High idle speed
Discussion
Do you have your old stepper motor cone to check with,
Clearly if it’s the wrong size or to small it won’t plug the hole so you’ll have excess air mixing with the fuel soon as the lambdas warm up they then detect lean mixture and close the steeper some more to compensate. If it reads zero you clearly hsve a problem.
If the arm is not the same length this will also cause a confusion in the steppers position.
I tried after market stepper and it didn’t work properly.the cone was different and I even tried using the arm and cone from the original but high idle or erratic idle was always there. At that time I only had Ecu mate so the stepper comes up as a set of numbers, these numbers never matched up to what was normal operation when stepper played up, ( out of sync )
It would work fine then stick for just a short time and car ran erratic again. I never did overcome it and what you need is a known working stepper off another Tvr to really be sure it’s actually this and not another vacuum leak or something else causing this high idle.
Your tickover speed will be effected by the timing so it’s important to sort that out as soon as possible. You can set it by ear but you’ll not hear full load pinking until going up a hill and even then much of this pinking will be inaudible from within the car so setting it with a strobe light in the first instance vital I’d have thought.
Clearly if it’s the wrong size or to small it won’t plug the hole so you’ll have excess air mixing with the fuel soon as the lambdas warm up they then detect lean mixture and close the steeper some more to compensate. If it reads zero you clearly hsve a problem.
If the arm is not the same length this will also cause a confusion in the steppers position.
I tried after market stepper and it didn’t work properly.the cone was different and I even tried using the arm and cone from the original but high idle or erratic idle was always there. At that time I only had Ecu mate so the stepper comes up as a set of numbers, these numbers never matched up to what was normal operation when stepper played up, ( out of sync )
It would work fine then stick for just a short time and car ran erratic again. I never did overcome it and what you need is a known working stepper off another Tvr to really be sure it’s actually this and not another vacuum leak or something else causing this high idle.
Your tickover speed will be effected by the timing so it’s important to sort that out as soon as possible. You can set it by ear but you’ll not hear full load pinking until going up a hill and even then much of this pinking will be inaudible from within the car so setting it with a strobe light in the first instance vital I’d have thought.
e635815 said:
Two years down the line and I am still having issues (well, a house construction prevented me from fiddling with the car).
This is where I am at the moment:
- car stationary in the garage
- ECU seeing 0 rpm on the Rovergauge
- TPS at around 11% absolute (0% corrected)
- base idle speed is around 700 rpm with hose clamped
- Everything reconnected, I start the engine and idle speed goes flying past 2000rpm
- After a considerable time, speed goes down to about target idle (around 900 rpm)
- idle stepper motor is clean and it works when disconnected (see above, it comes from a LR distributor)
- When stepper is disconnected and engine warm, idle speed just about stays at the minimum when starting the engine.
What's going on here, does anybody can shed some light on this issue?
Firstly you should have an RPM reading in RoverGauge- this is fundamental to getting the idle correct. Mind you the car would not run at all if it was not getting an RPM signal, but this is very odd. How does the megajolt feed the RPM signal to the ECU? Also what is the target RPM in RoverGauge, and is the ECU getting into idle mode? Try twisting the TPS a bit to try and get the reading below 10% as well. There are some fundimental things here that dont tally- if the stepper is at 0, then the car should be running on base idle only as the air feed is completely shut off. You could test this by using rovergauge to shut the stepper fully with out running the engine (ignition on only) and then disconnect the air feed to the stepper and try blowing into it and see if air gets into the plenum. You have a mechanical issue if it does.This is where I am at the moment:
- car stationary in the garage
- ECU seeing 0 rpm on the Rovergauge
- TPS at around 11% absolute (0% corrected)
- base idle speed is around 700 rpm with hose clamped
- Everything reconnected, I start the engine and idle speed goes flying past 2000rpm
- After a considerable time, speed goes down to about target idle (around 900 rpm)
- idle stepper motor is clean and it works when disconnected (see above, it comes from a LR distributor)
- When stepper is disconnected and engine warm, idle speed just about stays at the minimum when starting the engine.
What's going on here, does anybody can shed some light on this issue?
There is an excellent bit on idle control in the ECUmate manual- page 38 onwards
http://ecumate.com/docs/Ecumate%20inst.pdf
Edited by blitzracing on Thursday 26th April 10:45
How stupid I am.... Just read again my text and realized I spoke about rpm when I meant car speed.
The engine speed is seen by rovergauge and is realistic (set idle speed around 900 rpm).
I'll check tonight the "blow in the pipe" trick.
Also, I'll try and twist the throttle pot to go below 11% and I'll report out the findings.
Is it possible that this non OE stepper motor isn't as quick as the OE black plastic one?
The engine speed is seen by rovergauge and is realistic (set idle speed around 900 rpm).
I'll check tonight the "blow in the pipe" trick.
Also, I'll try and twist the throttle pot to go below 11% and I'll report out the findings.
Is it possible that this non OE stepper motor isn't as quick as the OE black plastic one?
Philippe although this might be difficult to understand English not being your first language I presume but please read from page 37 onwards from what Blitz has posted up from Ecu mate manual.
Just going round in circles mate.
That complete manual is worth a read to anyone wishing to understand the Cux system and self diagnose problems associated with it.
Just going round in circles mate.
That complete manual is worth a read to anyone wishing to understand the Cux system and self diagnose problems associated with it.
Yep, I've had a close look at the ECUmate manual (thanks for the link by the way).
But doesn't help me yet since my measurements don't correspond to what is described in the manual.
Let me explain what I did tonight:
1) I closed the stepper completely and tried blowing in the pipe: impossible to pass any air through.
2) I opened the stepper motor and blew again in the pipe. Free flow of air to the engine.
3) Checked my advance and I have ~23° BTDC at idle speed given by the Megajolt
4) With the stepper disconnected and pipes plugged, I set the base idle to ~575 rpm
5) Then I reconnected the pipes and stepper and started the engine. The stepper doesn't open fully as it did before. Previously, it would open to 100% whenever I would stop the engine. This time it stays at around 25% opening. As a result, the idle speed doesn't climb as much as before even though it still goes towards 2k rpm before settling down (engine warm) with a delay (5s). Target idle is 900 rpm
But doesn't help me yet since my measurements don't correspond to what is described in the manual.
Let me explain what I did tonight:
1) I closed the stepper completely and tried blowing in the pipe: impossible to pass any air through.
2) I opened the stepper motor and blew again in the pipe. Free flow of air to the engine.
3) Checked my advance and I have ~23° BTDC at idle speed given by the Megajolt
4) With the stepper disconnected and pipes plugged, I set the base idle to ~575 rpm
5) Then I reconnected the pipes and stepper and started the engine. The stepper doesn't open fully as it did before. Previously, it would open to 100% whenever I would stop the engine. This time it stays at around 25% opening. As a result, the idle speed doesn't climb as much as before even though it still goes towards 2k rpm before settling down (engine warm) with a delay (5s). Target idle is 900 rpm
Edited by e635815 on Thursday 26th April 18:49
The situation seems to have improved a little bit but still getting high idle for a longer time than expected.
Now the second issue. The throttle pot....
When the throttle is shut, I am supposed to measure around 0,3V between the brown and green wires. When fully open, max voltage should be measured (5V).
I get exactly the contrary.
4,84V between the Brown and Blue wire is the max I can get and this value stays constant across operation.
When the throttle is shut, I get 4,56V between the Brown and Green wires (0,28V difference)
And when fully opened, I get 0V reading across the two wires.
Seems like my throttle pot operation is reversed. According to many different posts, if the nominal value is different from 0,35V, this can play awoc on the idle speed.
What's going on here with my reversed voltage reading?
Now the second issue. The throttle pot....
When the throttle is shut, I am supposed to measure around 0,3V between the brown and green wires. When fully open, max voltage should be measured (5V).
I get exactly the contrary.
4,84V between the Brown and Blue wire is the max I can get and this value stays constant across operation.
When the throttle is shut, I get 4,56V between the Brown and Green wires (0,28V difference)
And when fully opened, I get 0V reading across the two wires.
Seems like my throttle pot operation is reversed. According to many different posts, if the nominal value is different from 0,35V, this can play awoc on the idle speed.
What's going on here with my reversed voltage reading?
Is the idle starting at 2000 rpm then dropping to 800-900 really a problem?
My standard 500 Griffith engine has always started at a higher rpm and then dropped to around 800 rpm ever since owned ( 16 years) and I never considered it a problem as the engine is otherwise fine.
I always isolate the electrics when garaged so the ECU will lose any references. I put it down to the ECU learning from the sensors on fresh start up but I stand corrected if this is incorrect.
My standard 500 Griffith engine has always started at a higher rpm and then dropped to around 800 rpm ever since owned ( 16 years) and I never considered it a problem as the engine is otherwise fine.
I always isolate the electrics when garaged so the ECU will lose any references. I put it down to the ECU learning from the sensors on fresh start up but I stand corrected if this is incorrect.
Interesting indeed. Since I had the battery disconnected while rebuilding the alternator on my 4.3 she now hunts a bit of start up then revs for a short while before settling down. This is on the initial start up of the day seems to be OK after that at least today she was. Will see how she starts again in the morning.
She was fine as Mat checked her over and reset her idle as she stalled on me three times on the Saturday Burghley BHP run out.
She was fine as Mat checked her over and reset her idle as she stalled on me three times on the Saturday Burghley BHP run out.
You really cant have the TPS wired backwards- the ECU would be chucking out TPS error codes, and I assume RoverGauge shows it going from minimum to maximum as you depress the throttle pedal? You can cheat if you want to hold the idle down by putting some sort of air restriction in the air feed pipe to the stepper. One of the TVR parts suppliers even had some made up- it was just a bit of metal rod that fitted in the pipe with a hole drilled in it. The size of the hole determines the peak RPM the engine can reach when cold and the stepper is wide open- I have about 6mm in my head as a starting point. I have to admit I have a small metal spacer fitted to the shaft on my stepper motor, so it wont fully retract that does the same thing. This means the engine never goes beyond 1000 RPM even when cold.
Mark,
That was exactly my feeling. I bought the car that way and I have never touched the TPS. And Rovergauge shows the throttle going from minimum to maximum. But it doesn't seem to bother you that I am measuring the contrary as what is written everywhere, does it?
In the ECUmate manual it is written that if the TPS voltage when closed is lower than 0,35V, the stepper reacts slower than usual. What I am supposed to do with this information? Can I twist the TPS position until reaching 4,49V (4,84-0,35) when closed ?
I am about to burn that damn thing down..... no, kidding of course!
Thanks
Philippe
That was exactly my feeling. I bought the car that way and I have never touched the TPS. And Rovergauge shows the throttle going from minimum to maximum. But it doesn't seem to bother you that I am measuring the contrary as what is written everywhere, does it?
In the ECUmate manual it is written that if the TPS voltage when closed is lower than 0,35V, the stepper reacts slower than usual. What I am supposed to do with this information? Can I twist the TPS position until reaching 4,49V (4,84-0,35) when closed ?
I am about to burn that damn thing down..... no, kidding of course!
Thanks
Philippe
Edited by e635815 on Friday 27th April 21:25
Edited by e635815 on Friday 27th April 21:25
Put the multi tester away at this point, and just use what Rovergauge is telling you. Just twist the TP slightly so it reads less than 10% when shut, and the car shows idle mode when ticking over, nothing more. If you can get to this stage, and you are still unhappy about the start up RPM, then put in a restrictor in the stepper air feed. You can use a plumbing gate valve, so you can alter the air feed to suit, but just be aware that if you cut the stepper feed pipe to fit one, you may not be able to get a new replacement pipe in the future.
A friend of mine fitted a megajolt to his car, and had idle problems like you , although I never had the chance to find the route cause as he was based in the Netherlands.
A friend of mine fitted a megajolt to his car, and had idle problems like you , although I never had the chance to find the route cause as he was based in the Netherlands.
Edited by blitzracing on Saturday 28th April 07:04
Not sure if OP is still here and still has high idle problem ?
After a similar issue I have finally fixed mine, it was vacuum leaks found by the use of a smoke leak detector.
Worth a try I'd say.
Have a look here
https://www.pistonheads.com/gassing/topic.asp?h=0&...
After a similar issue I have finally fixed mine, it was vacuum leaks found by the use of a smoke leak detector.
Worth a try I'd say.
Have a look here
https://www.pistonheads.com/gassing/topic.asp?h=0&...
Yep, still here but I have cured my idling problem.
Someone sells a restrictor somewhere over the internet for the pipe that runs to the stepper motor.
With it fitted, the idling speed is reduced by the correct amount to be bearable.
The only downside is with a cold engine, you need to play with the accelerator to maintain idle speed. But who drives a TVR in winter, huh?
Since then, I have tweaked, replaced and worked on soo many places on the car that I can't confirm the problem went away or is just hidden by the restrictor.
Someone sells a restrictor somewhere over the internet for the pipe that runs to the stepper motor.
With it fitted, the idling speed is reduced by the correct amount to be bearable.
The only downside is with a cold engine, you need to play with the accelerator to maintain idle speed. But who drives a TVR in winter, huh?
Since then, I have tweaked, replaced and worked on soo many places on the car that I can't confirm the problem went away or is just hidden by the restrictor.
Been reading this thread with interest as I just acquired a V8S.
This might be absolute b
ks but bear with me (or feel free to shoot down in flames)
What the OP is describing sounds to me like normal operation of the cold start function
As I understand it there is an additional ‘cold start’ injector driven by a thermotime switch. With a cold engine this provides extra fuelling for start up, and this will cause a high idle (c2000) as described. Effectively this is a version of automAtic choke, for those old enough to remember such things.
With a warm engine the extra injector is triggered from the starter circuit, so I see a short burst of high idle and then the stepper motor takes over and controls idle, settling down over a short period.
Btw, what a brilliant thing Rovergauge is, I have been tying it out and already producing nice logs in graph form…
This might be absolute b
ks but bear with me (or feel free to shoot down in flames)What the OP is describing sounds to me like normal operation of the cold start function
As I understand it there is an additional ‘cold start’ injector driven by a thermotime switch. With a cold engine this provides extra fuelling for start up, and this will cause a high idle (c2000) as described. Effectively this is a version of automAtic choke, for those old enough to remember such things.
With a warm engine the extra injector is triggered from the starter circuit, so I see a short burst of high idle and then the stepper motor takes over and controls idle, settling down over a short period.
Btw, what a brilliant thing Rovergauge is, I have been tying it out and already producing nice logs in graph form…
Edited by RayTVR on Wednesday 13th October 18:23
RayTVR said:
Been reading this thread with interest as I just acquired a V8S.
This might be absolute bks but bear with me (or feel free to shoot down in flames)
What the OP is describing sounds to me like normal operation of the cold start function
As I understand it there is an additional ‘cold start’ injector driven by a thermotime switch. With a cold engine this provides extra fuelling for start up, and this will cause a high idle (c2000) as described. Effectively this is a version of automAtic choke, for those old enough to remember such things.
With a warm engine the extra injector is triggered from the starter circuit, so I see a short burst of high idle and then the stepper motor takes over and controls idle, settling down over a short period.
Btw, what a brilliant thing Rovergauge is, I have been tying it out and already producing nice logs in graph form…
Not wishing to shoot anyone down BUT no the extra injector is only on the earlier 3.5s with the 'Flapper' air flow meter and earlier ECU.This might be absolute b
ks but bear with me (or feel free to shoot down in flames)What the OP is describing sounds to me like normal operation of the cold start function
As I understand it there is an additional ‘cold start’ injector driven by a thermotime switch. With a cold engine this provides extra fuelling for start up, and this will cause a high idle (c2000) as described. Effectively this is a version of automAtic choke, for those old enough to remember such things.
With a warm engine the extra injector is triggered from the starter circuit, so I see a short burst of high idle and then the stepper motor takes over and controls idle, settling down over a short period.
Btw, what a brilliant thing Rovergauge is, I have been tying it out and already producing nice logs in graph form…
Steve
RayTVR said:
Been reading this thread with interest as I just acquired a V8S.
This might be absolute bks but bear with me (or feel free to shoot down in flames)
What the OP is describing sounds to me like normal operation of the cold start function
As I understand it there is an additional ‘cold start’ injector driven by a thermotime switch. With a cold engine this provides extra fuelling for start up, and this will cause a high idle (c2000) as described. Effectively this is a version of automAtic choke, for those old enough to remember such things.
With a warm engine the extra injector is triggered from the starter circuit, so I see a short burst of high idle and then the stepper motor takes over and controls idle, settling down over a short period.
Btw, what a brilliant thing Rovergauge is, I have been tying it out and already producing nice logs in graph form…
A Rover V8 with Hotwire and 14CUX employs a double injector firing rate strategy during cranking and cold start to do the 'auto choke' thing. This lasts for about 3 seconds. There are no extra injectors, just the standard eight.This might be absolute b
ks but bear with me (or feel free to shoot down in flames)What the OP is describing sounds to me like normal operation of the cold start function
As I understand it there is an additional ‘cold start’ injector driven by a thermotime switch. With a cold engine this provides extra fuelling for start up, and this will cause a high idle (c2000) as described. Effectively this is a version of automAtic choke, for those old enough to remember such things.
With a warm engine the extra injector is triggered from the starter circuit, so I see a short burst of high idle and then the stepper motor takes over and controls idle, settling down over a short period.
Btw, what a brilliant thing Rovergauge is, I have been tying it out and already producing nice logs in graph form…
Edited by RayTVR on Wednesday 13th October 18:23
For markets where minimum climate temperatures fall below -18°C an additional strategy is used during cold start where the injector pulses are formed as micro-pulses and timed directly by RPM to aid atomization.
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