Still Chasing idle issue - any further thoughts
Discussion
As in title and seeking any further wisdom.
Done so far - todays job was double checking the camshaft timing which is correct as you can see in the picture below
The ruler runs through the middle of the camshaft sprocket bolt
1. Checked camshaft timing
2. Set timing (by garage as well as at home)
3. Sorted several vacuum leaks (rubber hose to rocker cover, 2 leaks on induction pipework)
4. Replaced all other rubber hoses with silicon just in case
5. Removed induction manifold and re-fitted sealing with a silicon sealant as well as gasket
6. Checked all electrical connections
7. Swapped ISCV with my spare - no effect
8. swapped throttle pot with my spare - no effect
9. Followed the car mechanics guide except for checking voltages as I don't have the fly leads to do these with the engine running without breaking the insulation and don't want to do that.
Other than the idle issue the car runs fine, has plenty of power and the rectification of induction leaks has brought the idle down to 1200rpm but now the car idles at 1200rpm (before rebuild was around 950rpm) all the time and when hot it doesn't return straight to idle following any revs being applied. Instead it returns to idle revs to 1200rpm and hunts between these two figures for 2 or 3 times before settling at 1200 rpm. When steady idling it was also occasionally hunt between 1200 and 2000. When cold the hunting issue is not there so appears heat related.
Any ideas from the gurus before I decide on taking it to the local motorsport garage?
Mark
Done so far - todays job was double checking the camshaft timing which is correct as you can see in the picture below
The ruler runs through the middle of the camshaft sprocket bolt
1. Checked camshaft timing
2. Set timing (by garage as well as at home)
3. Sorted several vacuum leaks (rubber hose to rocker cover, 2 leaks on induction pipework)
4. Replaced all other rubber hoses with silicon just in case
5. Removed induction manifold and re-fitted sealing with a silicon sealant as well as gasket
6. Checked all electrical connections
7. Swapped ISCV with my spare - no effect
8. swapped throttle pot with my spare - no effect
9. Followed the car mechanics guide except for checking voltages as I don't have the fly leads to do these with the engine running without breaking the insulation and don't want to do that.
Other than the idle issue the car runs fine, has plenty of power and the rectification of induction leaks has brought the idle down to 1200rpm but now the car idles at 1200rpm (before rebuild was around 950rpm) all the time and when hot it doesn't return straight to idle following any revs being applied. Instead it returns to idle revs to 1200rpm and hunts between these two figures for 2 or 3 times before settling at 1200 rpm. When steady idling it was also occasionally hunt between 1200 and 2000. When cold the hunting issue is not there so appears heat related.
Any ideas from the gurus before I decide on taking it to the local motorsport garage?
Mark
When I had idle issues I found that the throttle was partly open. The throttle should be completely shut at idle as the idle control valve supply's the correct amount of idle air. Mine had been set to idle on the throttle when I first bought it so when you took your foot off, the idle air valve opened and it held about 2000 rpm. The ECU then took a few seconds to try to correct the idle speed and it would slow down a bit.
Rob.
Rob.
Griffinr said:
When I had idle issues I found that the throttle was partly open. The throttle should be completely shut at idle as the idle control valve supply's the correct amount of idle air. Mine had been set to idle on the throttle when I first bought it so when you took your foot off, the idle air valve opened and it held about 2000 rpm. The ECU then took a few seconds to try to correct the idle speed and it would slow down a bit.
Rob.
Thanks, But have checked this - it is one of the early steps in the car mechanics article and I can confirm the throttle does fully shut when the accelerator pedal is allowed to return to the null positionRob.
Hi Mark
Have you used thr Star Tester? If not I passed mine on to phillpot and can let you have o copy on the instructions electronically to review first if that would help.
It does sound like a air leak on the induction (which would include into the plenum and the vacuum hose and servo). Have you tried spraying Bradex Easy Start around the induction while the engine is running as I have seen the AA do that to diagnose poor running issues
Norman
Have you used thr Star Tester? If not I passed mine on to phillpot and can let you have o copy on the instructions electronically to review first if that would help.
It does sound like a air leak on the induction (which would include into the plenum and the vacuum hose and servo). Have you tried spraying Bradex Easy Start around the induction while the engine is running as I have seen the AA do that to diagnose poor running issues
Norman
Norm,
If you could forward me the electronic instructions that would be good please. My fault code reader shows nothing though. Haven't done the easy start (or brake cleaner - someone else suggested) test yet so will do but the idle surge makes this difficult as engine note changes without this when it is hunting.
Certain it is not the servo as the servo holds a vacuum (is also fairly new - under 3 years old) and the hose to it has been replaced with re-inforced silicone during this fault finding process. You can test vacuum in the servo by stopping the engine and after 60 seconds twisting the non return valve, there should be a noise of air leakage into it - if nothing it is definitely leaking if there is it may be ok, but as my vacuum holds up for over 5 minutes I am sure this is fine.
The good thing is at least the car is drivable if annoying when stopped and idling so I have the smile back with an occasional grimace
Thanks all
Mark
If you could forward me the electronic instructions that would be good please. My fault code reader shows nothing though. Haven't done the easy start (or brake cleaner - someone else suggested) test yet so will do but the idle surge makes this difficult as engine note changes without this when it is hunting.
Certain it is not the servo as the servo holds a vacuum (is also fairly new - under 3 years old) and the hose to it has been replaced with re-inforced silicone during this fault finding process. You can test vacuum in the servo by stopping the engine and after 60 seconds twisting the non return valve, there should be a noise of air leakage into it - if nothing it is definitely leaking if there is it may be ok, but as my vacuum holds up for over 5 minutes I am sure this is fine.
The good thing is at least the car is drivable if annoying when stopped and idling so I have the smile back with an occasional grimace
Thanks all
Mark
Geralds idea of easy start (or even WD40) sprayed whilst idling is the common method for air leaks. generally tiny leaks only hinder at idle or are at least noticed, as when the revs are up the leak is a smaller percentage of the airflow so makes little or no difference.
silicone based hose for brake servo, isn't a great idea imho, whilst im sure its reinforced (usually wire spirals internally), silicone doesn't like long term exposure to petrol. It could be that its already porous. There are flouro lined silicone hoses, but they are rarely stiff enough for use with brake servos
To irradicate, remove the hose from inlet manifold and refit a short length of other hose into manifold but plugged, so theres no servo and no silicone hose in the equation
silicone based hose for brake servo, isn't a great idea imho, whilst im sure its reinforced (usually wire spirals internally), silicone doesn't like long term exposure to petrol. It could be that its already porous. There are flouro lined silicone hoses, but they are rarely stiff enough for use with brake servos
To irradicate, remove the hose from inlet manifold and refit a short length of other hose into manifold but plugged, so theres no servo and no silicone hose in the equation
Hey folks,
As the rubbish weather sets in, I have decided to lay up the TVR to try and sort a few things. The first on the list is this idle issue which the previous owner Mark was tackling 2 years ago. The car has actually run pretty good over summer with the ISCV unplugged, idling at a pretty steady 900 rpm, but I'd much prefer the car to be running properly, if I can find and sort the problem (not to mention that it is pretty lumpy to drive when cold with the ISCV not working).
Previous research suggests that the car quite simply shouldn't be running without the ISCV, as there shouldn't be enough air getting into the system to maintain an idle. I've taken the throttle body off and the butterflies look to seal pretty well (given that one has the hole in it) so I don't think it is that. I was going to take it to a garage and get it properly vacuum tested with smoke (if they still do that?) to try and completely rule out any leak issues and determine where it is getting it's air to maintain a 900 rpm idle.
Having subsequently found this thread, it appears Mark has done just about everything to try and sort the issue. I'm probably going to get a professional leak check, as my logic keeps telling me that unwanted air must be sustaining ignition and I want to rule that line of thinking out. I'd be grateful for any advice this forum could offer!
As the rubbish weather sets in, I have decided to lay up the TVR to try and sort a few things. The first on the list is this idle issue which the previous owner Mark was tackling 2 years ago. The car has actually run pretty good over summer with the ISCV unplugged, idling at a pretty steady 900 rpm, but I'd much prefer the car to be running properly, if I can find and sort the problem (not to mention that it is pretty lumpy to drive when cold with the ISCV not working).
Previous research suggests that the car quite simply shouldn't be running without the ISCV, as there shouldn't be enough air getting into the system to maintain an idle. I've taken the throttle body off and the butterflies look to seal pretty well (given that one has the hole in it) so I don't think it is that. I was going to take it to a garage and get it properly vacuum tested with smoke (if they still do that?) to try and completely rule out any leak issues and determine where it is getting it's air to maintain a 900 rpm idle.
Having subsequently found this thread, it appears Mark has done just about everything to try and sort the issue. I'm probably going to get a professional leak check, as my logic keeps telling me that unwanted air must be sustaining ignition and I want to rule that line of thinking out. I'd be grateful for any advice this forum could offer!
ukflyboy said:
Hey folks,
As the rubbish weather sets in, I have decided to lay up the TVR to try and sort a few things. The first on the list is this idle issue which the previous owner Mark was tackling 2 years ago. The car has actually run pretty good over summer with the ISCV unplugged, idling at a pretty steady 900 rpm, but I'd much prefer the car to be running properly, if I can find and sort the problem (not to mention that it is pretty lumpy to drive when cold with the ISCV not working).
Previous research suggests that the car quite simply shouldn't be running without the ISCV, as there shouldn't be enough air getting into the system to maintain an idle. I've taken the throttle body off and the butterflies look to seal pretty well (given that one has the hole in it) so I don't think it is that. I was going to take it to a garage and get it properly vacuum tested with smoke (if they still do that?) to try and completely rule out any leak issues and determine where it is getting it's air to maintain a 900 rpm idle.
Having subsequently found this thread, it appears Mark has done just about everything to try and sort the issue. I'm probably going to get a professional leak check, as my logic keeps telling me that unwanted air must be sustaining ignition and I want to rule that line of thinking out. I'd be grateful for any advice this forum could offer!
Might have this wrong as not too mechanically minded but i am sure the guys sprayed brake cleaner round mine to check for leaks. If the revs stay the same, no leak. As the rubbish weather sets in, I have decided to lay up the TVR to try and sort a few things. The first on the list is this idle issue which the previous owner Mark was tackling 2 years ago. The car has actually run pretty good over summer with the ISCV unplugged, idling at a pretty steady 900 rpm, but I'd much prefer the car to be running properly, if I can find and sort the problem (not to mention that it is pretty lumpy to drive when cold with the ISCV not working).
Previous research suggests that the car quite simply shouldn't be running without the ISCV, as there shouldn't be enough air getting into the system to maintain an idle. I've taken the throttle body off and the butterflies look to seal pretty well (given that one has the hole in it) so I don't think it is that. I was going to take it to a garage and get it properly vacuum tested with smoke (if they still do that?) to try and completely rule out any leak issues and determine where it is getting it's air to maintain a 900 rpm idle.
Having subsequently found this thread, it appears Mark has done just about everything to try and sort the issue. I'm probably going to get a professional leak check, as my logic keeps telling me that unwanted air must be sustaining ignition and I want to rule that line of thinking out. I'd be grateful for any advice this forum could offer!
Does this make sense?
Tony,
Yeah, I've heard that as a means of testing for leaks however, I'm not sure it will give me the thoroughness or accuracy I need given how long this problem has been around for and the testing that Mark has already conducted. I'd like to try smoke it out if the means are available and not too expensive!
Yeah, I've heard that as a means of testing for leaks however, I'm not sure it will give me the thoroughness or accuracy I need given how long this problem has been around for and the testing that Mark has already conducted. I'd like to try smoke it out if the means are available and not too expensive!
ukflyboy said:
Tony,
Yeah, I've heard that as a means of testing for leaks however, I'm not sure it will give me the thoroughness or accuracy I need given how long this problem has been around for and the testing that Mark has already conducted. I'd like to try smoke it out if the means are available and not too expensive!
Hi PeteYeah, I've heard that as a means of testing for leaks however, I'm not sure it will give me the thoroughness or accuracy I need given how long this problem has been around for and the testing that Mark has already conducted. I'd like to try smoke it out if the means are available and not too expensive!
Hope you get it sorted - at least we have winter to thoroughly sort the cars.
Had quite a few issues with mine of late but after a virtual full rewire, new air mass meter, chip, and custom rolling road map by Mark Adams, it runs as sweet as a nut and goes like the wind.
Had a mouse issue but a couple of traps and 2 dead mice later, all is peaceful in the TVR garage.
She is under wraps now until next year but having said that, tax and insurance is in place just in case!!
Hate this time of year as all cars laid up till spring/summer........bring on May when hopefully the sun is shining again
AMDBSTony said:
Hate this time of year as all cars laid up till spring/summer.......
Not mine 
Bicester Heritage
Shelsley Walsh
Edited by phillpot on Monday 9th November 09:00
phillpot said:
AMDBSTony said:
Hate this time of year as all cars laid up till spring/summer.......
Not mine I don't think I could go all the way through to May without going out for a blast in Austin. There are too many wonderful opportunities on bright sunny autumn/ winter/ early spring days with clear blue skies and lovely open twisty country roads: life's too short not to enjoy it while you can!
hi i had the same problem with mine i tried most of the above and i eventually cured it by changing one of the temp senders on the front of plenium chamber 1 of these controls sends info to the ecu so that it knows the temp of the engine if it is faulty it sends duff info to the ecu so that it thinks the engine is not warmed up and compensates by riching the fuel mixture try to borrow one to try i had a spare in another plenium so swapped it over be lucky
Thanks, but that isn't really helping! Mine isn't layed up because I don't want to drive it on nice days over winter (it remains insured, taxed and MOTed), I'm just using the generally worse weather to get the car sorted.
For those members who have the throttle body with the hole in the butterly, I'd be interested in hearing how your car runs with the ISCV disconnected... if it just konks out, then I must surely have a stray air problem!
For those members who have the throttle body with the hole in the butterly, I'd be interested in hearing how your car runs with the ISCV disconnected... if it just konks out, then I must surely have a stray air problem!
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