Code #15 again and more problems on 93Z

[lt1redz]

After my last post on 1/9 5:03 pm,I decided to go to grocery store 4 miles away.1/2 way there it died.After about 15-20 seconds it restarted drove about 500 feet died again.While coasting restarted in about 15-20 seconds.Made it to the turn light at the store,died again.Restarted 15-20 seconds.Rushed into parking lot died again no restart.Coasted in the lot till I found a well lit space.Opened the hood and called my neighbor for a ride.While I was on him let it cool off for 30 minutes till he got there.Restarted, high tailed
it home.Shut it off. Got out kicked the tires went inside.Next day at daylight went out side..This is what happened.[1] Started right up,ran for 30 minutes during which time the following happened.Fan switch on,hood up.During the 30 minutes idle was 650. I stepped on the gas and took it to 1500-2000 rpm many times. 30 minutes in, the idle increased to 1000 rpm and there was a slight dip on the dash volt meter. stepped on the gas died, no start. [2] after 40 minute cool down restarted with hesitation.Closed hood.After about 1 1/2 to 2 minutes code 15.Idled at 650 and I took it to 1500-2000 rpm. After 8 minutes the idle increased to 1000 rpm with same dip on volt meter,stepped on gas died, no restart.[3]After 45 minute cool down restated with hesitation. Closed hood, fan switch on,idled at 650.After 3 1/2 minutes,Idle increased to 1000 rpm. Stepped on gas died again. [4] After 65 minute cool down restarted again with hesitation.Fans switch on,hood closed. About 30-45 seconds code #15 on then off.Code #15 back on after 5 minutes and off at 6 1/2 minutes. At 8 1/4 minutes idle went to 1000rpm.Stepped on gas died. No restart..[5] 60 minute cool down.Restarted hard. Idle 650rpm.After 1 minute code#15on After 5 minutes same as above died, Restarted hard 650 rpm then it went to 1000.Didn't step on gas. After about 15 seconds idled back to 650.This went on for 3 minutes..Idle to 1000 rpm and back to 650 rpm about every minute. At 12 minutes in, idle to 1000 rpm, stepped on gas,died. No restart..Since it was getting dark I got out re-kicked tires said a few cuss words and called it a night.
During one of the above I checked a plug,no spark.Checked coil wire going to Opti no spark.Today I measured ohms of the temp.sensor at the temp.according to shoe box. First is temp,second is shoe box ohms,third is my ohms. go.-----212-177-172,194-241-212,176-332-290,158-467-425,140-667-600,
122-973-915,113-1188-1160,104-1459-1410,95-1802-1685,86-2238-2170,
77-2796-2720,68-3520-3310....Really hope someone can help correct this problem with the above info. Back to work tomorrow,maybe..

[Joe 1320]

After reading though your post, a few things come to mind. Although you get a code 15, that may either be a symptom or a cause. It appears as though there may be a thermal issue related to some form of heatsoak. When the car is exhibiting a no start condition, rather than let it cool, that is the time to run diagnostics. Anytime I find myself in a no start condition, The first thing I rule out is fuel. I take off the intake elbow and put in a few shots of starting fluid. If the engine fires up but dies without regular squirts of starting fluid, you know it's not spark/ignition. If it still doesn't fire, you've got a no spark condition.

That no spark condition may come from so many things. Shorts in the harness, suspect ignition parts that work when cold but short out when heated up (coil and /or coil driver module).

Here is a igniton diagnostic to be run while the car is in a no start condition, do this once you've ruled out the fuel pump (check pressure and volume) .

Step 1. Connect a spark plug tester to a spark plug wire and
check for spark while an assistant is cranking the engine.
Check each plug independantly. this checks for open
spark plug wires. Spark in one or more than one wire
indicates the problem is in spark plug wires or optispark.
If no spark exists, go to step 2.

Step 2. Check for spark at the coil wire with the spark tester
while cranking the engine. A spark indicates the problem
is in the distributer (optispark). If no spark go to step 3.

Step3. Perform check on ignition coil.
a: Unplug coil electrical connector and check pink wire for
12v. If power go to b.
b. using ohmeter low scale, hook up the leads to the
primary terminals on the ignition coil. Should indicate
very low resistance. If not, replace coil.
c. Using the high scale, hook up one lead to the primary
terminal, the other to the secondary terminal. Should
not read infinite resistance. If it does, replace coil.

Step 4. Disconnect the ignition module connector and with the
key on, check voltage at terminals A and D on the harness
side of the connector. (pink/black and white/black wires)
If under 10 volts check for faulty circuit from the ignition
module to the coil or check for grounded external coil
circuit. If 10 volts or more, change the voltmeter to a/c
scale and measure voltage on terminal B while engine is
cranking. (white wire). If 0 volts, Have ECM checked. If 1-
4 volts, with the key off, disconnect the module
connector. Install a LED type test light on the positive
battery terminal and probe terminal C on the harness side
of the connector (black wire). The light should illuminate.
If not, check ground wire in the harness to the module. If
the test light is on, go to step 5.

Step 5. Remove the coil wire from the coil and ground it to the
frame. Connect LED test light into the optispark harness
connector red wire terminal C. The harness connector that
you will use is located on the passenger side of the
engine up near the fuel rail. You will need to insert a back
probe pin into terminal C. If the test light flashes when an
assistant cranks the engine, the optispark is suspect. If
no flashes, replace the ignition module.

If the above tests results are correct and there is still no
start, it is tough to to tell the difference between a
faulty module or optispark. Module = Cheap$$, optispark
=moderate $$$.

Now as far as the code 15, that's a coolant temperature sensor low range. I've seen those cause tons of issues just like what you see. Now keep in mind the sensor could be bad (even now out of the box sensors can be bad) , there could be a short in the wiring harness, there could even be air pockets in the cooling system that allows the sensor to not be in contact with the coolant.

[lt1redz]

Joe 1320,
Thanks for replying..Did some the tests you mentioned..No spark at plugs.No spark at coil..Will retest coil for ohms.Noticed the coils center windings wiggle a little...?? On first test of coil,got low ohms,like 3 on low scale..On secondary got it read 9 on the high scale..When in no start condition checked ignition module and got 0 volts on A and B..A/C reading was 1.67 volts..Later when engine was cooled down,retested A and D and got 11 volts.
This is also something that happened.While in code 15 mode fans were running.I moved and shook the wiring all close to coil and ignition module.Fans went off and code 15 turned off..I could had haved moved coil [center winding]..I noticed a ground terminal on the engine that I could have touched.I disconnected the ground[little corroded] Cleaned all wires and reconnected.No help still code 15...Reshook all wires as before no help.Still code 15..Don't know if I touch coil[center winding]..Car continued to run. Went about 2 miles to get gas as was on empty..Returned home still in code15 kicked tires said many cuss words and called it a night.
It is now daylight and going back out to retest coil and complete the other tests you suggested..I'll let you know the results.Thanks again..

[lt1redz]

Guess what..Found the problem..Went to Advance Auto and bought a new coil.Installed it in their parking lot.Fired it up,,Code#15 fans kicked on. I wiggled some wires including to lead going to the temp.sensor.Fans went off and no code#15...Pulled lead going to temp.sensor.Took off the tape and found a red butt connector with a wire hanging out.Went back in store bought a box of connectors,reinstalled wire and made a solid connection.Fired right up.No code#15 idled at 500-600.. So out of this session of fixing the problem, I have a new coil,a box of connectors and have an opti with 189,000 and still going strong. Thanks to Joe 1320 and everyone else who tried to help...It took 4-5 days to find a stupid broken wire, but I learned a lot..Maybe this post will help someone else in the future.. Thanks again..........

[Injuneer]

Repair the wire with a high quality soldered connection plus shrink wrap, or you will be having another problem with the connector when it corrodes or works its way loose.

[Joe 1320]

Glad you found the problem. best of all, you didn't have to take it to the dealer.

[lt1redz]

Will solder connection today. Thanks again for the help...