ECU stupid or clever ?

[WokingWedger]

A few weeks ago I fitted a stepper hose Restrictor, which has been working a treat, much easier to drive and no revs hanging. I used the SC kit and had to open the hole up a bit.

Just today the revs were hanging high again. How ? Can the ecu learn to open the stepper motor more after a while ?

After approx 20 mins of urban driving the car tried to cut out when stationary for a few mins ( had to hold the revs up) but then settled back to high revs scenario.

I will clean the stepper when things have cooled down, but it was done not to long ago.

Thoughts anyone ?

[WokingWedger]

blitzracing said:

The stepper restrictor is a really bad idea- something else is wrong. This could be base idle as already suggested, air leak in the plenum, wrong throttle pot setting, wrong speed input, wrong temp reading. The ECU will control the idle quite nicely if everything is in order.

Well you have changed your tune ! (Your post 17th Jan 2008). Excuse the pun (tune)

With out restrictor , It runs as per everybody else's (holds 1200 rpm for a few secs) and I hate it !

[WokingWedger]

If I could just find my Rovergauge cable and remember how to use it I could check a few things, but Isn't it generally agreed that the ECU holds the revs 'by design' hence its fitted with a road speed input.

[WokingWedger]

Pupp said:

I never did resolve it (the restrictor trick did provide a mostly effective workaround) and it did spoil enjoyment of the car for quite a while.

Suspect those that have not experienced it just do not drive enough miles to encounter the triggering conditions

Did the restrictor work permanently for you or was it only temporary or a stop gap until going aftermarket ECU anyway.

[WokingWedger]

Englishman said:

Pupp said:

The hanging idle glitch was *the* determining factor for me in deciding to junk the Lucas ECU and go aftermarket.... I chased the problem around for literally months and do recall reading more than once from those that know the system initately that there was accepted to be an issue with the ECU code that caused this in certain conditions even with all sensors inputting correctly. I never did resolve it (the restrictor trick did provide a mostly effective workaround) and it did spoil enjoyment of the car for quite a while.

Suspect those that have not experienced it just do not drive enough miles to encounter the triggering conditions

Would you expect to experience it in over 200,000 miles/30 years of driving in RV8 based TVR's? Had stepper motor sticking issues a few times but never had a high idle issue that couldn't be resolved.

You NEVER came to a stop at traffic lights and felt the revs are to high for a few secs? NEVER?

Or when slowing down in gear felt the car pulling instead of slowing ,or noticed the revs dont drop enough when changing gear, none of this ?

If you have never experienced it, you are very lucky, or if you have and have 'fixed it, then yes seriously, any pointers as to what to check would be gratefully received.

[WokingWedger]

blitzracing said:

Steve Heath covered the idle control in depth in the ECUmate manual, and explains why you get the wrong step down rate if one of the settings is wrong. read page 37 onwards:

http://ecumate.com/docs/Ecumate%20inst.pdf

Yes its a good write up, thanks.

I note he also says 'When the car stops, the road speed signal will
also stop and about 2-3 seconds later the ECU will enter idle mode
and start to reduce the engine revs.'

This is what is annoying. This delay, and when crawling at 5 mph having high revs.

He also states 'When the throttle is released, the ECU will not attempt
to bring down the revs because the car is moving.
This means that the revs are kept higher during a gear change to help
prevent rear wheel lock up and that the ECU will only go down to
the low idle speed if the throttle is below the idle threshold and there
is no road speed signal.'

I don't want the revs held high when changing gear ! If I did I wouldn't bother taking my foot off the throttle.

Both the above are by design when everything is working as it should.

Its far from ideal !


I cleaned my stepper (plunger plug and orifice) and it was a bit sooty, but not bad.