1990 NA Timing?

[brian300zx]

Alright guys I just finished my first timing belt change a couple days ago and the car has a misfire when it’s cold. I didn’t remove the CAS but I’m thinking I should check the timing? The car idles perfect until I give it gas it has a misfire and once it warms up it completely goes away. There is no CEL the spark plugs are maybe a month old. I’m really leaning towards the timing because it ran perfect before the timing belt change. Thanks for any help!

[Ace2cool]

Possible you cracked a wire in the PTU. Timing is easy to check with a light though. If it was a timing issue it would stay persistent through a warmup as well though.

[brian300zx]

Yeah that’s what I was thinking although I didn’t disconnect anything sort of just flipped the harness out of my way so yes going to go through all the wires. Car feels super strong once it’s warmed up.. thanks!!

[macgiver]

mac, remember , some codes don't throw a MIL / CEL on . Scantool Check'm and rule out knock sensor , for I just did timing belt J30 recently and knock sensor was bad after for some reason (suspected intermittantly faulty for a while) 1) Failed Emiss. 2)made TWO other non MIL codes appear , Coolant temp sensor & L. O2 sensor (Both really were OK ) 3)Car either died upon start, after 4 seconds or ran poor tork till 3k rpm . 4) NO CEL lights whatsoever ! After new Knock sensor installed , base timing adj. gained even further performance !! So always scan for codes , not just assume codes ONLY exist when MIL/CEL lights-up. Eliminate that knock sensor - it IS KNOWN to trigger multiple negative EFFECTS.But-definately base TIME that puppy ! G 4/4/2018

[brian300zx]

So it’s definitely my ptu cause, when I wiggle the sub harness around I can hear the misfire go away and come back

[DCaff300ZX]

So it’s definitely my ptu cause, when I wiggle the sub harness around I can hear the misfire go away and come back

I had the exact same thing before all of my idle and other issues after buying my TT, and after replacing nearly ALL ignition and idle components same as you I was moving the harness while it was running and it nearly died- my problem was actually the entire PTU harness both from BAD corrosion of the connectors, and surely as you suspect a split/cracked/shredded wire. Once the subharness was replaced all is well, and it's now tucked away out of the air and moisture flow up front to further avoid potential issues with it.