Does anybody know if 4th gen Maximas have problems with the timing chain jumping? Dreading taking the cover off to check.
Went to start the car, it tried to fire , now no fire to cylinders, getting fuel.
Checks completed so far:
1. Coils checked ok, Got 12V to primary, Ground Ohmed out, Secondary voltage 350mv key on - 500mv to 1V when cranking ( this is suspect, supposed to be 0 to 200mv)
2. Checked condenser. Ohmed out good.
3.Checked All fuses. OK
4.Checked both crank sensors. REF sensor Ohmed good, got voltage . Pos sensor varied voltage when moving screwdriver in front of it.
5.Cam sensor Ohmed ok, got voltage.
6. Ohmed out secondary lines from coil back to PCM ( ECM ) . Good circuit.
7. No ignition codes , Got O2 codes and purge valve codes, assuming these were from raw fuel in exaust.
8. Suspect PCM. Going to wrecking yard to get one and try that.
9. Suspect timing chain jump sever enough to prevent starting, but doubtful. Maybe timing chain is broken?

When I crank the engine, it just spins. No backfire or rough idle.

 

Sounds like bad fuel injectors if u have raw fuel in exhaust. When u say no fire do u mean no spark

 

That is correct. No ignition spark in any cylinders. V6 with individual coil packs.

 

OK there's 2 sensor that are the main spark sensors. The one that's mounted to the crankshaft wheel or also some people say the tranny controls spark. But if that goes bad I think the car still should start but u will have misfires. The camshaft position sensor is the most important. That's our distributor for our cars and if unplug u will have the same symptoms that u just described above no spark or backfire just raw fuel going in the cylinders and I know from experience because i forgot to plug the harness back in and my car kept on cranking with a lot raw fuel smell and it was that sensor was not plugged in. Even though it ohms out great go to the junk yard and get a new one instead of an ecu because our ecu never go bad. That sensor read the timing chain and its probably bad.

 

Let me correct the above statement a bit.

The camshaft sensor controls fuel injector timing, not ignition. The car will start and run even if this sensor goes bad.

Both crankshaft sensors control ignition timing. CPS POS is located on the transmission bell housing and is accessed from under the vehicle. It points to TDC on all cylinders. CPS REF is located just above the main pully, it also plays an important role in ignition timing.

If any of the above 2 crank (CPS) sensors fail to provide a signal, you will encounter a no start condition.

 

Is this a 99 car? Security light lit solidly?

 

1995 Model. Has Security system, but seems to work fine. Light goes off when all doors shut. The wiring diagram shows to interrupt the starter, not ignition.

Just pulled the timing chain cover off ( omgosh, what a hassle ) Engine is in time . Going to grab new gaskets and seal and put her back together.After that , going to replace both crank sensors.

Am I missing any other checks? All the diagnostic checks up to now are listed in my first post, minus the timing chain marks being verified.

 

Update. Changed crank sensors and still no ignition spark. any other ideas would be appreciated .

 

Might sound dumb, but check the spark plugs?

 

This might seem rather basic, but does your car have gas in it? And if so, have you listened to the fuel pump to see if it's priming/functioning?

 

New spark plugs, fuel in tank, fuel pump pumping, fuel in cylinders, no ignition spark.
On a side note, after i put it back together and still wouldn't start, I ohmed the secondary lines between #1 and #2 , Between #2 and #3 , Between #3 and #4, and each time I came up with a closed circuit. Anyone know if this is normal ?

Grasping for straws right now. As I said earlier in above posts, I have checked for voltage and ground at coils, 12V on primary (red wire) have ground ( black wire) and 500mv on secondary ( multi colored wire ) . I have physically pulled the coil off and put a spark plug in it , grounded to the block and had my son turn the engine over. No spark.

Also, I had a mechanic friend tell me the ECM has individual ignition drivers for each cylinder and all 6 would need to go out for my problem to be the computer. Anyone know about that ?

 

Check the grounds. Its been said it plays an important part in our cars as for running condition.

 

I had tried grounding the block straight to the battery with my jumper cables , but had no luck with that .

On a side note , I had a friend come by today and when we were trying to start it after obtaining a used ECM from the wrecking yard, we noticed that the starter is turning slow. Charged the battery and load tested the battery. Battery seems fine, so put charger back on it, same thing, so we put the jumper cables on it to another vehicle and same thing. Would a bad starter cause a power drain bad enough to cause ignition trouble? How fast should the engine crank anyways? The starter should turn about 2700 rpm, but I have no way to check that.

 

I actually had this happen to me during the summer.the starter was drawing so much amperage it took a while for the car to start up. I ended up replacing the starter, crank sensor, and some relay that showed it powerd the relay.

 

I have never seen a starter do that before, but that is what it was. Car running fine now.

 

I'm having something similar happen with mine.. I'll be watching this thread for ideas.

 

What I think was happening was the starter was drawing so much amperage that the ecu couldn't function properly.