+1 for dashpot adjustment
07-02-08, 11:58 AM
#1
+1 for dashpot adjustment
88 T2
http://www.1300cc.com/howto/how2/dashpot.htm , FSM page 4B-50 for turbo cars
So a while back I decided to ditch my modified TB (it didn't have double throttle, thermowax, dashpot, etc) and put a stock one back on. I know that many people have no problems driving a car with the TB mod, and I could drive mine fine, but removing all the factory junk made some aspects of around-town driving irritating. With my ACT 6 puck clutch and lightweight flywheel, popping the clutch quickly would occasionally result in the engine stalling unless I kept my foot on the throttle just a tiny bit. This is particularly annoying when slipping the clutch and low speeds up a driveway or in a parking lot. It's also embarassing when you have a passenger and you have to say "you see, I recently modified the TB and now it's more prone to stalling..."
I thought it was a tuning issue at first on my Power FC, but I went through my maps and settings and they were ok. Just today I thought about adjusting the dashpot, and after some searches I found that link and the FSM pages. The FSM says to measure TPS resistance where the dashpot rod thingie and the butterflys first make contact as the throttle closes. FSM spec is 1.8K ohms - 3.8 K ohms , which is still a decently wide range even on the narrow-range s4 TPS. After playing around with it for a while and a couple test drives, I set it so that the dashpot first touches the butterflys at 2.2 K ohms. Everybody's TPS is a little different (I replaced mine with a brand new one) so you'll have to play with it yourself to see what works.
The result is that I don't have the idle stumble (or the car cut off) sometimes when I let off the throttle in these around-town driving situations or if I pop the clutch after a WOT pull. The rpm's drop noticeably slower, especially since i have a lightweight flywheel and they used to drop like a rock. This takes a little getting used to, but it's worth it to not have to deal with the car cutting off sometimes.
I'm not necessarily trying to start a debate about the TB mod again (and I do think that at least the double throttle system is practically useless), but I will say that since I put a stock TB and got it set correctly on the car I've enjoyed driving around town more. I don't have a BAC, but having the thermowax/fast idle system working makes the car more pleasant to drive on cold starts, and I don't have to bump up the idle with the TB stop screw to make it run better cold.
http://www.1300cc.com/howto/how2/dashpot.htm , FSM page 4B-50 for turbo cars
So a while back I decided to ditch my modified TB (it didn't have double throttle, thermowax, dashpot, etc) and put a stock one back on. I know that many people have no problems driving a car with the TB mod, and I could drive mine fine, but removing all the factory junk made some aspects of around-town driving irritating. With my ACT 6 puck clutch and lightweight flywheel, popping the clutch quickly would occasionally result in the engine stalling unless I kept my foot on the throttle just a tiny bit. This is particularly annoying when slipping the clutch and low speeds up a driveway or in a parking lot. It's also embarassing when you have a passenger and you have to say "you see, I recently modified the TB and now it's more prone to stalling..."
I thought it was a tuning issue at first on my Power FC, but I went through my maps and settings and they were ok. Just today I thought about adjusting the dashpot, and after some searches I found that link and the FSM pages. The FSM says to measure TPS resistance where the dashpot rod thingie and the butterflys first make contact as the throttle closes. FSM spec is 1.8K ohms - 3.8 K ohms , which is still a decently wide range even on the narrow-range s4 TPS. After playing around with it for a while and a couple test drives, I set it so that the dashpot first touches the butterflys at 2.2 K ohms. Everybody's TPS is a little different (I replaced mine with a brand new one) so you'll have to play with it yourself to see what works.
The result is that I don't have the idle stumble (or the car cut off) sometimes when I let off the throttle in these around-town driving situations or if I pop the clutch after a WOT pull. The rpm's drop noticeably slower, especially since i have a lightweight flywheel and they used to drop like a rock. This takes a little getting used to, but it's worth it to not have to deal with the car cutting off sometimes.
I'm not necessarily trying to start a debate about the TB mod again (and I do think that at least the double throttle system is practically useless), but I will say that since I put a stock TB and got it set correctly on the car I've enjoyed driving around town more. I don't have a BAC, but having the thermowax/fast idle system working makes the car more pleasant to drive on cold starts, and I don't have to bump up the idle with the TB stop screw to make it run better cold.
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