BigRob

Hey guys.

My Z28 has actually been running quite well but yesterday I went to leave and it cranks, but doesn't start.

I get a fuel smell and the fuel pump is priming, so I'm pretty sure it's not the fuel pump.

I'm leaning toward electrical atm. I was going to pull a plug wire, but everything is so shoehorned how in the hell am I supposed to get to one?

Plus over the past couple of weeks I have experienced an odd buzzing sound. It seemed to happen more often than not while accelerating and stopped whenever I stopped. It seemed to have come from around the dash area right in front of me (so the drivers side). I don't know if it's related or not....maybe the ignition is out?

Injuneer

Scan it for codes?

BigRob

I just tried running pcmread.exe off of carputing.com but after sitting there for five minutes with "establishing connecting to PCM" at 0% I figured something was wrong somewhere. I did try different ports "just in case" but they just gave "can not establish connection". So I had the right port but nothing was happening. At all.

Was I not patient enough? I figured it would scan pretty quick, but like I said 5 minutes of NOTHING.

edit: I just read online that the cooling fans should come one when scanning, but they didn't on my car.

Is something wrong with the PCM?

edit #2: I had a DOH! moment. I had used my wifes laptop since mine died a few months ago, and hers doesn't have the drivers on it. I will re-attempt scanning this evening when she returns from work.

BigRob

The optispark went out.

It was replaced and still didn't run. Thinking that he got a bad part the mechanic put another one in and it still didn't run. He called a buddy at GM who came to the shop with a more specific scanner and it turns out when the opti went out it took the wiring harness that runs between the opti and the PCM with it....and possibly the PCM as well.

So can someone direct me towards the correct wiring harness?

He doesn't do wiring and said if I found someone to do it that it would run 1000-1500...I don't have that. Is it something mechanically inclined people can do in a driveway? (son in law is a army mechanic, may ask him if he'd do it).

Is this the proper replacement?

http://www.jegs.com/i/Painless/764/65105/10002/-1

byrons1502

That doesn't sound right. I have never heard of a wiring problem like that. The connector is common on the opti.

BigRob

I've been in the lounge discussing this...


apparently I developed a crack in the water pump and it leaked onto the opti. The opti, being unvented, developed moisture in there and rusted...thus went out. I had the shop replace the waterpump and opti.

The car was still not running and the thought the wiring harness went out, but the guys in the lounge awared me of a short harness that tend to go out when opti's do that runs from the opti to the main harness. According to them it can cause the "low res" code 16 reading the mechanic mentioned.

So I have the Z28 back in my driveway and ordered the short harness. My fingers are crossed that it will get it running.

Injuneer

The short Opti harness goes "out" because 1) the clip that holds it on the Opti breaks off and its loose; 2) the pins are damaged; or 3) the pins are corroded. Did you see any signs of those problems when you inspected it?

BigRob

I happen to still have it so I looked at it real quick and see nothing you mentioned.

My son-in-law and I replaced the short harness and it still doesn't start.

Yesterday I sprayed some choke cleaner into the throttle body as my wife tried starting it....nothing.

Here is a vid of my wife trying to start it so you can see and hear what we do.

http://www.youtube.com/watch?v=34Re9zGo02o

I have a laptop and aldl cable, but accidentally clicked "no" when the plug and play came up. I understand that you are one of the PCM guru's, Injuneer. If you could tell me how to get the plug and play back up so I can load the driver for the cable then I can scan the car and post the results. I was told to shut off and restart the computer, but that didn't work.

Injuneer

I don't know the details of installing scan software, because I've been running an aftermarket computer since 2000.

Why not download DataMaster of FreeScan? I haven't seen too many people using "pcmread.exe"

http://www.ttspowersystems.com/DataMaster.html

http://andywhittaker.com/ECU/FreeSca...0/Default.aspx

BigRob

I just got it running.

I scanned about 450K bytes of info before I stopped...it's too damn hot atm to sit out there very long. I was out there about 1/2 hour as it was.

I may go out again either later in the evening or one morning this week if need be.

As I watched it scan I saw a lot about "pcm sending header" and "header detected but not interactive".

But here's some of what I got...it's all Greek to me:

1994 Z28

Coolant Sensor Volts 1.86
TPS Volts 0.57
Desired Idle RPM 3187
Road Speed 0
O2 Left 0.4
O2 Right 0.32
BLM Cell 0
BLM Left 128
BLM Right 128
Integrator Left 128
Integrator Right 128
Base PW L 0
Base PW R 0
IAC 129
Baro Air Pressure 1
MAP 1
TPS 0
MAT Volts 2.2
Knock Retard 0
Knock Count 0
Battery Volts 11.3
Air Flow 0
Spark Timing 0
Coolant Temp 31.3
MAT 44
Engine Running Time 0

Is there another chart that needs to be looked up? This is what was saved in excell.