Drivability issue :(

[JP1323]

Hey everybody! New to the forum but yeah I got a 1990 300zx N/A that i had for a while already and i got few questions and concerns about my cars problem. Short story short i had to get new cylinder heads. Took it down the road today not really far but the car backfires ( like it loads up?) mostly under a load. It will idle ok but has a noticeable misfire that happens intermittently. My first thoughts were the timing, when i checked it the mark will jump back and forth from 15 to 25(doesn't stay steady). I know my ex cam has a broken tang where the CAS slots into but im preeety sure i set it correctly, if not could being a tooth off(or two) be an issue? another thing, while i had the intake manifold off i upgraded to the new style injectors using the z1 adapters, got the injectors off of ebay(new reman/ohmed perfectly) if i can remember i think they were listed as 270cc but is there a way to tell? a few plugs looked fouled but really every plug looked different from each cylinder(ill try getting some pics.. maybe a video). how can i test for proper function of the injectors? also the car sat disconnected for a while does the ecu need to relearn or is there compatibility issue with the newer injectors? no ecu codes although like i said i only took it around the block could the the select fouled plugs just be from cold start? the car ran fine before the head swap and even though this was the 5th time the car got a new timing belt i guess it wouldn't hurt to pull the covers just to check but honestly it seems more like an engine management issue

[t.mcginley.jr]

First, if you haven't done so already you should really read through this it will help you understand some things about our cars:

Everything you need to know about the z32

As for the car, have you pulled error codes yet? You don't need a scanner or anything, just a screwdriver:

How to check error codes

The new style injectors don't have compatibility issues, I'm running the exact same setup you have complete with eBay reman'd injectors. I've driven about 7k miles with 0 issues. I did pinch 2 of the o-rings when I was installing them and that caused a bunch of issues like running rough, running super rich, gas dripping out onto the intake, etc.

You can test the injectors by doing a power balance test. with the car running, pull each of the coil pack connectors one by one to see if the idle drops (it should). If you pull one and the idle doesn't change, there's a problem with that cylinder (usually injector, but could be coil pack or spark plug). So pull one coil pack connector, listen, put it back, and repeat for all 6.

What was the reason for changing your heads?

[JP1323]

Ok, so heres the short story.. I bought my 300zx because well i fell in love with it and thought a small displacement 6 cyl dual overhead cam 24 valve engine would of been a good NA engine platform to play with(sadly there isn't much of a market). i got it with 180k, wasn't running the greatest and found out cyl 6 had low compression so i tore into it. Found the oil ring folded over and scored the cyl wall. i had the block overbored .020" and fitted with forged arias pistons but kinda got impatient and threw back the original heads just to finish. It ran good! but performance slowly started deteriorate due to the sealing differences but many months later and my luck the stud for the idler pulley broke off and lost my timing belt on the highway bent some valves etched my pistons a little no biggie. I decided i wasn't going to rebuild those heads so i got a good set of used tt heads with valves and had those machined instead. So thats that and where i am now.

today i pulled the CAS and spin checked to make sure that the injectors were plugged in the correct order, they were and the spark was good too but before i did that i messed with my ptu connector, straighten out the connector tabs and bent in the terminals on the other connector end. The cars idle seemed much smoother and the timing mark stayed steady, i didnt get a chance to drive it so i hope that was it

[JP1323]

Straightening out the ptu connector wasn't the fix but it seemed to help(i think?). I pulled off the timing covers and the marks line up, i did the power balance test and unplugging either the injector or coil pack on cyls 1 and 2 doesn't do much or anything at all so i then did a compression leak test on those cylinders and they both seal very well cyls 3 and 4 both have a big effect on the rpm while 5 and 6 isnt as easily accessible so i didn't do those. Can the CAS be skewed internally but still function? this is getting a little confusing lol would the nissan consult make things easier? also, ive been having thoughts that since i had the heads machined and the valve seats cut could this have an effect on the operation of the lifters??

[JP1323]

Yeeeah soo i had the biggest derp moment of my life.. had the coil pack connectors switched between cylinders 1 and 2 gotta quit doing drugs lol final test drive and maybe a video tomorrow

[JP1323]

sister finally let me use the pentax heres the vid http://www.youtube.com/watch?v=g1fJTJ5ECq8

[JP1323]

http://www.youtube.com/watch?v=DJROwuRgECU had to re-upload