#8DaleJr

I have a 1996 Z28. It seems to idle and run just a bit hotter than it used to. It also seems to have a slow coolant leak and has progressively started to misfire more and more. It has a new water pump, distributor, spark plugs, plug wires, radiator, radiator hoses, and heater hose assembly. Could it maybe be a cracked head? I never really see any coolant leaking and there's no white smoke coming out of the exhaust or anything. But it's the fact that it's misfiring with a brand new distributor that has me a little worried.

z28manlt194

ok say if ur normally cruising does it only misfire if u have it in a high gear at low rpms

Regecide

Clogged injectors? Have you checked them?

Has the car been sitting for a while?

Injuneer

You can buy a test kit to test for the presence of hydrocarbons in the coolant.

#8DaleJr

Initially when I first noticed any problem, I would only feel a misfire at about the 80 mph mark when I would really get on the gas. Going from 0-60 felt fine and it ran well on cruise control. Over the course of a couple weeks it started to get progressively worse. It started to miss out more and more during any type of acceleration. I wondered about the injectors myself. I've never checked or tested injectors before. Is it a difficult task? And no it wasn't sitting. It's an everyday driver for me. I might check on a test kit for the coolant too. Thanks for the info.

Regecide

Pretty simple, just loosen up the fuel rail, it pops in/out of place, after you unscrew it, then take a flathead and pop the clips holding the injectors out. Make sure the rings come out with them, look inside injector, check for gunk, clean, put back in. Repeat 7 more times.

Of if you have the tool to take them off it'll be even easier, but why do that when it's easy enough already.

First time took me about 2 hours, cause I wasn't sure what I was doing.

Ive done it 3 times since takes 10 minutes.

Oh and make sure you seperate your plugs, you don't want to plug one in to the wrong injector you'll just misfire more, hell that could be the problem too!

So many different things it could be. But checking the injectors is free! (don't break one!)

Injuneer

The injector harness connectors have numbers on them. Just remember to put them back where they belong. But you don't even have to uplug them to check the injectors.

Rather than trying to look in the injector for dirt, when you pop the fuel rails up (they can be hard to pull up if they haven't been off in a while) put containers under the injectors and have someone turn the key to "start" so you can observe the injector spray pattern. You'll easily identify a clogged injector.

Regecide

^That will save a lot of time if you just want to check them. Now it's a 2 minute job.

I was sitting here for about 10 minutes wondering why the heck I didn't try that, then I remembered lol, all mine were actually clogged so I had to pull them all out and clean up.

#8DaleJr

Thanks for the tips everyone. The injectors were fine. It actually turns out the plug wires were part of the problem, even though they were new wires from Jegs. They were bigger and better plugs than the factory ones so of course they didn't fit into the factory brackets. Plus one seemed really short to me. Anyway, putting on new wires seems to have fixed the misfiring issues. I had someone else do it this time and they also checked the compression on each cylinder. That's where the other problem lies. Cylinder 8 tested low. I was told a normal reading is about 160 and cylinder 8 tested at 110. So that doesn't sound very promising. I love this car but it's got a lot of miles on it so maybe it's time for an upgrade.