Injector kill switch for Autos

[cwa]

Dear All,

Has anyone tried Injector Kill switch for Automatics? How it works after EOC. Can someone shares the experience?

I know it is well suited to Manuals where bump start will start after EOC. WIth Autos, we may have to start the engine. Also EOC is not recommeded for mast of Automatics.

I thought that Injector Kill can not only be used in EOC, but also to avoid Traffic light Idleing as well.


CWA

[kamesama980]

same as EOC in autos...the engine'll stop, the trans will stop pumping and die. the other problem with that idea is that there already is one...it's called the ignition switch.

[RoadWarrior]

It can sort of work at engine speeds above around 2000rpm, because the tranny will still be driving the engine, below that it won't. So if you can rig it in a set/reset kind of fashion where it kicks the fuel back on if the engine revs drop too far, then it might work. It works like that in some manufacturers ECU programming. I've heard that some Saturn autos have rear pumps meaning that they might be able to cope with lower rev holds and still pick up again.

[petty]

I would like to install a switch to prevent my car from starting. I have done it in the past through the wiring of the starter. But just can't have any other options. Any idea?

______________________
Car Solutions.

[theholycow]

There's lots of ways to install a switch to prevent the car from starting. You could find an existing anti-theft wire coming from the steering shaft and interrupt it with a switch. You could interrupt the fuel pump fuse or relay. Or, as you've done before, you could find the starter wiring...

[mikemoss]

From my understanding if the motor stops spinning the transmission fluid pump the transmission will fry.

[Dr. Jerryrigger]

Some newer auto cars have this built in to their computers. When you are slowing they stop feeding it gas and let the wheels turn the engine until it is in danger of staling. I think my 99 subaru (auto) dose this. I only know this because I attached some wires to my O2 sensor so I can see the readout on the Fluk DMM in my cup holder. The signal jump way out of normal range when I'm coasting to a stop (in gear) or down shift to slow down.

I want to set up a switch to do this as well. I can predict when it should go on better than my computer.
The thing that makes this complicated is that the computer will think something is serously rong when you flip the switch. The way around this that I see is to make a voltage supply for all your sensors that will tell your computer that everything is working as normal. This supply would need to be hooked up to the same dash switch.

This seems like a good idea, as you get better mileage using no fuel then idling in N. (though you don't role as far w/engine braking effect)

[BEEF]

are you talking about DFCO deceleration fuel cut off?

all newer cars do this and I think it goes way back as to when it is done. If I had to guess, I would say that your car already does it.

on my wife's car, it shows about a 1 second lag time from when she takes her foot off of the gas to when she goes into DFCO. I don't think you can do better than this though if you could, I don't think it would be worth the effort

[Dr. Jerryrigger]

well there is one way to find out....
Maybe there are other ways..
I've got to go get some cat food. About a 5 min drive (each way) with lots of lights. I'm going to see when my car dose this based on O2 readouts, and with a stop watch see how much more time it could be off if I were controlling it. This would be a safer test with an assistant... oh well...
this will not be the most accurate test, and will very greatly from car to car, but it may give some idea if this is a complete waist of time...
I'll report back in 20 min or so.

[BEEF]

remember also that DFCO cuts off around 1000rpms or so. the engine goes into normal condition around that time.

how are you monitoring your 02 sensor?

[Dr. Jerryrigger]

I spliced some long wires into the signal wires, ran them threw a hole in the firewall, and to the DMM in my cup holder.

Anyway the planned test wasn't going to give any useful results, and there was far too much traffic. It seemed to only turns off over 35mph, but then I tried down shifting... My car seems quite quick to respond, under a sec to see change in the O2 reading from .335V(where it like to stabilize) to .450V.
The thing to determine is how much can we push the envelope on the lower RPM range past what the computer allows (engineers almost always give things some cushion room to prevent problems)
The thing that I learned from this test is that down shifting can really save fuel with some cars. It was cutting off even under 20mph if in 2nd.

[BEEF]

it doesn't cut off at a particular mph but a particular rpm. that is what to look for.

the scangauge will show you this without having to splice wires or pull out ye olde fluke meter. I know I keep pushing this but you can see actual open/closed loop along with instantaneous mpg. I have been meaning to do a video on this showing where it cuts off on my wife's car but haven't had the time.

maybe this is the push I need. I know that we give margin or buffer zones but that is to keep warranty and yourself intact. you may want to rethink the manual switch if you plan to do that because if you forget to turn it back on, it may damage all sorts of goodies.

[Dr. Jerryrigger]

A scangauge sounds like a excellent toy, which I hope to soon own. Do they make one that can plug into a laptop to make graphs and show derivatives and integrals of said graphs, that just seems too cool to be in production...

[BEEF]

I think they make data loggers that will do that. sadly, the scangauge will not.

it hooks into your obd2 port and it will give you trip info like trip MPG that shows you average over a trip and the likes.

definitely check out their web site www.scangauge.com

also, some use a data logger ELM (something something) maybe you could do a search or shoot a PM to the user theholycow. he is also a moderator. I think he knows at least what I am talking about.

[theholycow]

Most modern fuel injected cars can DFCO, but each has different behavior.

The ScanGauge is a specific model of OBDII product and does not connect to a computer. There are plenty of other brands that do.

There's a link in my sig to a DIY fuel rate meter. That is the most accurate and fastest-responding way to detect DFCO. Using that, I've gotten a pretty accurate understanding of DFCO behavior in my VW and my GMC. My GMC usually has an 8 second delay before DFCO!

[trollbait]

Originally Posted by mikemoss

From my understanding if the motor stops spinning the transmission fluid pump the transmission will fry.

Depends. Autos that can be flat towed (like behind a RV) can be safely EOCed.

How can you spot DFCO with a scangauge? I've heard it wasn't possible.

[theholycow]

Originally Posted by trollbait

How can you spot DFCO with a scangauge? I've heard it wasn't possible.

It's laggy and inaccurate, but it's useful enough. The quickest seems to be open/closed loop; when you see open loop you're in DFCO. You can also just watch instant MPG; when it goes to 9999 you're in DFCO, but it tends to take a few seconds of DFCO before it shows 9999.

[dkjones96]

Originally Posted by mikemoss

From my understanding if the motor stops spinning the transmission fluid pump the transmission will fry.

The engine will stay spinning under fuel cut unless either rpm falls to a point where there isn't enough hydraulic pressure to keep the transmission in gear or the transmission is shifted into neutral.

Also, you will get a check engine light with a cutoff switch unless you put a dummy load for each injector for the ecu to see.