Factory decel cutoff improvements? [ Archive] - GasSavers.org - Helping You Save at the Pump


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getnpsi
05-28-2008, 02:54 AM
I have a wideband in my 2004 Dodge srt-4. When I downshift and let off throttle, it takes up to 2 seconds for the wideband to register lean it shows (---). I know there is a bit of lag time of the WB itself, (it better not be that slow when I'm boosting :eek: )but if i add a vacuum switch to cut injectors myself as soon as there is more vacuum than seen at idle (<20) would there be an additional improvement realized? On decels my car starts giving the gas to stoich back at ~1400-1600rpm. If i have it cut at -21 psi no matter the rpm it should help, no?

Part 2: the car I'm trying to save all the money with is the 1995 ford aspire. Does this car have a decent decel cutoff or should I add one to this vehicle as well?

theholycow
05-28-2008, 08:34 AM
You can get quicker readings with a digital dwell meter hooked to one of your injector wires. See the "realtime monitoring tools for pre-obd2 cars (http://www.gassavers.org/showthread.php?t=7345)" thread and my "DIY fuel flow/injector gauge results (http://www.gassavers.org/showthread.php?t=7581)" thread.

I'd be interested in the way you propose making DFCO more aggressive. In my truck DFCO is almost useless and your low-tech idea sounds easy. However, I'm sure it would cause trouble codes done that simply; it would need a little bit of electronic help with simulated injectors, I suspect.

getnpsi
05-28-2008, 03:51 PM
I have one of the george wiseman paper books, and it said to add a vacuum switch for both the injectors to cut off in high vacuum situations like a downshift/coasting downhill, and a low pressure vac switch to turn off the alternator and ac (if you car doesnt turn off a/c) in a high stress low vacuum situation as a WOT to overtake a car or going up steep grades. I have no problem tinkering with the aspire. I get that car to stumble all the time and it never gives me a light or stops running. No battery resets and it nets me the same MPG's. The problems might arise in the 2004 as its obd-2 and I already have spliced the injector harness for upgrades. I do lots of city driving in the red aspire so I think im gonna go for it in that vehicle first, even tho I have yet to add monitoring tools. I was just a kid in the mid 80s when cars had all these geegaw so to research what parts to obtain might take a while. It's probably going to be difficult to explain to the counter guy at napa what im trying to do, when the switches are probably designed for HVAC and/or emissions.

getnpsi
05-28-2008, 06:19 PM
I stumbled on this site. If i need 2 switches its about <$50 with nice fittings for hose barbs

http://designflexswitches.com/designflex_switch_guide.htm