Stop technology....help please

[Jon Brown]

Hi guys, Finally getting a chance to use the car this year, after limited use last year. However Trevor seems to be jealous of these modern cars with the stop start tech and often cuts out at junctions

Normally this is when sitting at idle and it starts to slowly vary (almost coughing) its idle and die, this is pretty much the only issue it has and would love to get it sorted.

Any ideas? I had previously cleaned the stepper motor to no real effect

[shake n bake]

Can you hear the stepper winding open when the engine is turned off?
It could be lots of things, an air leak somewhere, base idle set too low, a few things to consider unfortunately.

[Jon Brown]

Yeah, can definetly hear it when I switch the car off. Don't think there are any air leaks, could be the base idle I guess

[shake n bake]

Probably not just base idle as it was ok before I assume? When did it last have a set of plugs? It'll be something simple.
Do you have any TVR chums locally you can borrow there stepper motor to try it?

[QBee]

Calling all Surrey TVR owners.......TVR In a surrey state needing your help.

[QBee]

I agree with trying another stepper.....I had weeks of this issue, despite cleaning the stepper and trying loads of other things. Mine was cured by......changing the stepper. It had become heat sensitive.

[Jon Brown]

Don't anyone locally but a new one wouldn't hurt. I'll give that a go, thanks

[blitzracing]

Jon Brown said:

Normally this is when sitting at idle and it starts to slowly vary (almost coughing) its idle and die, this is pretty much the only issue it has and would love to get it sorted.

Coughing? Anything that causes the idle to drop faster than the ECU programming expects like a misfire or poor mixture will cause the ECU to loose tick over stability. Try and get a point when the engine is warm and the idle is stable, then unplug the stepper (when running). Now take it for a run and see how it idles- it should be stable if every thing is OK as the stepper is not doing anything. If its still erratic, look elsewhere like ignition or air leaks.

[Oldred_V8S]

Ignition amplifier!

[Jon Brown]

blitzracing said:

Coughing? Anything that causes the idle to drop faster than the ECU programming expects like a misfire or poor mixture will cause the ECU to loose tick over stability. Try and get a point when the engine is warm and the idle is stable, then unplug the stepper (when running). Now take it for a run and see how it idles- it should be stable if every thing is OK as the stepper is not doing anything. If its still erratic, look elsewhere like ignition or air leaks.

Sounds like a plan, job for Saturday I think

Thanks guys, I'll let you know what happens