GMCtrk

iTrader: (27)

Good call, I forgot about that!

smartin84

Well I know where your coming from... I just swapped 4.8 to LQ9 and have the same problem as you. Very slow turn over.. Seems to drag and just barely have enough to crank. Mine is getting painted right now, but interested in what the problem could be. Thinking it might have something with tune, connection, or different starter. Keep us updated. Thanks

GMCtrk

iTrader: (27)

Well one good thing, I got the exhaust flange tightened up.

I went to start it to see if that stopped the exhaust leak and something bad happened. I tried to turn it over once and it didn't do it so I went to go again and it just died and my little green hazard's on the dash came on. After you take the key out it takes about 2 seconds for them to turn off I think I either fried my battery or my PCM. Should I be checking fuses? I also got a little pop from my speaker when locking the door? Help.

MGMC

iTrader: (46)

i have no problems using my original 4.8 starter for d/d 10,000 miles now. it cranks up just like it did with the 4.8. im sure you have a bad connection somewhere. get some fresh eyes to look over your install.

the flywheels are different between the two engines. there is a snout/spacer between the flywheel and the motor for the 4l80....unless this engine came out of a 1/2 ton

GMCtrk

iTrader: (27)

It came out of an escalade, we put the 4.8 flywheel back on anyways. I got the starter out and tested at autozone and the guy said it sounded weak, not like it should.

But guys, I really need help. I think I fried the electrical system trying to start it over and over. I thought maybe the battery was fried but I had it tested also and it was good. When I put the key in to the on position I get 12 volts but as soon as I go to start it the volts drop all the way down. Radio doesn't turn on. I checked as many fuses as I could under the hood and on the side of the dash and they all looked good. How do you get those gray blocks off in the fuse box under the hood? Is there a fuse under there that could have broke? Is it possible I fried my PCM? Dammit.

budhayes3

iTrader: (19)

If something's shorted in the starter it could cause some crazy stuff to happen like you're describing...not sure about the gray boxes, sounds like you're referring to relays. You should be able to access all of the fuses without tearing anything apart...can't remember if there's a fusible link on the positive battery cable or not though.

I saw how you mentioned that your battery cables were corroded...that will create big starting problems that will act like a weak starter motor...

GMCtrk

iTrader: (27)

Well, the starter did turn over on the bench test though. As for the corrosion, I took a metal wire brush to it and cleaned it all off. I guess everything will have to wait until I get the starter in, but what do you guys think the worst I'm looking at is? Is it possible I fried the PCM? I still have the 4.8L pcm I can stick back in.

budhayes3

iTrader: (19)

I doubt that you fried the PCM, if you turn on the key (just on, not start or run), do you see a check engine light? If so, the PCM is probably OK. Alot of times, when a PCM smokes, the check engine lt will not come on with the key on as it should.

GMCtrk

iTrader: (27)

No check engine light came on that I remember.

I checked all the fuses as well as I could and saw no blown fuses. As of now it's just a waiting game until I get the new starter in, which should be tomorrow evening depending when UPS drops it off.

The oddest thing, when I put the key to on, both of my turn signals came on in the dash

I guess my next move is to get the starter in and see if it works. If not, put the 4.8 pcm back in. If that doesn't work I think I'm out of options.

I appreciate your help Bud.

budhayes3

iTrader: (19)

May be voltage back feeding through that circuit, or something with the hazard relay? If any computer would cause something like that it would be the BCM (I would guess). Glad to help man, hope it works out for you