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
Take several steps backwards.
1) Get the paint stripper out and get the timing marks clear and set the timing with a strobe. Messing around with the timing like this could cause pre detonation, and wreck your engine. Its that serious. The idle speed will vary vastly with timing- you must get it correct to get the ECU to work as it should
2) Block of the stepper air feed pipe and check the idle- it should be around 600 rpm. Any more than that you have an air leak or the base idle is wrong.
All the other things you have tried have no bearing on this.
1) Get the paint stripper out and get the timing marks clear and set the timing with a strobe. Messing around with the timing like this could cause pre detonation, and wreck your engine. Its that serious. The idle speed will vary vastly with timing- you must get it correct to get the ECU to work as it should
2) Block of the stepper air feed pipe and check the idle- it should be around 600 rpm. Any more than that you have an air leak or the base idle is wrong.
All the other things you have tried have no bearing on this.
on a genuine one sorted it.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?
e635815 said:
Ok, the idle speed is very low with the stepper disconnected.
This is not what Im saying- the stepper simply adds air to the base idle setting, so lets say the base idle with the AIR FEED PIPE to the stepper clamped shut, you need about 600 rpm. The Stepper air feed then adds 2-300 rpms worth of air at idle to bring the idle speed up to around 850 rpm. Typically the stepper is open about 35% to achieve this. To get a stable idle you need:
The correct base idle.
Correct throttle pot setting ( This is the voltage when shut nothing to do with 5 sweeps??)
Correct speed reading to show the car is not moving.
Correct timing and stable timing. (you need to check this with a strobe- no messing about)
No air leaks in the plenum or pipe work.
A working stepper with no air leaks.
A mechanically sound engine and ignition system.
The ECU will try its best to make sure the actual idle matches the target idle, but can only do this when all the other parameters are as they should be.
Ive covered it here- about 1/3 of the way down the page:
http://www.g33.co.uk/fuel_injection.htm
Edited by blitzracing on Tuesday 5th July 10:20
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
e635815 said:
.....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........
This is basically what you said before but is not the correct way to set the base idle.And the engine holds that point without problems........
You need to disconnect the pipe between the idle valve and the side of the throttle body. Do this at the throttle body and plug both ends (the end of the pipe going to the idle valve and the metal pipe into the throttle body).
You do not need to electrically disconnect the stepper because it is no longer seeing any airflow.
Now using the screw on the throttle body set the base idle to 600rpm.
When you reconnect all the pipework the stepper should then control the idle to 850/900rpm.
Steve
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?
There is a rubber tube running from the stepper motor housing to the plenum intake. I use molegrips and a rag or two to prevent damage, and crimp it shut when I set the base idle.
It must be done with the engine fully warm. I'm sure most people know this but if not, it'll be set up wrong.
It must be done with the engine fully warm. I'm sure most people know this but if not, it'll be set up wrong.
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.
e635815 said:
.......I have followed Blitz's troubleshouting guide, disconnected the rubber pipe going to the stepper and blocked the circuit.
Have you blocked the rubber pipe and the metal tube you disconnected it from?e635815 said:
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........
It may be reluctant to start but once it is started and, as you say, running at a low idle that is when you use the bypass screw to bring the idle up to 600rpm. When it is running at 600 you have correctly set the base idle and can connect all the stepper back together.Steve
e635815 when your car's 500 engine was reworked and highly tuned by TVR they set the engine management system's base idle at 800 RPM in the car's ECU and more than likely set the throttle body base idle adjustment also for 800 RPM. I'd try adjusting your base idle for 800 RPM rather than 600, which is the Land Rover setting.
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?
Can you watch stepper motor position pulses on Rover Gauge.
Blitz mentions early on in this thread the stepper position is usually open about 35% to achieve 850 revs idle.
You might need to do a few checks on stepper motor actual position. If you keep getting 2000 revs at start turn engine off which should retract the stepper arm in fully so back to zero and remove it and check if it’s actually gone fully back. If the stepper sticks it can cause this quite easily as the values the computer pulses It in or out are not in line with its actual position.
High idle can only mean to much air.
Set base idle the correct way or your going in circles.
You’ve also moved the distributor about so you need to check timing ASAP.
Goodluck
Blitz mentions early on in this thread the stepper position is usually open about 35% to achieve 850 revs idle.
You might need to do a few checks on stepper motor actual position. If you keep getting 2000 revs at start turn engine off which should retract the stepper arm in fully so back to zero and remove it and check if it’s actually gone fully back. If the stepper sticks it can cause this quite easily as the values the computer pulses It in or out are not in line with its actual position.
High idle can only mean to much air.
Set base idle the correct way or your going in circles.
You’ve also moved the distributor about so you need to check timing ASAP.
Goodluck
The one thing that helped the most with mine was adjusting the TPS by twisting it (you may need to elongate the holes) so that it read 0.32 - 0.34V between two of the wires (sorry, can't remember the colours, but pretty sure it was the two on the left if looking from the rear of the car forwards).
I believe this gave a percentage reading of around 8% - sounds like yours might be a bit off this if it's at 11%.
As mentioned, make sure the base idle is set correctly first and then give this a go!
I believe this gave a percentage reading of around 8% - sounds like yours might be a bit off this if it's at 11%.
As mentioned, make sure the base idle is set correctly first and then give this a go!
GR_TVR said:
The one thing that helped the most with mine was adjusting the TPS by twisting it (you may need to elongate the holes) so that it read 0.32 - 0.34V between two of the wires (sorry, can't remember the colours, but pretty sure it was the two on the left if looking from the rear of the car forwards).
I believe this gave a percentage reading of around 8% - sounds like yours might be a bit off this if it's at 11%.
As mentioned, make sure the base idle is set correctly first and then give this a go!
This is also the place to start. If the readings are high at tickover it will introduce fuel and air thinking throttle butterfly is open... I think I believe this gave a percentage reading of around 8% - sounds like yours might be a bit off this if it's at 11%.
As mentioned, make sure the base idle is set correctly first and then give this a go!
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.
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