Base idle setting and timing
Discussion
I have finally fitted my new fully refurbed distributor and Afm, a new Ecu temp sender, and set the timing at 8 deg static with vacuum disconnected and blanked off.
Then I connected the distributor to full manifold vacuum, timing is now 18 deg at idle and drove it around today and it is indeed very smooth and I am happy with that.
Thing is, while driving it around, the idle is not quite right.
Starting from cold this morning, I had to feather the throttle to stop it stalling and then a minute or so later in settled at around 1500 rpm. A blip on the throttle brings it down to about 1000 rpm and then it climbs back to 1500 rpm and stays there. When I put the distributor in, I set the base idle, clamping the air hose at 600rpm, but with the vacuum off. Is this 1500 rpm idle to do with the extra advance when the hose goes back on?
The stepper was cleaned last week and it responds to RG commands to move it around so I am not sure that is the reason.
So I think it might be that the base idle is now wrong with the higher advance setting.
To set the idle at around 1000 rpm, how do I go about it so that when I connect the vacuum back to full manifold that the resulting idle speed is correct? Won't the stepper keep making other adjustments to meet whatever the ECU has set as a target idle speed?
Then I connected the distributor to full manifold vacuum, timing is now 18 deg at idle and drove it around today and it is indeed very smooth and I am happy with that.
Thing is, while driving it around, the idle is not quite right.
Starting from cold this morning, I had to feather the throttle to stop it stalling and then a minute or so later in settled at around 1500 rpm. A blip on the throttle brings it down to about 1000 rpm and then it climbs back to 1500 rpm and stays there. When I put the distributor in, I set the base idle, clamping the air hose at 600rpm, but with the vacuum off. Is this 1500 rpm idle to do with the extra advance when the hose goes back on?
The stepper was cleaned last week and it responds to RG commands to move it around so I am not sure that is the reason.
So I think it might be that the base idle is now wrong with the higher advance setting.
To set the idle at around 1000 rpm, how do I go about it so that when I connect the vacuum back to full manifold that the resulting idle speed is correct? Won't the stepper keep making other adjustments to meet whatever the ECU has set as a target idle speed?
Personally I did not have to reset the base idle when switching between ported and non ported vacuum, the system coped as it was. Having said that I have reprogrammed my idle anyway to 900 rpm. You do need to program the ECU to do this but is only a single setting you can do with tuner pro and the right hardware. Drop me a mail if you want a chip blown. I dont see a problem if you do want to reset the base idle with the new timing figure- the bottom line is you want a stepper about 30 to 40 % open at the desired idle.
Thank you, Mark, for your kind offer re changing the chip.
The first thing I am going to check is the base idle, using the 'rubber hose bung' in the air hose method, but with the vacuum connected to full manifold this time, as I had originally set it when the vacuum was off and I had set the timing at 8 degrees. If I recall, it was around 2 turns from completely closed. Maybe it needs to be adjusted again with the vacuum connected so that it idles back down to the 950 rpm odd it is supposed to work at.
I would like to play around with it without the stepper motor interfering to see where it is the happiest idling and am wondering if this is possible with the stepper motor connected, so I can see where it is in RG re the 30-40% you mentioned. If it then, say, 1000 rpm that is needed, then we could look at modifying that chip.
So far I have the ECU working with the white tune cat map, but once I set this up and the car is running well, I want to also try out the non-cat map I have and in particular, that map you sent me a few months ago that you have modded for your car.
From the short drive I did yesterday with the full manifold vacuum and white tune, the car feels as smooth as it did on the green tune before on the old distributor, so it will be even more interesting to see how it goes with the non-cat map with my new timing and AFM.
The first thing I am going to check is the base idle, using the 'rubber hose bung' in the air hose method, but with the vacuum connected to full manifold this time, as I had originally set it when the vacuum was off and I had set the timing at 8 degrees. If I recall, it was around 2 turns from completely closed. Maybe it needs to be adjusted again with the vacuum connected so that it idles back down to the 950 rpm odd it is supposed to work at.
I would like to play around with it without the stepper motor interfering to see where it is the happiest idling and am wondering if this is possible with the stepper motor connected, so I can see where it is in RG re the 30-40% you mentioned. If it then, say, 1000 rpm that is needed, then we could look at modifying that chip.
So far I have the ECU working with the white tune cat map, but once I set this up and the car is running well, I want to also try out the non-cat map I have and in particular, that map you sent me a few months ago that you have modded for your car.
From the short drive I did yesterday with the full manifold vacuum and white tune, the car feels as smooth as it did on the green tune before on the old distributor, so it will be even more interesting to see how it goes with the non-cat map with my new timing and AFM.
when I switched to manifold vacuum (std Griff 500) I had to adjust the base idle.
If I recall idle screw went from about 2 turns out to 1 turn out. I recall it was difficult setting up the base idle using the 550 rpm target (engine kept stalling). So I wound in the screw in bit at a time and checked on my ECUmate (initially the stepper was almost fully wound out to its 180 step limit at hot idle, it needs to be around the 160 mark at hot idle no accessories running).
My ignition timing went from 12 deg BTDC static to about 22 at idle. I found it a great mod, engine bay/exhaust system runs a lot cooler at idle and car is just easier to drive at lower speeds, pick up from idle noticeably better.
.
If I recall idle screw went from about 2 turns out to 1 turn out. I recall it was difficult setting up the base idle using the 550 rpm target (engine kept stalling). So I wound in the screw in bit at a time and checked on my ECUmate (initially the stepper was almost fully wound out to its 180 step limit at hot idle, it needs to be around the 160 mark at hot idle no accessories running).
My ignition timing went from 12 deg BTDC static to about 22 at idle. I found it a great mod, engine bay/exhaust system runs a lot cooler at idle and car is just easier to drive at lower speeds, pick up from idle noticeably better.
.
Ozstyle said:
when I switched to manifold vacuum (std Griff 500) I had to adjust the base idle.
If I recall idle screw went from about 2 turns out to 1 turn out. I recall it was difficult setting up the base idle using the 550 rpm target (engine kept stalling). So I wound in the screw in bit at a time and checked on my ECUmate (initially the stepper was almost fully wound out to its 180 step limit at hot idle, it needs to be around the 160 mark at hot idle no accessories running).
My ignition timing went from 12 deg BTDC static to about 22 at idle. I found it a great mod, engine bay/exhaust system runs a lot cooler at idle and car is just easier to drive at lower speeds, pick up from idle noticeably better.
.
I think there is the issue, my idle screw is just over 2 turns so winding it back in to about 1 turn hopefully will fix it.If I recall idle screw went from about 2 turns out to 1 turn out. I recall it was difficult setting up the base idle using the 550 rpm target (engine kept stalling). So I wound in the screw in bit at a time and checked on my ECUmate (initially the stepper was almost fully wound out to its 180 step limit at hot idle, it needs to be around the 160 mark at hot idle no accessories running).
My ignition timing went from 12 deg BTDC static to about 22 at idle. I found it a great mod, engine bay/exhaust system runs a lot cooler at idle and car is just easier to drive at lower speeds, pick up from idle noticeably better.
.
Did any of you find after connecting to full manifold vacuum that the car idled badly during initial cold start up, until it got warm? Starting it from cold, or from say a half an hour stop, it would not start, rev up a little and then settle to its idle speed as it usually does, it would run lumpily for about 30 seconds and then start idiling smoothly, albeit at 1500 rpm.
The only thing I can think of is that if the idle screw is 'way out' perhaps the stepper motor is also confused at start up and doesn't know what to do.
Reading this thread with interest and decided to check my base idle but I can't seem to find an idle adjustment screw on mine in the location pointed to in the Steve Heath book?
Am I being blind?.. or is it possible that later cars (mine's a 1999) don't have the adjustment screw? - The circular protrusion in the casting to the right of the throttle spindle just has a blank piece of metal in it - no screw...
Am I being blind?.. or is it possible that later cars (mine's a 1999) don't have the adjustment screw? - The circular protrusion in the casting to the right of the throttle spindle just has a blank piece of metal in it - no screw...
latham91 said:
Reading this thread with interest and decided to check my base idle but I can't seem to find an idle adjustment screw on mine in the location pointed to in the Steve Heath book?
Am I being blind?.. or is it possible that later cars (mine's a 1999) don't have the adjustment screw? - The circular protrusion in the casting to the right of the throttle spindle just has a blank piece of metal in it - no screw...
If you prise that cap off, you will find the screw underneath.Am I being blind?.. or is it possible that later cars (mine's a 1999) don't have the adjustment screw? - The circular protrusion in the casting to the right of the throttle spindle just has a blank piece of metal in it - no screw...
I used a long nail, which I tapped through it and then the cap came out. Not sure why it is there, but assume it might have something to do with the fact that sometimes the screws can leak.
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