Tach not working and hard starting.
Thread Starter
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Joined: Mar 2003
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From: Whiteland, Indiana
Tach not working and hard starting. Awhileback I went from an M6 to an A4 and changed out the wiring harness etc. The car has never been hard to start, but now it is. It takes about 7-8 revolutions for it to fire up. I'm assuming it maybe the tune?
Also the tach is not working, but I have a Aerforce Interceptor gauge and it reads the RPM's fine. My window switch also works fine, but the damn RPM gauge sits still.
Any help with those two issues will be greatly appreciated!
Also the tach is not working, but I have a Aerforce Interceptor gauge and it reads the RPM's fine. My window switch also works fine, but the damn RPM gauge sits still.
Any help with those two issues will be greatly appreciated!
FormerVendor
Joined: Aug 2005
Posts: 531
Likes: 0
From: Decatur IN.
check out cam position sensor ...it tells the PCM if it is on compression stroke or exhaust stroke ... The PCM is smart to tell itself what stroke it is actually on without or without the signal,and will eventualy fire.It just takes a lot of cranking time. Check and see if you are throwing any codes it will help! Post them up ASAP. It may be a faulty crank position sensor as you have no tach... always check your work when you have changed out something or other.
Brent Malone
P.S. my sig sucks ....FTW!!!
Brent Malone
P.S. my sig sucks ....FTW!!!
FormerVendor
Joined: Aug 2005
Posts: 531
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From: Decatur IN.
P.S.S
I do not know what a Aero interface gauge is??? But after installing a after market Tach on a LS2 I did have to install a 4.7k resistor in between the tach signal and a 12v reference in order to get the PPR enough signal voltage to amplify the weak signal from the PCM (special thanks to John @ spreartech) I think you may have problems in the cam sync... I hope this helps
Brent Malone
I do not know what a Aero interface gauge is??? But after installing a after market Tach on a LS2 I did have to install a 4.7k resistor in between the tach signal and a 12v reference in order to get the PPR enough signal voltage to amplify the weak signal from the PCM (special thanks to John @ spreartech) I think you may have problems in the cam sync... I hope this helps
Brent Malone
Captain,
I agree with the other guys. It's likely the cam sensor.
However, your aftermarket tach may be loading down the crankshaft position sensor that "reads" the reluctor wheel. I'd disconnect the aftermarket tach and see if anything gets better. Also, without knowing what the diagnostic trouble codes (DTC's) are, you can't really troubleshoot this problem.
Steve
I agree with the other guys. It's likely the cam sensor.
However, your aftermarket tach may be loading down the crankshaft position sensor that "reads" the reluctor wheel. I'd disconnect the aftermarket tach and see if anything gets better. Also, without knowing what the diagnostic trouble codes (DTC's) are, you can't really troubleshoot this problem.
Steve
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From: Whiteland, Indiana
Thanks for the replys. Please allow me to explain what this gauge is. First off I don't have an aftermarket tach, the gauge looks like this https://ls1tech.com/forums/showthrea...ce+Interceptor
It reads all the parameters of the engine, and it also reads the RPM's as well. If the cam positon sensor was bad, would the PCM still be able to read RPMs as it appears to do now?
And I never got a ses light to come on.
I really appreciate the help, guys.
It reads all the parameters of the engine, and it also reads the RPM's as well. If the cam positon sensor was bad, would the PCM still be able to read RPMs as it appears to do now?
And I never got a ses light to come on.
I really appreciate the help, guys.
This is Capt. under a different name.
After changing out the cam position sensor, it still starts hard and the tach is still not working. It is throwing a p0343 code I believe. After doing a search there doesn't seem to be many people who can answer what could be causing this. I have seen where it could be a loose timing chain, but the timing chain has 41k miles on it. This didn't start till we did the A4 swap, which means we didn't touch the engine internally. We can read the RPM's through HP tuners, but that is all.
It has done this even before the rebuild of my engine, and it is still doing it now.
After changing out the cam position sensor, it still starts hard and the tach is still not working. It is throwing a p0343 code I believe. After doing a search there doesn't seem to be many people who can answer what could be causing this. I have seen where it could be a loose timing chain, but the timing chain has 41k miles on it. This didn't start till we did the A4 swap, which means we didn't touch the engine internally. We can read the RPM's through HP tuners, but that is all.
It has done this even before the rebuild of my engine, and it is still doing it now.
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Verdad Gallardo The car did this before the new motor. Now the new motor has a new cam and a new crank so it can't be the reluctor wheels. The car also has a new cam position sensor. The crank position sensor is working because HPT is picking up RPM. The only thing I can think of is that the cam is walking for some reason and the reluctor wheel is not matching up with the sensor. But the engine has ZERO miles on it and only a few minutes of running time. The only constant between the two engines is the timing chain. I know the cam bolts were tightened correctly and I don't think they could back out in such a short time. Also when the car did this before on the old engine the old cam bolts were not loose. So I guess that leaves the timing chain?
I also wonder if it could be the PCM or harness. This started after is M6 to A4 swap. If something in the harness/PCM is interupting the cam position signal it would have the same effect. It's not the tach not working that bothers me, it's the hard starting and rough sound of the engine. We checked the wiring last night for any cuts or kinks but didn't see anything out of ordinary. ?????????
Launching!
Joined: Aug 2005
Posts: 211
Likes: 1
From: East Central Florida
tach gets its signal from the Crank position sensor, my starter overheated and it cooked my crank sensor harness, drop the starter and tale a test light to the wires at the PCM for both sensors
Originally Posted by dheck
I also wonder if it could be the PCM or harness. This started after is M6 to A4 swap. If something in the harness/PCM is interupting the cam position signal it would have the same effect. It's not the tach not working that bothers me, it's the hard starting and rough sound of the engine. We checked the wiring last night for any cuts or kinks but didn't see anything out of ordinary. ?????????
Teching In
Joined: Dec 2014
Posts: 9
Likes: 0
Awhileback I went from an M6 to an A4 and changed out the wiring harness etc. The car has never been hard to start, but now it is. It takes about 7-8 revolutions for it to fire up. I'm assuming it maybe the tune?
Also the tach is not working, but I have a Aerforce Interceptor gauge and it reads the RPM's fine. My window switch also works fine, but the damn RPM gauge sits still.
Any help with those two issues will be greatly appreciated!
Also the tach is not working, but I have a Aerforce Interceptor gauge and it reads the RPM's fine. My window switch also works fine, but the damn RPM gauge sits still.
Any help with those two issues will be greatly appreciated!
