ef1 521 more questions? this will blow your mind!

ok where do i start? last night i was setting the timing on my ef1521 and noticed it never really got smooth. now it is fuel injected with a modified 5.0 setup with 60lbs injectors. i started pulling the plugs off the injectors to see if they were working and only 3 of the 8 would make a difference and kill the engine? only the number 1,6,7 were working? how was it still running?

now i took the number 1 injector and replaced it in the number 2 spot, the number one still fired. so i think the injectors are fine. pulled the number 1 plug and placed it on the number 2 injector and it started working. i checked the wiring harness and all looked fine?i traced it back to the computer. well when we were pulling the injector plugs we tried it at idle and at 3000rpm, no difference? i cant believe how good the engine runs with just 3 injectors, just doesnt make any sence? i even tried it with the 2,3,4 injectors unplugged and it made no difference in how it ran?

now it gets even crazier, i was running the firing order for a 460 and then i tried the firing order for a 5.0 h.o, THE ENGINE RAN THE SAME WITH 2 DIFFERENT FIRING ORDERS!? i also tried pulling the chip from the ecu and it ran the same.

what do you all think? i am beginning to think its in the computer, thats about the only thing it could be? but how is this thing running as good as it does on only 3 injectors? this is just plain wierd?

That is one weird deal there. Couple of weeks ago, I was getting teched in at a race, had a small fuel leak, pulled the left bank of wires to get at a fuel line, and fired it up on the right 4 cyl.

i am running an edlebrock air gap manifold that has the nitrous bungs used for the injectors, i guess the fuel is bypassing around the runners and getting into the other runners? i am puzzled by this?

http://fordfuelinjection.com/?p=9

You might want to look at the bottom of the page under Fuel system.. = "A stock EEC can?t more than 2 amps per injector, and stock 19lb injectors draw 0.75 amps. Currently 50lb injectors are the limit; keep this in mind when buying larger injectors. You want to stay away from low impedance injectors with a stock computer."

This is just a thought...

While I dont know exactly what the problem is, I will add this. The Mass air PCM does not really care what the firing order is. You should leave the injector wiring alone when doing this swap, it will work fine.

Have you checked the wiring? When the key is on all the injector red wires should have 12 volts to them. The computer grounds the injector to open them.

Ray

i have checked all the injectors and they are all getting the 12 volts, there is one wire that feeds all of them and the connections are soldered on the 12vwire.

as far as the impedence i am not sure what is considered high impedence and what is low? i can check them with my meter to see what ohms they are.

the mass air is showing 1 volt at idle. if the mass air is unplugged the motor cuts off, so i think it is working.

i will check out ford fuel injection.com and see what i can find out.
thanks yall!

i just checked and the injectors are 12.4 ohms, i checked two of them and they were both the same. is that a high or low impedence?

i read some of that on fordfuelinjection.com but a lot of that stuff seems dated? went to the moates forum and that stuff is WAYYY over my head!

this looks like my injector, but i think they are siemens?
http://www.jegs.com/p/Edelbrock/Edelbrock-Fuel-Injectors/761385/10002/-1

i dont see a listing for the impedence on these? ill check edelbrocks site.

just looked up ford racing injectors for mustangs and they say 11-18ohms, so 12.4 should be in the right ballpark right?

I found this site for 60lb Siemens injectors and they say that they are Hign-Impedance which should work. http://www.ctsturbo.com/catalog/High_Impedance-20-1.html

You are correct that some of the information is dated on FordFuelinjection.com but it is a good gudie. Manufacturs are always pushing the boundries.

Like I said it was just a thought and something good to check?

What are you using to "chip" the computer with? I know if your using a tweecer you have to change the base programing for the bigger injectors and also need a new fuel curve added to match that engine's dispacement.

Have you checked for any codes? If have seen at Orilleies (how every that's spelled) a code reader for the EEC-IV computers. Neat little device and you don't have to count the light flashes. You need to start with the codes to see what else to check.

Also double check your base timing, the stock computer expects it to be at 10 deg BTC unless you change that with your "chip". If your timing is off the computer will adjust some but still won't work as good as expected.

The engine runing with only some injectors doesn't surpize me that computer will make it run or at least attempt to make it run. After the engine starts then it will start to normalize everything (grain of salt on this comment).

One last thought the pin outs are different on EEC as the years have gone up. Might want to double check and make sure your injectors are plugged into the correct spot on EEC. Look here for the difference wiring's for different cars/years. wiring

Hang in there you will find the one or two things throwing that computer into a craze.

Low impedance injectors are typically 1.7-3.5 ohms on the meter.The primary advantage of low impedance injectors is a shorter triggering time. When large injectors are fitted to high output engines, low impedance injectors will often give a better idle quality because of this fact. The primary advantage of high impedance injectors is the fact that less heat is generated in the drive circuit and often no external resistors are used.

as far as the chip goes there is one that the previous owner has placed in there. i am not sure who did it or what it consists of. i do know it has 2 wires coming from it. it is not a tweecer or anything like it. i have unplugged it and tried it, the engine seemed to run the same. i do have access to another a9l computer that i could try.

i am not about to give up on it, if it runs this good on 3 injectors, its really donna run on all 8! the car has a ron francis wiring harness, so i think the ecu is pinned correctly, but that is something i will check. i printed off the diagram for the pin locations, thanks for the link.

there is a dyno shop about 2 hours from me that will chassis dyno the car and " burn" a chip for $450. i will have them do this, but i would like to know that everything is in working order so that the tuner can go straight to work on it. the previous owner had done a lot of work and spent a ton of money on the car i am just tweaking it out. on the plus side i have learned a lot about the efi along the way and now i am kinda set on making it work, its not quite as hard as i thought! ha ha..

Another helpful diagnostic tool is a noid light. You unplug injector plugs one at a time, and plug the noid light into the plug. The noid will flash every time the ECU fires that injector. Noids are only a couple of dollars each, although they normally come in sets of 8 or 9 noids that cover all the different injector plugs used by the OEMs. You should be able to find a set under $20.

Craig

yea i am going to try that this weekend.

well tried the noid light and everything seems to be working? i think now that the plugs are fouled. i just had put them in about 2 weekends ago and i cant believe they are fouled already. i am running app3924, anyone recommend anything else? i have always used autolite and they usually work ok?

Autolite or NGK are the most recommended brands. An Autolite 3924 is 1 heat range colder than stock. It should be a good starting point for a N/A street engine. For a race only, or power adder application you would want a colder plug.

The noid light just proves that the ECU is trying to fire the injectors, not that a particular injector is actually opening. I wonder if you are running into a minimum open time problem. Every injector has a minimum time it can open for a given voltage. For example if a particular injector has a minimum open time of 1ms and the ECU only sends it .95ms pulse at idle, it may not open at idle, but would be fine at higher rpms, when it receives a longer pulse. Minimum open time is why sequential injection is desirable when running large injectors. Minimum open time goes up as battery voltage goes down. So check your battery/alternator voltage at idle.

Craig

thanks for the reply, i am taking the car to pro-dyno in fort mill sc on wednesday to have it tuned and a chip burnt for it. they will be able to go into the computer and set everything thats needed. i cant wait to see what this thing is going to do!

just got back from the dyno today. not as high as a number as i would have wanted, but it was at the rear wheels, i just have to wonder how much was lost in the drivetrain. my efi 521 made 399hp and 402 tq at the rear wheels. probably could have made some more pulls but the trans was heating up and the runs werent getting any better. i was able to get the efi tuned up and it really made a big difference in the smoothness of the engine and throttle. the roller rockers need to be adjusted, i dont know if they were ever right or not, you could hear a little noise from them so i am pretty sure they were out of adjustment.