I have two cars with Tweecers. One is a TT '65 FB and the other is a '94 Vert. I want to share what worked for my Vert. Hopefully, it will work on my TT as well as it does this worse than the Vert.
The symtom was bucking/surging just off idle under slight accel or decel conditions. Typical example would be slowing for a stop. If I left the car in 3rd and coasted to the stop, at about 1200 RPM the car would begin bucking. At 1100 it would be really bad. Another example would be idleing along in a freeway jam up. If I left the car in 2nd and coasted at idle, sometimes it would buck. Almost always, it would buck just slightly past the idle stop if I wanted to speed up a bit.
Anyway, I tried to fix this problem for a year. KMRFs are good, low RPM timing was reduced. Repeated data logging didn't show the problem. Out of desperation, I tried changing the dashpot prepostion function. I was under the idea that this was ISC duty cycle vs RPM. The vaules I had there were not to far off from the Cobra tune. I reduced the velues by 15% and give it a try. It worked!
I hope to try this on my TT soon. I will let yu know if it worked.
Eric
The symtom was bucking/surging just off idle under slight accel or decel conditions. Typical example would be slowing for a stop. If I left the car in 3rd and coasted to the stop, at about 1200 RPM the car would begin bucking. At 1100 it would be really bad. Another example would be idleing along in a freeway jam up. If I left the car in 2nd and coasted at idle, sometimes it would buck. Almost always, it would buck just slightly past the idle stop if I wanted to speed up a bit.
Anyway, I tried to fix this problem for a year. KMRFs are good, low RPM timing was reduced. Repeated data logging didn't show the problem. Out of desperation, I tried changing the dashpot prepostion function. I was under the idea that this was ISC duty cycle vs RPM. The vaules I had there were not to far off from the Cobra tune. I reduced the velues by 15% and give it a try. It worked!
I hope to try this on my TT soon. I will let yu know if it worked.
Eric