Ive noticed in my z it has a near constant misfire in the cylinder #1. When i first start the car in the morning it will run just fine, and as i drive it along it generally runs just fine. The problem arises when the engine reaches regular running temp or when I get onto he highway and actually give it some throttle to get up and go. I can hear it start to miss on and off for about 10 seconds before the whole cylinder practically dies out. If the car doesnt cool down all the way when i start it back itll immediately start misfiring again. Ive tried replacing coils, it didn't help unless I just got REALLY unlucky and both of them have the same problem. Ive also replaced the spark plugs, and the injectors are DWs less than 17k miles on them so im really hoping injectors arent the problem. Im new in the z field so any advice would help. Thanks.

Unfortunately it sounds like you have an injector issue with cylinder 1, and the deatschwerks injectors do have a history with inconsistency.
Time for fuel system testing, the factory service manual will be your friend. The fsm can be found in the "Everything you need to know...Z32" sticky on top of the General page.
Good Luck!

Just to confirm that it isn't the coil pack, swap with another cylinder and see if the issue moves. If not, it's gonna be either a wiring issue, an injector issue, or my bet, seeing as it's heat-related, is a PTU issue. Look up the PTU ohm testing procedure and do that. If that checks out, I'd look at those douche works injectors.

Ace2cool wrote: ↑

Sat Sep 22, 2018 5:09 pm

Just to confirm that it isn't the coil pack, swap with another cylinder and see if the issue moves. If not, it's gonna be either a wiring issue, an injector issue, or my bet, seeing as it's heat-related, is a PTU issue. Look up the PTU ohm testing procedure and do that. If that checks out, I'd look at those douche works injectors.

I agree that the PTU seems like a prime culprit, especially since I personally have had a long and difficult run with the PTU harness connectors. Next up would be the DW injectors and/or the connectors or harness cracking...but the best bet is to just succumb to checking everything thru the fsm since it's a good bet every connector needs at least SOME cleaning, replacement, whatever, and you will want to rule out everything and also do a service run to ensure you don't have more problems waiting to come up.

I have tried the coil swap and it didnt seem to help, same results as if I hadnt even swapped them. I was thinking it was the plug going to the coil pack at first as it is very brittle and needs replaced, but I dont think thatd cause it to misfire when only hot. Ill try the other options before going into the injector. I daily my Z and rarely every get a full or even half a day off of class and my job so its tough for me to do any jobs that require more than an hour of works, Thanks

If you've got a broken connector, it can expand when warmed up and slide off the coil pack, but that's just really grabbing. I'm assuming you've tried pushing on the connector while the issue is present, and no change?

I'm still leaning toward PTU. Shouldn't take more than 30min to ohm it out.

Ace2cool wrote: ↑

Mon Sep 24, 2018 1:06 pm

If you've got a broken connector, it can expand when warmed up and slide off the coil pack, but that's just really grabbing. I'm assuming you've tried pushing on the connector while the issue is present, and no change?

I'm still leaning toward PTU. Shouldn't take more than 30min to ohm it out.

^^^^and, the biggest issue and warning sign with the PTU beyond PTU failure is corrosion of the harness connectors so if you open them up and see green crud...you have found at least part of your problem right there. And you WILL find green crud unless you live in the driest area of the US.