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Thread: Recommend an ECM to replace my 8747?

  1. #1
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    Recommend an ECM to replace my 8747?

    I wonder if this ECM even came with my truck originally. I have a 93 K3500 w/ 7.4 and NV4500. PO told me the engine was not the original engine. I believe it was a used 80,000 miles engine pulled from another vehicle. I wonder if he pulled the ECM at the same time because the 8747 info page does not list my year and model as a possibility. Maybe that is just not a complete list?

    Anyway, I have suspicions that the current ECM could be struggling and I was considering getting into tuning. Both of those things would point me towards a different ECM and the tuning aspect leads me towards an ECM that has more support for it like the 7747, 7060 or a 7427?

    I would imagine with any of those I would have to re-pin the harness that plugs into the ECM (Except maybe the 7747?). Anything else I should be considering? Thanks.

  2. #2
    Super Moderator dave w's Avatar
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    I'm thinking the original ECM was 16171199. The wiring diagrams for ECM's 1227747, 1228747, and 16171199 are nearly identical. I would tune the 1228747.

    http://www.gearhead-efi.com/Fuel-Inj...Information-4F

    dave w

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    Fuel Injected! brian617's Avatar
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    According to my interchange the 1228747 is more than likely the original ECM given that it is a 7.4L manual trans. The other two choices for that application are 16147060 and 16168625 used in automatics.
    89 K1500 Scottsdale 5.7L 5spd 3:42 RamJet cam Dart iron TBI heads 427 PCM swap
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    Quote Originally Posted by brian617 View Post
    According to my interchange the 1228747 is more than likely the original ECM given that it is a 7.4L manual trans. The other two choices for that application are 16147060 and 16168625 used in automatics.
    What do you mean by your interchange? Another person I talked to who had me convinced he knew what he was talking about said that it should have the 8747 in it. Since both you and another person said it should have a 8747 in it, does that mean the page dave w and I linked to is not very complete? Thanks.

  5. #5
    Fuel Injected! brian617's Avatar
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    Hollander parts interchange, I work in a salvage yard.
    89 K1500 Scottsdale 5.7L 5spd 3:42 RamJet cam Dart iron TBI heads 427 PCM swap
    95 C2500 Cheyenne 6.5L turbo diesel 4L80e 4:10 DB2-4911 Manual pump conversion 0411 PCM trans control 2Bar COS
    05 Outback XT 2.5L turbo gas auto

  6. #6
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    Quote Originally Posted by dave w View Post
    I'm thinking the original ECM was 16171199. The wiring diagrams for ECM's 1227747, 1228747, and 16171199 are nearly identical. I would tune the 1228747.

    http://www.gearhead-efi.com/Fuel-Inj...Information-4F

    dave w
    There is a guy on 454ss who seems to really know 454 TBI trucks who said I should expect to have the 8747 in it as well. Between that and brian617, I wonder if the link you provided (I had already seen it which is why I wondered if I had a different ECM) is incorrect or incomplete?

    Anyway, the reason I'm considering replacing the ECM is because of a problem I'm having with the engine stalling anytime the engine compartment gets hot enough. I admit that since the ECM isn't in the engine compartment, that's kinda grasping at straws, but that's the point I'm at now.

    Anytime the engine compartment is warm (idling for awhile on a hot day) it starts idling erratically and then it finally stalls. When I try to re-start it is very difficult to get it to start.

    It's very difficult to diagnose because I cannot make it do it with the hood open and the air cleaner off. I think it would idle all day in 110 degree weather with the hood open and the air cleaner off so that I can watch injectors and spark while it happens.

    If I make it happen with the hood closed and then quickly remove the air cleaner and install a spark tester and try to restart it, it has spark but the fuel flow from the injectors is not the same as it would be on a normal start. You can see the spray but it's just very light. I have had the throttle body rebuilt and injectors tested and balanced by SPR Performance (tbiparts.com run by dctrumpet on thirdgen.org). I have also installed a fuel pressure gauge at the back of the throttle body and it is always between 11 and 14 pounds, (usually about 13). There are no codes (other than an occasional code 43 which just started happening for some reason). The entire ignition system is new, meaning new loaded distributor, new plugs, new wires, new coil (all OEM parts). I set the timing with the wire disconnected. A compression test reveals about 125 PSI which is withing standards for the L19 which came from the factory with pretty low compression.

    So I guess I'm down to wondering if there is a wiring problem or if the ECM is bad. Hence my question in the other thread about how to test the ground wires in particular.

    Anyway, it's been a challenge. Between wanting to tune it after I finally get it figure out and the possibility that the ECM (dctrumpet suggested that the injector drivers in the ECM could be flaky) is causing problems, I'm considering switching ECM's. Hence my question as to which one would be good for this truck.

    Another consideration is that I could imagine someday wanting to put a 4L80E in it. I think that would lead me quite directly to the 7060 ECM, but I'm not sure how likely that is. I do like 5 forward gears, but I've had enough clutch problems that I wouldn't mind getting rid of that headache as well.

  7. #7
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    Quote Originally Posted by dave w View Post
    I'm thinking the original ECM was 16171199. The wiring diagrams for ECM's 1227747, 1228747, and 16171199 are nearly identical. I would tune the 1228747.

    http://www.gearhead-efi.com/Fuel-Inj...Information-4F

    dave w
    Since this thread is sorta about the 8747 and you're a moderator, why is the 8747 thread at the top of the page a sticky? Just curious...

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    RIP EagleMark's Avatar
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    Quote Originally Posted by dpilot83 View Post
    What do you mean by your interchange? Another person I talked to who had me convinced he knew what he was talking about said that it should have the 8747 in it. Since both you and another person said it should have a 8747 in it, does that mean the page dave w and I linked to is not very complete? Thanks.
    Interchange is a book that salvage yards use to find parts.

    There's a possibility that any of the info pages are not complete, we do the best we can. It's been verified the ECM came in your truck so I don't think that is your issue. Grounds from ECM back to engine can always be an issue so check them on engine block, there's normally two sets of grounds, one near T stat housing and one on back of head or intake.

    From your description of problems I really doubt you have an ECM issue. Since the ECM is not under hood and you've obviously got an overheating under hood issue. I think you mentioned an engine change? I'd be looking at fuel lines first from your symptoms? It sounds like the fuel is boiling, you know like old carb vapor lock. It happens to TBI as well. See that the fuel lines are routed properly as they run from TBI down the frame near the exhaust etc...

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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    RIP EagleMark's Avatar
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    Quote Originally Posted by dpilot83 View Post
    Since this thread is sorta about the 8747 and you're a moderator, why is the 8747 thread at the top of the page a sticky? Just curious...
    Me too? Who made that a sticky? I just don't see a reason for it?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  10. #10
    Super Moderator dave w's Avatar
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    Quote Originally Posted by EagleMark View Post
    Me too? Who made that a sticky? I just don't see a reason for it?
    I don't think I made the post a sticky, maybe I unintentionally did. I don't think the sticky is an option in the Moderation Tools? Is there a short cut key / hot key that would make a post a sticky?

    dave w

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    Fuel Injected! JeepsAndGuns's Avatar
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    Just to confirm what has already been confirmed. I am currently (trying to) part out a 93 C3500 with a 454 and 5 speed. It too has the 8747 ecm with the bcc ARPY. It appears to have nmever been removed and I would believe its factory.

    If you were to swap to a different pcm, say for instance a 7427, the hardest part is going to be finding a 454 memcal. Right now your ecm uses the knock filter seperate from the ecm.
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  12. #12
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    Quote Originally Posted by JeepsAndGuns View Post
    Just to confirm what has already been confirmed. I am currently (trying to) part out a 93 C3500 with a 454 and 5 speed. It too has the 8747 ecm with the bcc ARPY. It appears to have nmever been removed and I would believe its factory.

    If you were to swap to a different pcm, say for instance a 7427, the hardest part is going to be finding a 454 memcal. Right now your ecm uses the knock filter seperate from the ecm.
    I wish you were closer, especially if your pickup was a crew cab with a tan interior. I need a rear seat (employee spilled gear oil all over it) the glove box hinge piece, and I'm sure about a zillion misc pieces that I am not thinking of right now.

    I haven't heard of the knock sensor being separate from the ECM. Can you elaborate on that more? Thanks.

  13. #13
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    Quote Originally Posted by EagleMark View Post

    there's normally two sets of grounds, one near T stat housing and one on back of head or intake.
    I have found the set on the thermostat housing. I'll look for the other at the back of the intake manifold. Thanks.

    Quote Originally Posted by EagleMark View Post

    From your description of problems I really doubt you have an ECM issue. Since the ECM is not under hood and you've obviously got an overheating under hood issue. I think you mentioned an engine change? I'd be looking at fuel lines first from your symptoms? It sounds like the fuel is boiling, you know like old carb vapor lock. It happens to TBI as well. See that the fuel lines are routed properly as they run from TBI down the frame near the exhaust etc...
    That's an interesting observation. I've owned this pickup for several years before it started doing this. It has never idled quite right and has missed occasionally under load, etc but it has not done this particular thing except for this year now that it's gotten warm. This winter we had SPR rebuild the throttle body and we added a fuel pressure gauge behind the throttle body. The fuel pressure gauge required quite a bit of manipulation to get the adapter installed between the throttle body and the steel fuel line. Perhaps the manner in which we manipulated the line caused it to be in a hotter area? I really don't think we moved it hardly at all, it's just that even moving it that small amont was quite difficult.

    How would you know whether the fuel in the lines are boiling or not? My pressure gauge always stays pretty steady. Honestly, I would not be at all surprised because it's pretty clear that something is coming out of the injectors, it's just not coming out as much as it does during a cold start.

    This is actually quite fascinating to think about. It would explain everything. It would explain:

    1. It looking like there is fuel coming out but it looks like not as much as a normal start
    2. It only happening while the engine bay is very hot
    3. How when it starts it kinda sputters to life and the more you get it going the better it runs and the better it runs the easier it is to keep it running. It's just introducing cold fuel into the lines that makes it run better and better the more it gets rid of the hot fuel. Revving it to 3000ish RPM simultaneously pulls a lot of air in and gets rid of a lot of hot fuel

  14. #14
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    All that fuel line has to do is hit a hot piece of metal and POOF! Vapor lock.

    You could also be on the verge of needing a fuel filter? Many times I've seen them work fine but the reduced flow would cause data to change...

    Revving motor to 3000 RPM also increases fuel flow by raising voltage just a little to pump. This would circulate all excess fuel back to return and cool things off.

    I think you have some sort of hot fuel issue?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  15. #15
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    Quote Originally Posted by EagleMark View Post

    You could also be on the verge of needing a fuel filter? Many times I've seen them work fine but the reduced flow would cause data to change...
    Is there any way for the fuel filter to be plugged if your pressure at the back of the throttle body is staying up? I do not have my remote electrical gauge hooked up so I don't know what the fuel pressure is doing under load, but I'm also not having any problems with it not running right under load, it's just during idle. During idle, even when it dies or when there is a hard start/no start situation the fuel pressure is always good (usually about 13 PSI).

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