My 97 z28 is not starting, for a while the Crankshaft position sensor has been going off on my OBD and now it just wont start. I just had to do a full rebuild before this because my engine overheated and one of my heads cracked but the car keeps throwing up this code. Ive cleaned everything and when it runs it runs perfect with no misfires anymore but sometimes it wont start. should I get a brand new OPTI, timing chain or something else? any help would be greatly appreciated

 

Moving to “LT1 Based Engine Tech”.

I have a few questions that I'll ask in a little while.

ADMINISTRATOR

 

I assume it's setting a code. What is the EXACT diagnostic code for the crankshaft position sensor (CKP)? There is one for the electrical circuit or CKP angle differs from Opti low resolution pulse angle by large # of degrees (P0335), or P0336 - small deviation of crank position from Opti low res signal. To read the amount of deviation between the CKP and the Opti, you have to have a tool like a Tech-2 that can display "CKP:Lo Resolution".

Quote:

it runs it runs perfect with no misfires anymore but sometimes it wont start.

Which is it.... sometimes it won't start, or it won't start at all?

The CKP has nothing to do with whether the engine will start, nor does it affect how the engine runs. The CKP was added in OBD-2 in 1996 for misfire detection only.

Do you have any other codes?

Do you have spark when the starter is cranking the engine?

When the starter is cranking the engine, does the tach needle move up about 200 RPM?

If the tach needle moves, the Opti is providing the low res signal to the PCM. If you have spark, the PCM is using that signal to time the ignition and telling the ICM to fire the plugs.

When the starter is cranking the engine, is there any sign of combustion - backfires, kinda starting, etc.?

One possible cause of the CKP codes is the cam dowel pin has slipped out of the index hole in the back of the Opti, throwing the timing off.

 

well its throwing up both P0336 and P0335 codes and its sometimes that it wont start and occasionally the P1371 "Missing Low resolution" will pop up thank you so much i will check the cam dowel pin and i will get back to you

 

P1371 is for the Opti. If it's an active code there will be no spark, the PCM will cut the fuel and the engine will not start. The PCM has detected high resolution pulses, but no low resolution pulses. The engine can't run without the low res pulses. It may be intermittent.

Check the harness connectors for the Opti.... the gray connector on the bracket on the passenger side of the intake manifold, and the connector right at the Opti (if it has a connector, some newer Opti's have the harness permanently attached). The connectors get corroded, or the locking clip breaks off.

Do you know what brand the Opti is, or how old it is?

 

its all OEM so that would make the OPTI 26 years old I replaced the crankshaft position sensor a while ago and the harnesses and that only cleared up one code so i thought maybe the new crankshaft position sensor was incompatible and it would run fine on a new harness but the code came back. still in the process of getting to the timing chain and OPTI ill let you know what happens

 

The crank sensor code will not affect the way the engine starts or runs. It simply disables misfire detection.

Did you watch the tach while the starter was cranking (but not starting) the engine? Did the needle move upwards?

The most reliable replacement for the Opti is made by Petris. Everything else is less reliable. The cheap Chinese crap sold on eBay and Amazon have reliability next to “0”. Auto parts store brands, Summit, MSD are 50/50.

https://petrisenterprises.com/collections/frontpage

 

Thank you sir for the link.

 

I notice your IP address traces to Bharti Airtel Limited in India. Are there many Camaros in India?

 

Yes there are, I have seen in blue, yellow, black and I own Chevrolet Camaro and it is white in color.

 

You know what’s really odd…. you entered your country of residence as “UM”. That indicates you live in a small island possession of the United States, located in the middle of the Pacific Ocean.

Can you explain that?

ADMINISTRATOR

 

My bad, hehe changed it now Thank you