RoverGauge

[Furgie101]

RoverGauge

When the car is idling the Target Idle green light on the RoverGauge isn't on should it be ?

If I lift the throttle just a little then it comes on !

Can I adjust this ?

[Steve_D]

What does RoverGauge show your road speed as?

Steve

[Furgie101]

The MPH is at zero , the car is standing still.

[Furgie101]

And if Its left ticking over after a run for 5 minutes it will put up Fault Code 48 but it hasn't put the code up if its driving along

[davep]

Furgie101 said:

RoverGauge

When the car is idling the Target Idle green light on the RoverGauge isn't on should it be ?

If I lift the throttle just a little then it comes on !

Can I adjust this ?

Normally, the Idle mode/target RPM lamp is On when the ECU is in Idle Mode, as a result the stepper motor is activated until the target idle value is met. To be in Idle Mode the road speed must be 3-4 MPH or lower and the throttle pot must be below a threshold of typically 6%. Your symptoms would seem to suggest that either the TVR road speed signal module is glitching and not sending the correct road speed signal to the ECU, and/or the throttle pot is faulty, hence Fault Code 48.

The road speed signal from the TVR module looks like this:



The signal is simply a Car Moving/Car Stopped indicator, if the ECU fails to receive the part of the signal where it passes 3-4 MPH going towards Car Stopped it will not enter Idle Mode.

If the car is idling as normal and the stepper operating as required and the Idle Mode lamp is Off it could be a connection problem, does the RoverGauge Communications lamp show Red or Green?

[Furgie101]

The Idle Light was on, that was me thinking dark green was on . I have a Throttle Pot reading is 7% and it ticks over at 900 - 950 rev , the car drives OK and Communication light is on. I never moved the car and after about 15 min ticking over it puts up Code 48. Speedo works when driving and goes back to Zero when standing still. You can hear the stepper working.

[davep]

Fault Code 48 means the ECU is trying to get to Target Idle by checking that MAF values are as expected and for one or more reasons it cannot set the stepper motor correctly:


© ECUmate Limited 2012

So consider the usual culprits:

- clean stepper motor
- check base idle
- check for air leaks in the vicinity of stepper motor (wrap the stepper motor thread in PTFE tape)
- check the TVR road speed signal module (provides road speed input to the ECU not the Speedo)
.
.

There's also an explanation here:

https://www.pistonheads.com/gassing/topic.asp?t=11...

Edited by davep on Monday 5th June 12:22

[blitzracing]

Furgie101 said:

The Idle Light was on, that was me thinking dark green was on . I have a Throttle Pot reading is 7% and it ticks over at 900 - 950 rev , the car drives OK and Communication light is on. I never moved the car and after about 15 min ticking over it puts up Code 48. Speedo works when driving and goes back to Zero when standing still. You can hear the stepper working.

The idle is a little high- it should be around 850 rpm max- and you should have a stepper position of about 30% open at the correct idle- so if you are getting that error code I would think the stepper is fully closed, (o%) and the ECU still cant drop the idle down as far as it should. As Dave says- air leaks or wrong base idle are the places to start looking, assuming the stepper is working in the first place. You do have the option to open and close the stepper with Rovergauge to see if you can reduce the idle manually- apply 30 steps should see a significant shift in RPM. You can end up with a tug of war with the ECU, as it does not expect manual intervention, and you may stall the engine, but it will prove if the stepper is working.

[Furgie101]

I have cleaned the stepper motor and put it back with PTEE tape( wasn't dirty) When the engine is warm the stepper can drop to 0% on idle. I have tried the open and closed it on the Rovergauge and it goes from 0% to 100% and you can hear it working. I dropped it to 254 from 255 click and it stopped. so do I drop it to 225 and try it ?

[blitzracing]

The point is here the stepper should never be at 0 at idle- it should be part open (at say 30%) so if the idle is too high (like yours is) it still has room to close the air off a bit- but it cant as its fully closed at 0 %- that's why you have the error. Don't mess around with big stepper moves- just clamp the air feed to the stepper off to stop any air getting to it. If the car is idling above about 600 rpm, the base idle is wrong, or you have an air leak. Basically the base idle is about as low a ticker as you can get reliably, and the stepper then adds extra air to bring it up a few hundred RPM. There are specific base idle settings for different ECU tunes, but the basic principals remain.

[Furgie101]

Ok I will try that. Is there a good way to test for air leaks ?

[Steve_D]

Set the base idle as Blitz says...if you keep winding the screw but the idle won't come down you have an air leak.

Steve

[Furgie101]

Thank you all for your help , I will have a go .

[Furgie101]

Hi, So I have had a go. When the engine was warm I clamped the air feed and turned the idle screw down to the bottom and the engine stopped. I then set the base idle to about 550 revs and released the clamp and it ticker over about 850 revs. The Idle Bypass is up at about 80% when the car first starts and then slowly drops to 0-2 %. If the fan cuts in the Bypass idle goes up to 10% and then comes down again. Should I try adjusting the stepper ?

[Furgie101]

[Dr Mike Oxgreen]

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[blitzracing]

Something does not quite tally here- you should have about 30% on the stepper at desired idle, and yet yours is still too low- ie the stepper is almost completely shut, yet you get a raise in RPM when you un clamp the stepper tube?. It would be an odd fault but it would tend in imply the stepper was not shutting off the air supply when its closed. You should be able to use RoverGauge to close the stepper completely, and you should end up with base idle, but it will only happen for a moment for the ECU takes control again. Have you checked the stepper housing internally where the stepper cone seats into the plenum, or for damage to the stepper cone. I suppose it could be jamming open, but you can test that with RoverGauge.

[Furgie101]

I looked in the whole it all looked clean . This can has a Tornado Chip fitted could the setting be different?

[Furgie101]

I been trying to see if I have a air leak with a smoke tester. Some Smoke is coming out of a little whole under the Throttle pot. Does any one know what the whole is for ?

[blitzracing]

Thats a crank breather, but it should not be leaking- its all balanced just enough to draw fumes from the engine without upsetting the idle airflow. Try winding the base idle down a turn or two and see if the stepper opens up a bit more to lift the idle.