Okay, what am I doing wrong?
Discussion
I took my 'fixed' car out on Saturday for a run out of about 40 miles from Ashford to Sevenoaks, a route that coves both motorway and A road.
The bottom line is that the cars was running like a dog, felt like it was only running on 7 and the exhaust nots was odd. The only time it seems to have it's old get up and go was on an A road where it seemed to bog down to start then clear and throttle response picked up.
I came home, checked the Laptop and the adaptives were all over the place again!
So, I went through the 'how to tune' pages of the TVR manual, the only thing I didn't to was clamp the purge pipe as I've seen posting from Jules that say not to bother.
Well, everything was done by the book, but once the adaptives were reset they started to rise again, producing the AFR error again.
I'm now to tuning the Cerb' am I doing something fundamentally wrong? Have the decats and lack of brack pressure caused a problem?
I'm hunting for ideas and any suggestions would be appreciated.
It's recently had new magnacor leads, plugs, and coil paks (just before I bought the car).
Thanks
Tim
The bottom line is that the cars was running like a dog, felt like it was only running on 7 and the exhaust nots was odd. The only time it seems to have it's old get up and go was on an A road where it seemed to bog down to start then clear and throttle response picked up.
I came home, checked the Laptop and the adaptives were all over the place again!
So, I went through the 'how to tune' pages of the TVR manual, the only thing I didn't to was clamp the purge pipe as I've seen posting from Jules that say not to bother.
Well, everything was done by the book, but once the adaptives were reset they started to rise again, producing the AFR error again.
I'm now to tuning the Cerb' am I doing something fundamentally wrong? Have the decats and lack of brack pressure caused a problem?
I'm hunting for ideas and any suggestions would be appreciated.
It's recently had new magnacor leads, plugs, and coil paks (just before I bought the car).
Thanks
Tim
Sounds like we're having similar problems. My car felt like it was running on half its cylinders and would idle badly at about 400 RPM. Very nerve wracking in London traffic 
I replaced the coil packs, magnecors already fitted, two new lambda sensors (they had failed within 400 miles of each other anyway...), new battery to replace my expensive race one, all engine connectors cleaned etc.
And it was still doing it, not all the time, but sometimes. Then I took a punt and adjusted the link rod between the two banks until the engine sounded 'right', this also raised the idle to about 1100 RPM. This has definitely helped (leading us into airflow imbalance...) although the car did go into 'bad running/low idle' on friday night when in heavy traffic and the engine temp was up around 100 degrees. It cleared itself up after the engine had cooled a little, again I wonder if the expansion of components is putting out the airflow balance.
Anyway, I have an airflow meter and am going to replace the ball and stud endings on the throttle link rod with small rod ends, as the ball and studs have developed a little bit of free play in them after only 18 months or so.
So after all that, I have no answers, but thought I'd let you know you're not suffering alone
I replaced the coil packs, magnecors already fitted, two new lambda sensors (they had failed within 400 miles of each other anyway...), new battery to replace my expensive race one, all engine connectors cleaned etc.
And it was still doing it, not all the time, but sometimes. Then I took a punt and adjusted the link rod between the two banks until the engine sounded 'right', this also raised the idle to about 1100 RPM. This has definitely helped (leading us into airflow imbalance...) although the car did go into 'bad running/low idle' on friday night when in heavy traffic and the engine temp was up around 100 degrees. It cleared itself up after the engine had cooled a little, again I wonder if the expansion of components is putting out the airflow balance.
Anyway, I have an airflow meter and am going to replace the ball and stud endings on the throttle link rod with small rod ends, as the ball and studs have developed a little bit of free play in them after only 18 months or so.
So after all that, I have no answers, but thought I'd let you know you're not suffering alone
[deep thought mode on] Tricky [/deep thought mode off]
Your possibilities are many and varied and its difficult to check everything on the car. Its possibly one of those rare times when I would suggest defering to a specialist.
With a fair amount of experience of this engine a specialist could directly you fairly accurately to fuel air or electrics. At least then you would have narrowed a large number of possibilites down to a manageable amount.
Look at it this way, a specialist opinion is not going to cost less than all the unnecessary things you've already replaced.
Sorry to sound so negative but the adapative are only telling you the engine is running out of limits and is trying to do the impossible.
Either that or borrow a syncronometer and start from basics
Your possibilities are many and varied and its difficult to check everything on the car. Its possibly one of those rare times when I would suggest defering to a specialist.
With a fair amount of experience of this engine a specialist could directly you fairly accurately to fuel air or electrics. At least then you would have narrowed a large number of possibilites down to a manageable amount.
Look at it this way, a specialist opinion is not going to cost less than all the unnecessary things you've already replaced.
Sorry to sound so negative but the adapative are only telling you the engine is running out of limits and is trying to do the impossible.
Either that or borrow a syncronometer and start from basics
Julian64 said:
[deep thought mode on] Tricky [/deep thought mode off]
Your possibilities are many and varied and its difficult to check everything on the car. Its possibly one of those rare times when I would suggest defering to a specialist.
With a fair amount of experience of this engine a specialist could directly you fairly accurately to fuel air or electrics. At least then you would have narrowed a large number of possibilites down to a manageable amount.
Look at it this way, a specialist opinion is not going to cost less than all the unnecessary things you've already replaced.
Sorry to sound so negative but the adapative are only telling you the engine is running out of limits and is trying to do the impossible.
Either that or borrow a syncronometer and start from basics
I'm, inclined to agree with you Julian,
The odd thing is I have a syncronometer and have balanced Left and Right bank, and at the point where everything's set, then the adaptives start going wild!
I agree about the associated costs of getting an expert in, all of the items I listed have been changed recently in the course of servicing and upkeep, the only things I've bought to help cure my recent problems have been lambda sensor and silenced decat pipes.
Tim
darreni said:
Once you have the throttle link rod set, put a dab of silicon sealant on the locknut, they will vibrate lose.
I did look into replacing the end ball joints with rose joints a while ago, i think demon tweeks can supply the joints for about £60.
Got mine for less than half that. The internet is a wonderful thing.
The are M5 rod ends, left and right hand thread.
Julian64 said:
[deep thought mode on] Tricky [/deep thought mode off]
Your possibilities are many and varied and its difficult to check everything on the car. Its possibly one of those rare times when I would suggest defering to a specialist.
With a fair amount of experience of this engine a specialist could directly you fairly accurately to fuel air or electrics. At least then you would have narrowed a large number of possibilites down to a manageable amount.
Look at it this way, a specialist opinion is not going to cost less than all the unnecessary things you've already replaced.
Sorry to sound so negative but the adapative are only telling you the engine is running out of limits and is trying to do the impossible.
Either that or borrow a syncronometer and start from basics
Thats my plan of attack too. I'll try a couple more things, and if it persists, take it Andy at APM, who looks after the car. Sometimes there is no substitute for years of experience.
TT Tim said:
[deep thought mode on] Tricky [/deep thought mode off]
Your possibilities are many and varied and its difficult to check everything on the car. Its possibly one of those rare times when I would suggest defering to a specialist.
With a fair amount of experience of this engine a specialist could directly you fairly accurately to fuel air or electrics. At least then you would have narrowed a large number of possibilites down to a manageable amount.
Look at it this way, a specialist opinion is not going to cost less than all the unnecessary things you've already replaced.
Sorry to sound so negative but the adapative are only telling you the engine is running out of limits and is trying to do the impossible.
Either that or borrow a syncronometer and start from basics
If all the standard stuff looks ok, then it could be leaks in the intake/exhaust manifolds?
I'm, inclined to agree with you Julian,
The odd thing is I have a syncronometer and have balanced Left and Right bank, and at the point where everything's set, then the adaptives start going wild!
I agree about the associated costs of getting an expert in, all of the items I listed have been changed recently in the course of servicing and upkeep, the only things I've bought to help cure my recent problems have been lambda sensor and silenced decat pipes.
Tim
TT Tim said:
[deep thought mode on] Tricky [/deep thought mode off]
Your possibilities are many and varied and its difficult to check everything on the car. Its possibly one of those rare times when I would suggest defering to a specialist.
With a fair amount of experience of this engine a specialist could directly you fairly accurately to fuel air or electrics. At least then you would have narrowed a large number of possibilites down to a manageable amount.
Look at it this way, a specialist opinion is not going to cost less than all the unnecessary things you've already replaced.
Sorry to sound so negative but the adapative are only telling you the engine is running out of limits and is trying to do the impossible.
Either that or borrow a syncronometer and start from basics
I'm, inclined to agree with you Julian,
The odd thing is I have a syncronometer and have balanced Left and Right bank, and at the point where everything's set, then the adaptives start going wild!
I agree about the associated costs of getting an expert in, all of the items I listed have been changed recently in the course of servicing and upkeep, the only things I've bought to help cure my recent problems have been lambda sensor and silenced decat pipes.
Tim
Tim .. send me the screenshots of the first diagnostics page in jpg format of the car idling, and also the adaptive trim pages for the odd and even banks .. I'll see if I can read into the data anything to help you ok?
send to sales@track-car-solutions.co.uk
trackcar said:
Tim .. send me the screenshots of the first diagnostics page in jpg format of the car idling, and also the adaptive trim pages for the odd and even banks .. I'll see if I can read into the data anything to help you ok?
send to sales@track-car-solutions.co.uk
Thanks Jules, I'll do it this afternoon.
Tim
darreni said:
Once you have the throttle link rod set, put a dab of silicon sealant on the locknut, they will vibrate lose.
I did look into replacing the end ball joints with rose joints a while ago, i think demon tweeks can supply the joints for about £60.
For any application where vibration causes even lock nuts to work loose, try these:
www.nord-lock.com/
They are magical, but you shouldn't re-use them. If you remove the nut, replace washers with fresh.
(This isn't a blatant plug - honest, guv - Ihave nothing to do with nordlock, but I have found them worth their weight in gold in the past).
Edited to add: never over-torque a nut fitted with a nordlock washer - it'll take two of you to get the b*****d back off!
>> Edited by J1mmyD on Monday 13th March 11:50
Jules,
Here are the screen grabs of my car, I've just been through the whole tuning process gain and got the same outcome. AFR Bad fault
Sorry about the fact that these are photos of the computer a) I'm a Mac user so know bugger all about PCs and b) The laptop can't be networked so I don't have any way to get anything off it!
I really hope you can point me in the right direction.
Tim
Here are the screen grabs of my car, I've just been through the whole tuning process gain and got the same outcome. AFR Bad fault
Sorry about the fact that these are photos of the computer a) I'm a Mac user so know bugger all about PCs and b) The laptop can't be networked so I don't have any way to get anything off it!
I really hope you can point me in the right direction.
Tim
Hmm we await Trackcar but that seems to be showing a fairly constant mismatch at every rev and pover level on one side of the engine.
One side of your engine is developing a different power to the other at both high and low power settings. Possibly one side running a weak mixture.
Can you discern anything further than that? I would be interested if anyone would like to explain if the figures show more to them?
Unless anyone has an answer is it possible for you to go for a little run and record the graph telemetry for us to see?
>> Edited by Julian64 on Wednesday 15th March 18:02
One side of your engine is developing a different power to the other at both high and low power settings. Possibly one side running a weak mixture.
Can you discern anything further than that? I would be interested if anyone would like to explain if the figures show more to them?
Unless anyone has an answer is it possible for you to go for a little run and record the graph telemetry for us to see?
>> Edited by Julian64 on Wednesday 15th March 18:02
Right, I think there's three things going wrong here.
first is there's an airflow inbalance in favour of the odd bank .. it seems to be adapting around 15% higher than the *trend* on the even bank (30s rather than 10s/20s everywhere), so first thing is to reduce the odd bank airflow by around 15% then raise the total airflow to bring the idle back up again. (you may find you have throttle link rod play, in which case don't fall into the trap of balancing at idle, but set the balance based on the trend of the part throttle trimming %s .. yours indicate that the odd is flowing more at cruise than the even bank .. so you need to address that first and largely forget about the idle situation, the idle will be out but you don't drive at idle so it doesn't matter at this stage)
Second thing is that for a 4.2 your throttle pot values at idle are too low .. get them up around 17.3, this will do two things : it'll move you up the fuelling maps meaning you'll add more fuel so less positive trim needs to take place, but also it'll ramp up the ignition so your tickover will increase, so you'll have to reduce the idle airflow again, so you'll have to increase the throttle pots again .. eventually after cycling through that routine a few times you'll reach a stable point where the idle is 900-1000 revs and the throttle pot is 17.3 on the even bank and the odd bank is very slightly lower (but is the same as the even bank if you open the throttle slightly and take up the play in the link rod) . The trend across both banks adaptive ranges after a run should be close to each other (but not necesarily close to zero) after doing this. Again I repeat don't set it off the idle figures, if you have play they are misleading you! do it off the part throttle trimming range only! Also don't open the throttle from the link rod in the engine bay, do it properly off the accelrator pedal to accurately replicate the action of taking up the play in the throttle spindles and link rod.
third thing is that'll possibly still not cure your positive trimming (though it will improve it).. but i reckon you'll need a 10% increase in fuel line pressure to get both banks close to zero, but you may not need this to make the car run smoothly if the total trim that needs to be applied is less than 15-20%.
Hope that helps.
PS i've just done a 4.2 that was in for service that had a similar problem, even with a new regulator it still wasn't brilliant (though was much improved) so i just wrote a new chip with about 10% extra fuelling everywhere, drives like a dream now
>> Edited by trackcar on Wednesday 15th March 20:33
first is there's an airflow inbalance in favour of the odd bank .. it seems to be adapting around 15% higher than the *trend* on the even bank (30s rather than 10s/20s everywhere), so first thing is to reduce the odd bank airflow by around 15% then raise the total airflow to bring the idle back up again. (you may find you have throttle link rod play, in which case don't fall into the trap of balancing at idle, but set the balance based on the trend of the part throttle trimming %s .. yours indicate that the odd is flowing more at cruise than the even bank .. so you need to address that first and largely forget about the idle situation, the idle will be out but you don't drive at idle so it doesn't matter at this stage)
Second thing is that for a 4.2 your throttle pot values at idle are too low .. get them up around 17.3, this will do two things : it'll move you up the fuelling maps meaning you'll add more fuel so less positive trim needs to take place, but also it'll ramp up the ignition so your tickover will increase, so you'll have to reduce the idle airflow again, so you'll have to increase the throttle pots again .. eventually after cycling through that routine a few times you'll reach a stable point where the idle is 900-1000 revs and the throttle pot is 17.3 on the even bank and the odd bank is very slightly lower (but is the same as the even bank if you open the throttle slightly and take up the play in the link rod) . The trend across both banks adaptive ranges after a run should be close to each other (but not necesarily close to zero) after doing this. Again I repeat don't set it off the idle figures, if you have play they are misleading you! do it off the part throttle trimming range only! Also don't open the throttle from the link rod in the engine bay, do it properly off the accelrator pedal to accurately replicate the action of taking up the play in the throttle spindles and link rod.
third thing is that'll possibly still not cure your positive trimming (though it will improve it).. but i reckon you'll need a 10% increase in fuel line pressure to get both banks close to zero, but you may not need this to make the car run smoothly if the total trim that needs to be applied is less than 15-20%.
Hope that helps.
PS i've just done a 4.2 that was in for service that had a similar problem, even with a new regulator it still wasn't brilliant (though was much improved) so i just wrote a new chip with about 10% extra fuelling everywhere, drives like a dream now
>> Edited by trackcar on Wednesday 15th March 20:33
Very interesting stuff. With the help of posts like this & Practical Performance Car, I’m understanding a lot more about engine management.
A while back on our 4.5 I found the MIL light came on at full throttle & some one here suggested the pots may have been going past full range, sure enough they were right. But it I think it was only one of the pots, as when one set of butterfly’s were fully open the other was quite a way past fully open, about 5mm at the edge of the butterfly, so I backed the stop off to make them even at full throttle, but figured they would be very uneven at part throttle, but didn’t have any thing to test it with. I couldn’t adjust the linkage as they were both closing perfectly together with no play in the ball joints so left it for a while, I guess the adaptive maps were coping with it all ok.
Recently I decided to overhaul the throttle bodies as the large lip just below the butterfly, where TVR had the bodies off centre when boring them out, was bugging me. I ground them smooth & welded new metal in to the opposite side where there was in inverse of the lip in the casting. Then when re-fitting them I filed the hole out & moved the ball down the linkage arm on the side that were moving to far till they both opened in sync.
It pulls much much better from part throttle now & is much smoother when cruising. The whole car used to vibrate at speed before, at what I think must have been the resonant frequency of the sub, as it made an interesting noise with out the stereo on…
Still my girl friend didn’t mind, in fact she rather liked it – the spin drier effect
A while back on our 4.5 I found the MIL light came on at full throttle & some one here suggested the pots may have been going past full range, sure enough they were right. But it I think it was only one of the pots, as when one set of butterfly’s were fully open the other was quite a way past fully open, about 5mm at the edge of the butterfly, so I backed the stop off to make them even at full throttle, but figured they would be very uneven at part throttle, but didn’t have any thing to test it with. I couldn’t adjust the linkage as they were both closing perfectly together with no play in the ball joints so left it for a while, I guess the adaptive maps were coping with it all ok.
Recently I decided to overhaul the throttle bodies as the large lip just below the butterfly, where TVR had the bodies off centre when boring them out, was bugging me. I ground them smooth & welded new metal in to the opposite side where there was in inverse of the lip in the casting. Then when re-fitting them I filed the hole out & moved the ball down the linkage arm on the side that were moving to far till they both opened in sync.
It pulls much much better from part throttle now & is much smoother when cruising. The whole car used to vibrate at speed before, at what I think must have been the resonant frequency of the sub, as it made an interesting noise with out the stereo on…
Still my girl friend didn’t mind, in fact she rather liked it – the spin drier effect
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