What efi system is best for a 4.5 pfi cadillac engine7

[S.O.B.B.]

Thanks Dave w.I do have the cadillac harness.I cut the injector harness wires today off the plug and separated the wires to the injectors to prepare for soldering onto the tbi harness wires.can you confirm for me that the tbi harness the blue and green are negative for each bank and the red and white are positive for both banks.thanks

[dave w]

1227747 Wiring Schematics are here: http://www.gearhead-efi.com/Fuel-Inj...Information-42

dave w

[S.O.B.B.]

I decided id burn my chip again.see if any change. Still no check engine light at key on but it did fire up and run for about 20 seconds so I must have spark and fuel.guess ill look closer when done work tomorrow. ☺

[S.O.B.B.]

Ok got my wiring figured out.had made a mistake on starter wires.had acc wire with crank wire on solenoid when it was supposed to be on the battery + lug.so at key on check engine light comes on then off then back on.as is supposed to. But I still can't get my laptop to connect.is there anything different the 7747 and 7427 to connect.I'm using a homemade cable and an usb converter. interface2.gif I used the A as ground and the pin below it on the 7747 and on the 7427 it won't connect.I tried it in the E pin and no luck.any suggestions would be great. I got it to run but terribly and only with pressing the gas pedal.stink of fuel.not sure shats up thete yet.all ecm wiring verified.the swap note said something about putting pin E to pin M.but that's the 2 I tried with out getting a connection to laptop.what could I try?

[S.O.B.B.]

interface2.gifthis is the first cable I made for the 7747.I'm not getting a connection to 7427.do I need to have this 2 transistor set upScreenshot_2018-10-28-17-11-46.jpgany help is appreciated. Thx

[sturgillbd]

That cable will not work on a 7427. The 7427 requires bidirectional communication. Easiest cable I have found to make is use a USB/serial TTL converter and hardwire to PCM. I just plug a USB cable into my PCM and it works. Here is what I use https://www.ebay.com/itm/FT232RL-FTD...-/121821751277 There are a few posts here on gearhead on how to use them. Basically you tie RX and TX pins together and this is the serial data terminal. The other connection you use is ground.
Simple and it works well

[S.O.B.B.]

That's the info I was after.thanks for your time.that will let me see what's up.the engine won't run with out pushing throttle so I'm suspecting iac not wires correctly.plus timing not set.hopefully the weather cooperates so I can finish up the rest of the reassembly and get running and tuning again.thanks again for the help