nicats

Ok I have cruzed thru some threads but I still want to ask as we have been trouble shooting this for awhile now and besides this is the best darn discussion board ever!

My car: 94 Z28

When we start the car it runs fine. The issues is after about 1 mile or so it just dies. It won't start right after this but within a few minutes it starts and no problems until you turn the car off for a little bit. We have tossed around several ideas from the fuel pump, ignition, electrical and oil sensor.

The gauges seem to be fine and no funny movement if it were electrical. The oil pressure seems a bit higher until it dies then its much lower after the restart. At first I noticed it would die while shifting but there has been one or two times that it has happened at normal driving speed. Always seem to occur with 1 to 5 miles. I have kept the gas tank full, and oil is full.

After it dies the check gauges light comes on and will stay on until it starts again and goes off. I don't usually notice any chugging or changes if it were a fuel pump issues. We wanted to try some starting fluid but by the time you take the darn thing apart to spray it in there it starts fine. I did notice the other night after it died and restarted I went to pass a slow car, down shifted and it was crappy on power sputtered a bit and all of a sudden took off like there was no problems.

At one point we thought it was a security problem since the key chip wire is bypassed due to it breaking in the cylinder a second time. But if that were the case it wouldn't turn over.

Just wanted some ideas here because replacing the fuel pump is costly (course easy enough since its been replaced thru the deck once already). I ran the scanner on the car and no codes except for the O2 sensor that has a broken wire and has been this way for 2 years. A few weeks back we had a oil sensor code but that was before it just started randomly dying, since then no oil code.

Whats mostly weird is that it died and I had to catch a ride to work, and after coming home I drove the car friday and saturday and it didn't die once and I went several places. Monday night I head off to work and it dies about 2 miles down the road. I leave work and it dies a couple of miles down the road. And has been this way every night since the weekend. So why does it pick the worse place to die on me and what the heck?! HA.

I have a video I took on my cell of the dash when the car dies (because I just knew it was gonna happen, and after about 20 tries) but can't upload it here (stupid dial up). Maybe if I can get to some wifi I can post it.

Thanks for you input, it is greatly appreciated.

bw_hunter

First, don't replace anything with performing diagnostic tests first. Test the fuel pressure before replacing the fuel pump.

Frankly, it sounds like an ICM issue. You can have that tested as well at your local auto zone. Be sure to take a heat gun or a hair dryer along so it can be tested at both room temperature and after you heat it up. A common failure mode for them is to work as per normal until they get hot then simply quit, only to work properly when cooled down. No codes is fairly common as well.

Good luck!

calaban

A ignition coil will do this as well.

Injuneer

If you have a broken wire on an O2 sensor, why haven't you fixed it for 2 years? If the O2 sensors don't work, the PCM can't go into closed loop and adjust for changes in the air/fuel control system.

You indicated you got a code for an oil sensor. There are no PCM codes for the oil level or pressure on the 94. Neither of those connect to the PCM, only to the dash. What scanner are you using?

There are codes for things like problems with the IC Module and Opti that are stored in the PCM, but do not turn on the SES light. All of those codes result in an engine shutdown.

nicats

Its an auto xray code scout 2500

code 52 Engine oil temp sensor low. If I am mistaken correct me but there is a oil/fuel sensor. Part number 1808e (??) 30 bucks. ~sorry just going off my memory here.

I just wondered why the check gauges light was coming on since they all seemed to be fine.

We ordered a new O2 sensor and they sent us the wrong one, didn't have the one we needed. Never had a problem driving it in the mean time. 23MPG but had other vehicle problems to tend to (like transmission in my Jimmy).

Thanks everyone for your input.

Injuneer

The reason you have a code for the oil temp sensor is because your engine does NOT have an oil temp sensor. Only the Corvette version of the LT1 has that. That's the problem with using the generic code list generated by the typical scanner. Use Shoebox's code list, specifically for the LT1. If the code isn't on that list, it isn't applicable to the LT1 in the F-Body.

http://shbox.com/1/Dtcs.htm

There is no "oil/fuel sensor". Again, the Corvette engine has an oil pressure switch that provides an interlock to the fuel pump... lose oil pressure and the fuel pump shuts down. Again... NOT supported on the F-Body version of the LT1.

The "check gauges" light comes on for low oil pressure, low alternator voltage or high coolant temperature. If the light comes on, it may be a signal that you have lost the voltage from the alternator, or when the engine stopped, the oil pressure dropped to "0".

Almost sounds like you have a Corvette, and not a Z28?????

TGGodfrey

The Check Gauges light comes on becuase the engine has died and the oil pressure gauge drops to zero.


Only way to give you any accurate advice is to test spark and fuel when it dies. Then you have some sort of direction to diagnose.

You first thought is that testing spark is a pain in the a$$....well all you need to do is put a spare plug wire on the coil and test for coil output with a spark plug or gap tester.

No spark.....investigate power and signal to coil. No signal.....go after module. You can use a 30.-50. module tester to test the spark module to verify. Snap-On sells them as well as other cheaper manufacturers.

I could go on with fuel but I think you got the idea.

Good Luck

Terry

nicats

You all are going to love this...

Took car to shop, they ran their high tech stuff on it. Nothing but the O2 sensor. Car drove fine over there. Left and by the time I got downtown (5 miles???) it died...would not restart. Ran around with my daughter who picked me up and went back and got it. Started fine. Drove less then a mile and died again...Had daughter pick me up since it wouldn't start again. She dropped me off about an hour later, started fine and I drove the stupid thing home!! (9 miles, no probs) The mechanic said he is stumped but would look into the icm first. He said other then keeping the car all day and letting it run until it dies he has no clue.

Someone tell me if they can see my video...I thought you used to be able to share a link. http://www.facebook.com/nicats

shoebox

When it dies and won't start, you have to immediately check spark and fuel pressure to rule one or the other out (since the trouble seems to quickly clear itself). You can't begin to narrow down your trouble until you do. Intermittents are the hardest to troubleshoot.

ItsRyan

Test the primary and secondary resistance range on your coil. Do this before and after it dies. If you have a meter check resistance.

I got these specs from AutoZone
Minimum Primary Resistance Range - .2 - .7
Minimum Secondary Resistance Range - 6.0k -15.0k

Also check +voltage at battery and at coil

I just recently had a similar problem with my 94 and tested my ICM at Oreilly's and was told it was bad. Nope, ICM was good the coil was bad.

nicats

got icm tested...not the problem. Got a new coil, apparently not the problem either because the car died a mile down the road. waited 8 minutes and it started. drove it back and it died in the driveway. Went to check spark and the darn thing started.

Very frustrating!

bw_hunter

Did you test the ICM at room temperature and at an elevated temperture? Room temp alone doesn't always catch it...

nicats

Yeah..the first test was cold and the machine they test it on heats it up and it was HOT...they tested it like 8 times.

nicats

Update on everything.....

Changed Opti seems the dying has stopped. Talked to a LT1 guy who said the opti will mess with the fuel and when its not right the car dies.

But now the car starts really hard likes its flooded. Bah bout ready to torch the darn thing. Next step have the PCM flashed over the winter while I am not driving it.

JGuy07

How would the opti effect the fueling? What did he tell you about it?