though as it connects onto plenum. I though yes! Its an air leak all along. Tightened it. Same problem. But small mercies, at least the brakes should be better.
The software that controls the stepper expects the engine idle to respond in a known manner as the stepper moves- so it sends a series of pulses to the motor then waits a period for the idle to stablise before it applies more pulses. The problem is if something makes the engine RPM move faster than "expected" then the idle control is too slow too respond, so the idle is highly unstable. Things that will make it do this are shifts in mixture (like airleaks) or ignition issues, so you end up chasing your own tail thinking the stepper is at fault, when infact you have a more basic problem. Try unplugging the stepper with the engine warm and running if you can get a stable idle, and then see if the idle remains stable when you drive the car. If it does not, its not the stepper or stepper control at fault.
There is a targer idle icon on RoverGauge that should show you in green when the ecu is in idle mode, ie there is no speed input and the throttle pot is in a closed position. You can also check this with the TP voltage and Speedo readings directly.
There is a targer idle icon on RoverGauge that should show you in green when the ecu is in idle mode, ie there is no speed input and the throttle pot is in a closed position. You can also check this with the TP voltage and Speedo readings directly.
Edited by blitzracing on Thursday 5th September 13:34
Hi
yes, i've tried running engine warm and idling with the stepper in place and plugged in (when it actually can hold an idle) and then disconnected the plug to the stepper. It can then maintain that idle rpm which it should. But then if you drive it its totally fine with the throttle control but starts hunting wildly when stopping at the lights or something. From what you said, the stepper is prob not a fault then?
I'll check what you said about the rover gauge showing idle mode or not. indicated speed on the screen when stopped is zero which would suggest that the speed sensor is functioning ok.
yes, i've tried running engine warm and idling with the stepper in place and plugged in (when it actually can hold an idle) and then disconnected the plug to the stepper. It can then maintain that idle rpm which it should. But then if you drive it its totally fine with the throttle control but starts hunting wildly when stopping at the lights or something. From what you said, the stepper is prob not a fault then?
I'll check what you said about the rover gauge showing idle mode or not. indicated speed on the screen when stopped is zero which would suggest that the speed sensor is functioning ok.
The fact that you can get an idle with the stepper disconnected is a good start, at least you dont have a fundamental mechanical or ignition issue if it idles smoothly- but think of it this way- you have managed to get it stable for a given engine condition and that is now fixed, even if the condition is not correct. Lets say in an ideal world sending 30 stepper pulses will drop the idle by say 150 rpm in 3 seconds, but in your case because lets say its leaning out due to a small air leak, it drops by 300 rpm, so now its below the point of a stable idle. It might stall, or if the ECU catches it in time and opens the stepper the RPM may lift again. This is just the ECU and stepper doing what its programmed to do, so its not the fault.
Try clamping off the air feed to the stepper, and then open up the base idle to say 1200 rpm. Then screw the base idle down slowly and see if the idle drops uniformly. You should be able to drop it down to 6- 700 rpm without the engine stalling (assuming the cam is not too wild!). If it suddenly drops its likely to be an air leak as the mixture becomes too lean to keep the engine running.
Try clamping off the air feed to the stepper, and then open up the base idle to say 1200 rpm. Then screw the base idle down slowly and see if the idle drops uniformly. You should be able to drop it down to 6- 700 rpm without the engine stalling (assuming the cam is not too wild!). If it suddenly drops its likely to be an air leak as the mixture becomes too lean to keep the engine running.
Gassing Station | Chimaera | Top of Page | What's New | My Stuff