I think the injectors on my Z are leaking. My car gets very hard to start after sitting for a day or so , and when it does start it smells as if it were flooded (unburned gas). Even then when it does start it chugs along until I rev the **** out of it then it smoothes out, just seems like flooding to me.
Anyway, I was wondering if I could replace the 22# injectors that my '93 came with, with some 24# injectors I have from a '95 LT1?
Would this be too much? Or would my ECM be able to adjust to compensate?
Any input would be greatly appreciated.

 

Well, the ECM won't adjust itself for the larger injectors, but the 94+ injectors should work. It may run a little richer without readjusting the injector flow rate value, but they will work.
Give them a try.

 

The PCM will "compensate" for the 10% larger injectors in "normal" (part load) driving by using the long term fuel corrections (BLM's) to reduce pulse widths. This is normally within the limits of the PCM (15% max fuel cut), but if its already pulling fuel with the stock injectors for some reason, the BLM's could bottom out and cause problems. And when you go WOT, the PCM will see it has been pulling fuel out in closed loop, and ignore those corrections at WOT, causing you to run at least 10% richer than you are now.

To check for leaking injectors, simply pull the fuel rails up with the injectors intact. Switch the key to "on" without starting the engine. Watch the injectors for drips. Do this with a cold engine.

 

Oh, one other detail,
I also forgot to add that my driverside exhaust manifold has the two end bolts (one on each end) snapped off inside the head and causes me to throw an O2 code and then the car runs rich (not too bad, but bad enough I only get 16mpg).

SOOOoo......, would the addition of the 24# injectors worsen this situation? Atleast until I get headers that do not use the outer bolt holes

No, I didn't break the bolts off, they were like that when I bought the car.

 

It sounds like your injectors are clogged. You should take them out and get them flow tested, if they are clogged have them cleaned and put back in. The 24# injectors will work but will run rich which will reduce power if you don't upgrade your chip in your ECU.

 

I don't know... at part throttle, maybe... but I did this on the dyno and the PCM definetely did not adjust at WOT.
The car went from stock 24#s to ACCEL 26#ers (which considering that they have been rated at 44.1 PSI, should be even closer than going from 22 to 24s...) and the WOT AFR was definetely slightly richer.

 

That's exactly what I said will happen.... if you put in larger injectors, the PCM can only adjust by cutting fuel at part load/closed loop conditions. Since the PCM is "cutting fuel" in closed loop, it defaults to 128 on the BLM's at WOT, and you end up running rich at WOT.

I'm pretty sure we are both saying the same thing.