Efi Vss

[workforce]

Yes I have a couple questions about the VSS I am running ford fuel injection. I am also running autometer phantom II programmable speedometer do I need to run the VSS signal into the speedo and then out to the computer so that it gets a buffered signal or just splice off of the VSS signal. And also how important is the VSS signal to the fuel injection system to make it run correct.

 

[scotts77]

I would call tech support @ Autometer. They would be able to answer that if no one else chimes in.

 

[rjlougee]

You don't need to buffer the VSS signal into the EEC, as for the gauge, couldn't tell you.

The importance of the VSS depends entirely on which EEC/wiring setup you use. With an A9P it seems more important to preclude stalling when approaching stoplights, the A9L didn't seem to care.
Joe

 

[Broncobowsher]

The ECM orignially got an unbuffered signal before, I don't see why it would need one now. You should be able to run the same signal to both.

As for running, it does a couple of things. It opens the IAC at higher speeds, reason is debatable. It also help with stalling on automatics going downhill. Apparently If it doesn't see VSS and you coast, the ECM tries to reduce the engine speed to idle. Since gravity is keeping the engine above idle speed the computer can never achieve this. The best it can do is completely close the IAC. When you do come to a stop it sees the idle speed too low and can't add IAC fast enough to keep the engine running, so it stalls.

There is also an alternative fuel/spark table that kicks in above 100 MPH as well in some mustang computers.

 

[workforce]

Thanks for your help. I just didn't know since the speedo had an output for the buffered signal if it would make any difference. I will run just straight from the VSS sensor. I am having some issues with idling and stalling when it reached normal temp it will die after it is warm when you put it in gear and didn't know if that would have anything to do with it. And as for what setup it is a DSS 347 RJM harness edelbrock upper & lower intake 30# injectors with matching MAF Granateli 90 MM wildhorse shorty headers edelbrock aluminum heads. I haven't had a chance to put it on the computer to see what codes I have. And I also have a chip that was suppose to be setup for this setup. It is a A9L computer. I know I should have been taking pictures of the build I just didn't take the time but I will take some just as soon as my painter decides to finish my top. Everything else is finished just waiting on that last thing.

 

[Broncobowsher]

Unless the chip was burned using the engine you are using I bet it is a hair off. Any chip burner can go in and look up the reference values for the MAF and injectors and burn a chip with those. But a good chip burner will need to have the engine running (preferably in a car on the dyno) to truely dial in the system. When I did mine I got it burned using the default values. It ran, stalled a lot, tended to be a little fussy. But it ran good enough to get a couple thermal cycles on the engine and give the rings a chance to seat a little. Then it ran enough to drive it to the tuner/dyno. Couple hours later it ran much better. The tranny shifting issues took a bit more work to fix, but that is another story and doesn't matter for an A9L.

 

[DonsBolt]

I am not sure, but part of your problem might be that granatelli Mass air meter

I would see if you can find a Lightning 90MM mass air meter

I used to run a PRO M in my lightning,wich is pretty much the same things as the granitelli, I now have a SCT Mass air meter, and it runs better.

You might also be better off with a Lightning 80 MM Mass air meter

 

[workforce]

Thanks for the info. I was lucky enough that I had already had the engine in the bronco before I took it apart to rebuild the bronco. I had a carb on it and it ran pretty good just got tired of always having to adjust the carb. And I also just wanted EFI. Yeah the guy that I bought the intakes from when I ordered all the stuff is the one that sold me the chip but he sent me 75 MM C&L MAF and told me the tube would recalibrate it all I needed was the sensor but after trying to buy just the sensor I got mad and just ordered the Granatelli 90 MM with the sensor in it. I wondered if that MAF was somehow affecting it. Can a MAF be too big MM size I mean. I have a edelbrock 70 MM throttle body. It runs fine just cruzing around but if you stand on it hard it will run fine for a second then it starts stumbling and I can't tell if it 2 much fuel or not enough. And I know your going to ask about the fuel system it is a BC broncos 23 gal EFI tank with a BBK 255 GPH pump inside with all steel braided 3/8 fuel line with a trick flow fuel filter inline and steel braided for the return also. It is stock mustang fuel rails. I took the chip out for while and ran it but it ran better with the chip in. I think your right that it is not tuned properly. My TPS is set at .098 but if I try to idle it down below 900 to 1000 RPM's I can't seem to get the surging out of it and the idling issues seem to get worse. And yes I'm resetting the TPS each time I try adjusting the idle. I just need to get it on the computer to see what it is doing. But I really appreciate all of your help.

 

[DonsBolt]

I was thinking about it a little

Is your mass air meter metal or plastic?? If it is plastic it might not be so bad.

To me unless you are running a supercharger, I don't see a need for more than a 80 MM Mass air unless you have a pretty agressive engine set up.

What kind of chip are you running??

 

[workforce]

Don't really know I don't know if I still have the box it came in or not I will look but I think it was something like SCT but I may be wrong. And it is a plastic MAF. Thanks for your help.