Dodgy Throttle
Discussion
Had my throttle jam open half a dozen times over the last week.
It happens when i give it some welly about 5k revs coming down the gears or breaking it sticks then.
It drops to about 3k then stays there tried blipping but stuck solid.
Stop the car ASAP and throttle has stuck open about 10mm i have to push the throttle hard to release or spring it forward.
Can't make it happen while pressing the pedal and watching or operate by hand.
Only thing i can think is about a month ago i used instant gasket on the plenum box where they join to minimise air leaks and replaced the stepper motor aswell.
Also the car idles at 1.5k unless car is at a dead stop then idles at 900.
Makes driving a bit uneasy as the car seems to drive itself so to speak.
Any thoughts anyone.
V8 Animal
It happens when i give it some welly about 5k revs coming down the gears or breaking it sticks then.
It drops to about 3k then stays there tried blipping but stuck solid.
Stop the car ASAP and throttle has stuck open about 10mm i have to push the throttle hard to release or spring it forward.
Can't make it happen while pressing the pedal and watching or operate by hand.
Only thing i can think is about a month ago i used instant gasket on the plenum box where they join to minimise air leaks and replaced the stepper motor aswell.
Also the car idles at 1.5k unless car is at a dead stop then idles at 900.
Makes driving a bit uneasy as the car seems to drive itself so to speak.
Any thoughts anyone.
V8 Animal
Pasco said:
Hi Paul how's Tricks
Spray the throttle assembly on the plenum with WD40 and clean up the springs.
I presume you have two large springs if not consider re fitting the second one often taken off by dealers prior to delivering the cars.
Pasco
Hi pasco,Spray the throttle assembly on the plenum with WD40 and clean up the springs.
I presume you have two large springs if not consider re fitting the second one often taken off by dealers prior to delivering the cars.
Pasco
Bit tricky with the car at the moment as you have read.
Sitting here wondering as what to do.
Got the trip tommorow night to GOG and was taking the car around the haynes motor museam track not sure thats now a good idea.
Only got tonite to try and sort it.
Both springs are on and as i say can operate linkage with foot and hand and can't get it to stick.
When it sticks have to move it forward to release.
Wondering if theres some old sealant in the plenum.
Anyone help please?
Thanks
Update,
Can't fix the problem the only thing i have found wrong is the air mass meter.
It reads .97v no amount of adjusting to set it at 1.8v sorts it so i assume it's broke.
Can't see this would create a sticking linkage.
It's not the cable as there is play in it poss too much it only happens at 4-5k
Seems to be running on choke.
Yet when on the drive it's very free.
Do i do the 400 mile round trip as planned the car operates ok if you don't give it alot of revs.
Won't do the planned track day there would be no point.
Gutted.
V8 Animal
Can't fix the problem the only thing i have found wrong is the air mass meter.
It reads .97v no amount of adjusting to set it at 1.8v sorts it so i assume it's broke.
Can't see this would create a sticking linkage.
It's not the cable as there is play in it poss too much it only happens at 4-5k
Seems to be running on choke.
Yet when on the drive it's very free.
Do i do the 400 mile round trip as planned the car operates ok if you don't give it alot of revs.
Won't do the planned track day there would be no point.
Gutted.
V8 Animal
Remove your throttle pot and see if you get a nice smooth action on the throttle. Also, it may be worth loosening the screws the butterfly to the shaft a little, fully open and close the throttle a few times to let the plate sit where it wants then retighten. This is very common on XJ jags, a bit of a bummer in an auto car approaching red lights!
Mine Chim was doing this very mildly a few weeks back. It was caused by tht throttle return spring coils over lapping where they should be sitting side by side. Worth a look....
Mine Chim was doing this very mildly a few weeks back. It was caused by tht throttle return spring coils over lapping where they should be sitting side by side. Worth a look....
Decided to make the trip and enjoyed the weekend!
Did 600 miles complete with sticky throttle getting a dab hand at blipping the gas when it sticks.
A few dodgy moments at the track but did'nt bin it.
Going to order a cable on monday just so i can eliminate this as i don't think this is the problem.
Can you take the butterfly and linkage out of the plenum?I can't see how this is done.
As for the lumpy running took the vacuume pipe off at a service station and the car was alot better for the other 500 miles.
Can't understand this unit seems to be a pain in the arse.
Regards.
Did 600 miles complete with sticky throttle getting a dab hand at blipping the gas when it sticks.
A few dodgy moments at the track but did'nt bin it.
Going to order a cable on monday just so i can eliminate this as i don't think this is the problem.
Can you take the butterfly and linkage out of the plenum?I can't see how this is done.
As for the lumpy running took the vacuume pipe off at a service station and the car was alot better for the other 500 miles.
Can't understand this unit seems to be a pain in the arse.
Regards.
I had this once - just before my engine grenaded.
Turned out the air intake had come undone at the filter and was Dysoning the road. Several large objects did nasty stuff to my engine internals, but some of the larger bits that wouldn't fit down the trumpets rattled about in the plenum and jammed the throttle on hard acceleration. These only came to light whe I stripped her down after bent valves, smashed skirts and dropped liners made a rebuild inevitable.
I'd have the plenum off and check if I were you ...
Turned out the air intake had come undone at the filter and was Dysoning the road. Several large objects did nasty stuff to my engine internals, but some of the larger bits that wouldn't fit down the trumpets rattled about in the plenum and jammed the throttle on hard acceleration. These only came to light whe I stripped her down after bent valves, smashed skirts and dropped liners made a rebuild inevitable.
I'd have the plenum off and check if I were you ...
VictorMeldrew said:
I had this once - just before my engine grenaded.
Turned out the air intake had come undone at the filter and was Dysoning the road. Several large objects did nasty stuff to my engine internals, but some of the larger bits that wouldn't fit down the trumpets rattled about in the plenum and jammed the throttle on hard acceleration. These only came to light whe I stripped her down after bent valves, smashed skirts and dropped liners made a rebuild inevitable.
I'd have the plenum off and check if I were you ...
Quiet a worrying post.Turned out the air intake had come undone at the filter and was Dysoning the road. Several large objects did nasty stuff to my engine internals, but some of the larger bits that wouldn't fit down the trumpets rattled about in the plenum and jammed the throttle on hard acceleration. These only came to light whe I stripped her down after bent valves, smashed skirts and dropped liners made a rebuild inevitable.
I'd have the plenum off and check if I were you ...
Had the plenum partily off the stepper motor bit is in the way of the windscreen mesh.
How did you overcome this?
Thanks
Had the plenum partily off the stepper motor bit is in the way of the windscreen mesh.
How did you overcome this?
i had this problem with my precat first take the stepper out atleast that is one thing out of the way then you should be able to turn the plenum clockwise whilst lifting the front thus with a bit of jiggery pokery forcing it out you will find that you may have to force it the last bit but the windscreen mesh bend quite well back into shape
hope this helps
ant
How did you overcome this?
i had this problem with my precat first take the stepper out atleast that is one thing out of the way then you should be able to turn the plenum clockwise whilst lifting the front thus with a bit of jiggery pokery forcing it out you will find that you may have to force it the last bit but the windscreen mesh bend quite well back into shape
hope this helps
ant
Fitted a throttle cable tonight.
Also dismantled then refitted throttle linkage noticed spherical bearing was seized the bit that the arm goes through.
Greased eveything up and reconnected.
Idles perfectly took it for a test run in drying roads and took revs up to 5k and pulled in all gears.
Dipping the clutch drops the revs straight away normal driving revs drop evertime when you stop no hesitation.
Car is now smooth at the boring 30mph bit as soon as you get a decent bit of road the car picks up speed straight away with no hesitation.
Had multimeter set wrongly so the air mass meter is not broke and was reading 6.4v now reading 1.8v
What difference that made i have no idea and the vacuume advance is disconnected.
The only problem i have even though you would'nt know is the throttle pot i can't change the reading of 3.2v the multimeter won't change.
Don't know it this pot got damaged with sticking throttle.
Apart from that very happy and money well spent.
For those of you who suffer from lumpy running,hesitation etc.I would recommend you change the cable at least you would have a spare.
Thanks for all your advice looks like you were mostly right
Regards,
V8 Animal
Also dismantled then refitted throttle linkage noticed spherical bearing was seized the bit that the arm goes through.
Greased eveything up and reconnected.
Idles perfectly took it for a test run in drying roads and took revs up to 5k and pulled in all gears.
Dipping the clutch drops the revs straight away normal driving revs drop evertime when you stop no hesitation.
Car is now smooth at the boring 30mph bit as soon as you get a decent bit of road the car picks up speed straight away with no hesitation.
Had multimeter set wrongly so the air mass meter is not broke and was reading 6.4v now reading 1.8v
What difference that made i have no idea and the vacuume advance is disconnected.
The only problem i have even though you would'nt know is the throttle pot i can't change the reading of 3.2v the multimeter won't change.
Don't know it this pot got damaged with sticking throttle.
Apart from that very happy and money well spent.
For those of you who suffer from lumpy running,hesitation etc.I would recommend you change the cable at least you would have a spare.
Thanks for all your advice looks like you were mostly right
Regards,
V8 Animal
V8 Animal,
Beginning to think my shunting could be throttle related, so would appreciate some advice
How the hell do you get a spanner on the nut at the plenum end of the cable
Also, I've noticed the inner is very slack (hence the above question), although the cable inner itself appears to move freely. Is it advisable to take out all the slack on the inner, or does it not make any difference ? Logic would say the inner should move the lever the instant the pedal is depressed (?)
Was the job of changing the cable in itself difficult ? I seem to recall a thread where someone disconnected the cable & successfully oiled it overnight without removing it from the car. Could have been on the 'car club' site though.
Thanks in advance,
Chris
Beginning to think my shunting could be throttle related, so would appreciate some advice
How the hell do you get a spanner on the nut at the plenum end of the cable
Also, I've noticed the inner is very slack (hence the above question), although the cable inner itself appears to move freely. Is it advisable to take out all the slack on the inner, or does it not make any difference ? Logic would say the inner should move the lever the instant the pedal is depressed (?)
Was the job of changing the cable in itself difficult ? I seem to recall a thread where someone disconnected the cable & successfully oiled it overnight without removing it from the car. Could have been on the 'car club' site though.
Thanks in advance,
Chris
chr1sb said:
V8 Animal,
Beginning to think my shunting could be throttle related, so would appreciate some advice
How the hell do you get a spanner on the nut at the plenum end of the cable
Also, I've noticed the inner is very slack (hence the above question), although the cable inner itself appears to move freely. Is it advisable to take out all the slack on the inner, or does it not make any difference ? Logic would say the inner should move the lever the instant the pedal is depressed (?)
Was the job of changing the cable in itself difficult ? I seem to recall a thread where someone disconnected the cable & successfully oiled it overnight without removing it from the car. Could have been on the 'car club' site though.
Thanks in advance,
Chris
Best mod you can do since you asked my opinion.Beginning to think my shunting could be throttle related, so would appreciate some advice
How the hell do you get a spanner on the nut at the plenum end of the cable
Also, I've noticed the inner is very slack (hence the above question), although the cable inner itself appears to move freely. Is it advisable to take out all the slack on the inner, or does it not make any difference ? Logic would say the inner should move the lever the instant the pedal is depressed (?)
Was the job of changing the cable in itself difficult ? I seem to recall a thread where someone disconnected the cable & successfully oiled it overnight without removing it from the car. Could have been on the 'car club' site though.
Thanks in advance,
Chris
Car is superb now instant power as soon as you press the pedal.
Always had a problem doing 30mph......... not now!!
Got mine from keith@clevor trevor.
Did mine over 2 nights
First night,
Take off plenum well enough to lift it only 6 bolts you can then get at the big nuts easily also removed stepper.
You can take the plenum of i did you have to bend the windscreen mesh a bit you can then clean it and the stepper bit aswell.
Also went to the trouble of removing the linkage that's when i found the seized bearing may or may not have been attriubuted.
The pig bit is the pedal end remove both 13mm nuts which is the pedal stop and both 14mm pedal nuts.
You can then pull the cable throuh the bulkhead but before you do remove big grommit from wing.
TIP
I taped the new one to the old one and then pulled it through.
Notice how smooth the new is against the old one mine was kinked at both ends and sprialled it flicked around when disconnected at plenum end also frayed a bit at pedal end.
CT Sells the modified cable.
Second night,
Reasembly is reverse please note there are 2 mounting holes for the pedal stop i put mine back in the wrong holes a couple of inches difference in pedal adjustment.
I felt there was no need to oil the cable as it was smooth enough did grease the pedal and throttle linkage.
Set the cable adjustment the same as the old one and there is play in the cable.
Don't forget to silicone the grommit.
Go do it!!
£58
Cheers
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