Boost Lag

funkbuster

Registered User
Hey. I just picked up an 89 SC. It runs good, but I am having a problem with lag. I didnt think I was until I watched a video on youtube of a guy's stock SC. His boost would hit full about as soon as he hit the gas. Mine builds up like my 93 talon TSI does. Say I am going down the highway at 65 in 5th, I lay into the gas, it take it a number of seconds to even reach boost, it has lag just like a turbo car. It will eventually reach in the range of 10lbs, but it takes hit a hot minute. This shouldnt be right? What could cause this?

Thanks in advance

Chase
 
Hey. I just picked up an 89 SC. It runs good, but I am having a problem with lag. I didnt think I was until I watched a video on youtube of a guy's stock SC. His boost would hit full about as soon as he hit the gas. Mine builds up like my 93 talon TSI does. Say I am going down the highway at 65 in 5th, I lay into the gas, it take it a number of seconds to even reach boost, it has lag just like a turbo car. It will eventually reach in the range of 10lbs, but it takes hit a hot minute. This shouldnt be right? What could cause this?

Thanks in advance

Chase

At 65mph in 5th you are at about 1500rpm. No one's SC makes mad boost at 1500rpm.
 
Maybe your bypass valve is not closing fast enough. Whatever the case, it's probably some sort of a leak in the vacuum lines or SC plumbing. Make sure that the vacuum line to your fuel pressure regulator (to the driver's side of the blower) is hooked up.
 
When I rev up the engine, from under the hood, I can see the little part that looks like the wastegate on my talon close when I rev it up. I dont hear a belt skreeching, but I can hear a little chirp, but I dont know. IF I lay into it, by around 2600rpms in 2nd gear, I am just hitting boost.
 
When I rev up the engine, from under the hood, I can see the little part that looks like the wastegate on my talon close when I rev it up. I dont hear a belt skreeching, but I can hear a little chirp, but I dont know. IF I lay into it, by around 2600rpms in 2nd gear, I am just hitting boost.

this is my sc when it was stock i got like 2 mods done now but this could help you when tryin to see if you have issues:rolleyes: ;)

http://youtube.com/watch?v=eiuM1vbmkDA
 
OK. I guess I will have to take mine a little higher in the rpms to see if it does like yours. The Main thing is like when you hit the gas, yours shot straight over to around 10lbs, When I hit my gas, it slowly builds up boost, it looks like a turbo more than a SC.
 
Was running about 55mph, dropped it into 3rd hit it, by about 3500rpms it was just climbing into boost, took it another few hundred to pass 5psi.
 
Sounds like your bypass valve is not closing all the way. Check to make sure the linkage isn't stuck against the back of the supercharger.

David
 
Keep in mind the blower is fully dependant on engine RPM not exhaust velocity.

You could have a bypass issue which is that diaphram you were watching. Disconnect the vacuume to it and see if it makes a difference. Also check to see how it move manually. Doe sit stick?

I would work on changing out all of the belts and do a tuneup if you havent done so already
 
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