I replaced the knock sensor on my 2004 g35 and after putting everything back together my car won't start. It will try to turnover but won;t. I don't think I damaged anything during the process. Clueless as to what the problem could be. I tried to also replace the knock sensor harness as well but could not figure out how to disconnect the old one from the main ecu harness.

Why did you have issues with the knock sensor in the first place? Need some additional background. What else happened before this? Pics of what you replaced?

My car was running s*** and was shutting off while driving brought it to the dealer and had a cam sensor replaced they also said I had a bad knock sensor. So I replaced the knock sensor and could not get it to start seemed flooded because it gave a strange odor when I tried to start it. I now changed my spark plugs and got it to start now. It is emitting white smoke and won't rev past 2500 rpms and stalls when I put it drive the car will idle fine though. I don't see how I could have a blown head gasket, so I'm not sure what this is.

Spie PK wrote:I replaced the knock sensor on my 2004 g35 and after putting everything back together my car won't start. It will try to turnover but won;t. I don't think I damaged anything during the process. Clueless as to what the problem could be. I tried to also replace the knock sensor harness as well but could not figure out how to disconnect the old one from the main ecu harness.

Why not try putting everything back the way it was before you started.
If the engine is cranking you need three items for the engine to start
1- Air so make sure the air filter is not clogged
2- Fuel so make sure the fuel pump is operating
3- Spark so make sure you are getting spark

There was a caller on Car Talk this past weekend that had a crank sensor problem and a failure there will cause no spark and no fuel pump operation

Telcoman

if you just changed your spark plugs is your check engine light on?

drivers side rear 2 coil pack connectors often get swapped and it will cause big issues. This will cause the CEL to come on instantly and will hate any throttle.

If you swapped knock sensors and didnt use an OEM sensor, you might consider changing to OEM. I'ver heard aftermarket sensors can cause lots of issues.

Yeah after I changed the spark plugs I forgot to connect the intake sensor. Connected it back together car is running good now. The knock sensor I put in is OEM . the only problem I have is when I start the car I have to step on the gas to keep it started otherwise it will stall.

You may have a TPS problem. Do you have a CEL on?

No CEL on But I don't know what a TPS is

Throttle Position Sensor. They were notorious for having issues.