Cranking no-start
 

Hello! This is my first post but I've been silently stalking this forum for years. I have an 05 LSJ which is currently not starting and getting me in all kinds of trouble with the wife. A little about the car. It's been daily driven for 5 years with no real issues. I'm running 60lb injectors, a 2.8" pulley, CAI, and some cooling mods. It was can-tuned by ZZP a couple years ago. The trouble started when I installed the ZZP long tube header kit and 3" Cat-back exhaust kit. I installed the header, started it up, very loud but ran fine, shut it off after a few seconds. Installed the down-pipe, very loud but ran fine, shut it off after a few seconds. Installed the cat back and it won't start up at all. Battery is good and charged, cranks over for days no problem. It has fuel pressure at the rail and no DTC's set. I don't think it has spark, I pumped it with starting fluid and it won't even spit. I'm about to pull all the plugs and test spark at the coils. Any ideas where to start? I have thousands of dollars in parts to throw at it, a $3000 Autel scanner and a $1000 Snap-on Ethos scanner at my disposal. I also run a parts store so parts aren't an issue. Could the PCM have gone bad in the 15 minutes it took me to mount the Cat-back? I'm running out of ideas! Please Help!

Compression good, No spark
 

Compression test shows all 4 cylinders over 85 psi seems low but maybe my tester sucks? One cylinder is about 120. Pulled 4 coils and no spark any cylinder.

If that series of events you laid out is exactly what happened it would seem you either bumped a wire while you were under there. The only way I can think that a cat-back would cause your car not to start was if it was clogged. But then you say you don't have spark which I'm having a hard time thinking of how installing an exhaust could affect that.

I don't know you but you have a compression tester and said you tested your coils so I am going to assume you did both of these things correctly? Because if your compression was really that low then I'd think you'd have some potentially serious problems. It's also hard to come up with a reason why you wouldn't have spark. Either your coils aren't getting power or the ECU isn't sending a signal for them to fire.

Just though Id ask, did you ground the plugs to the block with a jumper when you tested the spark. Resting them on the engine can not be a good enough ground sometimes.

Weird coincidence
 

Scanner showed CMP not oscillating. Replaced CMP and car starts and runs for 2-3 seconds and shuts off. I can keep it running with starting fluid. The fuel pump appears to also be bad, I can command the relay on but the pump isn't pumping enough fuel. Im still not sure how a pump and a CMP go out together in the span of 15 minutes but that's what it looks like. Good time to upgrade to the AEM e85 pump I guess? Long tube Header, Cat-less do and zzp 3" Cat-back sound GREAT for those 3 seconds though haha

In retrospect, I did try to start it while the RR corner was jacked up, probably cranking on a dry pump would cause it to go out especially with 170k on the odometer. I would have thought it would have at least tried to fire with the fuel still in the lines but maybe not. Oh well upgrade time again!