Bad injector = poor idle, backfire?

[SyHopeful]

So ever since I bought my GN, it's always idled a little rough. Now, it sometimes backfires too on startup. Could this be a bad injector? Car has 93,000 miles and I bet the injectors are the original ones. Also, just recently installed a fuel pressure gauge and I've noticed a 20psi drop in fuel pressure within...oh, 10 minutes after shutting the car off. Should the pressure be bleeding down this quickly?

It runs fine at higher RPM, so I think that I may have one or more injectors with a bad spray pattern and/or a leak. Would explain the backfires and the quick loss of fuel pressure after shutting down. And probably the hard starting sometimes, too.

Can anybody tell me if I'm on the right track? I have some 009s waiting to go in, but I want the car to run perfectly before I put them in, unless I can say for sure that the injectors are the problem.

 

[SyHopeful]

TTT

 

[turbojoe]

Mine takes about a half hour to go from 43 to zero upon shutting car down. don't know if this helps or not. Who knows, maybe mine are leaking down? Mine are also original and car has 65k on odo. Plan on replacing with 30lbers soon. The way i look at it, It's fairly cheap insurance.

 

[SyHopeful]

hmm....that sounds actually faster than mine. Mine bleeds from 40psi down to about 15 in that time, I don't know if it actually hits 0 but I would assume so.

Yeah, I have some 42.5lb'ers just waiting to go in, I just want to get the car running perfect before they go in so I don't risk compounding any problems that might already exist

 

[ledzeppac]

Originally posted by SyHopeful
hmm....that sounds actually faster than mine. Mine bleeds from 40psi down to about 15 in that time, I don't know if it actually hits 0 but I would assume so.

Yeah, I have some 42.5lb'ers just waiting to go in, I just want to get the car running perfect before they go in so I don't risk compounding any problems that might already exist

I would jsut put them in. It would eleminate that as a problem...

 

[TurboJim]

Timing chain may be stretched and the cam sensor is a tad off..that would cause a backfire. Could also be an injector, and injector o-ring, a bad coil, bad plug wire, a host of things.