Electronics help...!

[thewheelerZ]

We run a 2002 Maxima. Newly built car.  We had thinned out the wiring harness during the build.  
 

ran well at our one race this year, except for what seemed like a hot start issue, Where after a pitstop we couldn’t get it to start, But waiting another five minutes or so for it to cool and it would fire back up. We believed in our previous car that we solved that issue with a new crankshaft sensor and assumed it to be the same on this new car. 

 

we got the car home after the race and replaced the sensor, but then it wouldn’t start. Retraced a few issues back to a bad ECU Relay and replaced, the car fired up. We let it sit for 10 days and tried to fire it up again, and it wouldn’t go. It hasn’t started since.

 

it appears to have fuel (at least fuel to the rail) but no spark. We tried to ensure Ecu is getting power, with ignition on it does have power, but not sure if it does when cranking. The obd reader re-cycles when we crank using the key as if it is losing power and the dash/gauge panel goes out when key is triggered. In any case, just giving the starter 12V with the key in “on” position doesn’t do any good. 

 

We have tried the OEM ecu with the correct key (for anti theft) and a flashed ecu with antitheft deleted.  Neither makes a difference.
 

no codes whatsoever on OBD. 
 

we are getting pretty stumped on this one.... not sure where to even look next. 
 

any suggestions?

Edited August 6, 2021 by thewheelerZ

[mender]

I would start off by checking for injector actuation while cranking. You can either use a "noid" to do that or a stethoscope to listen to one of the injectors for the clicking that should be present. Either one would indicate that the ECU is getting a crank signal and is triggering the injectors.

 

If not, then check the CPS.  If you have a scanner you can check for an rpm reading while cranking. If you are unsure whether you're losing power while cranking because of a faulty ignition switch, wire a separate power lead and switch to the ECU to ensure that it has power while cranking. 

[Team Infiniti]

This may not solve much, but we did find an idiosyncrasy on the infiniti, where it’s too lean while manually cranking the starter (without sending the start signal through the computer as well.)

 

In addition to what has already been mentioned. Need to check if you have 12V @ injector while cranking, If still in doubt, a wiring diagram for the computer to check to see if 12 V is everywhere it should be.

Edited August 6, 2021 by Team Infiniti

[TKRiggs]

I would check the cam position sensors. These are known to go bad on VQ35s (on VQ30s they will keep the engine from starting if bad...I've read the same about the 35s).  If bad use Nissan only...won't be cheap but new design "eliminates" the failures.   Also...if you check them/take them out and notice one/both are oily...you'll need to clean the harness connector(s) as oil is known to accumulate in these as well.

 

 

Edited August 7, 2021 by TKRiggs

[Eman911]

Webers and points.

[thewheelerZ]

On 8/6/2021 at 8:12 PM, TKRiggs said:

I would check the cam position sensors. These are known to go bad on VQ35s (on VQ30s they will keep the engine from starting if bad...I've read the same about the 35s).  If bad use Nissan only...won't be cheap but new design "eliminates" the failures.   Also...if you check them/take them out and notice one/both are oily...you'll need to clean the harness connector(s) as oil is known to accumulate in these as well.

 

 

 
after chasing 12V around the engine bay, we got new cam sensors and installed. Guess what, rear cam sensor was bad. Fired right up. Ugh..! Great news but frustrating that we didn’t try that earlier. we figured that would be a code on the OBD so never bothered. 
 

great news is the car finally runs. We can now get down to prepping for the the October Mosport race!

 

thanks for the help all!

[Timothy G. Elliott]

Congratulations! It's nice to have a definite solution and to have posted here for us gear heads to add to our biological data bases! Who knows if a swap to this platform may be a future for my Rabbit! Not likely but you never know!

 

[Wheelman_99 - C Rallo]

On 8/8/2021 at 11:43 AM, thewheelerZ said:

 
after chasing 12V around the engine bay, we got new cam sensors and installed. Guess what, rear cam sensor was bad. Fired right up. Ugh..! Great news but frustrating that we didn’t try that earlier. we figured that would be a code on the OBD so never bothered. 
 

great news is the car finally runs. We can now get down to prepping for the the October Mosport race!

 

thanks for the help all!

Thank you for the follow up!!

 

On 8/6/2021 at 11:18 AM, Team Infiniti said:

This may not solve much, but we did find an idiosyncrasy on the infiniti, where it’s too lean while manually cranking the starter (without sending the start signal through the computer as well.)

 

In addition to what has already been mentioned. Need to check if you have 12V @ injector while cranking, If still in doubt, a wiring diagram for the computer to check to see if 12 V is everywhere it should be.

My 2002 Blazer was like that... Had an issue that required a starter button wired to the starter relay... I also had to turn the key at the same time to actually get it to start using the button. Boy did that baffle me for a minute!