alex722607

iTrader: (3)

So I spent the weekend rewrapping my LSx swap harness in techflex to it looks clean. Its a standard 99-02 LS1 f-body engine harness fully integrated by means of 4th gen underhood body wiring and the like.

I depinned the computer and repinned it after wrapping it. My issue is that it won't communicate for some stupid reason and stumbles occasionally in park. It actually stumbled so much, I thought it was going to shut down on its own, so I shut it off. No MIL light for codes, but it turns on when you turn the key on like normal. Not sure if something was pulled loose or what. I did drive it for a short distance and it seemed ok. The darn thing just won't communicate. I have checked all my pins twice, including the sheet that I used to pin everything. Since there is 160 possible spots to put pins, I am going to check it again tomorrow, but can anyone point me in some sort of direction.

What could cause an occasional stumble and no communication. (and the engine seeming like its going to die after about 10 minutes of running in idle park)

I also upgraded my battery cables to 2/0 guage and it seems on the gauge that its charging at 15 volts - if its over-voltage, the pcm would just shut off the alternator - right?

grngryoutmyway

iTrader: (1)

Did you check your grounds?

alex722607

iTrader: (3)

Actually I just spent the day going over everything, all pins, all connections and with the aid of a multimeter. I found that everything was the way it should be. I then Proceeded to look at the diagnostic port, I bypassed the one under the dash and got the power and ground from the source(fuse box and chassis).

As it turns out I haves loose connection at the port and therefore wasn't able to read anything. I wiggled the crap out of it and bam it works. As far as it running funny, I deduced that the ECM was learning itself, the air fuel ratio and what not. I also did not plug in the MAF and so that may have contributed to it. I can't understand why it didn't throw a code for it, but it works.

I literally thought I was going nuts and was afraid to take this car anywhere. (Didn't help that this is my daily driver). I hope I don't have to pull this harness anymore, I have done so three times because of wires touching the headers and me catching the issue before it caused problems. Live and learn right.

ghettocruiser

iTrader: (4)

Alex,

Glad you sorted it. Hopefully you're not like me, and experiencing issues with the wiring degrading. I'm using an original 99 LS1 harness. Ive been chasing gremlins for a while now, and have determined that vibrations/heat must have killed a couple wires. Its either that or my PCM is taking a crap...which is less likely IMO. After pulling my harness, swapping it a couple times, putting it in an environment that it wasn't meant for...i think its taking its toll on the 15 year old wiring. Right now I'm in the middle of re-wiring my #1 coil from the PCM and splices all the way to the coil. What a PITA haha.

J.

alex722607

iTrader: (3)

Well I kinda spoke to soon haha. I am having some sort of weird issue I didn't experience before. At idle in gear, she likes the ballpark of 400 rpm's. Typically before my little beautification venture she would do 500-525. I get a stumble and shaking. So my first thought is 02 wiring is switched cause it happens in closed loop. I had the exhaust apart recently and noticed when reassembling that water was in the midpipe. The sensors are new. Also I never played with the intake throttle blade setting so I have no idea if me tinkering uncovered a problem or created one. At the same time it's a 5.3 with an ls1 cam and running on a mail order tune. (It ran fine beforehand and I did a continuity test to make sure the pin at the pcm is indeed the same pin at the proper 02 sensor connector. So I'm not sure if the 02's went bad, or if it's something else.

alex722607

iTrader: (3)

But I know what you mean about brittle wires. I fried my trans wires and by crank wires twice, luckily I had the pins and proper color wiring to fix it in my wiring box. I am beginning to think maybe my pins have worn themselves out and that I should start replacing them. I'm starting with the injectors and working my way down.