Andy’s 1995 CCLB 7.4L TBI to Vortec Swap

Discussion in 'Member Trucks' started by andy396, Jun 22, 2019.

  1. andy396

    andy396 I'm Awesome

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    So I've got about 400 miles on it thus far. My main focus has been resolving the stalling and insufficient flow ECR code. Like I think I mentioned it would only stall when coming to a stop and it wouldn't do it every time. I came to the conclusion that it was transmission related based on the fact that I could see the transmission going into limp mode just before it would stall. So when I googled 4L80e stalling I got a ton of hits that sounded exactly like my issue. The best reference I got was https://www.yellowbullet.com/forum/showthread.php?t=1472106 from a Sonnax Tech. Basically when there is insufficient flow, the TCC circuit gets starved and doesn't have enough pressure to keep the TCC disengaged. One of the culprits is reduced flow through the transmission oil cooler. The '00 transmission uses all 3/8" cooling lines whereas in '95 they're 5/16". I replaced all the cooler lines except the the all hard line because the one on the parts truck was in poor condition and they don't sell that line. My '95 line was in good condition, or so I thought, so I just used it not thinking it would make a huge difference. I decided to go ahead and fabricate a new line out of 3/8" hoping this was the cause. When I took the 5/16" line off I discovered that it had gotten pinched by the connecting rod when it came launching out of the oil pan.

    upload_2019-7-19_22-18-58.png

    I now felt for sure this must be the cause of the stumble and stalling! I spent the next hour or so copying the bends of 5/16" line into a 3/8" line. Admitedly it turned out surprisingly well for a first crack at it. Then I went to put the flares on it. The flare tool I was using did a lousy job at making the flare in spite of very careful preparation. It couldn't keep it straight and the flare ended up off center. Not wanting to have to redo the entire line I set off to find someone with the nice hydraulic flare tool to just do it for me. I ended up at a local repair shop. But now there wasn't enough room to fit his flare tool on it before the first bend. So to salvage the line he had to splice in a short piece. His bender struggled to bend the 3/8" tubing without kinking it, so what should have been a quick job turned into much more. He finally got it and ended up only charging me for materials because he wasn't happy with the quality, but it was fully functional. I was very appreciative of what he did for me.

    upload_2019-7-19_22-29-36.png

    I put the new line on and took it for a test drive.

    It still stalled...
     
  2. andy396

    andy396 I'm Awesome

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    That's when I had an ah-ha moment a day or two later. It seemed to do it mainly when I came to a hard stop. What if it's just starving for fluid at the pickup? I'd check the fluid when I first drove it, but after driving it for a while sure enough it was a quart low. Topped it off and no more stalling! *shaking my head*
     
  3. andy396

    andy396 I'm Awesome

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    The EGR problem is solved now also. I decided to try to put the old EGR valve on and see if it behaved any differently. The old EGR valve was warped and one of the ears was hanging on by a thread. I threw it on as is and sure enough, no P0401 code and I could see it passing the EGR test. It would ramp the EGR closed, take a reference MAP reading, then ramp it up and the MAP reading would be higher.


    upload_2019-7-19_22-48-42.png


    I carefully resurfaced the old EGR valve on the belt sander and reinstalled it as carefully as I could not to completely break the one ear off. I drove it this way for a few more days until I could get another new EGR. Everything fell right in line with the original valve installed. The LTFTs even got closer to where they should be.

    upload_2019-7-19_22-56-24.png

    There's something clearly not working correctly with the first replacement EGR. It's a Delphi EG10021 and looks identical to the OEM part. Anyway, this time I went with an ACDelco part, except I got it from Advanced Auto under their BWD brand because with my discounts I could get it for $65 less. I put it on the other day and it too is working properly. However, the LTFTs aren't as good. On average it's now more in the -10 to -15 range in a good amount of areas. It's still a little better than it was on the Delphi valve, but not exactly like the OEM part. That's annoying.
     
  4. Christian Steffen

    Christian Steffen I'm Awesome

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    At the very least, im glad to hear the stalling is fixed!
     
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  5. andy396

    andy396 I'm Awesome

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    Updates:

    - New EGR seems to be working well.
    - Open CAT surgery was a big ‘ol fail. It’s back to rattling more than ever.
    - The heater bypass valve sprung a leak. Probably drove it that way for a couple days before I noticed it. When I went to replace it, one of the nipples broke completely off when I touched it.
    - It’s doing something weird on WOT 1-2 shifts. It’s almost like a double shift. It shifts, rpms drop, rpms increase, then drop how it should after a shift. I’m not sure if it’s slipping or what. It only does it at wot, if it’s just under that it shifts fine. I haven’t had a chance to look closer at the data log.
    - Driving in these last few days of 90’s and crazy high humidity the A/C was barely able to keep you comfortable. It was taking the humidity down, but just not getting the cab as cool as I think it should have been able to. My first thought was maybe the heater bypass valve. I don’t have it hooked up since the ‘00 donor didn’t have wiring for it. When I put the new valve on I just flipped the actuator so instead of holding it open it holds it in bypass so the hot coolant isn’t circulating through the heater core. This might be a problem come winter, but I’ll worry about that when it gets here. The next time I tested the A/C I would say it wasn’t noticeably better. I decided to pull the fan and look inside at the evaporator. Sure enough it was probably 25% blocked with pine needles and leaves around the outer edges and with lint and what not in the center. I cleaned it the best I could but there’s around 10% more to go. I just ran out of time. The other thing I found was that the recirc. door wasn’t moving. I checked functionality when I installed the dash, but all I did was listen for the motor. I could hear it go brrrrr-errrrrr when I toggled the recirc. button, but I never actually checked that the door was moving. Sure enough, it wasn’t. I tried to replace the actuator but the top screw is almost impossible to get to. I gave up and just propped the door in the recirc. position. Now the heat and humidity are gone and so I’m not sure if it’s any better. What I can say is that there was ice forming on the accumulator and return hose on my way in this morning! But that’s really not a good test as the fan was only on low the whole time.
    - Since it has almost 500mi on it I decided to get on it a little harder (and try to get more symptoms on the 1-2 shift thing). After about the second hard acceleration run it now won’t idle down to less than about 900 rpm in park, maybe 700 in drive. My first thought is vacuum leak? It was idling right around 600 before. I didn’t see anything obvious looking under the hood. Maybe IAC or EGR? Of course I wasn’t data logging this time.

    Edit: Put the scanner on it when I got home. Sure enough, IAC is hovering right around zero.

    Anybody have some GMT400 bug spray? I could really use some about now.
     
    Last edited: Jul 24, 2019
  6. Supercharged111

    Supercharged111 I'm Awesome

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    Your trans is fine, they lock the converter when WOT so that's what you're feeling.
     
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  7. andy396

    andy396 I'm Awesome

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    Found a picture of the donor truck before I took it apart.

    1398227_10202509959252502_1050899578_o.jpg
     
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