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Category: Chevy
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Experience:  ASE certified tech ADVANCED LEVEL SPECIALIST. Wisconsin certified emissions state inspector
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96 Impala SS- Computer fault code po336 comes up after installing

Resolved Question:

'96 Impala SS- Computer fault code po336 comes up after installing an after-market Accel Optispark dist. Local Chevy dealer cannot find out why this is happening. The parameters in the computer are -7 degrees of dev. to 10 degrees of dev. The scan tool says the dist. is at -10 degrees of dev. Because of local inspection regs., I cannot get an inspection sticker. What can be done to cure the problem
Submitted: 6 years ago.
Category: Chevy
Expert:  AMEDEE replied 6 years ago.



P0336 DI Crankshaft Position Sensor Performance - With Automatic TransmissionPossible Causes
CKP sensor connector has failed (check pins for damage, and for moisture)
Crankshaft reluctor wheel is damaged or improper installation
Distributor mechanical fault (i.e., too much distributor backlash)
Engine front cover damaged or timing gear is worn excessively
PCM has failed

Tests/Procedures: 1. Confirm the distributor is probably indexed on the splines.

2. Check for erratic high and low resolution signals from the distributor. Backprobe the Red and Black wire and the Purple and White wire in the diagnostic connector on the intake manifold.

3. Confirm the camshaft and crankshaft are the correct part and are identical to the original part.

Potential Causes:



Tests/Procedures: 1. Use the scan tool to check the CKP Lo Res Angle (Crankshaft Position Sensor Lo Resolution Angle). The value at idle with all accessories off should be between -10 to +7 degrees.

2. If the value falls outside this range stated is step 1, quickly rev the engine once and allow it to return to idle while watching the CKP Lo Res Angle. Does the value change from a positive value on acceleration to a negative value on deceleration?

3. If the value on step 1 is with in specification check the Cyl Mode Misfire Index (located in Misfire data list) with engine idling. Value typically should remain below 1000. If the value is below 1000, use scan tool to note parameters of when the DTC set. Drive vehicle under the same condition and not scan tool to see if it shows the diagnostic failed this ignition.

4. Use a lab scope to check for an erratic signal from Crankshaft Position (CKP) sensor.

Potential Causes:

Crankshaft Position (CKP) Sensor Connector - Connections at Crankshaft Position (CKP) sensor.
Crankshaft Position Sensor Reluctor Wheel - Crankshaft reluctor wheel damage or improper installation.
Distributor - Excessive distributor drive backlash or other mechanical distributor problem.
Distributor Drive - Excessive distributor drive backlash.
Damaged Front Cover
Mis-Adjusted Sensor - The sensor coming in contact with the reluctor wheel.
Sensor Connector - Poor connections/terminal tension at the sensor.
Worn Timing Chain
Worn Timing Gear

Customer: replied 6 years ago.
Hello, [by the way my name is Paul] Every thing that sent to me has been done by a Chevy dealer and they can't find out what is wrong or how to fix it. They want to replace everything that I installed with OEM parts until the problem is solved. I am a master certified mechanic. their estimate for the dist. is $1100.00. I replaced the following: timing chain & gears, ckp reluctor wheel, Accel Dist- new, ckp sensor. This car has 155000 miles on it. I was told by the GM tech. that there are software programs that can change the resolution parameters. Do you know of any such programs or reprogramers that can help. To me, any replacement part that is sold on the market should not effect the computer in any way. Paul
Expert:  AMEDEE replied 6 years ago.



You might be talking about a pcm re flash. This would be the new software that is flashed into the computer to give it new parameters.


However, if you have after market parts (camshaft or crankshaft sensors) this might just be your problem.

Customer: replied 6 years ago.
The continuing problem seems to be connected to the aftermarket dist. that I put in. Manufacturer has never heard of this problem, and the "tech" on the other end of the was not very friendly. Hepushed it off on an engineer that was away ubtil Tues. So, I cleared the code out of the computer, drove approx. 35 miles, told state inspection mechanic the problem and hooked up to the machine and it passed. The code came on after the next startup. The car is up for sale. Thank you for your time. After being a mechanic/technician/auto & diesel instructor for the past 40+ years I cannot believe that anyone can tell me what is wrong.
Expert:  AMEDEE replied 6 years ago.



A professional mechanic or diagnostician does not throw parts at cars. We are not hear to "tell" you what is wrong with your car. We can give you some ideas and can point your in the right direction and even give you pattern failures, but we do not have a crystal ball that tells us what is wrong with your car...especially without even looking at it. But seeing how you have been in this industry for 40 plus years, you should know this.


I told you what to check on your car. Its not my fault you cannot pinpoint it. Here is some more info to help YOU diagnose YOUR problem.


Code P0336- The camshaft position sensor signal was erratic when the engine was running. Enabling conditions: The PCM calculates the difference in the 4X crank signal and the 24X signal to determine the 4X signal was erratic. The battery voltage must be 5.0 to 17.0 volts with an engine speed of 500 to 4000 RPM. The 4X signal was erratic for 1 second. Blocking action: This code can block the following monitors:
Misfire monitor. Testing: Use a scan tool to check the crankshaft: for a signal to the PCM. The signal out of the sensor should be 4.0 to 6.0 volts AC with the engine cranking. This code sets when the signal has missing or extra pulses, so a lab scope is the best was to check the signal for noise or other problems.

Edited by AMEDEE on 11/9/2009 at 5:45 PM EST
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