Lumpy/uneven running at constant throttle
Discussion
Having just bought the Tuscan, it's quite apparent the previous owner didn't know too much about them. 
So, having taken the tyre pressure up from 20 PSI to 25 (
), the next thing on my list is the way it's running...
The car's power is spot on, but it's running really lumpy at constant throttle; slight hesitations causing it to push/pull. I was just wondering if anybody else has experienced this and what the cause was? My thoughts are currently:
* 95 RON petrol he was running it on (I've emptied half a tank of it, and filled it up with Optimax, but the problem's not gone away - think it might've improved a bit, though)
* HT leads/plugs (it was serviced 2k miles ago)
* Valve clearances
* Throttle pots
* Lambda sensors
Any thoughts?
>>> Edited by j_s_g on Tuesday 6th April 10:23
So, having taken the tyre pressure up from 20 PSI to 25 (), the next thing on my list is the way it's running... The car's power is spot on, but it's running really lumpy at constant throttle; slight hesitations causing it to push/pull. I was just wondering if anybody else has experienced this and what the cause was? My thoughts are currently:
* 95 RON petrol he was running it on (I've emptied half a tank of it, and filled it up with Optimax, but the problem's not gone away - think it might've improved a bit, though)
* HT leads/plugs (it was serviced 2k miles ago)
* Valve clearances
* Throttle pots
* Lambda sensors
Any thoughts?
>>> Edited by j_s_g on Tuesday 6th April 10:23
Plotloss said:
Give it a while I reckon, it'll take a couple of tanks for the Opti to completely replace the 95RON.
Say another complete tank full?
Gives you something to do today at least
That's what I was thinking! Just wasn't sure if that's the symptoms I'd be getting with an S6... never even tried running the Cerb on anything less than 97 (and usually 98), so I've got no real comparison. Can't hear any pinking, etc.
You have worn throttle bodies. Welcome to the world of Speed six niggles.
You could upgrade to roller throttle bearings in the throttle bodies. Dreadnought in Scotland do it. Do a search on here, there has been plenty of discussion about it before, YAHOO raves about them.
Have fun !
Whitey
You could upgrade to roller throttle bearings in the throttle bodies. Dreadnought in Scotland do it. Do a search on here, there has been plenty of discussion about it before, YAHOO raves about them.
Have fun !
Whitey
The speed six does seem quiet sensetive to the grade of petrol I always use 98 or Optimax,although the problem you describe can also be the throttle body spindle bushes wearing.See www.pistonheads.com/gassing/topic.asp?f=5&h=&t=46789
Nick
Nick
but if you treat the throttle pot adjustments just like you would an oil change or tyre pressure adjustment then i don't see it's a major issue.
a pain in the a*se, yes! and a bit dearer than adjusting pressures but just factor it in.
surely it's a small price to pay for such massive performance?!!
(JSG: i'm guessing you're new to Tuscan ownership: biggest tip: always let it idle til the oil is a wee bit warmed before driving anywhere nothing over 2500 til it's above 25, nothing above 3000 til it's above 45, and nothing over 4000 til it's above 50-55. apologies if you already know this)
a pain in the a*se, yes! and a bit dearer than adjusting pressures but just factor it in.
surely it's a small price to pay for such massive performance?!!
(JSG: i'm guessing you're new to Tuscan ownership: biggest tip: always let it idle til the oil is a wee bit warmed before driving anywhere nothing over 2500 til it's above 25, nothing above 3000 til it's above 45, and nothing over 4000 til it's above 50-55. apologies if you already know this)
tuscan_thunder said:
but if you treat the throttle pot adjustments just like you would an oil change or tyre pressure adjustment then i don't see it's a major issue.
a pain in the a*se, yes! and a bit dearer than adjusting pressures but just factor it in.
But I can sort out oil/tyre pressure problems on my drive. tuscan_thunder said:
surely it's a small price to pay for such massive performance?!!
Oh
tuscan_thunder said:
JSG: i'm guessing you're new to Tuscan ownership: biggest tip: always let it idle til the oil is a wee bit warmed before driving anywhere nothing over 2500 til it's above 25, nothing above 3000 til it's above 45, and nothing over 4000 til it's above 50-55. apologies if you already know this
New to the world of Tuscans and S6 engines. Veteran of the Cerb/AJP V8 world, though.
Thanks for the figures - was going to put up a post questioning peoples warm-up procedures. My standard on the Cerb was usually up to 2500 RPM for the first 5 mins, then nothing above 3,000 for the next 5 mins. Seemed to give everything plenty of time to warm up, and looks like it'll apply nicely to the Tusc too.
I'm going through this atm.
I used BPs new Ultima or whatever they call it over the weekend and the car is running lumpy as hell - like I'd been running the car on the dregs of the tank prior to filling it up - which I hadn't.
This was an emergency fill up, and having never used Ultima before, I only put a tenner in. Subsequently, when I made it to a Shell, I managed to stick about 40L of Optimax in there. But the ride is still terrible, and sounds worse. I guess it'll take a while to work out of the system.
I thought Ultima was supposed to be BPs answer to Optimax. I certainly won't be using that again...
I used BPs new Ultima or whatever they call it over the weekend and the car is running lumpy as hell - like I'd been running the car on the dregs of the tank prior to filling it up - which I hadn't.
This was an emergency fill up, and having never used Ultima before, I only put a tenner in. Subsequently, when I made it to a Shell, I managed to stick about 40L of Optimax in there. But the ride is still terrible, and sounds worse. I guess it'll take a while to work out of the system.
I thought Ultima was supposed to be BPs answer to Optimax. I certainly won't be using that again...
tuscan_thunder said:
throttle pots need adjusted i think. what speed does it idle at when hot and when cold?
does it feel slightly hesitant when going from constant revs when you put your foot down? ie, holding 3500rpm then cracking the throttle open to pass something?
Absolutely no hesitation at any revs - pulls like a bullet-train the second I touch the throttle. Just runs lumpy throughout the rev range. Seems worst in certain "bands", though - 3000RPM ish, for instance.
Idle speed is around 600RPM all the time. Little higher when warm, I think, but I wouldn't swear to it just yet.
>> Edited by j_s_g on Tuesday 6th April 11:20
yeh, just treat it with a bit of care and it should be fine! oil is a major issue with the speed six esp. with cam lubrication etc.
it could be the pots need adjusted which should take a TVR garage about 15 mins to do or if it's the bodies it'll take a wee bit longer. but it's not that dear really. the bodies should then last a good while. if they're properly greased when they go on too that make a difference.
side issue: if you were a little concerned about the previous owner with regard to pressures etc it would definitely be worth getting all the alignment, tracking and castor and camber sorted.
if you need the throttle pots done too then i definitely recommend dreadnought. they may be a wee bit away from you but book a hotel for a night and tackle some of the rather entertaining roads round about Callander.
it could be the pots need adjusted which should take a TVR garage about 15 mins to do or if it's the bodies it'll take a wee bit longer. but it's not that dear really. the bodies should then last a good while. if they're properly greased when they go on too that make a difference.
side issue: if you were a little concerned about the previous owner with regard to pressures etc it would definitely be worth getting all the alignment, tracking and castor and camber sorted.
if you need the throttle pots done too then i definitely recommend dreadnought. they may be a wee bit away from you but book a hotel for a night and tackle some of the rather entertaining roads round about Callander.
Naith said:
I thought Ultima was supposed to be BPs answer to Optimax. I certainly won't be using that again...
Ultimate is a load of crock. It's actually only 97 RON, whereas Optimax is guaranteed 98, and is regularly closer to 99. Even driven cars that prefer Sainsburys Super to Ultimate! For me, it's Shells finest, or nothing. Used to keep a bottle of octane booster in the boot incase I ever had to drop to something substandard in an emergency. Might start doing that again.
tuscan_thunder said:
it could be the pots need adjusted which should take a TVR garage about 15 mins to do or if it's the bodies it'll take a wee bit longer. but it's not that dear really. the bodies should then last a good while. if they're properly greased when they go on too that make a difference.
side issue: if you were a little concerned about the previous owner with regard to pressures etc it would definitely be worth getting all the alignment, tracking and castor and camber sorted.
I'm having the Nitrons transferred across to the Tuscan in a couple of weeks, so I'll have the full geometry works looked at on it then. tuscan_thunder said:
if you need the throttle pots done too then i definitely recommend dreadnought. they may be a wee bit away from you but book a hotel for a night and tackle some of the rather entertaining roads round about Callander.
Really can't be bothered going all the way up from the Midlands! Might be interested in getting them to send a set of their new throttle-bodies/whatever down to TVR Power/Joolz, though. Any idea on price?
Cheers for all that, anyway!
I have had the syptoms you describe in the past. I took my car to Shane at SFR Engineering near Manchester. He rebalanced the throttle bodies and this made a tremendous improvement - all for the cost of an hour or two's labour. He also replaced the HT leads with a newer version that TVR now use. The HT leads on earlier cars tended to break down (black ones I think, but don't quote me!).
How many miles has the car done? This may give an indication of whether the throttle bodies have worn or not. If so, Shane at SFR also now does a throttle body upgrade which involves rebushing the spindle bearings with a material that does not wear like the original design (which I believe TVR have recently also changed). This should cost under £400 to do.
Other item that TVR changed on mine, was to fit a 'dethrottle' chip. Do a search on here for an explanation of how that works by Fish. AFAIK, that is a 'free' upgrade that can be done at service time by your dealer.
How many miles has the car done? This may give an indication of whether the throttle bodies have worn or not. If so, Shane at SFR also now does a throttle body upgrade which involves rebushing the spindle bearings with a material that does not wear like the original design (which I believe TVR have recently also changed). This should cost under £400 to do.
Other item that TVR changed on mine, was to fit a 'dethrottle' chip. Do a search on here for an explanation of how that works by Fish. AFAIK, that is a 'free' upgrade that can be done at service time by your dealer.
TUS 373 said:
How many miles has the car done? [...]
Other item that TVR changed on mine, was to fit a 'dethrottle' chip. Do a search on here for an explanation of how that works by Fish. AFAIK, that is a 'free' upgrade that can be done at service time by your dealer.
Not had the car past 5500RPM yet, so I've no idea if the dethrottle chip'll be required! Wonder if I could get the throttle bodies done under warranty??
The car's done 20,000 miles, following a rebuild & upgrade to RR spec after 8,000 miles. Guess that'll mean something's most likely worn, then.
j_s_g said:
it could be the pots need adjusted which should take a TVR garage about 15 mins to do or if it's the bodies it'll take a wee bit longer. but it's not that dear really. the bodies should then last a good while. if they're properly greased when they go on too that make a difference.
side issue: if you were a little concerned about the previous owner with regard to pressures etc it would definitely be worth getting all the alignment, tracking and castor and camber sorted.
tuscan_thunder said:
if you need the throttle pots done too then i definitely recommend dreadnought. they may be a wee bit away from you but book a hotel for a night and tackle some of the rather entertaining roads round about Callander.
Really can't be bothered going all the way up from the Midlands! Might be interested in getting them to send a set of their new throttle-bodies/whatever down to TVR Power/Joolz, though. Any idea on price?
Cheers for all that, anyway!
Dreadnought charge about £500 on an exchange, and they do the work for you so you have to take your car there. That's what Claire told me last time we spoke.
Shane at SFR (Stockport, Manchester) needs to keep your car for a couple of days. He strips off the throttle bodies and sends them to a specialist company (who are experts at this kind of thing) and gets them rebushed, then refits them. Looking at about £300 + VAT.
BTW, if your car is idling at 600 rpm, that may need some attention. What are the miles on the clock, and have the valves been adjusted in the last 12K miles?
can't be bothered from midlands???!!!!!!!! for the quality roads at callander???? it's about the same distance we have to go from just north of Aberdeen!!
not sure about price for bodies.
if you're getting the nitrons put on and the geometry checked, then you may feel a bit of a difference!
hope i've been of some help!
not sure about price for bodies.
if you're getting the nitrons put on and the geometry checked, then you may feel a bit of a difference!
hope i've been of some help!
20K miles then quite likely to be worn throttle bodies. Yahoo got his done and said it transformed the engine making it as silky smooth as BMW straight 6!
HT leads are worth getting done too - costs about £100. All depends on what you want to spend - but then it should be OK for some time.
HT leads are worth getting done too - costs about £100. All depends on what you want to spend - but then it should be OK for some time.
TUS 373 said:
BTW, if your car is idling at 600 rpm, that may need some attention. What are the miles on the clock, and have the valves been adjusted in the last 12K miles?
What should warm-idle be? Know mine's at 650RPM-ish cold, but not paid any attention when warm yet. I'm guessing it should be more like 850? 20k on the clock, and I'll be checking the paperwork tonight to see what exactly was done at the 12k & 18k service.
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