Throttle stuck open!!! and dash saying 250mph??
Discussion
I'll keep it short and sweet... two major issues which have both cropped up at the same time. Both after a service at a new garage.
1. Throttle has got stuck wide open twice in on week... have had to take out of gear and switch off engine on the move. Not ideal!!!!
2. After around 15mins of driving my dash start to make up the speed, normally rising from the current speed right up to 250mph, back down, up again, and down again. The needle and the digital display both do it.
Does anyone know what is going on with my Tam, and if both things can be realated... and if they could be affect but a 24k service? I'm 100% sure they are related to the service as they happened the night I picked it up.
1. Throttle has got stuck wide open twice in on week... have had to take out of gear and switch off engine on the move. Not ideal!!!!
2. After around 15mins of driving my dash start to make up the speed, normally rising from the current speed right up to 250mph, back down, up again, and down again. The needle and the digital display both do it.
Does anyone know what is going on with my Tam, and if both things can be realated... and if they could be affect but a 24k service? I'm 100% sure they are related to the service as they happened the night I picked it up.
The throttle is a mechanical cable with no connection to your speed sensor and dash electronics, so these two problems are unrelated I think.
The indicated speed issue could be caused by a faulty speed sensor which is located on the diff, though I think problems in that area are more often on/off - either it works or it doesn't. If not the sensor, then some dodgy connection in the elecrics somewhere?
The indicated speed issue could be caused by a faulty speed sensor which is located on the diff, though I think problems in that area are more often on/off - either it works or it doesn't. If not the sensor, then some dodgy connection in the elecrics somewhere?
I`ve had a sticky throttle, nothing "full open" it just doesn`t return to the start that quickly but its very random. I`m going to "attempt" to trace the cable over the winter and locate any snags.
If the only thing you are experiencing is incorrect speeds then your sensor is awol. Its not hard to sort and any garage should do it in an hour. If your getting very weird results from all sensors then the dash is overheating and the small fan that keeps it cool is probably dead.
J
If the only thing you are experiencing is incorrect speeds then your sensor is awol. Its not hard to sort and any garage should do it in an hour. If your getting very weird results from all sensors then the dash is overheating and the small fan that keeps it cool is probably dead.
J
KillerJim said:
I`ve had a sticky throttle, nothing "full open" it just doesn`t return to the start that quickly but its very random. I`m going to "attempt" to trace the cable over the winter and locate any snags.
If the only thing you are experiencing is incorrect speeds then your sensor is awol. Its not hard to sort and any garage should do it in an hour. If your getting very weird results from all sensors then the dash is overheating and the small fan that keeps it cool is probably dead.
J
Your becoming quite an expert Jim. Not seen you out and about for a long time still going well?If the only thing you are experiencing is incorrect speeds then your sensor is awol. Its not hard to sort and any garage should do it in an hour. If your getting very weird results from all sensors then the dash is overheating and the small fan that keeps it cool is probably dead.
J
Speedo sensor might have been knocked during the "service" and only might need adjusting? Other possibility, if you have driven through a lot of standing water, this might effect the sensor, mine did this during the horrendous weather at London Thunder a couple of years ago.
If the brake/clutch fluid was replaced/topped up maybe the mechanic has caught the cable some how? worth a check in the footwell, also check the cable run through the engine bay to see if the cable has snagged in some way?
Good luck
If the brake/clutch fluid was replaced/topped up maybe the mechanic has caught the cable some how? worth a check in the footwell, also check the cable run through the engine bay to see if the cable has snagged in some way?
Good luck
bobd said:
KillerJim said:
I`ve had a sticky throttle, nothing "full open" it just doesn`t return to the start that quickly but its very random. I`m going to "attempt" to trace the cable over the winter and locate any snags.
If the only thing you are experiencing is incorrect speeds then your sensor is awol. Its not hard to sort and any garage should do it in an hour. If your getting very weird results from all sensors then the dash is overheating and the small fan that keeps it cool is probably dead.
J
Your becoming quite an expert Jim. Not seen you out and about for a long time still going well?If the only thing you are experiencing is incorrect speeds then your sensor is awol. Its not hard to sort and any garage should do it in an hour. If your getting very weird results from all sensors then the dash is overheating and the small fan that keeps it cool is probably dead.
J
I`m out and about most weekends in the Sagaris and the odd week day if its dry but she`ll be going into a garage in the next few weeks til probably March time (bar the odd clear blue sky day or car show...)
Should give me a chance to fix a few minor gremlins (fogged lenses, rattles, fattening the door seals, etc.) and get Greg to replace the clutch.
I really need to get to a TVR meet but I`m always busy the Saturday's its on!
If the speed sensor is hitting 250mph then its faulty, I doubt moving it would fix it as if its out of position it will read zero (which I`ve had..) and if it sits at 250mph its going to push your total miles up pretty quickly
James
Thank for all those points... very useful indeed!
Those fluids could well have been changed, it was the largest service they do, so that is very interesting about wires and sensors.
I had assumed that both problems where unrelated, but they both happened after a service.
The dash issue is only the speed reading (digital and dial) and it seems to rise and fall three times almost like a funny start up sequence?
What are the veiws on the TVR rev limiters? I ask as the second time the throttle was stuck, I had to take the car out of gear. This meant that it was bouncing off the limiter untill I could reach the key (about 3 secs). Its clearly better to not hit or go near the limiter, however what do you think about potential damage caused if any?
Thanks
Stu
Those fluids could well have been changed, it was the largest service they do, so that is very interesting about wires and sensors.
I had assumed that both problems where unrelated, but they both happened after a service.
The dash issue is only the speed reading (digital and dial) and it seems to rise and fall three times almost like a funny start up sequence?
What are the veiws on the TVR rev limiters? I ask as the second time the throttle was stuck, I had to take the car out of gear. This meant that it was bouncing off the limiter untill I could reach the key (about 3 secs). Its clearly better to not hit or go near the limiter, however what do you think about potential damage caused if any?
Thanks
Stu
piscola90 said:
What are the veiws on the TVR rev limiters? I ask as the second time the throttle was stuck, I had to take the car out of gear. This meant that it was bouncing off the limiter untill I could reach the key (about 3 secs). Its clearly better to not hit or go near the limiter, however what do you think about potential damage caused if any?
If she was cold I would be seriously concerned about that occuring, what is happening when she hits the rev limiter - are you accelerating hard? Does the accelerator pedal get stuck down? If you restart her does it immeditately go away?I`ve not idea if the engine ECU (MBE) can cause the car to rev that high but I`ve known mine (especially after a service or maybe a reset) to rev it to 1600rpm after starting before settling to 950rpm (idle) within a few seconds. Therefore it might be the ECU but I`m not into the internal workings of the ECU / Engine (not yet anyway
)J
KillerJim said:
piscola90 said:
What are the veiws on the TVR rev limiters? I ask as the second time the throttle was stuck, I had to take the car out of gear. This meant that it was bouncing off the limiter untill I could reach the key (about 3 secs). Its clearly better to not hit or go near the limiter, however what do you think about potential damage caused if any?
If she was cold I would be seriously concerned about that occuring, what is happening when she hits the rev limiter - are you accelerating hard? Does the accelerator pedal get stuck down? If you restart her does it immeditately go away?I`ve not idea if the engine ECU (MBE) can cause the car to rev that high but I`ve known mine (especially after a service or maybe a reset) to rev it to 1600rpm after starting before settling to 950rpm (idle) within a few seconds. Therefore it might be the ECU but I`m not into the internal workings of the ECU / Engine (not yet anyway
)J
The trottle problem happens when I have had my foot flat down for some time. So unfortuantly I went to change gear a 6200rpm and the car wouldnt ease off. I took it out of gear so I didnt hit the guy in front of me at which point it bounced of the limiter... so I turned it off sharpish. I resarted while rolling and all seemed back to normal, however I had pumped the throttle a few times to try and fix the problem before restarting?
piscola90 said:
KillerJim said:
piscola90 said:
What are the veiws on the TVR rev limiters? I ask as the second time the throttle was stuck, I had to take the car out of gear. This meant that it was bouncing off the limiter untill I could reach the key (about 3 secs). Its clearly better to not hit or go near the limiter, however what do you think about potential damage caused if any?
If she was cold I would be seriously concerned about that occuring, what is happening when she hits the rev limiter - are you accelerating hard? Does the accelerator pedal get stuck down? If you restart her does it immeditately go away?I`ve not idea if the engine ECU (MBE) can cause the car to rev that high but I`ve known mine (especially after a service or maybe a reset) to rev it to 1600rpm after starting before settling to 950rpm (idle) within a few seconds. Therefore it might be the ECU but I`m not into the internal workings of the ECU / Engine (not yet anyway
)J
The trottle problem happens when I have had my foot flat down for some time. So unfortuantly I went to change gear a 6200rpm and the car wouldnt ease off. I took it out of gear so I didnt hit the guy in front of me at which point it bounced of the limiter... so I turned it off sharpish. I resarted while rolling and all seemed back to normal, however I had pumped the throttle a few times to try and fix the problem before restarting?
. Your throttle cable sticking is a potentially serious safety problem, and should be a simple fix so I'd suggest should be a priority to attend to. The speed sensor is your prime suspect for the speedo reading if for no other reason than it is so common for them to fail/misbehave.I suspect the problem is at the point where the outer core of the throttle cable is fixed above the throttle pedal.
The bracket which holds the cable is often bent to an angle which causes the inner braided steel cable to rub on the outer sheath and fray slightly; the friction increases to the point where the spring is not powerful enought to return the thrttle to neutral when released. It is easy to fix before the fraying occurs (although sometimes the bracket snaps and needs to be replaced) but once the cable begins to fray it should be replaced before it sticks completely of snaps. It's not a big job.
The speedo is a separate issue.
John F
The bracket which holds the cable is often bent to an angle which causes the inner braided steel cable to rub on the outer sheath and fray slightly; the friction increases to the point where the spring is not powerful enought to return the thrttle to neutral when released. It is easy to fix before the fraying occurs (although sometimes the bracket snaps and needs to be replaced) but once the cable begins to fray it should be replaced before it sticks completely of snaps. It's not a big job.
The speedo is a separate issue.
John F
Edited by Dr John on Tuesday 18th November 11:06
Great... thanks for all the help. I will check out the cable at the drivers end asap and see if its suspect? The garage have been very responsible about the whole thing and are calling the car back in to fix anything that they may have done wrong.
Looking forward to salt free roads so I can get driving!!!
Looking forward to salt free roads so I can get driving!!!
Well at last I got time to get the kick plate off and check the cable. It seems nice and smooth with no signs of wear... so I guess I will have to get the car back in to the garage which is a bit of a ball ache!
Thanks for all the help.
p.s At the same time I went to do this mod on the battery (the one posted on here to stop the live hitting the chasis) and I couldnt see how on earth you get to the battery. I removed the carpet cover but it then seemed that the live entered the battery through a grommit. Can you not access the battery? I have seen pics that would suggest otherwise?
Thanks for all the help.
p.s At the same time I went to do this mod on the battery (the one posted on here to stop the live hitting the chasis) and I couldnt see how on earth you get to the battery. I removed the carpet cover but it then seemed that the live entered the battery through a grommit. Can you not access the battery? I have seen pics that would suggest otherwise?
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