High idle speed
Discussion
Yes, I know, another High idle speed post....
But I have used the search function and applied everything suggested without success.
Let me explain !
The engine went through a partial rebuilt (well camshaft only….) and upon re-assembly, I have reset the ignition to the best I could. I say the best because I have painted over the timing marks by error. It is now extremely difficult to get the timing straight (as you can understand...
).
Not wanting to dismantle the engine again (Le Mans Classic is coming soon), I have been trying to adjust the distributor by trial and error.
Initially the timing was set with too little advance, the engine would be hesitating a lot, impossible to climb in the rpms but the idle speed was ok.
Then I put more advance. The engine feels much better now without any difficulty to accelerate.
When rotating the distributor to its new position, the idle speed rose quite a lot before the idle control valve managed to regulate.
Ever since, when starting the engine, the idle speed goes to 2000 rpm before dropping down to an acceptable 800-900 rpm.
I had to change the idle control valve because It broke when over tightening it. So a sticky valve is out of the equation.
I did reset the TPS by applying 5 full strokes with the power on.
I did try to reset the idle control valve by powering the engine and removing the connector (as explained somewhere on the forum).
I disconnected the ECU for 5 minutes as well.
I did screw the idle control screw on top of the plenum as well.
The plenum and trumpets have not been removed since I have changed the orientation of the distributor. I don’t think there is any air leak which developed in between the two situations.
And today, the idle speed keeps jumping at 2000 rpm upon startup and hangs there for 20s before dropping down to 900 rpm.
What can I do next?
Thanks
Philippe
But I have used the search function and applied everything suggested without success.
Let me explain !
The engine went through a partial rebuilt (well camshaft only….) and upon re-assembly, I have reset the ignition to the best I could. I say the best because I have painted over the timing marks by error. It is now extremely difficult to get the timing straight (as you can understand...
).Not wanting to dismantle the engine again (Le Mans Classic is coming soon), I have been trying to adjust the distributor by trial and error.
Initially the timing was set with too little advance, the engine would be hesitating a lot, impossible to climb in the rpms but the idle speed was ok.
Then I put more advance. The engine feels much better now without any difficulty to accelerate.
When rotating the distributor to its new position, the idle speed rose quite a lot before the idle control valve managed to regulate.
Ever since, when starting the engine, the idle speed goes to 2000 rpm before dropping down to an acceptable 800-900 rpm.
I had to change the idle control valve because It broke when over tightening it. So a sticky valve is out of the equation.
I did reset the TPS by applying 5 full strokes with the power on.
I did try to reset the idle control valve by powering the engine and removing the connector (as explained somewhere on the forum).
I disconnected the ECU for 5 minutes as well.
I did screw the idle control screw on top of the plenum as well.
The plenum and trumpets have not been removed since I have changed the orientation of the distributor. I don’t think there is any air leak which developed in between the two situations.
And today, the idle speed keeps jumping at 2000 rpm upon startup and hangs there for 20s before dropping down to 900 rpm.
What can I do next?
Thanks
Philippe
Ok, the idle speed is very low with the stepper disconnected. I would say less than 800 rpm.
And you can't really start the engine without opening the throttle. Therefore I don't think there is a leak.
The stepper works perfectly. It is just much quieter than the old one and I couldn't hear it park.
So, the stepper works fine, it just takes 10s + to close the by-pass.
Can it all be due to the ignition timing?
And you can't really start the engine without opening the throttle. Therefore I don't think there is a leak.
The stepper works perfectly. It is just much quieter than the old one and I couldn't hear it park.
So, the stepper works fine, it just takes 10s + to close the by-pass.
Can it all be due to the ignition timing?
I fully understand what you are saying and I am trying to answer your points 1 by 1.
I have disconnected the stepper motor and played around with the bypass screw in order to settle the idle speed to around 7-800 rpm.
And the engine holds that point without problems.
The stepper is a Britpart sold by a Land-Rover parts specialist.
I have conmpared the rod lenght and cone and they do correspond.
I have checked the stepper works by disconnecting its lead when the idle settles down to 900 rpm and it is about 1/3 out.
I will go through the steps you suggest but I just can't do it right now.
Firstly because I don't have any 14CUX diagnostic tool at the moment and the LMC is showing up next WE.
Thanks a lot for your advices.
Regards
Philippe
I have disconnected the stepper motor and played around with the bypass screw in order to settle the idle speed to around 7-800 rpm.
And the engine holds that point without problems.
The stepper is a Britpart sold by a Land-Rover parts specialist.
I have conmpared the rod lenght and cone and they do correspond.
I have checked the stepper works by disconnecting its lead when the idle settles down to 900 rpm and it is about 1/3 out.
I will go through the steps you suggest but I just can't do it right now.
Firstly because I don't have any 14CUX diagnostic tool at the moment and the LMC is showing up next WE.
Thanks a lot for your advices.
Regards
Philippe
I am getting confused with what I am doing right now.
A good night sleep is all what I need.
I have taken the stepper out of the plenum and plugged the hole with a rag thus preventing any by-pass air from being used.
Then have I setup the plenum screw in order to achieve the lowest possible idle speed.
And only then did I remove the rag and plugged the stepper back in.
Therefore, I think I have setup the base idle the correct way.
Can onybody confirm that I need the diagnistic cable + Rovergauge in order to check the points raised by Blitzracing?
A good night sleep is all what I need.
I have taken the stepper out of the plenum and plugged the hole with a rag thus preventing any by-pass air from being used.
Then have I setup the plenum screw in order to achieve the lowest possible idle speed.
And only then did I remove the rag and plugged the stepper back in.
Therefore, I think I have setup the base idle the correct way.
Can onybody confirm that I need the diagnistic cable + Rovergauge in order to check the points raised by Blitzracing?
I am progressing in my quest.
I have fiddled with the speed sensor, tried closing the gap with the toothed wheel and cleaned the electrical connections.
As of today, the engine speed doesn't hold anymore when shifting gear. At least the car can be driven in a normal way.
I have followed Blitz's troubleshouting guide, disconnected the rubber pipe going to the stepper and blocked the circuit.
The engine can't even start. I must lift the throttle a bit. Then, idle speed stabilizes at a very low value before the engine dies --> I don't think there is an air leak in my circuit.
Stepper reconnected and the problem resurfaces: 2000 rpm idle speed for 10s then down to 800 rpm.
I can't go any further without a diagnostic tool.
I have fiddled with the speed sensor, tried closing the gap with the toothed wheel and cleaned the electrical connections.
As of today, the engine speed doesn't hold anymore when shifting gear. At least the car can be driven in a normal way.
I have followed Blitz's troubleshouting guide, disconnected the rubber pipe going to the stepper and blocked the circuit.
The engine can't even start. I must lift the throttle a bit. Then, idle speed stabilizes at a very low value before the engine dies --> I don't think there is an air leak in my circuit.
Stepper reconnected and the problem resurfaces: 2000 rpm idle speed for 10s then down to 800 rpm.
I can't go any further without a diagnostic tool.
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?
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?
I am running megajolt so no distributor anymore.
Base idle is set and stepper fully retracts when ignition is cut.
I can command the stepper using Rovergauge and it moves.
But I don't see 35% when idling, rather 0%. Meaning the stepper has to close completely for achieving idle speed.
Can it be that the cone is too small and the stepper speed too slow? It isn't the OE black unit.
I can log a startup tonight and record the time it takes.
Base idle is set and stepper fully retracts when ignition is cut.
I can command the stepper using Rovergauge and it moves.
But I don't see 35% when idling, rather 0%. Meaning the stepper has to close completely for achieving idle speed.
Can it be that the cone is too small and the stepper speed too slow? It isn't the OE black unit.
I can log a startup tonight and record the time it takes.
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?
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?
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
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.
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