can't seem to stop this miss firing

[Nagalf]

OK so here a lil history on the problem idk if it will help someone solve my problem but here it goes..
My clutch was placed in poorly and in a short time it went just about 6 months, it was replaced then I had a cracked Radiator.. it was replaced then the car started miss firing so the injectors and the wire harness were both replaced.. then the cart was removed and it ran fine for like 10 mins.. now its miss firing again. I changed the ecu just because i thought it might help nothing..

When I drive the rpm go up pretty fast but the car is moving hella slow and when it hits about 4500 its sound like everything is firing and then I shift n back to miss firing..

Also I hear something like a leak but I put the harness up n check to make sure everything was connected cant find it..

Have any advise I would greatly appreciate it.

[CrazedZ32Owner]

did the car overheat really bad when the radiator went out??? if so you may have some work ahead of you

[Nagalf]

It could have it never came to a stand still or anything , but there was a crack and I didnt catch it it time. what are you thinking?

also I have a bad cluster so my temp never showed.

[evildky]

just hrowing random parts ar a problem is never a good idea

first step si to determine which cylinder(s) are misfiring, with the car idling disconect one cop at a time, each tiem you unplug one the idle should drop or the car will die, if you find a cylinder ro cylinders where when you unplug the cop the idle does nto change then we have foudn the cylinder in question

honestly with a low rpm mis it's likley a spark issue (cop, plug or ptu) or it's a cylinder sealing issue (cracked valve seat)

[Nagalf]

I changed the injectors because one wasnt firing, the top right one, also changed the gasket set just a few months ago.

But thanks I think it may been the gasket again from the vacuum sound im hearing. I know ur an expert on the car so let me ask if the gasket is blown, wouldnt the car start terrible idle rough and fluids would mix and such and coolant would come out the exhaust?

[evildky]

what gaskets did you change?
a blown headgasket generaly presents as one of the following:
loss of compression in one or more cylinders
exhaust coming out the coolant overflow resivior (after blowing most of the coolant out of it)
coolant in the cylinders (this generally hhows up as large plumes of white sweet smelling smoke at start up)
coolant in the oil (oil will tend to look milky or might just seem to be overfull all fo a sudden)

you replaced a bad injector, now they all ohm good, right? but you still have a misfire at low to mid rpms right?

[Nagalf]

No I changed all the injectors the time I did the plenum pull and I replaced the head gasket at that time o-rings etc. I closed it up and there was a Vacuum leak which I struggled with but eventually fixed. Then I had to splice my old efi harness (couldnt get my hands on one at the time) but now I replaced it.

As for those symptoms I not experiencing any of those so i hoping that it stay that way.

I bought the parts all from usautoparts.com never had any issues with them before.

I just swapped out two spark plugs an the idle changed ran better but still a slight miss, im going to the store again to purchase four more (was hoping two would do the job but i should never mix products). I'll keep you posted and let me know if anything come to mind because I still hear that Vacuum sound coming for the back of the motor.

[Nagalf]

also changed the fuel filter, I had an rx4 that did the same thing and it ended up being the fuel filter.

[Nagalf]

took it to a shop and they couldnt figure it out =(
Going to get the ptu looked at tomorrow morning hopefully.

someone help me, save me from a summerless Z driving

[evildky]

RX4 was carb'd and had no pistons or valves or heads etc, as it was powere by the mystical barrel of power so it's a different animal all together

if the car idles on all 6 cyliders but has an unexplained misfire at idle that clears up when driving it might be a valve seat issue, I had this problem with mine, a leakdown test can confirm

[Nagalf]

I have come down to the ptu or cas on my own, a few mechanics have looked at it and only one said the CAS also, all other didnt know the ecu gave me the CAS code.

So im currently tryin to remove it but its really stuck on there. I put wd40 on it two days back to back. and tips on removing it?