suddenly had this issue with my 97 Camaro LT1 V8.

HISTORY
Engine was working normall but suddenly started to loose power.. then the engine went off and wasnt starting at all..

TROUBLE CODES
P0336: Crankshaft Position Sensor A Circuit Range/Performance - had it for some time
P0135: O2 Sensor Heater Circuit (Bank 1 Sensor 1) - due to removed O2 Sensor
P0141: O2 Sensor Heater Circuit (Bank 1 Sensor 2) - due to removed O2 Sensor


DIAGNOSES
1. at the begining suspected that the fuel pump wasnt working properly as it sounded lower than usual while turning the key to the on position, i currently dont have a fuel pressure gauge to check pressure. but when i opened the valve, the pump was pushing gasoline all over the place.

2. while checking ignition by removing one of the spark plug wires and bringing a grounded wire near the coil side.. no spark was jumping out of the coil (number one spark wire).. ofcourse that was while cranking the engine.. i then used an inline spark tester and it was showing spark but kind of looked very weak...

CONCLUSION
i do believe that the ignition is the problem as this type of engine is really known to have bad ignition "Optispark" system. how can i make sure 100% that this is the problem before buying a new coil or new optispark.

 

What was working normally, started to lose power even when you ground it? What component did you ground?

Why are you running the engine with no O2 sensors on one bank?

 

sorry i wasnt clear..

the O2 sensors are actually removed as i have headers installed..

the engine was running normally then it started to loose power and went off..

 

OK.... so what did you "ground"?

And did you have it tuned to run open loop (without at least the Bank 1 pre-cat O2 sensor)?

 

forget about that part.. i was writing something then i wrote something else and didnt delete the old stuff.. what i was going to say was i connected a test light to the ground and tested the coil for ignition..

and yes, i did have it tuned to run in open loop all the time..

 

i just did the tests which are shown in the shbox website

4th Gen LT1 F-body Tech Articles

and all was fine... i am suspecting that the problem could be from the coil itself as its not giving a powerful enough spark..

on my 2001 Tahoe 5.3L i can take the test light away from the coil plastic connecter about an inch and still get spark.. but with this one now.. i really have to stay very close to see a spark..

 

Opti sends low voltage (0-5 volt) DC pulse to the PCM, the PCM adjusts it for timing and sends a low voltage (5-0 volts) pulse to the ICM, the ICM amplifies that pulse to about 200 volts (like an old fashioned CD ignition system) and feeds the 200+Volts to the coil, the coil jacks up that voltage to 20-40,000 volts. I'm not clear on how you tested for spark, you say removed #1 plug wire , but then tested for spark to ground at coil. I would expect to easily see a good 1/4 inch blue spark from the coil output HV wire or terminal to chassis ground when cranking, or from the plug end of the plug wire through some kind of metal extension in the boot. If spark is weak I all wiring and voltages are good then I suspect defective ICM not amplifying signal to coil, coil bad, or the possibly the opti HV rotor/cap half if spark was checked at plug, however rotor is eliminated from the picture if checked at coil output wire or terminal. .
Just for info.. The 'B' to ground at 1-4 volts AC in shbox.com test you referenced is actually reading the 5 To 0 volt pulses from the PCM to ICM. Pulsating DC can be read as AC with a volt meter and faster the engine is cranking/running (more pulses) the higher the AC voltage reading. So your signal to ICM looks like its there.

 

here is a summery of the full issue i am having..

1. engine was cranking but no start.
2. i didnt do any changes to the engine, fuel system nor ignition
3. when the problem happened i tested the ignition and found that i have weak spark and changed the coil, then i had a strong healthy spart which was tested from the Coil directly, from spark plug wire 1 and 3
4. i also tested control signals at the ICM which were all fine
5. i tried spraying carb cleaner in the intake and cranked the engine at which did help in making it startup for a second or two then dies out.
6. i dont have a fuel pressure gauge but pressure does buildup in the fuel rail and sprays everywhere when i press the pressure relief port in the fuel rail.

for now what i do expect could be something wrong with the harness which is preventing the injectors from firing up...

any suggestions..

 

What about the trouble code PO336 crankshaft position sensor ???
you don't have that on your new list and I didn't see were you ruled it out
doesn't that send code to pcm and shuts the fuel off from the injectors
I don't know I'm asking here so please correct me

 

still didnt rule it out.. it was there for some time.. i did replace it but still the code is there

i am sure its a wiring problem with it..

 

does anyone have the wiring diagram for the CKP sensor and camposition sensors?

alldatadiy.com are showing me the EVAP circuit

 

Courtesy of Shoebox:

http://shbox.com/1/1996_ec_03_ign_system.jpg

Cam position sensor is in the Opti, and it's at the bottom of the page labeled "Optical Sensor".

 

i believe the problem has showed up now.. today the scanner did show code P1371 which would cause the engine to shut down the fuel system...

and with all of the checking i have been doing i did find that the harness is really crap! found lots of spots where cables are just cut and joined together with some electric tape around it.. mainly the cut cables are all around the ignition related wiring.. i really need to replace the harness as i do have a new one here..

how hard is it to replace the harness? and how much time would it need?

 

as an update.. i still didnt replace the harness as i didnt find the time to start..

but what i did do was checked for continutity on each pin of for all connectors of the ignition and fuel system.. and all are ok.. i should be receiving the fuel pressure gauge i ordered just to see how much pressure i have from the pump..


this is really burning me up and i dont want such an issue to make to sell it off!

i even changed the CKP sensor to make sure its not the problem..

 

So you didn't believe me when I told you it wasn't a problem with the CKP sensor?