Now what?! TPS? Stuck pedal? Vid inside
#1
Now what?! TPS? Stuck pedal? Vid inside
ok so, finally get the car to start and stay lit... but the idle is going up and down. I figured AAV, but by dumb luck found the pedal seems to be sticky. If I bring it all the way back it idles up and down. If I just touch it it idles fine but too high. If I go to the throttle stand and twist the throttle all the way shut it starts idling weird again and only gets set a little open again if the pedal is touched....even with the pedal sticking there's no reason for the idle to pulse... is the TPS bad? I set it a month ago
https://streamable.com/ebzz8
https://streamable.com/ebzz8
#2
Join Date: Mar 2008
Location: Pacific Northwest USA
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Look for some sort of binding in the linkages or cable. Perhaps the notorious throttle bushings? Perhaps disconnecting the cable will help isolate things.
Also there's a bushing at the pivot point of the throttle pedal. Worth taking a peek at it
The idle surge is almost certainly too much air coming in....from somewhere. When the RPM reached xxx-level the ECU cuts off the fuel and the idle momentarily drops. Repeat, repeat......
On principles make sure both throttle blades are set to .002", the throttle bores are clean, and the linkage is synchronized.
Cheers
DD
Also there's a bushing at the pivot point of the throttle pedal. Worth taking a peek at it
The idle surge is almost certainly too much air coming in....from somewhere. When the RPM reached xxx-level the ECU cuts off the fuel and the idle momentarily drops. Repeat, repeat......
On principles make sure both throttle blades are set to .002", the throttle bores are clean, and the linkage is synchronized.
Cheers
DD
#4
Look for some sort of binding in the linkages or cable. Perhaps the notorious throttle bushings? Perhaps disconnecting the cable will help isolate things.
Also there's a bushing at the pivot point of the throttle pedal. Worth taking a peek at it
The idle surge is almost certainly too much air coming in....from somewhere. When the RPM reached xxx-level the ECU cuts off the fuel and the idle momentarily drops. Repeat, repeat......
On principles make sure both throttle blades are set to .002", the throttle bores are clean, and the linkage is synchronized.
Cheers
DD
Also there's a bushing at the pivot point of the throttle pedal. Worth taking a peek at it
The idle surge is almost certainly too much air coming in....from somewhere. When the RPM reached xxx-level the ECU cuts off the fuel and the idle momentarily drops. Repeat, repeat......
On principles make sure both throttle blades are set to .002", the throttle bores are clean, and the linkage is synchronized.
Cheers
DD
#5
#6
#7
Look for some sort of binding in the linkages or cable. Perhaps the notorious throttle bushings? Perhaps disconnecting the cable will help isolate things.
Also there's a bushing at the pivot point of the throttle pedal. Worth taking a peek at it
The idle surge is almost certainly too much air coming in....from somewhere. When the RPM reached xxx-level the ECU cuts off the fuel and the idle momentarily drops. Repeat, repeat......
On principles make sure both throttle blades are set to .002", the throttle bores are clean, and the linkage is synchronized.
Cheers
DD
Also there's a bushing at the pivot point of the throttle pedal. Worth taking a peek at it
The idle surge is almost certainly too much air coming in....from somewhere. When the RPM reached xxx-level the ECU cuts off the fuel and the idle momentarily drops. Repeat, repeat......
On principles make sure both throttle blades are set to .002", the throttle bores are clean, and the linkage is synchronized.
Cheers
DD
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#8
those rods are used in radio controlled models. Something like this.
https://www.aliexpress.com/item/10PC...06.4.10.j1eTeO
https://www.aliexpress.com/item/10PC...06.4.10.j1eTeO
#9
Join Date: Mar 2008
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Possible, I reckon, but I've never seen any that caused a problem, personally. They will obviously wear a bit over time but the rod adjustments can compensate for that.
Does the movement not feel smooth?
Cheers
DD
#10
before the butterfly's start to move.
#11
You can adjust that play out. There is backlash in the whole setup.
Remove the links from the throttle bodys and adjust the butterfly's with everything disconnected, put the links back on the TB's. Then remove one of those rods and adjust the other one to take up all the slack, remove it install the other one and do the same. Put them both back on.
Lastly check both butterfly's open simultaneously and you're done.
Remove the links from the throttle bodys and adjust the butterfly's with everything disconnected, put the links back on the TB's. Then remove one of those rods and adjust the other one to take up all the slack, remove it install the other one and do the same. Put them both back on.
Lastly check both butterfly's open simultaneously and you're done.
#12
You can adjust that play out. There is backlash in the whole setup.
Remove the links from the throttle bodys and adjust the butterfly's with everything disconnected, put the links back on the TB's. Then remove one of those rods and adjust the other one to take up all the slack, remove it install the other one and do the same. Put them both back on.
Lastly check both butterfly's open simultaneously and you're done.
Remove the links from the throttle bodys and adjust the butterfly's with everything disconnected, put the links back on the TB's. Then remove one of those rods and adjust the other one to take up all the slack, remove it install the other one and do the same. Put them both back on.
Lastly check both butterfly's open simultaneously and you're done.
#14
Here you go.
They were posted a long time back, maybe you missed them.
Adjusting the V12 throttle discs.doc
SETTING THE THROTTLE CAPSTAN AND RODS GRANT.doc
They were posted a long time back, maybe you missed them.
Adjusting the V12 throttle discs.doc
SETTING THE THROTTLE CAPSTAN AND RODS GRANT.doc
#15
Here you go.
They were posted a long time back, maybe you missed them.
Attachment 202299
Attachment 202300
They were posted a long time back, maybe you missed them.
Attachment 202299
Attachment 202300
#16
The following users liked this post:
Grant Francis (09-05-2017)
#18
This is to ensure the ham-fisted do not set the rods so the throttles are held open by the rods/capstan system, but, once the spacers are removed, are properly against the throttle body stops, with a tiny bit of free play on the rods system, including a bit of play in case of thermal expansion of the rods etc when the heat gets into the engine.
The following users liked this post:
Grant Francis (09-05-2017)
#19
The manual does mention that, but its just habit now for me, same as the LH and RH threaded rods. Seen a few of them snapped due to the lack of thought of the spanner man, and the manual does not tell you that one.
V12's are so special, just like most owners.
#20
Greg, this is a very important point! Before following Grant's method I had a high idle after having driven long enough to really heat things up under the hood. IIRC When I did the math ( I was bored ) I came up with .4mm expansion in the rods from ambient to full hot engine bay. My rods were snug with no rotation of the capstan and, sure enough, it raised idle when hot. When I went in to set them via Grant's 2mm spacer method I took note, and it gives the rod just about .4mm slack. I prefer to think someone had their slide rule out rather than that it was by chance.
The following 2 users liked this post by JigJag:
Grant Francis (09-05-2017),
Greg in France (09-05-2017)