Just bought my son a 97 z24 w/150k on motor, the P/O had replaced the IDI box,Coils,Spark Boots, ICM and MAP sensor,also ohmed the injectors.He said all it needed was a new Cat as it would glow after a few seconds of running. I towed it home put a new cat and o2 sensors on it. I started it and it sounds like a damn go kart, went to yard and picked up a whole set of the IDI/ICM setup and bought a Map Sensor, still no change. Put on a FPR and new o-Rings on the Fuel injectors, STILL no change. Went back to the yard and picked up a PCM, did the relearn and still no change. WTH. Did a compression check all was good. Really no motor noise unless I put it in gear and give it a little gas then I can hear a ticking noise. Also only code it will throw is the PO300 multiple misfire. sorry for long post just trying to throw it all out there. Thanks. oh yeah cat was definitely plugged and plugs were either wet or fouled.
did you try swapping the injectors? they could ohm good but still be plugged or something... As for the Ignition parts... you sure they are good? My car has been swapped for the 2.2 system to ditch all the crap under the IDI so I don't have any of those issues.
Sounds like you've replaced just about everything but there has to be something else hiding somewhere.
I did swap injectors (a jy set) and Im not positive about all of them being good for sure, I even put in the old set of ignition parts, so thats three sets i've tried, and absolutely no change.
At this point I might try the 2.2 swap or maybe another solution is I've found a 01' 2.4 with 100k on it for $450, would rather not go that far but IDK
What about the plugs themselves?
Put 2 sets in ( just cheapies til Ifigure out the misfire) #3 cylinder was pretty fouled kinda wet with raw gas #2 was fouled as well and 1&4 light brown, looked like they had been in there for a while not just 10 minutes of running
Are you using a new or used IDI housing? The big plastic thing that the coils go into and the boots connect to the bottom. I have 200k on my Z24 and roughly every 40k it goes bad and I hear a loud tick and sluggish performance. I would buy a NEW one from the auto part store because I have taken plenty from the yard all to have the same problem. I've checked the ohms on the junk yard ones that seemed fine but were bad.
This is what im talking about
Coil housing
Yeah the first swap by the PO was new stuff, I have the receipt. Starting to think internals. When I put it in drive and the motor is under a load it sounds like a bad lifter in an old Chevy. Gonna check timing Saturday when I'm off see if maybe it jumped a tooth or? Did compression check and was good but idk if maybe a bent/ broke valve. Any other ideas would be appreciated. Thanks guys
Well guys, I tore into the timing and everything looks good.
check your o2 sensors, run some fuel injector cleaner and see where that gets you
I read this thread but posted on the other thread about misfire
this thread
basically about new injectors needed as part of every major tune up, good battery tests, filters, no vacuum leaks,
and with a clogged exhaust I don't know what happens if it's driven so long like that
o2 sensors were one of the first things i swapped, i swapped out injectors (with new orings) no change.
Thanks for all the help guys, after two old sets of coils/housings/boots and one new one by the p/o I ditched it all and went for the 2.2 swap. Running great now.
