ECU programming?

[NicBowman]

Hi, Getting there nearly, for those who read the noise issue last Saturday, it seems induction air casuing the issue, so no panic.

Last problem is tickover, no matter what it seems to want to hold the tickover at 2000rpm until I am stationary. This is a recurring issue amongst TVR's I believe (am I wrong?). Has anyone got ECU source code, so this irritating failure mode can be switched off somehow.

I know I can disconnect teh stepper, but then the car wont start in the cold, and sometimes it is good to have anti stall, but not 2000 rpm!

Any answers (apart from clean the stepper!).

Ta


Nic

[GreenV8S]

NicBowman said:

I know I can disconnect teh stepper, but then the car wont start in the cold, and sometimes it is good to have anti stall, but not 2000 rpm!

Have you actually tried it? Mine no longer has a stepper and it was OK with just a little help needed to keep it going for the first few seconds on freezing cold days.

If you are sure you want to keep the stepper then it may be that you can get rid of the annoying high idle by disconnecting the road speed sensor.

[NicBowman]

Interesting point, I could disconnect it at teh ECU.

Currently, if I disconnet the stepper it will die for a few seconds even starting when hot. But, when actually running hot with no stepper it is much better.

Do you use any throttle on normal cold start?

Ta


Nic

[blitzracing]

NicBowman said:

Has anyone got ECU source code, so this irritating failure mode can be switched off somehow.
Nic

Its very a very old MC6803U4 CPU, and I think its CPU micro code is held separately to the 5 fuel maps and all the trim data, but all on the 2764 or 27128 Eprom. I had simular ideas on patching some of the data, but its not that simple. I however do have the maps in emailable format if you want to try looking at it,and are old enough to remembmer this architecture, but you really however need a Lucas development unit and the associated program alter the various parameters. If its tickover racing, it can just be a stuck stepper, or I read somewhere it will hold the rpm high on the catalyst map if certain faults are detected to preserve the catalyst. You would need a fault code reader to determin this. Personaly I have been running without stepper control at all, by simply blocking of the air feed pipe to the stepper, and turning up the base idle. No problems in the summer, but might no be so good in lower temperatures.

[NicBowman]

Hi

Stepper not stuck as it works fine once the car is stationary. It just wants the tickover high when moving.

Will try the disconnect trick and see if I can get used to it.


Nic

[adyw]

Try the hose at the back of the Plenum by the throttle, I had the same issue and it turned out to be a split in the underside of this pipe leaking air through.

[NicBowman]

Did your car ever idle propery with this air leak? Or always high revs?

Ta

Nic

[BlueArsedFly]

I think I read somewhere it could be the road speed sensor as this allows the ECU to keep up the revs when changing gear. eg http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[Pupp]

Another 'work-round' that is effective, if not actually a cure, is to put a restrictor in the hose that feeds the stepper... on mine, from memory, a plug with a 6mm hole at the 'throttle end' of the hose just lets enough air through to give some cold start boost and a tiny lift on approach to junctions without hanging idle at 2k+. In terms of driving feel, it has transformed the car.

[griffter]

NicBowman said:

Hi, Getting there nearly, for those who read the noise issue last Saturday, it seems induction air casuing the issue, so no panic.

Last problem is tickover, no matter what it seems to want to hold the tickover at 2000rpm until I am stationary. This is a recurring issue amongst TVR's I believe (am I wrong?). Has anyone got ECU source code, so this irritating failure mode can be switched off somehow.

I know I can disconnect teh stepper, but then the car wont start in the cold, and sometimes it is good to have anti stall, but not 2000 rpm!

Any answers (apart from clean the stepper!).

Ta
Nic

Yours is a 4.3 yes?

I put a TVR Power chip in my car - standard 4.3, but I believe a different map to the TVR 4.3 map. The coasting/stationary idle was much much better. However it's going through a phase of holding it high til stationary again now - but only really when warming up. I think the reason the revs are held so high is to prevent shunting and ensure that the engine 'pulls' the transmission when off throttle in gear rather that vice versa.

Edited by griffter on Thursday 25th October 12:32

[trackcar]

Pupp said:

Another 'work-round' that is effective, if not actually a cure, is to put a restrictor in the hose that feeds the stepper... on mine, from memory, a plug with a 6mm hole at the 'throttle end' of the hose just lets enough air through to give some cold start boost and a tiny lift on approach to junctions without hanging idle at 2k+. In terms of driving feel, it has transformed the car.

that's one of my favourite mods .. you allow just enough bleed for say 1200rpm high idle even with the stepper fully open, but it doesn't affect the stepper operation for speeds lower than 1200rpm. it's one of the easiest fixes for problems like this.