Greenstu1

Hi me again you closed my last post cause you didn't think I was listening to you. Well i took motor out checked crank and had a 2007 crank but everything looked to be the same but still changed it out. So everything except the block and pistons is 2007. I reinstall motor hooked things up and guess what still have the same problem that I first asked about. So I did what you said and I still have the same issue. Now I will ask again and maybe you will listen to me I have RPM when cranking motor it will go away when it starts. Runs great no miss fire no ruff running. I even changed the crank sensor out again.

donbrew

Maybe somebody can help you, not me.

whopper

Go back and read what was posted in your other thread. I really don't think we can help you beyond that.

Oldblue

It would be a process of elimination then, perhaps a missed ground wire, a loose harness connection, if it starts a runs but won’t take fuel , the maybe injectors, fuel pressure regulator or fuel pump.

Grizzly old man

Oldblue, he said the engine runs fine its just that the Tach doesn't register any RPM once the engine starts.

Oldblue

Sorry, I did not see the word tach in the origin post in this thread. So that brings us back to loose wires.

Cat Man HHR

What get's me, with all his mechanical ability, the possibility of a wiring/ECM issue was never explored.

aradmahogany

Which is the only way the tach is ran in the HHR........Basically my understanding is that when the motor is turning over the tach moves but when idling and driving it stays at zero. Clearly a bad signal meaning 99% sure its a wiring issue. as I understand with how the cluster gets readouts... ITS ELECTRIC (boogie woogie)

donbrew

I asked for information that was not provided: how many teeth on the reluctor and how many wires on the sensor? And explained in detail why I was asking.

According to GM there is a difference between 2005 and 2007. Greenst1 claims his are identical. I don't know what to do with that.

The reason it might work until it is started is that the sensor will send a baseline signal until it senses a real signal, just like a broken/miswired digital temp sensor reads something like 68F. It is digital magic.

Oldblue

My tach shows 650 to 700 rpm at idle, only zero with the engine turned off.