Haltech cold start tuning
12-01-09, 11:38 PM
#27
Haven't we ALL heard this
My car almost refuses to start when it is cold.
12-02-09, 09:49 AM
#30
BDC Motorsports
Yep drop it down. It'll depend upon the porting style (stock vs. high overlap bridgeport) and the compression ratio. A good place to start is 5* in my opinion.
B
B
12-02-09, 08:12 PM
#32
I recently installed a BAC and spent quite a bit of time tweaking things. I also dropped my ignition crank to around 6 or 7 degrees. It used to be over 15 (I didn't make the previous tune). My car has been starting and idling great, cold or warm! No excessive cranking. I've gotten my idle to around 12.5:1 ratios. It used to be terrible around 11:1. So far things are working out.
I've also read in the FSM that using a thinner oil can increase cranking speeds. Now that it's December and cold here in NY, I'm thinking of switching to 10w30. A quick crank speed could also help in start ups.
I've also read in the FSM that using a thinner oil can increase cranking speeds. Now that it's December and cold here in NY, I'm thinking of switching to 10w30. A quick crank speed could also help in start ups.
12-07-09, 06:50 PM
#34
what kind of control does the E6K give over the BAC valve? I am looking through my E6X Halwin and it says that all the main BAC valve settings are only available in the E11?
with a large streetport I always had unacceptably slow cranking without a BAC valve. The BAC valve runs at 244hz according to the FD service highlights document, and the FD and FC valves are very similar in terms of the coil design. From the factory the FC BAC valve runs at about 95% duty during cranking to give extra air. The thermowax helps cold starts too. To elaborate:
A USDM spec FC has 4 additional sources of air during cranking and it sounds like most of the people in this thread have removed all of them. The first is the accelerated warmup system, and as we all know that's just overkill and should be removed. The second is the thermowax system, which opens the throttle plates during cold start and low water temps. The third is the bypass air port in the BAC valve that is adjustable by a screw. A similar bypass air port screw is under the TB elbow of the FD throttlebody, and on top of the non turbo FC dynamic chambers. The bypass air port is completely independent of BAC valve duty. With the BAC valve unplugged the bypass air port is still supplying idle air. I have actually pressurized the valve on a bench to confirm this.
The 4th source of bypass air is the cycling of the BAC valve itself. With the AFM removed, the BAC valve doesn't even need a hose or anything. You can put a filter on top of it or just open it to atmosphere if you don't care much. You can skip the coolant hose as well unless you are in a very cold area and are concerned about the valve freezing up. The BAC valve duty is adjustable with the "post start duty" "min cold duty" and "cold open duty" settings in the Haltech. There is also closed loop control logic for it by setting a target idle speed and setting PID coefficients, just like Haltech boost control.
So when you reinstall the BAC valve on an FC, you are actually supplying two sources of additional air during cranking.
Another thing to consider is that a lot of aftermarket fuel pressure regulators don't hold fuel pressure like the stock one. That especially hurts cold starting. I have noticed that on my Aeromotive regulator.
with a large streetport I always had unacceptably slow cranking without a BAC valve. The BAC valve runs at 244hz according to the FD service highlights document, and the FD and FC valves are very similar in terms of the coil design. From the factory the FC BAC valve runs at about 95% duty during cranking to give extra air. The thermowax helps cold starts too. To elaborate:
A USDM spec FC has 4 additional sources of air during cranking and it sounds like most of the people in this thread have removed all of them. The first is the accelerated warmup system, and as we all know that's just overkill and should be removed. The second is the thermowax system, which opens the throttle plates during cold start and low water temps. The third is the bypass air port in the BAC valve that is adjustable by a screw. A similar bypass air port screw is under the TB elbow of the FD throttlebody, and on top of the non turbo FC dynamic chambers. The bypass air port is completely independent of BAC valve duty. With the BAC valve unplugged the bypass air port is still supplying idle air. I have actually pressurized the valve on a bench to confirm this.
The 4th source of bypass air is the cycling of the BAC valve itself. With the AFM removed, the BAC valve doesn't even need a hose or anything. You can put a filter on top of it or just open it to atmosphere if you don't care much. You can skip the coolant hose as well unless you are in a very cold area and are concerned about the valve freezing up. The BAC valve duty is adjustable with the "post start duty" "min cold duty" and "cold open duty" settings in the Haltech. There is also closed loop control logic for it by setting a target idle speed and setting PID coefficients, just like Haltech boost control.
So when you reinstall the BAC valve on an FC, you are actually supplying two sources of additional air during cranking.
Another thing to consider is that a lot of aftermarket fuel pressure regulators don't hold fuel pressure like the stock one. That especially hurts cold starting. I have noticed that on my Aeromotive regulator.
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immanuel__7
2nd Generation Specific (1986-1992)
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09-05-15 10:23 AM
