ok can anyone tell me from this log what may cause the car to stall out so badly now and run soo rough from this datalog. i had to bump the idle adjustment just to get this. 1st page is log second is knock oh and shes running really rich I can see problem just started say 3 days ago i changed the fuel filter today with no change.

 

A few things:

Your BLM's are actually showing lean, not rich.

You're also getting a lot of knock counts. Shouldn't be getting any at idle.

Something odd happens at time index 108 where your battery voltage drops to 11.4. Then at time index 109.2, it cuts out completely. Almost like your whole electrical system hiccuped. Right after that the O2 sensor drops to near zero (leans way out probably due to injectors shutting off), IAC counts jump up to 139 (ECM trying to keep the engine alive). Engine shuts off at time index 114.5.

Check your battery connections (ground and positive). Maybe one of them is loose or corroded. Also check your main engine and chassis ground as well as your positive connection at the starter.

 

I also had a similar problem occur a year or two ago, ended up being a bad fusible link. At least when all of them were replaced it appears to have solved that problem... <knock on wood>

 

so you both think it's electrical then because I was worried about a blown headgasket or something I have tomorrow off so I will be able to try to take out the gm service manual and my multimeter and see what I can find but if there are any different ideas please let me know lol daily driver has become a daily annoyance

 

im sitting at work and wondering. Do you think it could have something to do with my ignition system? i have a new cap and rotor and new plugs and wires though less than 2000 miles on new motor. just dont see how it could be the fusables. I even coughed the idea though that it could be the fact i grounded my fan because the relay was gone maybe putting extra drain on system but that would hint of an alternator. She leans way out as you can see and I am seeing alot of knock. could this have anything to do with the timing in my prom that fast355 helped me with?

 

To be honest, I don't see the excessive knocking contributing to the sudden engine cut-out. Though, you still want to get that issue addressed.

As far as grounding the fan, I assume you mean the fan turn-on signal wire from the ECM? In which case, that would leave your fans running continuously. However, I don't see that causing a cut-out either since. Curious I don't see in the data whether the fans are actually on or not.

 

Check the pass side cylinder head grds. Clean and tighten them

Bad ignition switch has similiar symptoms.

later
Jeremy

 

rear cylinder grnds are all tight and good bout to check coil and fuel pump relay battery was fine and so was altenator

 

ok well coil is fine and replaced relay was only 6 bux but still the same problem engine will just die while driveing cant be ignition switch cause only the motor dies lights and power never dies

 

Can we get another datalog of this? I can't seem to open the first one...

 

Did you check everything on the positive side of the battery? Also the alternator.

If there's some intermittent short to ground somewhere on this circuit, it'll rob the rest of the vehicle of electrical power.

Also try running your car with the battery cable disconnected from the back of the alternator.

 

well wouldnt that drain the bat so that it wont crank? as far as testing the positive side of the bat what you mean and how?

 

well the 8746 does not have a fan cut on or off switch in the prom it is conroled by a relay with input from the cts

 

It should run for a little while on the battery alone. How long after you start the engine up does it run before it cuts out? A few minutes?


I mean just check the connections at the battery for corrosion, check the wire frays, damage, etc.

 

I'll throw VATS out there.(cause no fuel)

Bad pick up coil.(cause no fuel)

later
Jeremy

 

ok checked all terminals connectors and vacuum lines i havent checked vats or pick up coil

 

Doubt it's vats, that would keep ot from starting at all.

Have you tried the fuel pressure gauge on the windshield trick to see if the fuel pressure is going away before it dies?

I'd still like to see a datalog that catches the dieing, too. Could well be the ignition module. If so, one of these times you won't get it to restart.....

 

its saved as an excell file

 

whats the fuel pressure trick?

 

Vern's saying to put a fuel pressure gauge within view so you can watch it and see if the engine dying is preceded by a drop in fuel pressure.


With all due respect to Vern, I'm not at all hopefull that this will be the case. I looked at the data again, and now I'm even more convinced it's somewhere in your vehicle electrical system- specifically in your alternator, and potentially a short circuit from positive to ground when it's operating.

Check this out: During normal operation, your seeing 13.9 volts. However, at time index 108, the battery voltage drops to 11.14 volts and then all the way to 0 at time 109.2. It stays at zero until the engine dies and then comes back upt to 12.6 after the engine shuts off. The only thing I can see that would cause this would be the alternator. Which is why I wanted you to run the car without the battery cable or the alternator harness hooked up to the alternator to eliminate the possibility of the short during this test run. Like I said, you should get a several minutes of operation without the alternator hooked up. As I asked before, does the problem occur pretty quickly after you start the engine up?

 

Since I can't open the zip file, I didn't have the benefit of seeing what you did - the logs. Thanks for the "respect", but from what you're saying I think you're on the right track and I'm the one who is all wet on this issue. Those voltage drops are a definite indication of a problem, most likely in the alternator (its internal regulator most likely) just as you suggested.

 

not really till im cruizing at about 1500 rpm now i will post another log today

 

It's definitely hard to do these online diagnostics. But this voltage drop is the only thing I see out of the ordinary in the data (aside from the high-BLM's and excessive knock counts- neither of which would cause a stall from 1500 rpm). Unless there's some other engine fault that the ECM does not monitor, I can't think of it.
----------
Yeah, definitely do that. It'll be interesting to see if it resembles your initial data.

Does the stall happen at a predictable time after running engine? For instance, always 10 minutes after start up? Or is it just random driving down the road?

 

I agree on the diags. Sounds like you're on the right track though. I'll try to look at the next log too.....

 

ok been alot of early mornings and late nights, thats why still no logs. It's pooring rain right now, but hopefully it wil clear up. While it's on my mind doesn't this seem like a vacuum related? requires higher idle adjustment, but idles, dies when you put her in gear, but not when you add a little gas, after driving a few seconds tranny hifts and vacuum changes. seems all problems occur during a time where there would be alot of vacuum change. I'm throwing this up. couldp it be a MAP sensor?

 

Your MAP sensor data doesn't support that. Like I said, the only anomalous data in your log is that battery voltage sense at the ECM.

 

stopped raining just long enough for me to drive 2 laps around block heres the log

 

ttt

 

I don't have a ads to view the log but from the sound of it, I'd say loose wires on the starter is something to check. I had a bad intermittant issue on my GP that would just cut out like that. Ended up being a frayed fusible link wire. Had one strand of wire holding it together. No idea how the car ran like that.

 

Can't open the file... did you zip it differently this time than last time?

 

yeah lemme try something else
----------
ok

 

here

 

Wierd... it's still giving me problems. The last time I downloaded it, I was at work. Let me try again tommorrow. Either that or e-mail it to me.

ultm8z@yahoo.com


EDIT You probably don't need to zip it actually. The file is all text anyway, probably a dozen kB or less.

 

ok

 

So I'm looking at your data...

Can you describe in words what you're doing during this run? Your vehicle speed sensor output suggests that you're moving... It also appears as though there were multiple engine cutouts. Looks like you had to start it up again a couple of times?

I'm seeing a lot of peculiar things going on here. But I also see your battery voltage sensor indicating strange happenings with your electrical system again.

The battery voltage is an input to the ECM. So it should at least battery voltage (around 12V) at all times even if the engine is off. However, I'm seeing instances where it's 0V, .937V, and even one where it's 74.1V (though that one could be a misread by the ECM), at which points, some of your other readouts start going haywire.

At the risk of sounding like a broken record, you really need to go through your chassis electrical system. I'm not a thirdgen expert so I'm not familiar with the chassis wiring on a thirdgen Camaro/Firebird. You may want to ask around about it here or on one of the other forums.

 

ok well ill look into the electrical then and repost this in electrical forum. And yess I drove car around block and let the car sputter and die a cpl times/not by choice it just died on the way around the block so had to get her back

 

The thing that caught my eye was the knock counts.
They just cycle to 255 continuously.
Check if the memcal is loose or something at your ESC module (If you have one)
Then wiggle/separate and reconnect all the connectors at the ecm to be sure they are making good contact.
And I hope the coolant temp is reading in degrees F!
Those are not the cause just something else to check later.

Start looking at point 82 thru 92 and 100 to 119
Your voltage drops as you are driving until you start throwing errors and then stalls. Your alternator is not plugged in good or is just has a bad regulator.
Nothing will make voltage slowly go down except battery drain (That I'm aware of anyway)

 

The battery voltage field in the '8746 ALDL list is the ignition switch voltage input to the ECM. Once it drops below 4 volts the ECM starts the engine shutdown process. This is how the ECM knows/thinks that the ignition key has been turned off.

Part of the shutdown process is to set the injector PW to 0, which will effectively shut off the engine.

What other vehicle electrical devices also flicker at the same time the engine dies? This can help narrow down where the issue is. If the head lights are OK, but the radio dies, then it is not the battery or alternator. Check the fusible links at the starter, check the fuse under hood in line with the main power feed to the ECM.

Check the ignition switch. Put a DVM on the input to the ECM and monitor it (pin A6). Does the voltage really drop? If not, the ECM is most likely bad. If the voltage does drop on the DVM, move the DVM further upstream to the ignition switch, what happens to the voltage there?

Then check at the fuse box, it may be something as simple as a bad or loose fuse. Keep moving toward the battery with the DVM until the voltage is stable when the engine dies. Then move 1 step back toward the ECM, in between will be the culprit.

RBob.

 

I've seen one situation personally where the knock counts cycled like that. It was when I first put in my 383. I was using a base chip from a MAF powered car and needed to have a SD chip. What are you using for the piggyback chip, and what mask did you use for your base starting point?

 

i am running a modified caprice tbi bin and $61 mask on the 27a32 eprom chip i believe, i have to uv erase it. headlights dont dim and i thing cd player stays on cant remember i turned it nearly off just so i could see if i could hear anything. now the ignition switch has given me problems b4 cause when car is running i can pull down on the steering wheel and car dies thinking its shorting the ignition system making the ecm thing car is in off position and from what rob says i believe that could be where my problem lies but since i go to college in the mornings and work full time on nights and weekends i believe im going to have to have her towed into the shop Thursday due to lack of time

 

COLTS45S - Sounds liek your problem is a misadjusted ignition switch. That switch is on the bottom of the steering column and can be accessed once the panel above the pedals is removed. Since the car dies when you pull down on the column, which could change the engagement of the metal lever your key switch moves to operate this remote ignition switch, I'd say either the switch is bad or just needs to be adjusted a little to make a full engagement. Wiring connector going into the switch could also nbe loose and just barely making connection.

Of course, you could just tighten up the column, too.....

 

checked fuel pressure, had a slow fuel pump replaced it and cured the problem unfortunatly my 3 in exhaust got in the way so took a cpl extra hours cutting and dropping it out then rewelding

 

So it was fuel pressure after all... interesting....


Vern, you guessed right after all!


Glad you got it fixed though...

 

What can I say? Even a blind big finds an acorn every now and then....