Setting Idle CO
10-07-2010, 08:10 AM
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Setting Idle CO
Hello team
Fitted my MSD chip today and using a gas analyser, attempted to set the idle CO to the suggested 2.7%-3% CO
I did a lot of turning of the pot on the ECU attempting to get the CO down, as it was sitting at around 7%, but I couldn't get it any lower than about 7%
Someone please tell me how I can get my CO down. My car now seems to be hunting on idle quite a lot since I changed the chip, and I'm worried about borewash too
I especially need to know how to get the CO screw to a position where it starts having an effect on the CO, as I couldn't seem to get any change
Thanks!
Fitted my MSD chip today and using a gas analyser, attempted to set the idle CO to the suggested 2.7%-3% CO
I did a lot of turning of the pot on the ECU attempting to get the CO down, as it was sitting at around 7%, but I couldn't get it any lower than about 7%
Someone please tell me how I can get my CO down. My car now seems to be hunting on idle quite a lot since I changed the chip, and I'm worried about borewash too
I especially need to know how to get the CO screw to a position where it starts having an effect on the CO, as I couldn't seem to get any change
Thanks!
10-07-2010, 12:10 PM
#3
Hello team
Fitted my MSD chip today and using a gas analyser, attempted to set the idle CO to the suggested 2.7%-3% CO
I did a lot of turning of the pot on the ECU attempting to get the CO down, as it was sitting at around 7%, but I couldn't get it any lower than about 7%
Someone please tell me how I can get my CO down. My car now seems to be hunting on idle quite a lot since I changed the chip, and I'm worried about borewash too
I especially need to know how to get the CO screw to a position where it starts having an effect on the CO, as I couldn't seem to get any change
Thanks!
Fitted my MSD chip today and using a gas analyser, attempted to set the idle CO to the suggested 2.7%-3% CO
I did a lot of turning of the pot on the ECU attempting to get the CO down, as it was sitting at around 7%, but I couldn't get it any lower than about 7%
Someone please tell me how I can get my CO down. My car now seems to be hunting on idle quite a lot since I changed the chip, and I'm worried about borewash too
I especially need to know how to get the CO screw to a position where it starts having an effect on the CO, as I couldn't seem to get any change
Thanks!
10-07-2010, 11:28 PM
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I tried calling MSD 3 times from New Zealand where I live, on Saturday morning UK time, during the business hours they are said to operate but I got the 'outside business hours' response so I'm guessing someone forgot to switch the phones over 
2WD Saff. I'm running Greys, t34 .63, plenum spacer plate and ported & flowed with standard valves and cams, RS500 cooler, brand new engine with standard compression
I haven't checked the fuel pressure at this stage. The cap is still on the reg so looks like it's never been tweaked, although it was checked at last tune and deemed ok
Does anyone know approximately what resistance I should have accross my mixture screw potentiometer at the correct idle CO?
In the mean time, feel free to drive behind me and collect all my unburnt fuel
2WD Saff. I'm running Greys, t34 .63, plenum spacer plate and ported & flowed with standard valves and cams, RS500 cooler, brand new engine with standard compression
I haven't checked the fuel pressure at this stage. The cap is still on the reg so looks like it's never been tweaked, although it was checked at last tune and deemed ok
Does anyone know approximately what resistance I should have accross my mixture screw potentiometer at the correct idle CO?
In the mean time, feel free to drive behind me and collect all my unburnt fuel
11-07-2010, 12:18 AM
#7
The screw is what we call a global modifier in as much as it adds a percentage to the entire fuel map.
If your engine is just borderline safe on boost, leaning the CO can and will destroy teh engine when flat out. The correct base position is in teh region of 5 turns clockwise and 2 turns anticlockwise to put you back in teh ballpark, but this is of course dependant on MANY MANY factors such as heads, cams, sensors, fuel pressure etc etc...
If your engine is just borderline safe on boost, leaning the CO can and will destroy teh engine when flat out. The correct base position is in teh region of 5 turns clockwise and 2 turns anticlockwise to put you back in teh ballpark, but this is of course dependant on MANY MANY factors such as heads, cams, sensors, fuel pressure etc etc...
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11-07-2010, 01:22 AM
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Mate, you are a LEGEND for finding that!
I tried searching a few times but couldn't find that info!
I'll go and adjust it now based on that and will get it checked tomorrow before power run
Cheers so much!
I tried searching a few times but couldn't find that info!
I'll go and adjust it now based on that and will get it checked tomorrow before power run
Cheers so much!
11-07-2010, 01:37 AM
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Oh crap...
Just went and did 5 turns clockwise and two anti-clockwise and started it up
Started fine, but had a bad miss when accelerator was pressed, and loads of smoke is coming out!
I'm guessing it's running VERY rich? Might take plugs out for a look
Anyone know which way to turn screw to lean mixture off!?
Just went and did 5 turns clockwise and two anti-clockwise and started it up
Started fine, but had a bad miss when accelerator was pressed, and loads of smoke is coming out!
I'm guessing it's running VERY rich? Might take plugs out for a look
Anyone know which way to turn screw to lean mixture off!?
11-07-2010, 02:03 AM
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Plugs were black and sooty. They are IK27s gapped at .6mm. I'm on standard ignition and coil. The tip of the centre electrode did seem clean however.
Plugs didn't especially smell of fuel, nor did the cylinders, and nor did the exhaust (this is the only time I've checked them since I changed the chip yesterday though, so since I just changed mixture screw this last time, it may have leaned it out a little, and the blackness may have been from previous rich mixture)
Have left plugs out for now in case it does need to dry out a bit
I did pull out the dipstick and the oil does have a petrol smell to it...hmmm....just did a change too - again this could be a result of previous rich mixture
So either way, the last time the car was started, it smoked and missed when the accelerator was pressed, but seemed to idle ok, even though it idled at about 1500+ RPM as it's about 6 degrees outside and it was cold started - and I shut it down after about a minute
Plugs didn't especially smell of fuel, nor did the cylinders, and nor did the exhaust (this is the only time I've checked them since I changed the chip yesterday though, so since I just changed mixture screw this last time, it may have leaned it out a little, and the blackness may have been from previous rich mixture)
Have left plugs out for now in case it does need to dry out a bit
I did pull out the dipstick and the oil does have a petrol smell to it...hmmm....just did a change too - again this could be a result of previous rich mixture
So either way, the last time the car was started, it smoked and missed when the accelerator was pressed, but seemed to idle ok, even though it idled at about 1500+ RPM as it's about 6 degrees outside and it was cold started - and I shut it down after about a minute
11-07-2010, 04:56 AM
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Ok!
To update - went outside and decided to try the 5 turns clockwise, two counter clockwise thingy with the old chip so I can drive to and from work in the morning
Then, as I looked at the mixture potentiometer, I realised that the (WARNING! TECHNICAL INDUSTRY TERMINOLOGY AHEAD) 'bendy metal thingy' that connects the screw head on the casing to the pot had slipped out of the groove on the pot and it was flailing in the breeze!
No wonder I was getting no change in my CO on the analyser!
So i re-located it. Did the five turns, two turns thing whilst watching to make sure it didn't slip out again and BOOM!
Sorted...for now...I think. Took it for a spin. Got it hot. Gave it a little boost and blew all the shit out the back. Then re-adjusted base idle. Runs like a dream!
Excited to turn the boost up tomorrow on the dyno
Cheers to everyone on Passionford who helped with this case, and from previous posts that led me to this place
Ben
To update - went outside and decided to try the 5 turns clockwise, two counter clockwise thingy with the old chip so I can drive to and from work in the morning
Then, as I looked at the mixture potentiometer, I realised that the (WARNING! TECHNICAL INDUSTRY TERMINOLOGY AHEAD) 'bendy metal thingy' that connects the screw head on the casing to the pot had slipped out of the groove on the pot and it was flailing in the breeze!
No wonder I was getting no change in my CO on the analyser!
So i re-located it. Did the five turns, two turns thing whilst watching to make sure it didn't slip out again and BOOM!
Sorted...for now...I think. Took it for a spin. Got it hot. Gave it a little boost and blew all the shit out the back. Then re-adjusted base idle. Runs like a dream!
Excited to turn the boost up tomorrow on the dyno
Cheers to everyone on Passionford who helped with this case, and from previous posts that led me to this place
Ben
11-07-2010, 09:15 AM
#12
Nice one glad its coming together pal
So just to re cap when you set it up set the fuel pressure to 3 bar... 3.5 with vac pipe off, get the car warm and set the idle to around 900rpm with the iscv disconnected, plug it back in and the revs should pick up slightly then settle back to 900, set the Co screw so the mixture is between 2.7-3%
as you say your plug gaps are 0.6 so that should be fine just dont forget to change the oil before you use it in anger lol
So just to re cap when you set it up set the fuel pressure to 3 bar... 3.5 with vac pipe off, get the car warm and set the idle to around 900rpm with the iscv disconnected, plug it back in and the revs should pick up slightly then settle back to 900, set the Co screw so the mixture is between 2.7-3%
as you say your plug gaps are 0.6 so that should be fine
just dont forget to change the oil before you use it in anger lol
11-07-2010, 02:28 PM
#14
i "think" from memory the mixture screw on the L6 & L8 differs, L6 is left to weaken and on L8 is left to make richer
this is the process i followed when setting the base idle when i put me MSD chip it, had it bang on the co% of 2.7 with siemens injectors. (L6 ecu)
run engine up to temp
unplugg the iscv (leave engine running) (iscv is on top the throttle body grey plug)
adjust idle on throttle body screw to 900rpm
re connect iscv, and idle should stay stable.
(do this before the cooling fans come on)
Turn ecu screw in 5 turns, this takes it back past zero, then 2.5 turns out.
the screw only has 5 turns of adjustment, so wherever it is set,turning it 5 turns will make it zero. Remember, its a potentiometer, not a normal screw, so it only adjusts a certain amount, no more or no less, even if you turn it 100 times, turning it back 5 times will still take it to zero.
2.5 takes you to the mid pount,which is a good starting point
this is the process i followed when setting the base idle when i put me MSD chip it, had it bang on the co% of 2.7 with siemens injectors. (L6 ecu)
run engine up to temp
unplugg the iscv (leave engine running) (iscv is on top the throttle body grey plug)
adjust idle on throttle body screw to 900rpm
re connect iscv, and idle should stay stable.
(do this before the cooling fans come on)
Turn ecu screw in 5 turns, this takes it back past zero, then 2.5 turns out.
the screw only has 5 turns of adjustment, so wherever it is set,turning it 5 turns will make it zero. Remember, its a potentiometer, not a normal screw, so it only adjusts a certain amount, no more or no less, even if you turn it 100 times, turning it back 5 times will still take it to zero.
2.5 takes you to the mid pount,which is a good starting point
12-07-2010, 07:32 AM
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Yeah, as posted above:
Clockwise richens L8
Clockwise leans L6
I got the car on the analyser again at the tuner and although it briefly dipped below 3% CO briefly, I think the pot was maxed out, and I couldn't get it to stay under 3% CO, so had no choice to proceed at 3.3% ish
Did a few runs progressively increasing the boost
Final result is 355.8hp @ 24 psi (spiked to about 26psi)
AFR was still well within parameters, but decided 24psi is plenty
Thanks to MSD, and people who have posted on Passionford, you guys are great!
Ben
Clockwise richens L8
Clockwise leans L6
I got the car on the analyser again at the tuner and although it briefly dipped below 3% CO briefly, I think the pot was maxed out, and I couldn't get it to stay under 3% CO, so had no choice to proceed at 3.3% ish
Did a few runs progressively increasing the boost
Final result is 355.8hp @ 24 psi (spiked to about 26psi)
AFR was still well within parameters, but decided 24psi is plenty
Thanks to MSD, and people who have posted on Passionford, you guys are great!
Ben
19-07-2010, 06:12 PM
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21-07-2010, 07:24 AM
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It's Ruapuna Raceway in Christchurch, New Zealand
It's winter at the moment. We had double figures celsius today! Was luxuary! Good skiing snowboarding at the moment though, plus, and more importantly, intake temperatures are optimal
Car is idling like a bitch. It seems ok with the ISCV disconnected. Been meaning to post a thread but been to busy enjoying boost
Could the throttle position sensor (which has developed the flat spot at the cruise position) be responsible for the shitty idle at all?
Base idle is fine when warm and ISCV disconnected, but cold starting is dicey, and warm idle sounds like I've got lumpy overlapping cams - sounds cool actually, but it's not what it's meant to do
It's winter at the moment. We had double figures celsius today! Was luxuary! Good skiing snowboarding at the moment though, plus, and more importantly, intake temperatures are optimal
Car is idling like a bitch. It seems ok with the ISCV disconnected. Been meaning to post a thread but been to busy enjoying boost
Could the throttle position sensor (which has developed the flat spot at the cruise position) be responsible for the shitty idle at all?
Base idle is fine when warm and ISCV disconnected, but cold starting is dicey, and warm idle sounds like I've got lumpy overlapping cams - sounds cool actually, but it's not what it's meant to do
21-07-2010, 08:17 AM
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Ok, back from my drive with the ISCV DISCONNECTED
Drives fine. Car was still a little warm so imagine it may have been a different story from a cold start
Idle was great
Still has the flat spot from really low rpm. On granny style takeoff, it's bad enough hesitation to cause bunnyhopping. Quite hard to get it to stutter on the flat spot in normal driving though
When I got back, I let it idle, and then when I put the ISCV back on, it went back to overlap cams style idle ha ha
Drives fine. Car was still a little warm so imagine it may have been a different story from a cold start
Idle was great
Still has the flat spot from really low rpm. On granny style takeoff, it's bad enough hesitation to cause bunnyhopping. Quite hard to get it to stutter on the flat spot in normal driving though
When I got back, I let it idle, and then when I put the ISCV back on, it went back to overlap cams style idle ha ha
21-07-2010, 09:03 AM
#28
Thinking about it this could be while your co is a little too high,
you still on a L6 Ben?
multimeter black probe on pin 11 of the ecu, red probe on pin17
should read
4.5-5v at closed throttle
<0.35v at wide open throttle
you still on a L6 Ben?
multimeter black probe on pin 11 of the ecu, red probe on pin17
should read
4.5-5v at closed throttle
<0.35v at wide open throttle
Last edited by Miller 3; 21-07-2010 at 09:28 AM.
21-07-2010, 04:30 PM
#29
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Car is idling like a bitch. It seems ok with the ISCV disconnected. Been meaning to post a thread but been to busy enjoying boost
Could the throttle position sensor (which has developed the flat spot at the cruise position) be responsible for the shitty idle at all?
Base idle is fine when warm and ISCV disconnected, but cold starting is dicey, and warm idle sounds like I've got lumpy overlapping cams - sounds cool actually, but it's not what it's meant to do
Could the throttle position sensor (which has developed the flat spot at the cruise position) be responsible for the shitty idle at all?
Base idle is fine when warm and ISCV disconnected, but cold starting is dicey, and warm idle sounds like I've got lumpy overlapping cams - sounds cool actually, but it's not what it's meant to do
21-07-2010, 06:58 PM
#30
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Yes, I still have the L6 ECU
I thought that to test the TPS, I'd need the ECU connected and the ignition on but engine not running as otherwise the TPS circuit wouldn't be energised and I wouldn't see any voltages?
If so, do I make the test with the ecu connected, and test on the pins on the inside of the ecu with the cover off and ignition on?
Appreciate the info BTW
I thought that to test the TPS, I'd need the ECU connected and the ignition on but engine not running as otherwise the TPS circuit wouldn't be energised and I wouldn't see any voltages?
If so, do I make the test with the ecu connected, and test on the pins on the inside of the ecu with the cover off and ignition on?
Appreciate the info BTW
01-08-2010, 10:47 AM
#33
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Oiiii Cossirob!
I actually haven't done the test on the TPS yet to see if it's adjusted correctly or not
I plan to in the next few days
Car is going into storage soon as I'm moving overseas
Been great driving it so seems a shame to take it apart
Anyone know if you can still get 2WD TPS or do you have to convert it to run a 4WD?
Pros and cons?
Cheers
Ben
I actually haven't done the test on the TPS yet to see if it's adjusted correctly or not
I plan to in the next few days
Car is going into storage soon as I'm moving overseas
Been great driving it so seems a shame to take it apart
Anyone know if you can still get 2WD TPS or do you have to convert it to run a 4WD?
Pros and cons?
Cheers
Ben
04-08-2010, 11:18 AM
#34
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Ok...so today my Cossie was put into storage
Likely won't be driven again till around Christmas. Ran out of time to make any tests
It's been idling high the last few days, and today, it did sit at 950ish RPM and idled beautifully for a few mins, so it was nice to enjoy that ha ha. Still got the missfire too
When I'm back I think I'll try some new sensors, like dizzy phase, ECT, ACT, TPS and see if I get some improvement with that
Thanks to everyone for their help and amusement in recent times
Ben
Likely won't be driven again till around Christmas. Ran out of time to make any tests
It's been idling high the last few days, and today, it did sit at 950ish RPM and idled beautifully for a few mins, so it was nice to enjoy that ha ha. Still got the missfire too
When I'm back I think I'll try some new sensors, like dizzy phase, ECT, ACT, TPS and see if I get some improvement with that
Thanks to everyone for their help and amusement in recent times
Ben
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