Crank Position sensor learning procedure fails
Thread Starter
Instructor
Joined: Sep 2021
Posts: 108
Likes: 28
From: Duisburg, Germany
Crank Position sensor learning procedure fails
Good morning guys,
I had the crankshaft and camshaft position sensors changed in my 2007 base model. It ran quite badly afterwards, pops and bangs and low on power, very rich exhaust fumes. And the RPM gauge was dead. So I fired up the old Tech2 and did a crankshaft position relearn procedure. It went all as the Tech2 said. Start the engine, put on the handbrake, turn off the AC, press brake pedal, give it WideOpenThrottle until fuel cuts out at 4000 RPM. Tech 2 said learning procedure was successful. Turned the car off and on again. Started right up, RPM Gauge worked, ran and drove perfect. Next morning, it started very reluctanty, starter running, Check Engine Light is on, and after 15 seonds it starts, Check Engine Light goes off, car runs and drives perfect.
So I do the relearn procedure again. Same as above. Afterwards I turn the car off and on again a couple of times, starts right up every time. Next morning......starts very reluctantly again with Check Engine Light on....
It is, as if the car "forgets" what the Tech2 learning procedure has done. Once it starts..... perfect.....
Any ideas ?
Thanks in advance and greetings from Germany
Oliver
I had the crankshaft and camshaft position sensors changed in my 2007 base model. It ran quite badly afterwards, pops and bangs and low on power, very rich exhaust fumes. And the RPM gauge was dead. So I fired up the old Tech2 and did a crankshaft position relearn procedure. It went all as the Tech2 said. Start the engine, put on the handbrake, turn off the AC, press brake pedal, give it WideOpenThrottle until fuel cuts out at 4000 RPM. Tech 2 said learning procedure was successful. Turned the car off and on again. Started right up, RPM Gauge worked, ran and drove perfect. Next morning, it started very reluctanty, starter running, Check Engine Light is on, and after 15 seonds it starts, Check Engine Light goes off, car runs and drives perfect.
So I do the relearn procedure again. Same as above. Afterwards I turn the car off and on again a couple of times, starts right up every time. Next morning......starts very reluctantly again with Check Engine Light on....
It is, as if the car "forgets" what the Tech2 learning procedure has done. Once it starts..... perfect.....
Any ideas ?
Thanks in advance and greetings from Germany
Oliver
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,539
Likes: 4,018
From: Cape Coral, Florida
Good morning guys,
I had the crankshaft and camshaft position sensors changed in my 2007 base model. It ran quite badly afterwards, pops and bangs and low on power, very rich exhaust fumes. And the RPM gauge was dead. So I fired up the old Tech2 and did a crankshaft position relearn procedure. It went all as the Tech2 said. Start the engine, put on the handbrake, turn off the AC, press brake pedal, give it WideOpenThrottle until fuel cuts out at 4000 RPM. Tech 2 said learning procedure was successful. Turned the car off and on again. Started right up, RPM Gauge worked, ran and drove perfect. Next morning, it started very reluctanty, starter running, Check Engine Light is on, and after 15 seonds it starts, Check Engine Light goes off, car runs and drives perfect.
So I do the relearn procedure again. Same as above. Afterwards I turn the car off and on again a couple of times, starts right up every time. Next morning......starts very reluctantly again with Check Engine Light on....
It is, as if the car "forgets" what the Tech2 learning procedure has done. Once it starts..... perfect.....
Any ideas ?
Thanks in advance and greetings from Germany
Oliver
I had the crankshaft and camshaft position sensors changed in my 2007 base model. It ran quite badly afterwards, pops and bangs and low on power, very rich exhaust fumes. And the RPM gauge was dead. So I fired up the old Tech2 and did a crankshaft position relearn procedure. It went all as the Tech2 said. Start the engine, put on the handbrake, turn off the AC, press brake pedal, give it WideOpenThrottle until fuel cuts out at 4000 RPM. Tech 2 said learning procedure was successful. Turned the car off and on again. Started right up, RPM Gauge worked, ran and drove perfect. Next morning, it started very reluctanty, starter running, Check Engine Light is on, and after 15 seonds it starts, Check Engine Light goes off, car runs and drives perfect.
So I do the relearn procedure again. Same as above. Afterwards I turn the car off and on again a couple of times, starts right up every time. Next morning......starts very reluctantly again with Check Engine Light on....
It is, as if the car "forgets" what the Tech2 learning procedure has done. Once it starts..... perfect.....
Any ideas ?
Thanks in advance and greetings from Germany
Oliver
Thread Starter
Instructor
Joined: Sep 2021
Posts: 108
Likes: 28
From: Duisburg, Germany
Thread Starter
Instructor
Joined: Sep 2021
Posts: 108
Likes: 28
From: Duisburg, Germany
I bought them from a german carparts importer, but I ordered a genuine ACDelco replacement just to be sure. Should be here next week.
Thread Starter
Instructor
Joined: Sep 2021
Posts: 108
Likes: 28
From: Duisburg, Germany
Soory guys for the long delay, but the Corvette keeps on giving. The error log is now empty all the time, but the long cranking and stuttering start are still there. I re-learned the crank position sensor a couple of times and also tried to drive it immediately afterwards for over 2 hours - next morning it´s gone. Am I supposed to turn the engin off and on again after the re-learn ? I have a genuine GM sensor coming to Germany, perhaps that will solve the problem.....
Pro
Joined: Feb 2014
Posts: 714
Likes: 106
From: England
Soory guys for the long delay, but the Corvette keeps on giving. The error log is now empty all the time, but the long cranking and stuttering start are still there. I re-learned the crank position sensor a couple of times and also tried to drive it immediately afterwards for over 2 hours - next morning it´s gone. Am I supposed to turn the engin off and on again after the re-learn ? I have a genuine GM sensor coming to Germany, perhaps that will solve the problem.....
Need to fix the slow crank first.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,539
Likes: 4,018
From: Cape Coral, Florida
Soory guys for the long delay, but the Corvette keeps on giving. The error log is now empty all the time, but the long cranking and stuttering start are still there. I re-learned the crank position sensor a couple of times and also tried to drive it immediately afterwards for over 2 hours - next morning it´s gone. Am I supposed to turn the engin off and on again after the re-learn ? I have a genuine GM sensor coming to Germany, perhaps that will solve the problem.....
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Thread Starter
Instructor
Joined: Sep 2021
Posts: 108
Likes: 28
From: Duisburg, Germany
Good evening guys,
I don´t think it´s the "Slow Crank" Problem, but I made 2 Videos for you to see. One is immediately after successful Crankshaft-Sensor Relearn, the other is the next morning....
I don´t think it´s the "Slow Crank" Problem, but I made 2 Videos for you to see. One is immediately after successful Crankshaft-Sensor Relearn, the other is the next morning....
Pro
Joined: Feb 2014
Posts: 714
Likes: 106
From: England
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,539
Likes: 4,018
From: Cape Coral, Florida
I really wouldn’t call your “bad” crank a “slow crank” problem but a long crank…the nomenclature you use is very important…engine is turning over normally but it’s not starting…I’m not seeing the Tach moving at all during cranking…you’ll have to focus on the crank sensor.
Last edited by C5 Diag; Jun 29, 2023 at 02:49 PM.
Thread Starter
Instructor
Joined: Sep 2021
Posts: 108
Likes: 28
From: Duisburg, Germany
Guys, I am floored, this car drives me insane.
I imported a genuine GM crankshaft position sensor (blue rubber) and had it installed. Try to start - long cranking as before. I start the GMTech2, check for codes. Nothing. I do the re-learn procedure. GMTech2 says it is successful and I should press "exit".
Check for fault codes again. Nothing. Try to restart the car - again the long cranking as in the video. Nothing changed.
I have no clue what to do now....
I imported a genuine GM crankshaft position sensor (blue rubber) and had it installed. Try to start - long cranking as before. I start the GMTech2, check for codes. Nothing. I do the re-learn procedure. GMTech2 says it is successful and I should press "exit".
Check for fault codes again. Nothing. Try to restart the car - again the long cranking as in the video. Nothing changed.
I have no clue what to do now....
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,539
Likes: 4,018
From: Cape Coral, Florida
Guys, I am floored, this car drives me insane.
I imported a genuine GM crankshaft position sensor (blue rubber) and had it installed. Try to start - long cranking as before. I start the GMTech2, check for codes. Nothing. I do the re-learn procedure. GMTech2 says it is successful and I should press "exit".
Check for fault codes again. Nothing. Try to restart the car - again the long cranking as in the video. Nothing changed.
I have no clue what to do now....
I imported a genuine GM crankshaft position sensor (blue rubber) and had it installed. Try to start - long cranking as before. I start the GMTech2, check for codes. Nothing. I do the re-learn procedure. GMTech2 says it is successful and I should press "exit".
Check for fault codes again. Nothing. Try to restart the car - again the long cranking as in the video. Nothing changed.
I have no clue what to do now....
Is your camshaft position sensor you changed OEM ??…a long crank can be a cam sensor…did you look at the fuel pressure with key ON, while running and then see if the fuel pressure drops quickly after shutdown ??…you should find someone that has a scope that can check your cam and crank sensors to make sure they have a good signal…to 5 volts and then to ground…my 08 cam/crank below.
Last edited by C5 Diag; Jul 5, 2023 at 12:29 PM.
Thread Starter
Instructor
Joined: Sep 2021
Posts: 108
Likes: 28
From: Duisburg, Germany
The camshaft position sensor is not OEM, it was not in stock when I ordered the parts. To change that one you have to remove the crank pulley if I remember right ?
Fuel pressure is at about 38 when I turn it on, goes to about 40 when running and stays there for about 10 minutes after shutting the motor off.
Fuel pressure is at about 38 when I turn it on, goes to about 40 when running and stays there for about 10 minutes after shutting the motor off.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,539
Likes: 4,018
From: Cape Coral, Florida
The camshaft position sensor is not OEM, it was not in stock when I ordered the parts. To change that one you have to remove the crank pulley if I remember right ?
Fuel pressure is at about 38 when I turn it on, goes to about 40 when running and stays there for about 10 minutes after shutting the motor off.
Fuel pressure is at about 38 when I turn it on, goes to about 40 when running and stays there for about 10 minutes after shutting the motor off.
Last edited by C5 Diag; Jul 5, 2023 at 12:52 PM.
Thread Starter
Instructor
Joined: Sep 2021
Posts: 108
Likes: 28
From: Duisburg, Germany
Sorry, that was a misunderstanding. And I wrote it wrong. Had a look at my gauge, I was one digit off.
I have around 4.0 BAR which translates to around 58 psi.
Can the scope thing be done with the sensors in place ?
I have around 4.0 BAR which translates to around 58 psi.
Can the scope thing be done with the sensors in place ?
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,539
Likes: 4,018
From: Cape Coral, Florida
I did my scope reading by accessing the ECM and using two piercing probes to get onto each signal wire…fairly easy to do…I believe your LS2 also has a 58X crank and 4X cam as my LS3 does…I moved this thread to Tech.
Thread Starter
Instructor
Joined: Sep 2021
Posts: 108
Likes: 28
From: Duisburg, Germany
I will try and find someone around here who can do this. It´s a little tricky to get such exotics repaired here, the normal shops will only touch domestic/european cars, or of course all the japanese imports, but the Corvette...... no way......
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,539
Likes: 4,018
From: Cape Coral, Florida
The Corvette is "hardly" an exotic !!...the only 2 things different about the Corvette is the fuel system and torque tube...any shop should be able to fix EVERYTHING else...I myself wouldn't even touch a Mercedes !!
Thread Starter
Instructor
Joined: Sep 2021
Posts: 108
Likes: 28
From: Duisburg, Germany
Hehe, you see, thats the same here : Mercedes/BMW-technicians : "I wouldn´t even touch a Corvette" - or any American car at all......
But I have tracked down a specialty shop in my area which only deals with "newer" American cars, I think they might be able to do the oscilloscope thing.
Would change the cam sensor if it wouldn´t be such a hassle to get to it....
But I have tracked down a specialty shop in my area which only deals with "newer" American cars, I think they might be able to do the oscilloscope thing.
Would change the cam sensor if it wouldn´t be such a hassle to get to it....