Erratic Idle on pre cat 4441 cc Griff
Discussion
I have an NCK 4.5BV engined 92 Griff (came out of a 450 SE), which was rebuilt by Ray Webb at V8D. A new ECU EPROM was supplied by John Eales based on Rays build spec (Original TVR NCK build but with V8D 218 hybrid cam). The car runs an enlarged plenum, 45mm flared trumpets and ported inlet. Everything else is stock.
Car drives well and produces stacks of power, but the idle has always been erratic - sometimes it controls well, at other time it simply refuses to idle. Thought it was about time I sorted it as I haved lived with problem for 5 years !
Checked the idle mixture which is OK , Idle stepper valve has been cleaned several times with no improvement.
Took to local motor sport specialist (Pro-tec mootorsport at Clifton Preston) they diagnosed a sticking idle valve. Ordered a new one from a reputable supplier and fitted today. With this valve the car won't idle at all. Put the old idle valve in and it is much better but erratic as before.
Have I got a duff idle valve, is there any test to check they are working correctly ?
I have tried adjusting the idle on the plenum plus or minus a turn with no effect. Really wanted to cure idle problem any ideas on next step ? I guess I should return the valve and try another one............
Car drives well and produces stacks of power, but the idle has always been erratic - sometimes it controls well, at other time it simply refuses to idle. Thought it was about time I sorted it as I haved lived with problem for 5 years !
Checked the idle mixture which is OK , Idle stepper valve has been cleaned several times with no improvement.
Took to local motor sport specialist (Pro-tec mootorsport at Clifton Preston) they diagnosed a sticking idle valve. Ordered a new one from a reputable supplier and fitted today. With this valve the car won't idle at all. Put the old idle valve in and it is much better but erratic as before.
Have I got a duff idle valve, is there any test to check they are working correctly ?
I have tried adjusting the idle on the plenum plus or minus a turn with no effect. Really wanted to cure idle problem any ideas on next step ? I guess I should return the valve and try another one............
Edited by Mickygee on Wednesday 27th August 19:39
You will need to set base idle,
Proceedure:
with the hose to the stepper pinched shut so that the stepper can't breath, set the idle to run at around 600 rpm, you'll probably need to open the throttle a tad and this will also involve resetting the trottle potentiometer, you'll need a digital multimeter with long probes this must read 0.33 volts +/- 0.01 at throttle closed position as you open the throttle it will climb steadily to around 4.5volts at throttle open.(push probes into plug connector with ign switched on)
after achieving 600rpm turn ign off, disconnect ECU for 30 secs reconnect ecu remove restriction to stepper and engine should purr at 900 or what ever the chip has been set to.
Proceedure:
with the hose to the stepper pinched shut so that the stepper can't breath, set the idle to run at around 600 rpm, you'll probably need to open the throttle a tad and this will also involve resetting the trottle potentiometer, you'll need a digital multimeter with long probes this must read 0.33 volts +/- 0.01 at throttle closed position as you open the throttle it will climb steadily to around 4.5volts at throttle open.(push probes into plug connector with ign switched on)
after achieving 600rpm turn ign off, disconnect ECU for 30 secs reconnect ecu remove restriction to stepper and engine should purr at 900 or what ever the chip has been set to.
Thanks Tim,
Reset the base idle so that engine idles (lumpily) at 600rpm with the idle valve hose clamped shut. Had to unscrew the the idle screw about one and a half turns to get it to idle as it just stalled initially. Checked throttle potentiometer and it is at .321 volts so is OK. Reset ECU and started up the car.
Engine would not idle at start up it just stalled. However tried again using throttle to maintain revs idle eventually settled at 1000rpm which is what the chip set at. Rev the engine and idle settles down perfectly. All of this is with the new stepper motor.
However when driving the car it still stalls or idles lumpily at about 600 rpm before slowly recovering to 1000rpm.
Is this a problem with the road speed sensor, which again has worked intermittently in the past ? (Sometimes revs elevated to 1800rpm before actually stopping the car). It doesn't seem to be working at the moment.
An interesting aside the new stepper motor doesn't retract as far as the old one - is this an issue ?
Any clues as to what next to try. The contact number you gave Tim is that for in office hours ?
Cheers,
Mick
Reset the base idle so that engine idles (lumpily) at 600rpm with the idle valve hose clamped shut. Had to unscrew the the idle screw about one and a half turns to get it to idle as it just stalled initially. Checked throttle potentiometer and it is at .321 volts so is OK. Reset ECU and started up the car.
Engine would not idle at start up it just stalled. However tried again using throttle to maintain revs idle eventually settled at 1000rpm which is what the chip set at. Rev the engine and idle settles down perfectly. All of this is with the new stepper motor.
However when driving the car it still stalls or idles lumpily at about 600 rpm before slowly recovering to 1000rpm.
Is this a problem with the road speed sensor, which again has worked intermittently in the past ? (Sometimes revs elevated to 1800rpm before actually stopping the car). It doesn't seem to be working at the moment.
An interesting aside the new stepper motor doesn't retract as far as the old one - is this an issue ?
Any clues as to what next to try. The contact number you gave Tim is that for in office hours ?
Cheers,
Mick
Mickygee said:
Thanks Tim,
Reset the base idle so that engine idles (lumpily) at 600rpm with the idle valve hose clamped shut. Had to unscrew the the idle screw about one and a half turns to get it to idle as it just stalled initially. Checked throttle potentiometer and it is at .321 volts so is OK. Reset ECU and started up the car.
Engine would not idle at start up it just stalled. However tried again using throttle to maintain revs idle eventually settled at 1000rpm which is what the chip set at. Rev the engine and idle settles down perfectly. All of this is with the new stepper motor.
However when driving the car it still stalls or idles lumpily at about 600 rpm before slowly recovering to 1000rpm.
Is this a problem with the road speed sensor, which again has worked intermittently in the past ? (Sometimes revs elevated to 1800rpm before actually stopping the car). It doesn't seem to be working at the moment.
An interesting aside the new stepper motor doesn't retract as far as the old one - is this an issue ?
Any clues as to what next to try. The contact number you gave Tim is that for in office hours ?
Cheers,
Mick
Yes call 9-6pmReset the base idle so that engine idles (lumpily) at 600rpm with the idle valve hose clamped shut. Had to unscrew the the idle screw about one and a half turns to get it to idle as it just stalled initially. Checked throttle potentiometer and it is at .321 volts so is OK. Reset ECU and started up the car.
Engine would not idle at start up it just stalled. However tried again using throttle to maintain revs idle eventually settled at 1000rpm which is what the chip set at. Rev the engine and idle settles down perfectly. All of this is with the new stepper motor.
However when driving the car it still stalls or idles lumpily at about 600 rpm before slowly recovering to 1000rpm.
Is this a problem with the road speed sensor, which again has worked intermittently in the past ? (Sometimes revs elevated to 1800rpm before actually stopping the car). It doesn't seem to be working at the moment.
An interesting aside the new stepper motor doesn't retract as far as the old one - is this an issue ?
Any clues as to what next to try. The contact number you gave Tim is that for in office hours ?
Cheers,
Mick
Sounds like you're getting there
Tim
Just a warning note, there are some 'orrible pattern steppers out there from China. The brand new one I had let air in past the motor, (held withing the hexagonal area)so the idle was all over the place. One thing that has not been mentioned as this is precat, is the CO setting on the side of the AFM. This has a wide range, and can overfuel or underfuel the engine badly at tickover, leading to erratic and lumpy idling. Personnally Id only set it up with a CO meter, I dont like the DC voltages system recommended by RPI, as there are too many variables.
Heres my bit: http://www.g33.co.uk/fuel_injection.htm
Mark
Heres my bit: http://www.g33.co.uk/fuel_injection.htm
Mark
Spoke with Tim and he gave me a few pointers on setting up the butterfly, and I have already set the CO (thanks for the tip Mark) which is still a little high, but I think that has something to do with the John Eales mapping being generous on the fuelling.
As per Marks suggestion looked a little closer at the new stepper and found it isn't a genuine Lucas item but some sort of pattern part. It has visible a few differences in the casting as well as the spring, and features a bright cone rather than the black standard one. In operation it deosn't fully retract when the ignition is switched off (which my old one does) and also when fully extended, the shaft and cone stepper falls out the housing (which my old one doesn't). Also lastly it does not provide a gas tight seal allowing air to be pulled into the plenum - you can blow through the stepper body. In summary not what you expect for about £120, and totally unsuitable for use !
Had another go at cleaning the old stepper and gave it a good dose of WD40 and reinstalled, now that the base idle is ok the car runs like a dream with a steady 1100rpm idle, no stalling and good starting.
It looks like my problems were a combination of base idle settings and the new stepper leaking/not homing. Need a few more miles to verify if problems are sorted but it looks encouraging. Probably will still try and get a new Lucas stepper, as the old one has been problematic.
Spoke to reputable supplier who was very helpful and have offered to replace with a genuine Lucas part. They are going to investigate how these parts have got into their stock.
Will try and post some pics later which show the differences.
Buyers beware !
As per Marks suggestion looked a little closer at the new stepper and found it isn't a genuine Lucas item but some sort of pattern part. It has visible a few differences in the casting as well as the spring, and features a bright cone rather than the black standard one. In operation it deosn't fully retract when the ignition is switched off (which my old one does) and also when fully extended, the shaft and cone stepper falls out the housing (which my old one doesn't). Also lastly it does not provide a gas tight seal allowing air to be pulled into the plenum - you can blow through the stepper body. In summary not what you expect for about £120, and totally unsuitable for use !
Had another go at cleaning the old stepper and gave it a good dose of WD40 and reinstalled, now that the base idle is ok the car runs like a dream with a steady 1100rpm idle, no stalling and good starting.
It looks like my problems were a combination of base idle settings and the new stepper leaking/not homing. Need a few more miles to verify if problems are sorted but it looks encouraging. Probably will still try and get a new Lucas stepper, as the old one has been problematic.
Spoke to reputable supplier who was very helpful and have offered to replace with a genuine Lucas part. They are going to investigate how these parts have got into their stock.
Will try and post some pics later which show the differences.
Buyers beware !
Mickygee said:
Spoke with Tim and he gave me a few pointers on setting up the butterfly, and I have already set the CO (thanks for the tip Mark) which is still a little high, but I think that has something to do with the John Eales mapping being generous on the fuelling.
As per Marks suggestion looked a little closer at the new stepper and found it isn't a genuine Lucas item but some sort of pattern part. It has visible a few differences in the casting as well as the spring, and features a bright cone rather than the black standard one. In operation it deosn't fully retract when the ignition is switched off (which my old one does) and also when fully extended, the shaft and cone stepper falls out the housing (which my old one doesn't). Also lastly it does not provide a gas tight seal allowing air to be pulled into the plenum - you can blow through the stepper body. In summary not what you expect for about £120, and totally unsuitable for use !
Had another go at cleaning the old stepper and gave it a good dose of WD40 and reinstalled, now that the base idle is ok the car runs like a dream with a steady 1100rpm idle, no stalling and good starting.
It looks like my problems were a combination of base idle settings and the new stepper leaking/not homing. Need a few more miles to verify if problems are sorted but it looks encouraging. Probably will still try and get a new Lucas stepper, as the old one has been problematic.
Spoke to reputable supplier who was very helpful and have offered to replace with a genuine Lucas part. They are going to investigate how these parts have got into their stock.
Will try and post some pics later which show the differences.
Buyers beware !
Umm, Id say so......Those nasty pattern ones are about £25 on ebay, and even the genuine Range Rover part can be as low as £65 at times from some of the Land Rover parts suppliers, so I recon they owe you two !As per Marks suggestion looked a little closer at the new stepper and found it isn't a genuine Lucas item but some sort of pattern part. It has visible a few differences in the casting as well as the spring, and features a bright cone rather than the black standard one. In operation it deosn't fully retract when the ignition is switched off (which my old one does) and also when fully extended, the shaft and cone stepper falls out the housing (which my old one doesn't). Also lastly it does not provide a gas tight seal allowing air to be pulled into the plenum - you can blow through the stepper body. In summary not what you expect for about £120, and totally unsuitable for use !
Had another go at cleaning the old stepper and gave it a good dose of WD40 and reinstalled, now that the base idle is ok the car runs like a dream with a steady 1100rpm idle, no stalling and good starting.
It looks like my problems were a combination of base idle settings and the new stepper leaking/not homing. Need a few more miles to verify if problems are sorted but it looks encouraging. Probably will still try and get a new Lucas stepper, as the old one has been problematic.
Spoke to reputable supplier who was very helpful and have offered to replace with a genuine Lucas part. They are going to investigate how these parts have got into their stock.
Will try and post some pics later which show the differences.
Buyers beware !
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