idabomb00

5.7L v8 6-speed manual (mostly stock, no major mods)

As the title states, my car randomly dies, very annoying. Usually if I let it sit for 3 minutes to 30 minutes, it starts up like nothing happened.

It's not vats, security light doesn't flash.

Seems to happen after it warms up to operating temperature and under a medium-heavy load. It will idle just fine, sometimes when taking off again after this happens it dies again.

This morning I checked for DTCs and got all of these:
MALF 16: Lo-Res Fail
MALF 36: Hi-Res Fail
MALF 41: EST Open
MALF 42: EST Grounded
MALF 51: EPROM/Flash Checksum Fail

A couple weeks ago the coolant level sending unit fell out and sprayed my motor with coolant.

I am wondering if it just ruined the wiring harness to the opti? I have done research that DTC 16 is just like if the timing chain fell off therefore shutting the engine without warning.

Opti has about 15k miles.

I'm not ignoring DTC 51, I see it.

Any ideas?? I really need this car to work...

fbody_brian

Question is, with a DTC51 can you actually trust any of the other codes?

Mine did the same thing by the way, I tightened up my battery cables, grounds, wiggled the pcm wiring around, then it just stopped happening.

idabomb00

Possibly, EST grounded and EST open seem to contradict each other. I just don't know anything about the PCM I guess.

Bow Tie Power

Just to toss in my $.02, I also have a '94 Firebird Formula with very light mods and it does the same thing. She started doing that shortly after I replaced the opti. It dies randomly, you never have the slightest clue when she'll die. Every time it happened, I got my ICM('s) tested MULTIPLE times from AutoZone and every single time they tested bad. I bought the more expensive one with a lifetime warranty (ended up being around $125 I believe) and it still keeps going out. If I ever mashed the gas, it'd die instantly. I then replaced the coil and she drove beautifully... For about a week. Then she randomly died again, but about 3 minutes after the car died, the battery died. I was told to check into engine harness because it could be shorting out both the coil and ICM. You just might want to take that into consideration.

idabomb00

Thanks for the info, I'm gonna check for shorts soon, there seems to be something causing the brain to not work properly.
Ideally I'd love to just change out all the wiring with new wires but in the real world I don't have the time or money.

Bow Tie Power

I'm in that exact same situation. Several people told me the engine harness is prolly bad and needs to be replaced but I don't exactly have the money burning a hole in my pocket. I'm probably going to try doing what F body Brian suggested with the cables grounds and wiring first to see if that works before spending any more money. Might be best for you to try it too.

pumasixtynine

Check harness to opti at the connector

idabomb00

This is kinda old...
My car is currently not running but...
what fixed this problem was replacing the opti!!! lol I wish I was driving her again...

Project84

I have a similar thread open, with pics of a water damaged PCM. Opti only has 600+/- miles on it, many new parts, etc etc.

I'm going to try battery cables ASAP as well as swap in a friend's PCM.

EDIT: Might I ask what you used to pull the codes? I don't have any means to do so, and it seems I'm going to have to educate myself and make this a part of my troubleshooting.

idabomb00

ALDL USB cable $55
http://www.reddevilriver.com/aldl.html

TTS Datamasters trial for pc
http://www.ttspowersystems.com/DataM...ownloads2.html

Just took the laptop out to the car, nothing major. I'm not spending 300 dollars for an outdated scan tool.

EDIT: You can also build your own cable, but I'm not sure of a schematic, they're out there. I know it has some resistors in there somewhere. Just thought it was worth mentioning.