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Thread: What efi system is best for a 4.5 pfi cadillac engine7

  1. #91
    Fuel Injected! S.O.B.B.'s Avatar
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    Thanks Dave w.The sense resister jumpers and memcal mod are the 2 things I did do long ago.it's been sitting in a box waiting for this conversion. But since doing those 2 mods I read the memcal mod was not needed.I also unsoldered the factory chip from the memcal and soldered in a socket and then a zif.I don't have an extensive background in electronics per say unless rc cars qualified.I'd guess not.:rolleye
    Jeeper
    87 sjimmy powered by a 92 cadillac 4.9L pfi on 7427pcm /700r4/ 8.8 3.55 rear/disc brakes.

  2. #92
    Fuel Injected! S.O.B.B.'s Avatar
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    Screenshot_2018-10-07-00-54-31.jpg this mod is the one I was asking about.pin 2 to pin 5 jumper.I was not questioning if the sense resister jumper was needed.just the memcal mod.I've done both.I'm supposed to repin my harness in the morning and still have to do mechanical hook ups to test fire so I guess I'll try it as is with both mods.I had a bit of a steering shaft issue and had to slice a rectangle out of the header and flip it and weld it back in to create a notch for steering shaft clearance.a little less work than moving the colum over.I just hope this all works.
    Jeeper
    87 sjimmy powered by a 92 cadillac 4.9L pfi on 7427pcm /700r4/ 8.8 3.55 rear/disc brakes.

  3. #93
    Super Moderator dave w's Avatar
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    The memcal mod is required so the injectors are triggered once every 4th distributor reference pulse (DRP). Without the memcal mod the injectors are trigger every DRP.

    dave w

  4. #94
    Fuel Injected! S.O.B.B.'s Avatar
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    Thank you Dave w. Once I get it fired up I'm sure I'll be asking more questions. The tbi was my first tuning experience over the last almost year logging and making changes. So this is a first time tuning experience for mpfi once it fires up. Thanks again. Much appreciate your time.
    Jeeper
    87 sjimmy powered by a 92 cadillac 4.9L pfi on 7427pcm /700r4/ 8.8 3.55 rear/disc brakes.

  5. #95
    Fuel Injected! S.O.B.B.'s Avatar
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    Harness repin complete. Had left over wires.a couple from last swap.C1 C2 from A.I.R.C9 crank signal.C12 ETM.B9 EVRV. Still have a bunch to do and just waiting on the weather. anyone know what wire I need to run to B10 cruise signal or if I need one for the cc to function?
    Last edited by S.O.B.B.; 10-07-2018 at 11:42 PM.
    Jeeper
    87 sjimmy powered by a 92 cadillac 4.9L pfi on 7427pcm /700r4/ 8.8 3.55 rear/disc brakes.

  6. #96
    Fuel Injected! S.O.B.B.'s Avatar
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    Finally got a bit of not so freezing on the fingers weather. I tried a start up today after lots of wiring and connecting everything and at key on I have no check engine light and do not hear fuel pump.I gave it a crank just to see that it would. When I'm cranking the check engine light comes on but turns off when I stop crank. I'll have to go threw my repin again (3rd time) and see what is up.anyone else run in to this b4.any ideas are greatly appreciated. The only thing not currently plugged in is speed sensor as I've not installed the new one yet.the iac I couldn't find a definition for each wire accept color and letter on the plug.so I wired a to a b to b etc.the dodge diagram I have does not specify a hi a low or b hi or low.it just says number 1 2 3 and 4.I doubt that if this is wired incorrectly that it would cause no check engine light at key on.the dodge tps I was able to find correct label for wires.using gm map sensor so no wiring change on that.it got dark so I did not check for spark but I doubt I'd have any as it seems I may have a wire in the wrong spot or something. Thanks in advance for any ideas
    Jeeper
    87 sjimmy powered by a 92 cadillac 4.9L pfi on 7427pcm /700r4/ 8.8 3.55 rear/disc brakes.

  7. #97
    Fuel Injected! S.O.B.B.'s Avatar
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    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. ☺

  8. #98
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    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?
    Jeeper
    87 sjimmy powered by a 92 cadillac 4.9L pfi on 7427pcm /700r4/ 8.8 3.55 rear/disc brakes.

  9. #99
    Fuel Injected! S.O.B.B.'s Avatar
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    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
    Jeeper
    87 sjimmy powered by a 92 cadillac 4.9L pfi on 7427pcm /700r4/ 8.8 3.55 rear/disc brakes.

  10. #100
    Fuel Injected! sturgillbd's Avatar
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    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
    Attached Images Attached Images

  11. #101
    Fuel Injected! S.O.B.B.'s Avatar
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    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
    Jeeper
    87 sjimmy powered by a 92 cadillac 4.9L pfi on 7427pcm /700r4/ 8.8 3.55 rear/disc brakes.

  12. #102
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    Got the usb to ttl functional.very cool.thanks for that tip. Got it idling.it ran Decent until I set the timing. It was at 30 and I put it to 10.plugged bypass back in and no change.like no advance.I am getting a code 43.need to check knock sensor and circuit. As for the timing I am going to check at distributor for continuity at bypass wire to pcm.any advice on what else I should be checking for in ignition system.the advance worked on the other set up and this is same distributor and harness.thanks in advance for any help��
    Jeeper
    87 sjimmy powered by a 92 cadillac 4.9L pfi on 7427pcm /700r4/ 8.8 3.55 rear/disc brakes.

  13. #103
    Fuel Injected! sturgillbd's Avatar
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    Did you pull power to the pcm to reset codes? If you did, then you have a problem with the esc circuit. Check wiring from distributor to the pcm. That's where I would start.

    Brian

  14. #104
    Fuel Injected! S.O.B.B.'s Avatar
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    Thanks for that.I did reset 2 times and got the same code before setting the timing and the same code after and after clearing codes once timing bypass plugged back in.it seems the code comes only after reving it.checking the wiring to distributor and knock circuit is first on the list.will post what I find. Appreciate the help
    Last edited by S.O.B.B.; 11-02-2018 at 05:23 AM.
    Jeeper
    87 sjimmy powered by a 92 cadillac 4.9L pfi on 7427pcm /700r4/ 8.8 3.55 rear/disc brakes.

  15. #105
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    Well I won't get to drive this till tomorrow but I do have it running and going into closed loop and no codes so that's awesome. I don't know if the knock sensor failed or was the wrong one.the one I had laying around seems to have stopped the code 43 and the advance seems to work now.I did another search for the Chrysler iac and found I had it incorrect.I'm not sure how to tell if it's correct now but it seems to respond as it should.the data seems a little glitchy but it does not seem to interfere. Once I go for a drive and log some data I have the wideband ready to install. The tune feels better than the tbi 7747 that's for sure.will update once I get the drive time in.thanks for all the help.I doubt I could have accomplished this mpfi conversation with out this site.
    Jeeper
    87 sjimmy powered by a 92 cadillac 4.9L pfi on 7427pcm /700r4/ 8.8 3.55 rear/disc brakes.

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