Slow return to idle

[jimmyV8]

My Griff is quite slow returning to idle when coming to a halt, normally holds around 1500-1800 revs before dropping off to just below 1000. I have cleaned the stepper motor and its housing, but has had no effect. ANything else i could try?

[Barreti]

Sounds like mine. I faffed about with the stepper motor but it had no discernable effect. I just put it down to Thats The Way It Is.

[scoule]

If the battery has been flat or disconnected recently, it might still just be learning how much stepper bypas it needs to get the tickover correct ... Mine is a bit like that after a battery disconnect but learns after a few cold starts.

[TVR Beaver]

Iv'e had this a couple of times... Once I found it was and air leak that we holding it up before it fell back... The next time it was running cold as I had a 'summer' stat in the thing and it was down at 70 deg or so.. end result it was putting the choke on a bit as it thought it was still warming up. Mark Adams set it up following this and he cured this issue also. I now run with a 82 deg stat all year round.... so it may be the cold thats the problem??
Another one is to unplug the ECU for a min or two... this can sometimes clear the problem... Hope this helps... Cheers...

[FlipFlopGriff]

I'm no technical expert but I've been told my idling and stalling issues may be down to a road sensor behind the dash, which feeds back into the ECU. No idea what it looks like so any help appreciated (pre cat). It may either be a loose connection to the sensor or a loose connection inside the box. I have been told it is a Rolls-Royce part.
If anyone has a picture or can identify where to look I'd be grateful.
FFG

[LordGrover]

scoule said:

If the battery has been flat or disconnected recently, it might still just be learning how much stepper bypas it needs to get the tickover correct ... Mine is a bit like that after a battery disconnect but learns after a few cold starts.

Mine's like that. I don't think it's anything to worry about - probably some kind of over-eager anti-stalling setting.

[adam_rbts]

jimmyV8 said:

My Griff is quite slow returning to idle when coming to a halt, normally holds around 1500-1800 revs before dropping off to just below 1000. I have cleaned the stepper motor and its housing, but has had no effect. ANything else i could try?

Could try driving around with the stepper unplugged to identify if that's the cause. Make sure she's warmed up and idling ok before you unplug it..

[zippy500]

As far as I know, if the road speed sensor was at fault, your speedo would be playing up too.

You could try checking the base idle is 2.5 turns up from bottom of it's travel. Some folks have fiddled with these in the past to compensate erratic idle and messed things up a tad. Food for thought.

[adam_rbts]

Quinny said:

Adam are you up for Chatsworth??

Also, I've found the perfect sized innertube to do your main beam lamps if you want some (Plenty left)

Not going to make it I'd forgotten the dates to be honest

I just bought some tube too! I'm sure if anyone has ideas to use up surplus rubber it's you

Edited by adam_rbts on Tuesday 20th April 15:48

[BliarOut]

LordGrover said:

scoule said:

If the battery has been flat or disconnected recently, it might still just be learning how much stepper bypas it needs to get the tickover correct ... Mine is a bit like that after a battery disconnect but learns after a few cold starts.

Mine's like that. I don't think it's anything to worry about - probably some kind of over-eager anti-stalling setting.

I *think* it's by design to prevent rear lockups, the revs drop back to idle in two distinct stages.

[Dungman]

Also had this problem despite a new stepper and resetting the ECU. Answer for me was a household radiator valve spliced into the breather hose to act as a restrictor. This can then be adjusted to your preference. Revs now drop instantly and stay at about 800 - 900 without hunting.

[TVR Beaver]

Dungman said:

Also had this problem despite a new stepper and resetting the ECU. Answer for me was a household radiator valve spliced into the breather hose to act as a restrictor. This can then be adjusted to your preference. Revs now drop instantly and stay at about 800 - 900 without hunting.

??.. Breather hose?.. do you mean the one from the plenum front to the stepper motor housing... and if so, wouldn't the same be achieved by screwing the tickover screw in to restrict the flow in the same way instead of having it set to it's normal setting ??
.
BTW on my car's it's about 8 turns out...

[zippy500]

8, that is rather high.

Should be 2.5

[TVR Beaver]

It's actualy 8 half turns I think, not full ones... so 4 full ones... But you should set it by seting the base idle.. Blocking off the pipe etc... can't remember how you do it now... will have a look...

here ya go:-
You need to set the base idle by bunging of the rubber pipe that leads to the stepper once the engine is warm. Then restart the car and wind the base idle up or down to get about 650 rpm, and make sure this is stable but if it keeps varing you may still have an air leak. Then remove the bung and the tickover should lift a few hundred RPM, depending on the chip mapping.

Edited by TVR Beaver on Wednesday 21st April 09:56