# Z31 misses



## JeremiahB (Aug 10, 2013)

Hey guys 

I just got the Z31 to stay running. Replaced the MAf and had no problems, it idles fine. Now I have a new problem. 

As im driving the car misses. It seems to happen more in the morning compared to any other time of the day. Ill press the gas and hear a little sputter and it wont pick up for a few seconds. Sometimes in the morning I will press the gas and nothing happens just followed by a backfire. Fuel pressure is good, Im getting no codes on the computer, and I just replaced all the spark plugs. The car idles fine no problem. I can rev it up and it is always responsive. Only seems to happen when driving. 

Any idea ..... CHTS


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## i r teh noobz (Apr 26, 2007)

Revs in neutral, misses under load. Sounds ignition related. I'd start with timing and whatnot. The CHTS is always worth a look.


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## JeremiahB (Aug 10, 2013)

It doesn't do it all the time. Tonight I just drove across the whole city and it barely happened. Im sure it will do it in the morning though.


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## BeyondBiscuits2 (Jan 18, 2006)

I had a similar situation with my Z31 before I rebuilt the engine. In the morning, no matter what temperature it was outdoors, it wouldn't want to start. I'd have to crank, crank, crank and it would backfire, sputter, miss, etc. before it would eventually go. For the first few minutes when it was running, she'd die out if given throttle until she warmed up. I was told by a Z31 mechanic this was due to carbon build-up in the engine, and that the VG30E has notorious issues with being a carbon monster. When I rebuilt the engine, I thoroughly cleaned every inch of the intake system and cylinders of carbon and deposits. Since then, she starts easily every time.

Long story short, you might try a carbon deposit cleaner. It surely can't hurt! On a side note, my CTHS was also bad. I replaced it when I rebuilt the engine, so that could also be a factor.


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## i r teh noobz (Apr 26, 2007)

Did you replace the wires, cap, and rotor? Check for vacuum leaks? 

You might want to try the PRW-2 ignition transistor upgrade. I have not done it, but many on Z31performance say it makes a noticeable difference in how their cars run, even if there weren't any real issues before. PRW-2 ignition transistors should be widely available at any local pick-n-pull type junkyard. You have to move a couple wires around in the connector to make it work.


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