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DoubleVision 07-09-2012 04:37 AM

Question on 1996 Lumina
 
As stated working on a 96 Lumina. After getting past the Vats system on it and getting the car started it has a issue. I can start it and leave it at idle for 10 minutes, all's okay. Get in, put it in gear, go 30 yards it goes dead and won't fire back up for several hours. Only code I get is 341, camshaft position sensor. However I know it'll run without it so it made me think of the next culpruit, the crankshaft position sensor. Years ago on another vehicle that was similiar to this one I ran into the same problem, I replaced the crank position sensor and the problem was solved. It too never gave a crank sensor code. The one on it is coated with grease and oil, but I don't think that effects it much on how it works. I was reading the bigger possibility is the PCM has gone bum. I want to get other opinions on this before I bother changing the crank position sensor, as this car belongs to a old lady on a really strict budget. Any help is appreciated.

copo nova 07-09-2012 02:11 PM

Sounds like fuel pump sometimes will idle then as soon as you take off you use fuel in carb it will stop and now its hot so wont restart to idle tell it cools off.

DoubleVision 07-09-2012 04:12 PM

It's fuel injected and I've checked the fuel pump. After it shuts off it's still getting good fuel pressure and the pump is coming on as it should.

LATECH 07-09-2012 05:20 PM

Seems the power and ground circuits are tied together in paralell on the cam and crank sensor.
It sounds like a crank sensor to me also. I think the fault detection strategy on those old 3.4 is kinda faulty itself.
Your correct in assuming the cam sensor failing would not cause a no start no run situation also.That would be a crank sensor.
Put in the crank sensor.

T-bucket23 07-09-2012 06:08 PM

I would also take a hard look at the power and ground circuits. Could be when you put it in gear and the engine shifts when you step on the gas it is pulling a wire in the harness. If it was heat related I would think it would also die if you let it idle. I cant imagine the temperature would change in a 30' drive.
You can locate the harness that has the wires for the crank and cam sensors and try moving it around to see if you can make it die.
When it wont start check for power and ground at the connectors for the sensors.
Not sure if Chevy had the same setup but on the Pontiac's and Buick's there is a ground junction in the drivers side door sil that gets all green. You could get to it by pulling the carpet back. I saw several of these on the Pontiac's and Buick's. The tip off was that usually the power windows or heater or something else didn't work or the windows would be real slow.
It was a connector with a metal blade that connected a bunch of grounds together.

S10 Racer 07-09-2012 06:31 PM

You can test the crank sensor using an ohm meter. It should read somewhere around 500 - 900 ohm. If it checks out ok, I would be looking at the ICM

LATECH 07-09-2012 06:53 PM

Doublevision... which engine do you have? and which type of sensor does it have? I was thinking it has the Hall effect sensor behind the balancer.
The permanent magnet sensor was an earlier style , that pushed in through the side of the block. Not sure at what production date they changed.
I have had both style crankshaft sensors cause a diveability problem like yours.
An ohmeter may or may not give a good indication of a defective Permanent magnet sensor , if it ohms out , it could still be bad, if it has a couple windings shorted to gether, amplitude of the sine wave( PM Generator) may be lower than threshhold voltage required and the signal generated can have a momentary "flat spot" or "glitch" that fails to signal or trigger the signal processor in the ICM /ECM
Ohming a hall effect type sensor is not recommended as usually wont give a good enough indication of health of the sensor.
A hall effect is designed to generate a square wave signal that can only be checked with an oscilliscope.

T-bucket23 07-09-2012 07:06 PM

LA you just jogged something in my memory. I had one with the sensor on the back of the block near the fire wall and the clip that held the wire died with age. The wire was loose and it was shorting out on the exhaust manifold. Found a bare melted wire after tracing the harness. It was the wire that went right from the coil pack down to the crank sensor. It was a little later setup that actually used the 2 crank sensors but it is worth looking at

LATECH 07-09-2012 07:12 PM

Quote:

Originally Posted by T-bucket23 (Post 1572332)
LA you just jogged something in my memory. I had one with the sensor on the back of the block near the fire wall and the clip that held the wire died with age. The wire was loose and it was shorting out on the exhaust manifold. Found a bare melted wire after tracing the harness. It was the wire that went right from the coil pack down to the crank sensor. It was a little later setup that actually used the 2 crank sensors but it is worth looking at

Hey thats right. They did use 2 crank sensors on the one design. Funny thing, the Mc parts stores stock the one that is easy to change, its not the one that fails either.LOL Its allways the one behind the balancer that fails. I guess they sell the easy one for the DIY guys. Then they bring it to the shop for you and me. :thumbup:

T-bucket23 07-09-2012 07:40 PM

Quote:

Originally Posted by LATECH (Post 1572334)
Hey thats right. They did use 2 crank sensors on the one design. Funny thing, the Mc parts stores stock the one that is easy to change, its not the one that fails either.LOL Its allways the one behind the balancer that fails. I guess they sell the easy one for the DIY guys. Then they bring it to the shop for you and me. :thumbup:

It is the "I replaced everything and it still wont start" customer. Got to love them and the ones who take what the kid behind the counter at Autozone says as gospel. Its what keeps it interesting.
The funny thing is they always think they are saving money by doing it themselves and they buy $300 worth of parts when they had a cracked vacuum line or broken wire.

I would like to have a nickel for every EGR valve that was changed that was not bad, or gas caps.

DoubleVision 07-09-2012 09:50 PM

I was going to next start on cleaning the grounds and checking them all. This is the 3100 V6 and it has the crankshaft position sensor right behind the balancer. I am going to clean it up real good while I'm in there. I had the same idea that it maybe losing it's ground since it dies when rolling but not sitting and idling. I really appreciate all the good tips guys. I want to do the best I can to get this old lady's car back going so she can get around again.
I'll make sure to give the wires a tug to see if that shuts it down also, if so I'll know I have some wires to trace down. I also had read the oil on the sensor can cause it to read incorrectly. What puzzles me about the crank position sensor is why doesn't it throw a code? As said I had a car before this do the same thing and it never threw a code, it would just go dead.
Thanks again for the help guys.

rx191 07-09-2012 10:30 PM

after it dies do you have spark?

That engine does use 2 crank sensors a 24x in the block reads off the crank, and a 3x that reads off the trigger on the balance. the computer uses this sensor at engine speeds above about 1800-2000rpm. I have seen the crank sensor at the front fail many times and never leave a code.

Also does it die like you shut off the key or does it die like you dumped the clutch in a stick shift car?

T-bucket23 07-10-2012 06:47 AM

If it is a 2 crank sensor engine, it will run without the front one plugged in. Check to be sure you dont have 2.
Edit:
According to my documentation it has 2 crank sensors. Look at the 2 wire harness that goes straight down from the module to the back of the engine. I bet you will find damaged wires.

price 07-10-2012 03:49 PM

lumina
 
Pull the fuel injection out and install 6 motorcycle carbs. This will take time but it will allow some breathing room while you figure out how Gm didn,t stay bankrupt.:D


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