Rrassi300zx

Hello once again, I'm here with a problem, I have a 1990 300 zx Na, I decided to check the air filters, (never thought it was so difficult until now) but I got to them and my god it looked liked they had never been exchanged before! They had crud on them and they both said Nissan Japan so I figured they had never been changed! But I went ahead and bought some new ones at advanced auto and after a bit of trouble trying to put everything back together I accomplished it, then I decided to clean the engine a little bit with a rag and wd40, I cleaned it up a little bit looked real nice, now. I'm going to start her up, when I did I noticed a lot of hesitation so I figured may more oxygen is going in so I disconnected the negative to the battery so the computer would re adjust itself, and now the car wont start! What happened? Maybe a sensor ? Maybe it was used to not breathing so much oxygen that it needs to be retuned?I don't know, can anyone offer some advice please, thanks

KSpakes87

Definitely wouldn't be a tuning issue. The computer measures air flow through the Mass Air Flow Meter (MAF) connected to the air box. I would start by making sure you hooked the air box back up completely and check to see if you might have knocked the MAF connector loose. Then go on to check all other connectors to see if you might have knocked any loose while cleaning.

Another issue with these cars is the PTU. It can cause the engine to run rough and die when warm. It would then cause restart difficult and in some cases impossible. It is located on the front of the timing cover on the passenger side. It can cause the problems that you are having. There are 2 different styles. The early style was recalled. The new style would be solid black. The old style is a ribbed grey metal.

Also check the CAS. It's located on the opposite side of the engine from the PTU. It is a big circular sensor. Make sure it is connected and has no corrosion on the terminals in side the connector. This could cause the car to continuously crank and not start.

Hope this information helped.

Rick Luevano

Make sure there the MAF sensor is fully connected and clamped properly. Especially after the MAF. If its leaking air, it won't start.

Rrassi300zx

I just wanted to thank you guys for your input, yeah it was an old brittle harnes cleaned it up real good and plugged in back in and started right up, no problem, thanks again