BAC valve
12-09-10 | 12:38 PM
#1
Thread Starter
(>'-')>
Joined: May 2008
Posts: 204
Likes: 0
From: Detroit Michigan
BAC valve
ok so the accelerated warm up on my car doesnt work well at all. it maybe goes to 2000 rpms for 3 seconds then drops to 1000. also this just may b another issue but wen my engine is cold i cant get any acceleration and it hesitates to take off. i was just wondering if this could be the BAC valve alone and is there any way to fix it without replacing it or do i have to get a new one
12-09-10 | 09:59 PM
#4
Some info like the year of the car would be useful.
The BAC isn't going to have any effect on acceleration, so something like an unplugged coolant temp sensor may be your issue. It's on the back of the water pump on both S4s and S5s. You should also test compression and pull engine codes.
As far as the accelerated warmup system, the BAC and AWS valve work together to boost engine speed for ~17 seconds. If one is missing or not working, you could see a drop in engine speed.
The BAC isn't going to have any effect on acceleration, so something like an unplugged coolant temp sensor may be your issue. It's on the back of the water pump on both S4s and S5s. You should also test compression and pull engine codes.
As far as the accelerated warmup system, the BAC and AWS valve work together to boost engine speed for ~17 seconds. If one is missing or not working, you could see a drop in engine speed.
12-09-10 | 11:30 PM
#5
The way your AWS is working right now is actually better in my opinion. For a car to rev up to 3k as soon as its started (while cold) is a stupid idea. Since yours goes to 2k for a few seconds then to basically idle is probably doing less wear and tear.
RotaryRocket has the right start. Check the coolant temp sensor on the back of the water pump. If this sensor is somewhat faulty then the ecu will read it wrong and run funky till its warmed up. That coolant temp sensor is related to the ECU, not to be confused with the coolant temp sensor thats on the drivers side of the block thats for the temp gauge, which isnt involved with your problem.
RotaryRocket has the right start. Check the coolant temp sensor on the back of the water pump. If this sensor is somewhat faulty then the ecu will read it wrong and run funky till its warmed up. That coolant temp sensor is related to the ECU, not to be confused with the coolant temp sensor thats on the drivers side of the block thats for the temp gauge, which isnt involved with your problem.
12-09-10 | 11:47 PM
#6
Thread Starter
(>'-')>
Joined: May 2008
Posts: 204
Likes: 0
From: Detroit Michigan
well its an 87 n/a with a rebuilt engine so im going to assume the compression is ok, i may have missed something when putting everything back together tho, and i need to look up how to check codes as well and do that when i have some time. thanks guys for the help
12-10-10 | 12:22 AM
#7
Since it a S4 (86-88 models) then you wont get "limp mode"
Its a bad idea to assume compression is good. Whats the point on chasing problems if you dont know if the core is good?
Checkin codes is cheap and easy. Your going to need 2 LED lights and 3 male spade connectors. You can use this same tool to adjust the throttle position sensor (TPS)
Heres a link: http://www.teamfc3s.org/info/article...odes/main.html It looks way more confusing then it really is
Heres a link for compression testing: http://www.rotaryresurrection.com/2n...ion_check.html
Its a bad idea to assume compression is good. Whats the point on chasing problems if you dont know if the core is good?
Checkin codes is cheap and easy. Your going to need 2 LED lights and 3 male spade connectors. You can use this same tool to adjust the throttle position sensor (TPS)
Heres a link: http://www.teamfc3s.org/info/article...odes/main.html It looks way more confusing then it really is
Heres a link for compression testing: http://www.rotaryresurrection.com/2n...ion_check.html
